peter attia paul grewal covid-19

Omega-3 and Omega-6 Fatty Acids, EPA, DHA, Fish Oil Supplements, and More – Bill Harris, Ph.D. on The Peter Attia Drive

Check out The Peter Attia Drive Episode Page & Show Notes

Key Takeaways

  • The different types of fats:
    • Saturated fats (lard, butter)
    • Monounsaturated fats (olive oil, canola oil)
    • Polyunsaturated fats 
      • Polyunsaturated fats are further divided into omega-3 (fish oils) and omega-6 (vegetable oils) fatty acids
  • Omega-6 fatty acid metabolism:
    • We consume linoleic acid (which is mainly found in corn and soybean oils), which is then converted by the liver into arachidonic acid
  • Omega-3 fatty acid metabolism:
    • We consume alpha-linolenic acid (which is mainly found in flaxseed, canola, and soybean oil), which is then converted to EPA by the liver. EPA can then be converted into DHA.
  • In individuals with normal triglyceride levels, EPA/DHA supplementation reduces total cholesterol 
  • Fish oils capsules aren’t entirely made of EPA/DHA
    • Typically, only 80% (or less) is DHA/EPA – the rest is a mix of monounsaturated/polyunsaturated fats
  • EPA is heart-healthy 
  • EPA/DHA levels are typically measured by measuring concentrations in red blood cells membranes – the measurement is known as “omega-3 index”
    • The optimal omega-3 index (the amount of EPA plus DHA in red blood cell membranes) is 8-12%
      • The average American has an omega-3 index of around 5%
  • Fish with the highest levels of EPA/DHA: Salmon, mackerel, herring, and sardines
  • In fish, the benefits of EPA/DHA outweigh the potential adverse effects of mercury
  • Worry more about increasing your EPA/DHA intake than decreasing seed oil consumption 
  • Linoleic acid, the primary omega-6 fatty acid found in vegetable oil, isn’t as unhealthy as you think
  • Taking fish oil supplements with food increases absorption

Supplements Mentioned


  • Host – Peter Attia (@peterattiamd)
  • Bill Harris, Ph.D. is an internationally recognized expert on omega-3 fatty acids
    • Bill is a Professor in the Department of Medicine at The University of South Dakota Sanford School of Medicine, as well as the President & CEO of OmegaQuant

The Different Types of Fats

  • Saturated fats (AKA saturated fatty acids)
    • These are long chains of single-bonded carbon atoms 
    • Examples: Lard, butter 
    • Saturated fats are solid are room temperature
  • Monounsaturated fats (AKA monounsaturated fatty acids)
    • These are long, single chains of carbon atoms – most are single-bonded, but there’s one double bond (when there’s a double bond in a molecule, it has a point of “unsaturation”)
    • Examples: Olive oil, canola oil
    • Monounsaturated fats are liquid at room temperature but become solids when refrigerated  
  • Polyunsaturated fats (AKA polyunsaturated fatty acids) are like monounsaturated fats but contain two or more double bonds
    • They’re liquid at room temperature and when refrigerated

Polyunsaturated Fats Are Further Divided Into Omega-3 and Omega-6 Fatty Acids

  • For background, the “omega” carbon denotes the last carbon in the molecule (the “alpha” carbon is the first carbon in the molecule)
  • What’s the difference between omega-3 and omega-6 fatty acids?
    • The position of the first double bond: Omega-6 fatty acids have their first double bond six positions away from the final carbon; omega-3 fatty acids have their first double bond three positions away from the final carbon
  • Vegetable oils (safflower oil, corn oil, sunflower oil) are heavy in omega-6 fatty acids
  • Fish oils are heavy in omega-3 fatty acids

Cell Membranes Are Composed of Fatty Acids

  • “These fatty acids basically make up the most important parts of our body. Every membrane of every cell is formulated with these, and it seems that they have a profound impact on our health.” Peter Attia
  • The membranes of each cell type most likely have different fatty acid compositions
    • Why? – Depending on the needs of the cell, the membrane either has to be stiff or floppy; the fatty acid composition of the membrane controls that flexibility 
  • Where do the fatty acids that compose cell membranes come from?
    • Our diet!
    • That said, between someone who eats <10 grams of saturated fat/day and someone who consumes >75 grams of saturated fat/day, there might only be a 10% difference in the amount of saturated fat within their respective cell membranes

Omega-6 Fatty Acid Metabolism

  • It all starts with linoleic acid, the principal omega-6 fatty acid in our diet (we can’t make it, so we have to consume it)
    • The dominant sources: Vegetable oils (mainly corn and soybean oils)
  • When linoleic acid is consumed, the liver converts it to arachidonic acid

Omega-3 Fatty Acid Metabolism (How The Body Forms EPA and DHA)

  • This all starts with alpha-linolenic acid (ALA) (found in high amounts in flaxseed oil and chia seed oil) 
    • Once again, our body can’t make ALA naturally
    • ALA is also found in canola and soybean oil (~70% of the fatty acids in soybean oil are ALA)
  • Once consumed, the liver converts ALA to EPA, which can further be converted to DHA

Average Daily Consumptions of EPA and DHA

  • The average American, who is not supplementing with fish oil, consumes ~150 mg of EPA+DHA per day
    • Older cultures that ate more seafood, like the Okinawa, consumed ~1,500-2,000 mg of EPA+DHA per day

Bill’s Groundbreaking Study | Salmon Oil Lowers Cholesterol and Triglycerides 

  • Back in ~1980, Bill organized a 28-study in which patients consumed ~25 grams of EPA/DHA per day through a combination of eating salmon steaks and drinking salmon oil (~20 grams of the EPA/DHA came from the latter)
    • (One key point: These patients had normal triglyceride levels at the start of the study)
    • Results:
      • Patients showed reduced total cholesterol (by ~20 points) and triglyceride levels (from ~100 to ~75)
      • Also, platelet function was inhibited (resulting in a blood-thinning effect)
        • (EPA, like Aspirin, is an antiplatelet – it prevents blood clots)
  • Why was cholesterol lowered?
    • Remember, salmon oil = fish oil = omega-3 polyunsaturated fatty acid
    • When you consume more omega-3s, and less saturated fat (for example), the chemical fluidity of your cell membranes change (as described above) 
      • LDL receptors are found on cell membranes (LDLs are the primary lipid particles that carry cholesterol in our blood) 
        • So – the properties of the cell membrane are changed such that it becomes more efficient at removing LDL particles from the blood, thus lowering cholesterol

EPA/DHA Supplementation Raises Cholesterol in Individuals with Hypertriglyceridemia

  • Later on, Bill went on to discover that high-dose fish oil supplementation (~6 grams of EPA+DHA) increased LDL cholesterol in patients with elevated triglycerides (but their triglyceride levels decreased)
    • Bill’s hypothesis for the cause: Slowed LDL-receptor activity (thus, they weren’t clearing LDL particles from the blood as fast as they should have been)

EPA Improves Cardiovascular Health in Patients with Hypertriglyceridemia

  • This was found in the REDUCE-IT study using the drug, Vascepa (an EPA drug)
  • Specifics:
    • All patients were on statins
    • All patients had elevated triglycerides (in the range of 150-500)
    • All patients had risk factors for heart disease
    • Patients were dosed with 4 grams of Vacepa per day
  • Results:
    • 25% reduction in risk for overall cardiovascular events (need for angioplasty, heart attack risk, etc.)
    • A ~15% reduction in triglyceride levels
  • Takeaways: EPA may be an excellent supplement to take if you’re on a statin 

The VITAL Study

  • The main finding: EPA/DHA (~850 mg) reduces heart attack risk by ~20%
  • Specifics:
    • Lovaza was the EPA/DHA drug that was used
    • Participants were relatively healthy

Eskimos Ate a Diet High in Saturated Fat

  • Mostly consisting of seafood (seal blubber, whale meat, and some fish)
  • More specifics:
    • 80% of their calories consisted of fat
    • They ate ~100 grams of fat/day
      • ~6-7% of this was polyunsaturated fat (mainly omega-3-based)
      • ~70% of this was saturated fat
  • One key point: Eskimos had very low heart attack rates 

Comparing Over-The-Counter and Doctor-Prescribed Fish Oils

  • Lovaza is an EPA/EHA drug that lowers triglycerides in individuals with triglyceride levels >500
    • It contains ~85% EPA+DHA (it’s a 1,000 mg capsule of which ~850 mg is EPA+DHA)
  • A key point: Fish oils capsules are not entirely EPA/DHA
    • Typically, only 80% (or less) is DHA/EPA, the rest is a mix of monounsaturated/polyunsaturated fats
  • Peter’s preferred over-the-counter fish oil brands:

Comparing EPA and DHA

  • EPA is heart-healthy
    • How?
      • It makes the blood platelets less “sticky” (and thus reduces blood clots)
      • It reduces inflammation
      • It increases cellular metabolism (it changes membrane fluidity in such a way that the enzymes within the membrane improve cellular metabolism)
      • It increases heart rate variability, a marker of the autonomic nervous system’s control of the heart
    • (DHA is thought to have similar benefits)
  • Supplements richer in EPA (compared to those richer in DHA) are to be better at reducing depressive symptoms

Omega-3 Index

  • EPA/DHA levels are typically measured by measuring concentrations in red blood cells – the measurement is known as “omega-3 index”
    • Red blood cell omega-3 contents correlate with that of the heart, muscle, liver, and small/large intestines
  • On last check, Peter’s red blood cell EPA level was ~2.2%, and his red blood cell DHA level was ~8%
  • The optimal omega-3 index (the amount of EPA plus DHA in red blood cell membranes) is 8-12%
    • The average American has an omega-3 index of around 5%

Measure Your Omega-3 Levels

  • 🎧 “I think measuring blood omega-3 levels are really important. Whether it’s with the omega-3 index, which is the red blood cell EPA/DHA… I think we need to see more doctors measuring omega-3 because it means a lot. I want to encourage people to make the assessment of omega-3 status in their patients as important as measuring cholesterol.” Bill Harris
  • You can order an omega-3 index test through Bill’s company, OmegaQuant
    • Know that it takes ~4 months to achieve a new steady-state after adjusting omega-3 intake

In Fish, the Benefits of EPA/DHA Outweigh the Potentially Adverse Effects of Mercury

  • Fish with the highest levels of EPA/DHA: Salmon, mackerel, herring, and sardines
  • Pregnant women should avoid the following fish due to a mercury concern: Tilefish, swordfish, king mackerel, and shark
    • Why? – Mercury can adversely affect the development of an unborn baby’s brain
  • “I think people get that balance way out of whack; they’re far more concerned about minuscule amounts of mercury, and they forego the good benefits of EPA and DHA in a food like albacore tuna (white tuna) because they’re afraid of small amounts of a toxin. The benefits of eating fish, even if there’s some mercury in it, far outweigh the downside of the mercury.”Bill Harris 

Arachidonic Acid Isn’t as Bad as You Think (And the Problem with the Omega-3 to Omega-6 Ratio)

  • Remember: Our body converts the linoleic acid (an omega-6 fatty acid) we get from food (mainly from vegetable oils like corn and soybean oils) into arachidonic acid
    • BUT: Only ~1% of linoleic acid gets made into arachidonic acid
  • Arachidonic acid does give rise to several inflammatory compounds, but this got taken too far
    • (To add – Arachidonic acid also gives rise to several anti-inflammatory molecules)
    • Because of this, omega-6s became known as pro-inflammatory, whole omega-3s (EPA and DHA) became known as anti-inflammatory, resulting in the whole idea of an omega-6 to omega-3 ratio
  • We can’t assume omega-6s are “bad”
    • Bill recalls a meta-analysis which found that the higher the levels of linoleic acid in the blood, the lower the risk of heart disease and diabetes (arachidonic acid levels were unrelated to either of these outcomes)
      • (Blood linoleic acid levels can only be raised by consuming more linoleic acid-rich vegetable oils)
  • A key point: You can have the same omega-6 to omega-3 ratio with either very high levels of omega-6/omega-3, or very low levels of omega-6/omega-3

So… Worry More About Increasing EPA/DHA Intake Than Decreasing Seed Oil Consumption

  • Seed oils = vegetable oils = canola oil, safflower oil, sunflower oil, corn oil, etc.
    • These types of oils are typically found in salad dressings
  • 🎧 “I don’t like to get too far down the omega-6 pathway other than to say, I don’t think it’s the evil that people think it is. The problem is, we need to get more EPA and DHA in our diet, not necessarily get all hung up on omega-6.”Bill Harris

Additional Notes

  • The adverse effects of smoking seeming to be mitigated by high omega-3 intake
  • Taking fish oil with food increases the absorption
Drive with Dr. Peter Attia : , , , , , , , , , ,
Notes By MMiller

More Notes on these topics

Top Insights and Tactics From

31 Best Podcasts of All Time

FREE when you join over 35,000 subscribers to the
Podcast Notes newsletter

No Thanks