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Specialized Pro-resolving Mediators (SPMs): The Resolution of Inflammation

Key takeaways:
~ Resolving inflammation is an active process: The body doesn’t just let inflammation fade away; it actively produces specialized pro-resolving mediators (SPMs) to end inflammation and restore tissue health
~ SPMs are lipid molecules synthesized from dietary omega-3s—mainly DHA and EPA—which are often lacking in modern diets.
~ A lack of pro-resolving mediators can allow inflammation to continue, leading to many chronic diseases.
~ Genetic variants can affect how efficiently your body converts dietary fats into SPMs, meaning some people may need more DHA/EPA or benefit from specific supplement forms.

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Chronic disease, unresolved inflammation, and prevention

In the U.S., 60% of adults have been diagnosed with a chronic disease, and 40% have two or more conditions – that’s a lot of unhealthy people. Most chronic diseases have persistent, low-level inflammation as their underlying cause.[ref]

Diseases rooted in chronic inflammation include:[ref][ref]

Disease/Condition Connection to Inflammation/Resolution Deficit
Heart disease Persistent inflammation, lack of SPMs
Alzheimer’s Chronic inflammation, SPMs involved in clearance
Rheumatoid arthritis Elevated cytokines, insufficient resolution
Type 2 diabetes Impaired SPM receptor function
Neuropathic pain SPMs modulate pain pathways
Mood disorders Inflammation, SPMs linked to symptom improvement
IBD (Crohn’s, ulcerative colitis) Defective SPM biosynthesis
Obesity, fatty liver disease Chronic inflammation, SPMs reduce adipose inflammation
Multiple sclerosis Impaired SPM biosynthesis, disease progression
Chronic kidney disease Low SPMs, persistent inflammation
Arthritis (other forms) Low SPMs, pain, and inflammation
Cancer Poor resolution, SPMs in tumor microenvironment
Asthma Lower protectin D1, airway inflammation
Tissue fibrosis SPMs promote tissue regeneration

Chronic inflammation is a big problem, but… inflammation is only half the story. Over the past decade or so, researchers have discovered the mechanisms through which inflammation is resolved. This paradigm-shifting research can be summed up as:

The resolution of inflammation is an active process.

Inflammation doesn’t just fade away like doctors used to think. Instead, the resolution of inflammation is an active process. Pro-resolution molecules are produced to both halt the inflammatory processes and initiate a bunch of processes to clean up and return the tissue to homeostasis.

These molecules are called specialized pro-resolving mediators (SPMs). They are lipids (fatty acids) that signal for the resolution of inflammation.

Importantly, these SPMs are synthesized from the omega-3 fatty acids DHA and EPA, which are often lacking in modern diets.

To be clear: Specialized pro-resolving mediators and the active process of resolving inflammation are different from anti-inflammatory drugs or supplements that block inflammation. While antioxidants and anti-inflammatory supplements can be helpful, they only address the suppression of inflammation, not the complete resolution and return to health.

In summary, unresolved inflammation underpins a wide range of chronic diseases, and insufficient production or action of specialized pro-resolving mediators (SPMs) is a key factor in disease persistence and progression.

Before we get into the pro-resolving mediators, let’s take a quick trip through the basics of inflammation and talk about a few key players.

Inflammation: Quick Overview

The immune system is ready to respond when you get a cut, are infected by bad bacteria, or break a bone.

When an insult occurs – a cut, a pathogen, or an injury – a cascade of inflammatory events is set in motion.

White blood cells, also called leukocytes, are a type of immune cell that protects the body from invaders. White blood cells (leukocytes) originate in the bone marrow from hematopoietic stem cells. Leukocyte is a general term. There are specific subtypes of white blood cells, including neutrophils, eosinophils, basophils, lymphocytes, and monocytes (which become macrophages). They all play a role in inflammation and in protecting your body from infection.

Inflammation is classically characterized by warmth, swelling, redness, and pain. (Calor, Dolor, Rubor, and Tumor, if you like it in Latin)[ref] These signs of inflammation are due to increased blood flow, capillary dilation (swelling), leukocyte infiltration, and the production of inflammatory cytokines.

Example:
You get a piece of wood stuck in your finger. It becomes swollen, painful, and red. Pus with lots of white blood cells may collect where the splinter was. You eventually get the tiny piece of wood out of your finger, and the next day your finger is back to normal-no more redness, swelling, or pain.

What happened? The foreign object (a sliver of wood), cell damage, and bacteria were detected. Neutrophils rushed in and inflammatory cytokines were released, causing vasodilation and fluid to rush into the area. More inflammatory cytokines were recruited, mast cells released their mediators, macrophages engulfed the bacteria on the splinter, ROS were produced to kill the bacteria, and then… resolution. Back to normal.

Until recently, scientists didn’t realize that the resolution of inflammation was much more than just the cytokines passively slipping away and the immune system cells retreating.

Concurrent with acute inflammation is the onset of the resolution of inflammation. Pro-resolving mediators are produced by immune system cells to actively cause the resolution of inflammation and healing back to normal. It happens at the same time as inflammatory processes.

Chronic inflammation is due to a lack of resolution

Anti-inflammatory drugs are often prescribed for chronic diseases. For example, NSAIDs or leukotriene inhibitors block the production of inflammatory cytokines. Biologics that block TNF, such as anti-TNF antibodies, are used to reduce the symptoms of rheumatoid arthritis (RA). However, side effects include a suppressed immune system that makes patients more susceptible to pathogens.

But why do inflammatory cytokines like TNF-alpha stay elevated in RA? One big part of the picture seems to be an inadequate or insufficient resolution of the inflammation.

One study explains: “While it was previously thought that passive disappearance of pro-inflammatory factors was sufficient for the cessation of inflammation, it is now known that the resolution of acute inflammation (or inflammation-resolution) is an active and highly coordinated process. Inflammation resolution is governed by a panoply of endogenous factors that include SPMs, protein/peptide mediators such as annexin A1 and interleukin 10, gases such as carbon monoxide and hydrogen sulfide, and nucleotides such as adenosine and inosine.”[ref]. (We’ll stick to talking about SPMs here, but keep in mind that, as in-depth as SPMs are, there’s more to the topic.)

SPMs (specialized pro-resolving mediators) are not only important in halting the inflammatory response, but they also “orchestrate the clearance of tissue pathogens, dying cells, and debris from the battlefield of infectious inflammation.”[ref]

This isn’t just about chronic disease. SPMs are also important in turning off the immune response and returning the body to normal after a bacterial, viral, or fungal infection. The lack of pro-resolving mediators is thought to be a cause of severe COVID-19 symptoms such as acute respiratory distress syndrome.

Macrophages in the Immune Response:

Macrophages are important players in inflammation. They are a specialized type of leukocyte (white blood cell) that can differentiate into two different forms.

  • M1 form:  pro-inflammatory, producing high levels of cytokines such as TNF-α, IL-1ß, IL-6, IL-12.
  • M2 form: anti-inflammatory – and a big part of the resolution of inflammation.

The M2 form of the macrophage is programmed by the SPMs and cleans up the inflammation – engulfing and removing the remaining inflammatory debris.[ref]

In all, the resolution of inflammation by SPMs includes:[ref]

  1. Removal of microbes, dead cells, and debris
  2. Restoration of the integrity of blood vessels
  3. Regeneration of tissues
  4. Remission of fever
  5. Relief of pain

Low SPMs in Chronic Disease:

The final point to drive home here: people with chronic inflammatory diseases have lower pro-resolving mediator levels that are specific to the resolution of their chronic condition.[ref]

Chronic disease isn’t just the low levels of continuing inflammation; it is also the lack of clean-up and restoration. The house burned down (acute inflammation), and not only did the remains still smolder, but there also was no clean-up crew to remove the mess and rebuild.

Here is a screenshot from a great Frontiers in Immunology article that sums up the process of resolution of inflammation:

 

Let’s dig into the details of what is currently known about the resolution of inflammation.

Lipid mediators: What are they?

We often think of the fats (lipids) that we eat as just something that produces energy  — or something that makes you fat when it comes to eating fried donuts.

Energy production or fat storage are just two of the many functions of fat in the body. For example, lipids (fats) also make up the cell membrane surrounding the trillions of cells in your body, and lipids are also essential for creating certain hormones.

Lipid is a general term for fats, including the fatty acids that we are familiar with eating (saturated, unsaturated, long chains and short). Fatty acids are chains of hydrogens and carbons. They are categorized by the bonds, such as all saturated bonds or with an unsaturated bond at a certain spot (e.g., omega-6 or omega-3  polyunsaturated fatty acids).

In addition to being used for creating cellular energy, certain lipids act as signaling molecules, which means that they can bind with a receptor and cause something to happen in a cell.

Specialized pro-resolving mediators (SPMs) are lipids derived from polyunsaturated fatty acids.

Creation of the specialized pro-resolving mediators

The SPMs are produced using polyunsaturated fatty acids (PUFAs) as the base molecules. Specifically, DHA and EPA are the precursors for many SPMs, and arachidonic acid (AA) is also a precursor. DHA and EPA are omega-3 PUFAs found in fish oil. Arachidonic acid is an omega-6 fatty acid found in meat and plant oils.

These precursors come from eating foods that contain the needed omega-3 and omega-6s. The precursor fatty acids are then converted by specific enzymes produced by certain cell types when triggered by acute inflammation.[ref]

Overview of creation of pro-resolving mediators. Screenshot from PMC4315926 – worth reading.

 

There are five types of pro-resolving lipid mediators:

SPM Type Precursor Fatty Acid Key Subtypes Main Functions/Notes
Lipoxins Arachidonic acid Lipoxin A4, B4 Early resolution, heart/brain protection, lung repair
Resolvins EPA, DHA, DPA RvE1-4, RvD1-6, RvT1-4 Atherosclerosis, neuroprotection, infection clearance, pain
Protectins DHA, DPA Protectin D1, D2 Switch macrophages to M2, reduce Alzheimer’s plaques, asthma
Maresins DHA MaR1, MaR2, eMaR Tissue regeneration, bone health, pain modulation
Cysteinyl SPMs DHA MCTR1-3, PCTR1-3, RCTR1-3 Tissue regeneration, cardiovascular protection

1) Lipoxins

Lipoxins are derived from arachidonic acid (omega-6 fatty acid) and are created at the onset of inflammation. The pro-resolution processes start almost as soon as acute inflammation begins.

While the majority of specialized pro-resolving mediators are derived from omega-3 fatty acids (DHA and EPA), lipoxin is the outlier and is formed from the conversion of an omega-6 fatty acid, arachidonic acid (AA). There are several lipoxin types, named lipoxin A4 and lipoxin B4.

Here are a few examples of what lipoxins do:

  • Lipoxins are important in preventing heart disease via the resolution of inflammation in atherosclerosis.[ref]
  • Lipoxins are important in protecting the brain in neurodegeneration and glaucoma.[ref]
  • After a stroke, lipoxins are important in resolving inflammation.[ref]

2) Resolvins

Resolvins derived from EPA are named RvE1 through RvE4 (resolvin E1, etc.). Resolvins derived from DHA are called the D-series. They are named RvD1 through RvD6.[ref] Resolvins derived from DPA, another omega-3 fatty acid, include RvT1, RvT2, RvT3, RvT4. The details aren’t important here – I’m just wanting to drive home the point that there are multiple resolvins derived from omega-3 fatty acids.

What do resolvins do?

  • After a stroke, RevD1 is important in resolving inflammation.[ref]
  • Resolvin E1 is important in protecting against atherosclerosis, carotid artery disease, and clearance of tumor cell debris. Resolvin D5 is important in clearing out bacterial pathogens.[ref][ref]
  • Animal studies show the potential of resolvin E1 and D1 in neurodegenerative diseases.[ref]
  • Resolvin D2 is important in periodontal disease in preventing bone loss.[ref]

3) Protectins

Protectin D1 is derived from DHA, while protectin D2 is synthesized from DPA (another omega-3 fatty acid).[ref] Protectins are important in switching macrophages from the proinflammatory to the anti-inflammatory type.[ref] As I mentioned above, macrophages can increase inflammation (M1 type), or they can clean up and stop inflammation (M2 type). Protectins can initiate the switch to M2 type.

  • In animal studies, protectin D1 is important in reducing the amyloid-beta plaque, which causes Alzheimer’s disease.[ref]
  • Protectin D1 is important in the cornea to protect from injury and in the retina.
  • Protectins are also important in resolving inflammation in adipose (fat) tissue. Chronic inflammation goes hand-in-hand with obesity, and protectins have reversed the inflammation.[ref]
  • Protectin D1 also dampens hyperactivity in the airways. People with asthma have lower levels of protectin D1.[ref]

4) Maresins (derived from DHA)

Maresins are also derived from DHA and abbreviated MaR1, MaR2, and eMaR. Maresins are important for:

  • Tissue regeneration and bacterial infections.[ref]
  • Pain sensitivity and bone regeneration.[ref]
  • Bone health. Low maresin 1 is found in osteoporosis.[ref]
  • Inhibiting the activation of NF-κB, improving Treg/Th17 imbalance, and alleviating endoplasmic reticulum stress.[ref]
  • Maresin 1 pretreatment (animal study) shows that it stops UVB damage.[ref]
  • Maresin 1 helps ameliorate fibrosis and heal muscle loss from trauma/surgery.[ref]

5) Cysteinyl SPMs

Discovered within the past couple of years, cysteinyl SPMs are also derived from DHA and are peptides conjugated with the other lipid mediators. The family of cysteinyl SPMs includes MCTR1, MCTR2, MCTR3, PCTR1, PCTR2, PCTR3, RCTR1, RCTR2, RCTR3. They are involved in tissue regeneration and cardiovascular protection.[ref]

Conversion enzymes: Biosynthesis of SPMs

The precursor molecules for the lipid mediators are pretty straightforward and easy to understand: DHA, DPA, and EPA, which are omega-3 polyunsaturated fatty acids found in fish oil, and Arachidonic Acid (AA), which is an omega-6 polyunsaturated fatty acid.

You need enough of the precursor fatty acids to make the lipid mediators. If you never get any DHA/EPA in your diet, you are likely behind the 8-ball when it comes to producing pro-resolving lipid mediators. But what if you are eating fish daily? Getting enough arachidonic acid… Doing it right for the precursors?

The precursor fatty acids still need to be converted into the SPMs via enzymatic processes, and then they need the receptors available to bind to and complete their pro-resolution actions.

Here’s an overview of what is going on here:

SPM Biosynthesis: Precursors, Enzymes, and Genes
Step/Component Details/Genes Involved Notes/Variants Affecting SPMs
Omega-3/6 Intake DHA, EPA, DPA, AA (from diet) Modern diets often low in omega-3
Conversion Enzymes 5-LOX (ALOX5), 12-LOX (ALOX12), 15-LOX (ALOX15), COX2 Genetic variants affect enzyme efficiency
Key Genes FADS1, FADS2, ELOVL2, ALOX5, ALOX5AP, ALOX12, COX2 Variants can reduce conversion or increase risk
Receptors FPR2, GPR37, GPR18, CMKLR1, LGR6 Variants affect SPM signaling and disease risk

The enzymes that convert DHA, EPA, and DPA into the SPMs include 5-LOX, 12-LOX, and 15-LOX.

  • The ALOX12 and ALOX15 genes encode 12-LOX and 15-LOX, which convert DHA and DPA into the D-series resolvins, protectins, and maresins.[ref]
  • The ALOX5 gene encodes the 5-LOX enzyme that is also needed in the conversion of the D-series resolvins, as well as the E-series resolvins and DPA-derived resolvins.

Cell studies show that when lower amounts of these enzymes are produced, there is more chronic inflammation. One study looked at the role of SPMs in tendonitis, which is common in people with diabetes. The diabetic tendon samples showed chronic inflammation plus low levels of the enzymes needed to produce the pro-resolution lipid mediators.[ref]

Omega 6 to Omega 3 ratio and bioactive lipids:

I’ve mentioned several times that there’s been a shift in our modern diet to eating more omega-6 fatty acids (corn oil, soybean oil, etc) and less omega-3. Part of the problem is that we don’t get enough DHA and EPA in the diet, but the other half of the equation is an excessive amount of Omega 6’s.

The enzymes that convert the omega-3 fatty acids into pro-resolving enzymes are the same enzymes that convert some of the omega-6 fatty acids, such as arachidonic acid, into pro-inflammatory lipids. For example, ALOX12 is essential in the conversion of DHA into maresin 1 (pro-resolving mediator), but it is also part of how arachidonic acid is converted into 12-HETE, which is a pro-inflammatory and involved in inflammation and immune cell recruitment.[ref]

Thus, the type of fat you eat (omega-6 oils vs. omega-3) interacts with your ability to convert the lipids into both pro-inflammatory and pro-resolving lipid mediators.

Aspirin and the conversion of SPMs

Willowbark, which contains salicylic acid (the active ingredient in aspirin), has been used to stop inflammation since at least 4,000 BCE.[ref] It turns out that aspirin, though, doesn’t just stop inflammation by blocking the formation of inflammatory prostanoids. It also helps to form pro-resolving mediators.

In addition to the enzymes above, the COX2 enzyme is involved in converting the resolvins and lipoxin in a special way that involves aspirin. Aspirin is a COX1 inhibitor at lower levels, and at higher levels, it also changes the enzyme function of COX-2 via acetylation.[ref]

Aspirin is unique among NSAIDs in that it acetylates COX2, which then triggers the formation of ‘aspirin-triggered specialized pro-resolving mediators‘ or AT-SPMs. These aspirin-triggered SPMs include AT-lipoxin A4, AT-resolvin D1, and AT-resolvin D3.[ref][ref] Aspirin-triggered SPMs have a prolonged half-life and act to resolve inflammation for longer.[ref] This is likely why aspirin, and not other NSAIDs, helps to prevent heart disease and reduces the risk of colon cancer (for some people).

Very recently, researchers discovered that an endogenous compound can also act to form the so-called aspirin-induced SPMs. “In addition to aspirin, N-acetyl sphingosine (N-AS), generated from acetyl-CoA and sphingosine via sphingosine kinase1 (SphK1), also acetylates COX2 and increases RvE1 and 17R-RvD1.”[ref]

Receptors for SPMs:

Pro-resolving lipid mediators resolve inflammation by binding to a cellular receptor and causing an action to take place. Some of the actions triggered include: blocking inflammatory cytokines, converting macrophages to anti-inflammatory, promoting stem cells for tissue regeneration, and cleaning up cellular debris.

The cell types receiving the SPM pro-resolution signals via these receptors include platelets, macrophages, eosinophils, dendritic cells, epithelial cells (skin, intestinal cells), regulatory T cells, neutrophils, mast cells, and endothelial cells (lining of blood vessels).

Receptors for SPMs include:[ref]

  • ALX (encoded by the FPR2 gene) is a RvD1 receptor. In mice, a lack of this receptor causes endothelial dysfunction, cardiomyopathy, and obesity.
  • Protectin D1 activates GPR37 “Mice lacking Gpr37 display defects in macrophage phagocytic activity and delayed resolution of inflammatory pain”
  • RvD5n-3 DPA was shown to bind to an orphan receptor GPR101 with high selectivity and stereospecificity.
  • ERV1/ChemR23 is the receptor for several SPMs
  • DRV1/GPR32
  • DRV2/GPR18
  • LGR6 (maresin 1 receptor on phagocytes)[ref]

The different SPMs bind with receptors on the cells to inhibit inflammation, stimulate the clearance of cellular debris, or promote tissue regeneration.

Let me give you some examples to illustrate how the different SPMs binding to receptors can cause a plethora of reactions that resolve inflammation as well as promote healing.

  • Protectin D1 binds to receptors on neutrophils, inhibiting the release of  TNF-alpha and interferon-gamma.[ref]
  • Resolvin D2 binds to receptors on muscle stem cells and promotes an increase in muscle cell creation (important in muscular dystrophy).[ref]
  • Pain is part of inflammation, and SPMs specifically target and reverse pain. Through inhibiting TRPV1, maresin R1 blocks neuropathic pain. Resolvin E1, resolvin D1, and aspirin-triggered resolvins reduce pain by knocking down TRPV3.[ref]
  • The interaction of resolvin D1 with the FPR2 receptor causes an increase in PPARγ, which stops the migration of NF-ᴋB into the nucleus.[ref]
  • In type 2 diabetes, it has been shown that upregulating the SPM receptors – especially the receptor for resolvin E1, potently regulates blood glucose levels.[ref]
  • Resolvin D1 and D2 counteract histamine when it comes to watery eyes in allergic reactions. Resolvin D1 blocks histamine action via the H1 receptor (acted on by β-adrenergic receptor kinase 1 and protein kinase C phosphorylation).[ref]
  • Resolvin D1, D2, and E1 prevent histamine-induced TRPV1 sensitisation. It may be important for stopping gut irritability in IBS.[ref]
  • In periodontal disease, maresin R1 and resolvin E1 increase periodontal ligament stem cells, which regenerate lost tissue in gum disease.[ref]

Receptor agonist drugs:
In addition to natural SPMs binding to the receptors, pharmaceutical companies are working on drugs to promote these same pathways of the resolution of inflammation.[ref][ref][ref] Phase I clinical trials are underway.[ref]

Making connections: Chronic diseases and resolution of inflammation:

I want to tie together the resolution of inflammation with chronic diseases and genetics.

Most chronic diseases are due to a combination of genetic susceptibility, combined with diet/lifestyle/environmental factors. Click through to the related article to check your genetic susceptibility and then consider how SPMs also interact with your diet/lifestyle/environment.

Cardiovascular Disease (CVD):
In cardiovascular disease, ALOX5, an enzyme involved in SPM synthesis, was identified in an early genetics study. In addition to SPM synthesis in the presence of EPA, the ALOX5 enzyme can also synthesize inflammatory lipid mediators. The discovery that the gene was linked to CVD was the first signal that there was something wrong with resolving inflammation in heart disease. Currently, researchers point the finger squarely at the lack of resolution of inflammation as causal in heart disease. One recent study explains: “Atherosclerosis is a major human killer and non-resolving inflammation is a prime suspect” [ref]

Related article: Coronary Artery Disease: Genetic Susceptibility to Heart Disease

Chronic Obstructive Pulmonary Disease:
COPD is a general term that includes inflammatory lung diseases such as emphysema and chronic bronchitis. The anti-inflammatory and resolution effects of lipoxin are very important in the lungs. In the lungs, lipoxin A4 triggers the migration of epithelial cells to repair injured bronchial tissue. Lipoxin B4 inhibits the migration of excess neutrophils into the area. Aspirin-triggered lipoxins also play a role in resolving inflammation in the lungs. Resolvin D1 is also important in lung immune system modulation and in the response to cigarette smoke. COPD patients generally have both lower levels of lipoxins and lower levels of the receptors for lipoxin in the lungs, which could cause the persistence of inflammation in the lungs via the lack of resolution.[ref]

Major Depressive Disorder:
A placebo-controlled clinical trial of multiple dosing levels of EPA and DHA showed a good response rate for major depressive disorder at high doses. The results showed that 4 g/d of EPA  and 1.2 g of DHA for 12 weeks decreased inflammatory levels, increased pro-resolving mediators, and decreased depression. Importantly, the 1 to 2g/day of EPA/DHA wasn’t enough to make a difference compared to placebo.[ref][ref]

Related article: Depression, genetics, and inflammation

Chronic back pain:
Lower back pain is due to neuroinflammation. Animal models of herniated lumbar disc pain show that protectin D1 (from DHA) decreases inflammatory cytokines (IL-1β and IL6), facilitates healing, and attenuates the pain.[ref]

Related article: Back Pain and Genetics

Arthritis:
From RA to osteoarthritis to gouty arthritis, inflammation is at the heart of this painful condition. Studies show that patients with arthritis have lower levels of specific SPMs, depending on the type and aggressiveness of the disease. Treatment with resolvin D1 or MaresinR1 acts as an analgesic for days to weeks. Supplementation with DHA and EPA also has some effectiveness in helping reduce inflammation in arthritis.[ref]

Related articles: Osteoarthritis and Rheumatoid Arthritis

Multiple sclerosis:
SPM biosynthesis is impaired in people with multiple sclerosis, and low levels of SPMs correlate with disease progression in MS.[ref] This may be a key to the chronic inflammation involved in MS, which eventually causes demyelination of the neurons.

Related article: Multiple sclerosis and genetic variants

Inflammatory bowel disease:
Crohn’s and ulcerative colitis are caused by chronic intestinal inflammation. The lack of resolution of inflammation is thought to be a strong contributing factor: “…defective expression of pro-resolution mediators may contribute to the chronic inflammatory response associated with IBD. Notably, colonic mucosa from UC patients demonstrates defective LXA4 [lipoxin A4] biosynthesis, which may contribute to the inability of these patients to resolve persistent colonic inflammation.”[ref]

Related article: Inflammatory Bowel Diseases

Diabetes:
In type 2 diabetes, research shows that the BLT1 receptor for resolvin E1 is impaired. Interestingly, higher levels of resolvin E1 were able to overcome some of the inflammatory dysregulations.[ref]

Related article: Type 2 Diabetes Genes

Neuropathic pain:
Damage to the central nervous system can cause peripheral neuropathy, mechanical allodynia, MS, or other pain syndromes. While it makes sense that the resolution of inflammation would stop pain, researchers have discovered that the role of the SPMs may be more in-depth when it comes to neuropathic pain. Research points to the role of SPMs in both opioid receptors and TRP channels, which may signal to stop pain through the central nervous system.[ref]

Research on neuropathic pain and supplemental SPMs shows an array of positive results (mostly in animal studies). Lipoxin A4 reduces inflammatory hyperalgesia, inhibits NF-kB, and reduces IL-1B, TNF-a, and IL6. Resolvins blunt pain perception, down-regulates NF-kB in the lower back, prevents inflammatory hypersensitivity, and acts as an analgesic.

Getting a little more specific: Resolvin D1 and resolvin D2 can directly inhibit TRP channels on the surface of sensory neurons. TRPV1, TRPV3,  TRPV4, and TRPA1 are inhibited by these resolvins, and this reduces sensitivity to heat-induced pain as well as agonist-induced pain. Additionally, maresin R1 acts on the TRPV receptors. These receptors are also activated by capsaicin in hot chili peppers.[ref]

Related article: TRPV1 receptor variants

Infections:
Sepsis is an out-of-control inflammatory reaction, usually in response to a bacterial infection. SPMs, in addition to all their anti-inflammatory and pro-resolving properties, also enhance the clearance of bacterial and viral pathogens while at the same time limiting collateral tissue damage.[ref]

Specialized pro-resolving mediators also play a role in host defense against viruses such as influenza A, RSV, and HIV. Clearance of bacterial pathogens also involves SPMs. For example, animal studies show that the absence of lipoxins in Lyme disease causes chronic disease symptoms such as joint pain.[ref]

Related articles: chronic Lyme disease

Atrial Fibrillation:
A-fib persistence increases inflammation through excessive ROS production in the endothelium. Researchers now think that resolvin D1 may inhibit the increase in inflammation.[ref]

Related article: Atrial fibrillation genes

Cancer: Inflammation and SPMs

Cancer can, in some ways, be viewed as a wound that doesn’t heal, and research is currently focused on the role of SPMs in cancer. With chemotherapy, surgery, or radiation, a tumor can be reduced in size, but whether or not the cancer is ‘cured’ is conditional upon the clearance of debris. Essentially, dead cancer cells trigger a proinflammatory immune response which paradoxically stimulates tumor growth. Traditionally, the focus has been on anti-inflammatory drugs, which have so far yielded only a transient effect on stopping tumor activity. Therefore, pro-resolution mediators are of great interest in cancer research.[ref]

  • Researchers are looking at the use of resolvins prior to surgery or chemotherapy to prevent metastasis from occurring due to micro-metastase escape.[ref]
  • Other research points to positive outcomes using pro-resolving factors along with cancer treatment to prevent cancer cells from being available to move through the bloodstream or lymphatic system.[ref]

Increasing DHA/EPA in the diet, along with decreasing omega-6 fatty acids, reduces the viability of breast cancer cells in cell studies. The current Western diet averages a ratio of up to 20:1 for omega-6:omega-3 intake, which is many-fold higher than the ratio was historically. Changing that ratio in breast cancer cell lines to 1:1 omega-6:EPA/DHA stopped cancer growth.[ref] Keep in mind that this is a cell study pointing to a mechanism of action and not a cure-all.

Resolvin D1 and D2 have been shown in cell studies to inhibit the proliferation of prostate cancer.[ref]

Related article: Prostate Cancer and BPH

As mentioned above, aspirin-triggered pro-resolving mediators have a longer half-life than their non-aspirin-triggered counterparts. Additionally, low-dose aspirin, along with EPA, increases levels of resolvin.[ref] Regularly taking aspirin intake is associated with a decreased colon cancer risk in some people. New research points to aspirin-triggered resolvin D1 as a big reason aspirin has anticancer activity. Researchers used animal models of cancer to figure out that blocking the receptor for AT-resolvin D1 blocks the antitumor action of aspirin. Thus, the pro-resolving mediators created by the interaction of aspirin, COX, and EPA are likely the key to cancer prevention by aspirin.[ref]

Circadian rhythm and the production of SPMs

Your circadian rhythm – the 24-hour built-in clock – controls the rhythmic production of hormones, enzymes, proteins, and more. Your body prioritizes the processes needed when you are awake and active and then switches to cellular repair and restoration processes while you sleep.

There is a circadian rhythm to SPM production, and the highs and lows of the rhythm are important in healing. SPM concentrations from healthy volunteers rise high and then fall over the course of the day, but in people with heart disease, the rhythm is flat.[ref]

Without the production of SPMs to stop the chronic inflammatory processes going on in heart disease, the inflammation continues unchecked and atherosclerosis builds in the blood vessels. Researchers found that in mice, the core circadian clock gene BMAL1 controls the concentration of pro-resolving mediators. As BMAL1 rises and falls, so do these important healing compounds, but without the core circadian clock, SPM levels remain low and flat.[ref]

Related article: BMAL1

Post-Covid and pro-resolving mediators:

As mentioned above, pro-resolving lipid mediators are important in keeping inflammation under control in viral infections, and Covid is no exception. One study showed that severe Covid patients had a low omega-3:omega-6 index (4.15%) compared to healthy controls (average 7.84%). The study also showed that a higher omega-3 index was associated with a 70% lower risk of death in severe Covid.[ref]

A study of people who had Covid looked at their macrophages, which are an essential part of the inflammatory response. The results showed that macrophages from people with mild SARS-CoV-2 infection showed an inflammatory imprint for at least 5 months after infection. Specifically, the macrophages had a downregulation of pro-resolving factors and an increased production of pro-inflammatory leukotrienes, which are synthesized from omega-6 PUFA.[ref]

 

Next, let’s take a look at how your genes specifically interact with SPM production (assuming you have all the DHA, DPA, and EPA you need).


Pro-resolving Mediators Genotype Report:

Omega-3 Fatty Acid conversion:

The precursor molecules for specialized pro-resolving mediators are EPA, DPA, DHA, and AA. DHA and EPA are obtained directly in the diet through eating oily fish or taking fish or krill oil supplements.

Plant-based omega-3s include flaxseed and chia seeds. They have high amounts of alpha-linolenic acid, which can be converted to longer-chain EPA, DPA, and then DHA fatty acids. They are converted using the enzymes encoded by the FADS2, FADS1, and ELOVL genes.

People with variants in the FADS1/2 enzymes convert very little plant-based omega-3 fatty acids into DHA/EPA.

Omega 3 and Omega 6 fatty acids conversion chart
My simplified overview of the genes involved in PUFA conversion.

 


FADS1 gene:
The FADS1 enzyme converts flaxseed oil and chia seed oil into DHA and EPA. Multiple FADS1 variants are inherited together, such that if you inherit one, you should inherit all the variants. Below, I’ve only included one variant, rs174546 (T is the risk allele)– which is almost always inherited together with rs174547 (C allele), 174537 (T allele), rs174550 (C allele), and rs174548 (G allele).[ref]

Check your genetic data for rs174546 (23andMe v4, v5; AncestryDNA)

  • T/T: low FADS1 enzyme activity; benefits more from direct EPA/DHA intake[ref][ref][ref][ref]; Arachidonic acid is also reduced[ref]
  • C/T: lower FADS1 enzyme activity, benefit more from direct EPA/DHA intake
  • C/C: typical FADS1 activity

Members: Your genotype for rs174546 is .

FADS2 gene: The FADS2 variant is inherited together with the FAD1 variant for many people. It is also important in converting omega-3 oils into DHA/EPA.

Check your genetic data for rs1535 (23andMe v4, v5; AncestryDNA):

  • G/G: low FADS2 enzyme activity, decreased ALA to EPA conversion[ref], benefits the most from fish oil supplement post-heart attack[ref], high intake of EPA/DHA decreases asthma risk in kids[ref]
  • A/G: somewhat decreased FADS2 enzyme activity
  • A/A: typical FADS2

Members: Your genotype for rs1535 is .

ELOVL2 gene: encodes an enzyme also needed to transform fatty acids into longer-chain fats.

Check your genetic data for rs3734398 (23andMe v5; AncestryDNA):

  • C/C: associated with higher levels of EPA and DPA, lower levels of DHA (e.g., decreased conversion of EPA to DHA)[ref]
  • C/T: associated with higher levels of EPA and DPA, lower levels of DHA (e.g., decreased conversion of EPA to DHA)
  • T/T: typical

Members: Your genotype for rs3734398 is .

Enzymes that produce SPM

The research here is fairly new, and I’m sure there will be more to come on the way genetic variants interact with diet in the formation of pro-resolving mediators. So take this information as more of an introduction with (hopefully) more to come.

ALOX5 gene: encodes the enzyme responsible for converting EPA and DHA into resolvins, maresins, and protectins. But this enzyme is also used to convert AA from omega-6 oils into inflammatory leukotrienes. Thus, higher enzyme production may be associated with higher inflammation in people eating a lot of omega-6 fatty acids, but the enzyme is also needed to produce SPMs from EPA/DHA. Thus, the influence of the omega-6 to omega-3 ratio in the diet is likely important and is also likely not considered in the studies.

Check your genetic data for rs4987105 (23andMe v4; AncestryDNA):

  • C/C: most common genotype (higher levels of type 2 diabetes, higher levels of C-reactive protein – a study done in the EU)[ref]
  • C/T: decreased risk of type 2 diabetes, lower levels of C-reactive protein (a marker of inflammation)
  • T/T: decreased risk of type 2 diabetes, lower levels of C-reactive protein (a marker of inflammation)

Members: Your genotype for rs4987105 is .

ALOX5AP gene: encodes an enzyme needed for ALOX5 activation. This enzyme is involved in increased inflammation from inflammatory lipids produced from Arachidonic Acid, as well as pro-resolving mediators produced from DHA/EPA. Similar to ALOX5 research, I think the diet of the study group likely influences whether the variant has a positive or negative effect. So keep in mind that the average diet includes a lot of omega-6 oils and not a lot of DHA/EPA these days.

Check your genetic data for rs17216473 (AncestryDNA):

  • A/A: increased risk of heart attacks[ref]
  • A/G: increased risk of heart attacks
  • G/G: decreased risk of heart attacks[ref]

Members: Your genotype for rs17216473 is .

ALOX12 gene: encodes the enzyme needed to convert EPA/DHA into SPMs. This enzyme, though, is also used in turning AA from omega-6 oils into inflammatory mediators such as 12-HETE. Thus, like the ALOX5 genetic variants, the research results are likely dependent on the amount of omega-6 vs. DHA/EPA that the study participants eat. High levels of the inflammatory mediators from ALOX12 are linked to increased cancer risk and heart disease.

Check your genetic data for rs1126667 R261Q(23andMe v4, v5; AncestryDNA):

  • A/A: decreased risk of breast cancer in White women (study done in the US)[ref], lower blood pressure, and decreased enzyme function (study done in the EU)[ref]
  • A/G: slightly decreased risk of breast cancer, lower blood pressure, and decreased enzyme function
  • G/G: typical

Members: Your genotype for rs1126667 is .

COX2 gene: encodes the enzyme that converts arachidonic acid into proinflammatory mediators. Acetylation of COX2 by aspirin interacts with SPMs to create aspirin-triggered pro-resolving mediators.

Check your genetic data for rs4648310 (AncestryDNA):

  • T/T: typical
  • C/T: low DHA/EPA intake is associated with a significantly increased risk of prostate cancer, but high DHA/EPA intake ameliorates the increased risk
  • C/C: low DHA/EPA intake is associated with a significantly increased risk of prostate cancer, but high DHA/EPA intake ameliorates the increased risk[ref]

Members: Your genotype for rs4648310 is .

Check your genetic data for rs5275 (23andMe v4, v5; AncestryDNA):

  • A/A: typical
  • A/G: increasing the intake of EPA/DHA (eating salmon once a week) reduced prostate cancer risk by 70%
  • G/G: increasing the intake of EPA/DHA (eating salmon once a week) reduced prostate cancer risk by 70%[ref]

Members: Your genotype for rs5275 is .

Receptors for the SPMs:

Several of the genes that encode receptors for various pro-resolving mediators were classified up until recently as ‘orphan receptors’. Researchers knew the gene existed, but they weren’t really sure what activated the receptor.

A variant in the FPR2 gene (not covered in Ancestry or 23andMe data), rs11666254  causes downregulation and is linked to an increased risk of sepsis, which shows the importance of this receptor in the resolution of inflammation due to bacterial pathogens.[ref]

GPR18 gene: encodes the receptor for resolvin D2.

Check your genetic data for rs3742130 (23andMe v4):

  • A/A: identified in a large genetic study as altering the risk of IBD[ref]
  • A/G: identified in a large genetic study as altering the risk of IBD
  • G/G: typical

Members: Your genotype for rs3742130 is .

CMKLR1 gene encodes the ERV1/ChemR23 receptor for both resolvin E1 and chemerin1 (an adipokine). Animal studies show that this receptor is important in preventing hyperglycemia and hyperinsulinemia, and the results seem to hold true in people who are overweight. Higher EPA intake, coupled with the ERV1 receptor, prevents hyperinsulinemia.[ref]

Check your genetic data for rs1878022 (23andMe v4, AncestryDNA):

  • C/C: increased receptor expression, reduced inflammation in obesity[ref]
  • C/T: increased receptor expression, reduced inflammation in obesity
  • T/T: typical

Members: Your genotype for rs1878022 is .

GPR37/PaelR encodes the receptor for protectin D1, which is important in resolving inflammation in the brain.[ref] Variants are related to Parkinson’s and autism.

Check your genetic data for rs149031046 T589M (23andMe v5):

  • G/G: typical
  • A/G: possibly important for autism[ref][ref]
  • A/A: possibly related to autism (rare)

Members: Your genotype for rs149031046 is .

LGR6 encodes the receptor for maresin 1, which is important in bone health (and more)

Check your genetic data for rs10920362  (23andMe 4,v5):

  • C/C: typical
  • C/T: increased risk of osteoporosis
  • T/T: increased risk of osteoporosis[ref]

Members: Your genotype for rs10920362 is .

 


Lifehacks: Increasing SPMs

Is the cure for all chronic diseases to take a couple of fish oil pills?
I don’t think it is that simple. Instead, there is a lot of nuance in how much EPA, DHA, and DPA are needed – as well as avoiding inhibitors of the production of SPMs.There are also questions surrounding the oxidation of fish oil supplements, especially the cheap stuff that you get at the grocery store, and whether oxidized fish oil has a negative impact instead of a positive benefit.

Let’s dig into dietary unsaturated fats, supplements, dosages, and more…

Start with your current DHA/EPA consumption:
Knowing how much DHA/EPA you normally consume is an important first step. Cronometer.com is a free web app where you can track what you eat. It breaks down your nutrient intake, including omega-3 and omega-6 fats, and it’s fairly detailed in its list of foods. For example, you can differentiate between regular eggs vs. omega-3-enhanced eggs and grass-fed beef vs. regular beef. It doesn’t break out DHA/EPA vs. other omega-3 fats, though.

Increasing fish consumption or supplemental marine oils:

The pro-resolving lipid mediators are derived from EPA and DHA, found in saltwater fish oil, as well as arachidonic acid, found in meat or derived from linoleic acid. If you aren’t eating much fish or getting much DHA or EPA in your diet, then you may want to consider supplemental marine oil.

Talk to your doctor if you have any questions on whether supplements are right for you and at what doses. High doses of fish oil may interact negatively with certain medications or act as a blood thinner at more than 3g/day in people who are on blood thinners[ref].

Fish Oil Clinical Trials:

Most of the clinical trials on omega-3 fatty acid supplements don’t show miraculous results, which leads to the belief that DHA and EPA aren’t important.[ref]

  1. Most studies use relatively low doses of fish oil (e.g. less than 2g)
  2. In epidemiological studies, there are legitimate questions on the quality of fish oil and whether it is oxidized.
  3. Many studies are short-term

Prescription DHA/EPA:
Pharmaceutical companies contend that regular fish oil isn’t good enough. High-dose, pharmaceutical-grade DHA and EPA pills, such as Omega-3 Acid Ethyl Esters, have been shown in clinical trials to increase several specific SPMs.[ref] Omega-3 Acid Ethyl Esters is prescribed for reducing triglycerides.[ref]

Will taking fish oil cause atrial fibrillation?
A 2022 study using information on almost 500,000 people in the UK found that people who took fish oil were ~1% more likely to have atrial fibrillation. This association was seen only in people who were not diagnosed with cardiovascular disease.[ref] Again, there are questions on whether it is the consumption of cheap, oxidized fish oil supplements or if there is a true risk from high DHA and EPA. The same study showed that eating oily fish did not increase a-fib.

However, a clinical trial using 4g/day esterified EPA/DHA was halted early when it didn’t show benefits for heart attacks and strokes. Noted in the paper is that a tertiary endpoint showed an increased rate of new-onset a-fib (0.9% more in the EPA/DHA group than in placebo).[ref]

Related article: Atrial Fibrillation Risk Genes

What about bleeding?
While there does seem to be a risk of increased bleeding in people who are taking high doses of fish oil along with blood thinners, a study of 1,500 people undergoing heart surgery showed that taking 8-10 g/day of fish oil up to two days before surgery (and 2g/day after surgery while still in the hospital) did not increase bleeding.[ref]

Clinical trials of high doses of DHA/EPA:
Clinical trials using 2.1 to 4.5 grams of DHA/EPA and also measuring specialized pro-resolving mediators (SPMs) show:[ref]

  • In chronic kidney disease, 4g/day of an omega-3 supplement for eight weeks increased resolvins (RvE1, RvE2, RvE3, RvD5).
  • In pregnancy, 3.7 g of supplemental DHA/EPA increased SPMs in offspring.
  • In peripheral artery disease, a 4.4g supplement of DHA/EPA for 3 months increased resolvin E3.
  • Another study of peripheral artery disease found that a marine oil supplement of 4.5g (DHA/EPA/DPA) increased maresins.
  • In people with arthritis, a microalgae oil supplement containing 2.1g DHA/day for ten weeks increased SPMs.

Oxidation in fish oil supplements:
A real concern with taking fish oil supplements is that many are oxidized, possibly leading to negative effects from the supplement rather than increased SPMs. Exposure to air or to higher temperatures accelerates the oxidation of fish oil supplements. You’ll want to check the expiration dates on fish oil supplements. Some people suggest keeping them in the refrigerator, especially if you live in a warm locale.[ref]

ConsumerLab.com tests supplements off the shelf. Of the brands tested, a couple were shown to be oxidized: Jamieson Omega-3 and Wiley’s Finest Wild Alaskan.

The CL top pick for high-dose marine oil was Carlson Maximum  Omega 2,000 and Kirkland brand for low dose. All of the tested marine oils passed the heavy metals tests.

Arachidonic acid in foods:
Arachidonic acid (AA) is the omega-6 precursor to lipoxins, and most people get plenty of AA in their diets. Foods high in arachidonic acid include chicken, eggs, pork, beef, milk, and salmon. The body can also convert linoleic acid into arachidonic acid. Linoleic acid is found in vegetable oils, nuts, and seeds – abundant in the modern diet.

Medications and supplements that can influence SPMs:

Certain medications can block the synthesis of SPMs, while some natural supplements can promote the formation.

Here’s an overview, with details to follow:

Substance/Drug Effect on SPMs Notes
Ibuprofen Blocks SPM formation May delay muscle healing
Zileuton Blocks SPM formation Leukotriene inhibitor
Aspirin Increases AT-SPMs Unique among NSAIDs
Traumeel Increases SPMs (animal data) Herbal, injectable/cream
Vitamin D Increases ALOX5 and SPMs Especially in T2D
Tripterygium wilfordii Increases SPMs Thunder God Vine, traditional medicine
SPM supplements Directly supplies SPMs Expensive for effective doses

Medications that block the formation of SPMs:

  1. Ibuprofen (Advil): A study examining how muscles rebound from unaccustomed hard exercise showed that ibuprofen blocks the formation of proinflammatory mediators, which was expected. But the researchers also detected that ibuprofen blocked the formation of SPMs (lipoxins, resolvins, and protectins).[ref]
  2. Zileuton, a leukotriene synthesis inhibitor, also blocks the formation of SPMs.[ref]

Medications that increase the formation of SPMs.

  1. Traumeel, an herbal pain relief product offered as an injection or cream, has been shown to increase the production of resolvin D2, resolvin D5, and lipoxin A4 after 24 hours (animal study, injections).[ref]
  2. Aspirin increases certain SPMs. more below.

Specialized Pro-resolving Mediator Supplements and Stacks:

Natural substances that increase the formation of SPMs

Vitamin D: A study in patients with type 2 diabetes found that increasing vitamin D also increased ALOX5 (the enzyme that converts DHA/EPA to SPMs).[ref] This may be one important connection between vitamin D levels and a number of chronic diseases.

Tripterygium wilfordii, also known as Thunder God Vine, is a traditional Chinese medicine used for rheumatoid arthritis. Recent research shows that it induced “pronounced formation of specialized pro-resolving mediators (SPM) and related 12/15-LOX-derived SPM precursors, without COX and 5-LOX activation.”[ref] Other research identifies that celastrol is the active component of Thunder God Vine that is responsible for elevating SPMs.[ref]

Dihydrochalcone MF-15 is a natural substance that increases the formation of SPMs in the presence of omega-3 fatty acids.[ref] While more research is needed here, it is encouraging to see researchers looking at the combination of natural substances and DHA/EPA in the formation of SPMs.

Enhanced marine oil supplement (SPM-specific supplements):

Marine oil is a general term for omega-3 supplements, including fish, krill, or algae oil. Essentially, it means an omega-3 supplement that contains DHA and EPA derived from something that lived in the sea.

A few companies now offer supplements made from enhanced marine oil and marketed as SPM supplements. It usually means that, in addition to EPA and DHA, several of the metabolite intermediaries are included.

A 2019 clinical trial in 22 healthy adults looked at SPMs produced after different doses of marine oil. The supplement contained EPA, DPA, and DHA along with several SPM precursors (17-hydroxy-docosahexaenoic acid, 17-HDPA, and 18-HEPE). Doses tested were 1.5, 3, and 4.5 g of total fatty acids. The results showed a significant increase in all of the measured SPMs for 2 to 6 hours after supplementation for the 3g and 4.5g doses. The 1.5g dose wasn’t much different from the placebo.[ref] Just as a heads up, this stuff isn’t cheap…

Recap: 3 to 4.5 g of marine oil increased SPMs significantly for 6 hours.

Krill oil vs. fish oil vs micro-algae oils:

When you start looking into different fish oil supplements, you’ll find a wide array – from cod liver to fish oil to krill oil to microalgae oil. Both krill oil and fish oil have DHA and EPA. Check the labels to see how much is in the supplement you are considering, since amounts vary a lot.

If you eat a vegan diet, microalgae oil is your option for DHA and EPA. This also may be a good option if you have a histamine reaction to fish oil. (Some people with histamine intolerance/MCAS are fine with non-fermented fish oil, but others may react.)

A number of studies have looked at the differences between krill oil and fish oil. Some studies, funded by the manufacturer, show that krill oil is more bioavailable.[ref]  Other studies show that there is no difference in bioavailability.[ref] Krill oil often doesn’t have the fishy aftertaste (no fish burps).

When comparing supplements, be sure to look for the amount of DHA and EPA in the supplement.

Stacking with low-dose aspirin:

Daily or regular use of aspirin is not right for everyone. If you have any questions about this, talk with your doctor about your bleeding risk or other concerns.

Aspirin-triggered resolvins have a longer half-life than non-aspirin resolving. This means that they stick around longer and have a more pro-resolution impact.[ref]

A clinical trial using supplemental fish oil (3g/day) along with low-dose aspirin showed efficacy in resolving periodontal disease.[ref]

Stacking with anti-inflammatory natural supplements:

It makes sense to combine pro-resolving mediators along with supplements that inhibit inflammatory cytokines. You would be going at chronic inflammation from both sides…

Vitamin D,  probiotics, krill oil: A study using an animal model of gut inflammation found that a mixture of krill oil, Lactobacillus reuteri (probiotic), and vitamin D decreased intestinal inflammation, reduced TNF-α, IL-1β and IL-6 levels (inflammatory cytokines), and increased IL-10 (anti-inflammatory).[ref] This may be important for anyone with IBS. 

Stacking with cannabinoids?

Anabasum, a synthetic analog of Δ8‐tetrahydrocannabinol (THC)‐11‐oic acid, at doses higher than 20 mg triggers “the biosynthesis of specialized pro‐resolving lipid mediators including LXA4, LXB4, RvD1, and RvD3. Collectively, we demonstrate for the first time a striking anti‐inflammatory and pro‐resolution effect of a synthetic analog of THC in healthy humans.”[ref]  Anabasum is a synthetic cannabinoid being developed and researched for inflammatory diseases.

DHA and EPA derivatives can also bind to cannabinoid receptors, but at a much lower affinity than endocannabinoids or cannabis-derived cannabinoids.[ref] The receptor that resolvin D2 binds to, GPR18, also engages with endogenously produced endocannabinoids.

Researchers believe that SPMs alleviate neuropathic pain by acting synergistically with endocannabinoids such as anandamide and 2-AG.[ref]

Intermittent hypoxia triggers SPM synthesis:

Hypoxia, or lack of oxygen, increases the biosynthesis of SPMs. Hypoxia is often found in inflamed tissue and tumors. It makes sense, then, that hypoxia is a trigger for SPM creation.[ref]

While in general, hypoxia isn’t good on a long-term basis (gotta have that 02), intermittent hypoxia is a technique being utilized by athletes and for healing certain types of injuries.[ref] Breathwork and focused breathing in different types of yoga also create periods of intermittent hypoxia.[ref]

A 2016 study looked at the effects of intermittent hypoxia as a therapy for cardiovascular disease. It found that “short-term daily sessions consisting 3–4 bouts of 5–7 min exposures to 12–10% O2 alternating with normoxic durations for 2–3 weeks can result in remarkable beneficial effects in the treatment of cardiovascular diseases such as hypertension, coronary heart disease, and heart failure.”[ref]

Not wanting to invest in expensive equipment? Look into breath work – box breathing, physiological sigh, and other types of breathing exercises.

Timing of supplementation:

The connection between circadian rhythm, BMAL1 (core circadian clock gene), and the production of SPMs is interesting. This leads to the idea that taking DHA/EPA in the morning may be more beneficial than at night.

One study looked at how long the effects last from SPM-enriched marine oil supplements. The results showed that levels peak in about two hours and fade at six hours for a 3 g dose. With 4.5g doses, the plasma SPM levels remain elevated for close to 24 hours.[ref]

screenshot from https://www.ahajournals.org/doi/full/10.1161/CIRCRESAHA.119.315506

Omega-6 to Omega-3 ratio in your Diet:

Why do we have so many unhealthy people with chronic diseases in this time of modern medicine? One big change over the last 100 years is a huge dietary switch to seed oils, such as corn or soybean oil, which are very high in omega-6 fatty acids.

Historically, people used to eat approximately the same amount of omega-3s as omega-6s. But today, people eat around 15-fold higher amounts of omega-6 fatty acids. It is mainly due to the use of seed oils (soybean, corn, canola), but adding to the shift in ratio is a decrease in omega-3s in meat, eggs, and dairy due to grain feeding instead of pasture grass.[ref]

Let’s take soybean oil as an example. In the past 100 years, the use of soybean oil has risen 1,000%. While our modern diet still contains some omega-3 fatty acids, researchers estimate that tissue concentrations of DHA, EPA, and AA have declined from 36% to 22% since 1909. The change in omega-6 to omega-3 ratio is due to increased omega-6s, not decreased fish consumption. The amount of fish typically eaten has stayed pretty steady since the early 1900s.[ref]

PMC3076650

A randomized, controlled study in Sweden looked at the impact of switching out saturated fat with omega-6 oils. At the time, the theory was that saturated fat was causing heart disease. The seven-year-long study found that the switch to omega-6 oils actually resulted in a >60% higher mortality rate.[ref]

Grain-fed conventional beef vs. grass-fed beef:

Another dietary switch comes from what animals are fed. A recent study showed that grass-fed beef had higher levels of EPA/DHA/DPA and lower levels of omega-6 fatty acids when compared to grain-fed beef.[ref] Switching to grass-fed meat instead of grain-fed may help a little bit in decreasing your omega-6:omega-3 ratio.

Pasture-raised vs. Omega-3 Eggs:

Chickens that can free-range in a pasture will produce eggs with higher omega-3 and lower omega-6 concentrations.[ref][ref]

You may have seen eggs that advertise ‘high omega-3’ on the carton. These are usually produced by chickens that have flaxseed included in their feed. This tends to triple the DHA content in the egg yolks.[ref]

What about flaxseed or chia seeds as a source of omega-3s?

I mentioned in the genetics section that some people convert plant-based omega-3 fatty acids into DHA/EPA better than others. Here’s a quick recap of that information before we go any further.

Gene RS ID Risk Allele YOU Notes about the Risk Allele:
FADS1 rs174546 T These variants significantly decrease the conversion of plant-based omega-3s into DHA/EPA.
FADS2 rs1535 G
ELOVL2 rs3734398 C If you have this risk allele highlighted, you may want to investigate supplements labeled as SPMs if you have a chronic condition. This allele affects the conversion of EPA to DHA.

The omega-3 fatty acid found in plants is alpha-linolenic acid. Overall, men tend to convert ALA from flaxseed or chia seeds into EPA a little better than women do. But ALA is “a limited source of longer chain n-3 PUFA in humans.”[ref] On average, not taking into account genetic differences, alpha-linoleic acid is converted to EPA at a rate of about 6% and to DHA by 3.8%.[ref]

Flaxseed oil is about 70% alpha-linolenic acid (ALA). Thus, if you take 2g of flaxseed oil a day, 1.4g is ALA, which is converted to 0.084g of EPA (if you’re an average converter).

Food sources of DHA and EPA (grams/serving):

If you are considering supplementing with marine oil, you also should take into account the amount of DHA and EPA you already get from eating salt-water fish. For example, if you eat salmon several times a week, you may want to cut back or skip supplements on fish day.

(Adapted from NIH nutrition fact sheet)

DHA (g/serving) EPA (g/serving)
Salmon, Atlantic, farmed cooked, 3 ounces 1.24 0.59
Salmon, Atlantic, wild, cooked, 3 ounces 1.22 0.35
Herring, Atlantic, cooked, 3 ounces* 0.94 0.77
Sardines, canned in tomato sauce, drained, 3 ounces* 0.74 0.45
Mackerel, Atlantic, cooked, 3 ounces* 0.59 0.43
Salmon, pink, canned, drained, 3 ounces* 0.63 0.28
Trout, rainbow, wild, cooked, 3 ounces 0.44 0.4
Oysters, eastern, wild, cooked, 3 ounces 0.23 0.3
Sea bass, cooked, 3 ounces* 0.47 0.18
Shrimp, cooked, 3 ounces* 0.12 0.12
Lobster, cooked, 3 ounces* 0.07 0.1
Tuna, light, canned in water, drained, 3 ounces* 0.17 0.02
Tilapia, cooked, 3 ounces* 0.11
Scallops, cooked, 3 ounces* 0.09 0.06
Cod, Pacific, cooked, 3 ounces* 0.1 0.04
Tuna, yellowfin, cooked 3 ounces* 0.09 0.01

Cooking Oils: Omega-6 to Omega-3 ratios

Limiting omega-6 fatty acids along with increasing omega-3 fats in the diet is thought to shift the balance away from the creation of inflammatory lipid mediators to increased pro-resolving lipid mediators.

The largest source of omega-6 fats in the diet is usually seed oils. Pretty much anything you get at a restaurant that is fried is going to contain a high amount of omega-6s. Watch out also for salad dressings or mayonnaise, which are often made with soybean oil. Bread, baked goods, and many packaged foods also have a surprising amount of omega-6 fat in them.

(Adapted from Wikipedia)

Food Serving size Omega-6 (mg) Omega-3 (mg) Approx. Omega-6 : omega-3 ratio
Avocado oil 1 Tbsp (14 g) 1754 134 13: 1
Butter (mostly saturated fat) 1 Tbsp (14 g) 382 44.1 9: 1
Canola oil 1 Tbsp (14 g) 2610 1279 2 : 1
Corn oil 1 Tbsp (14 g) 7224 157 46: 1
Cottonseed oil 1 Tbsp (14 g) 6953 27 257 : 1
Flaxseed oil 1 Tbsp (14 g) 1715 7196 1 : 4
Grape seed oil 1 Tbsp (14 g) 9395 13.5 696 : 1
Lard (mostly saturated fat) 1 Tbsp (13 g) 1300 128 10: 1
Olive oil (mainly monounsaturated) 1 Tbsp (14 g) 1318 103 13 : 1
Palm oil (mostly saturated fat) 1 Tbsp (14 g) 1228 27 45 : 1
Peanut oil 1 Tbsp (14 g) 4950
Perilla oil 1 Tbsp (14 g) 1680 8960 ~1 : 5
Soybean oil (hydrogenated) 1 Tbsp (14 g) 6116 378 16.2 : 1
Soybean oil, (Unhydrogenated) 1 Tbsp (14 g) 6807 917 7.4 : 1
Walnut oil 1 Tbsp (14 g) 7141 1404 5.1 : 1

What options are low in omega-6 fatty acids?

Ghee, coconut oil, and tallow are usually low in omega-6 since they are mainly saturated fats. Alternatively, if you watch your saturated fat intake, olive oil is primarily a monounsaturated fat.

Recap of your genes:


Conclusion:

Targeting the resolution of inflammation rather than just blocking the formation of proinflammatory cytokines is likely to help prevent and reverse chronic diseases.

While this whole article has focused on the resolution of inflammation, the other half of the picture is to stop the source of inflammation.

Modern sources of inflammation include cigarette smoke, air pollution exposure, a crappy diet, poor sleep, chronic infections (e.g., gum disease), or stress.

Your source of chronic inflammation is likely not the same as mine.

Not everyone reacts to inflammatory substances in the same way. One person may be able to eliminate a little arsenic with no problem, but they may not be able to handle organophosphate pesticides.

Start by looking at your genetic variants that increase inflammatory cytokines. Also, look at your detoxification genetic variants. If you see a lot of risk alleles highlighted, go and read the article. For example, some people should be careful to avoid BPA or phthalates, while others should focus on certain pesticides. Arsenic in your well water may be a problem when combined with certain genetic variants. If air quality is poor in your area, an indoor air filtration system may be a good investment.

Consider ways to limit inflammatory conditions in the body, and then couple that with ways to boost the resolution of inflammation.


Related Articles and Topics:

TNF-alpha: Inflammation and Your Genes
Do you feel like you are always dealing with inflammation? Joint pain, food sensitivity, etc? Perhaps you are genetically geared towards a higher inflammatory response. Tumor necrosis factor (TNF) is an inflammatory cytokine that acts as a signaling molecule in our immune system.

L-theanine for anxiety: genetics and nature’s chill pill
L-theanine is known for reducing anxiety and promoting sleep. Discover the many benefits of l-theanine and how supplementation might work for you.

Quercetin: Scientific studies + genetic connections
Quercetin is a natural flavonoid acting as both an antioxidant and anti-inflammatory. This article focuses on the results of clinical trials involving quercetin as well as linking to specific genetic topics. By using your genetic data, you can make a more informed decision on whether quercetin is worth trying.

Depression Causes: Genetic Overview
Depression can have multiple physiological causes. This article ties together 9 separate articles on depression to simply your genetic search.

References:

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About the Author:
Debbie Moon is the founder of Genetic Lifehacks. Fascinated by the connections between genes, diet, and health, her goal is to help you understand how to apply genetics to your diet and lifestyle decisions. Debbie has a BS in engineering from Colorado School of Mines and an MSc in biological sciences from Clemson University. Debbie combines an engineering mindset with a biological systems approach to help you understand how genetic differences impact your optimal health.