#83 – Bill Harris, Ph.D.: Omega-3 fatty acids

KEYPOINTS

• 01

  Harris has studied omega-3s for over 40 years

  After a PhD in nutrition in 1978, Harris did his postdoc with Bill Connor in Portland, Oregon. He has published over 300 papers on EPA and DHA, and founded OmegaQuant about 10 years before this conversation. Attia was introduced to him in 2011 through Tom Dayspring. Keep his testing company in mind when weighing his advice on testing.

• 02

  How fatty acids are named

  The notation gives the number of carbons and double bonds: palmitic acid is 16:0 (saturated), oleic acid is 18:1. 'Omega' (or n-) tells you where the first double bond sits, counted from the tail end, so oleic is omega-9. Linoleic acid (LA, 18:2) is the main omega-6. EPA has 20 carbons and five double bonds, and DHA has 22 carbons and six. Fish oils are rich in omega-3s, and vegetable oils such as safflower, corn and sunflower in omega-6s.

• 03

  The 1980 salmon-oil study found an unexpected effect

  Participants drank salmon oil straight, about 25 g of EPA plus DHA a day. Triglycerides fell from about 100 to 75 mg/dL, and cholesterol dropped modestly (around 250 to 230). Nobody had known fish oil lowered triglycerides, and the paper came out just as the US was entering its 15–20-year era of fat phobia. In patients with extremely high triglycerides, 18–20 g a day took levels from around 2,000 down to 250. In some people, LDL rose (for example from 120 to 140–150).

• 04

  Typical intake is tiny compared with traditional fish-eating diets

  The average American gets about 100–250 mg (roughly 0.15 g) of EPA plus DHA a day, out of 80–100 g of total fat. When Bang and Dyerberg studied Greenland Inuit in the 1970s, they documented about 6–7 g a day. The body converts little plant omega-3 (ALA) into EPA and DHA: even 12 g of ALA barely raises EPA.

• 05

  The omega-3 index tracks status better than plasma

  The index measures EPA plus DHA as a percentage of red blood cell membrane fatty acids. It reflects most tissues, including the heart, which Harris validated using biopsies from heart-transplant patients, though it reflects the adult brain less well. Harris targets 8–12%. The average American is around 4–5%, and some non-supplementers are at 2%. Attia's own index was about 10–11% (EPA 2.2%, DHA 8%). Harris has seen no clear adverse effects at higher levels. International bodies consider up to 5–6 g a day of EPA plus DHA safe.

• 06

  REDUCE-IT: 4 g a day of purified EPA cut cardiovascular events by about 25%

  The trial included about 8,000 statin-treated patients with triglycerides of roughly 150–500 and other risk factors. They received 4 g a day of EPA ethyl ester (Vascepa) or a mineral-oil placebo. Events fell by about 25%. Attia notes that was a bigger effect than in the PCSK9-inhibitor trials, though REDUCE-IT also ran longer, about five years against roughly 2.2 for FOURIER and 2.4 for ODYSSEY. Critics question whether mineral oil was a truly neutral placebo. Japan's JELIS trial, published in 2007, had also used an EPA drug.

• 07

  VITAL found little effect at a low dose in low-risk people

  Reported at the same meeting as REDUCE-IT, VITAL gave about 20,000–25,000 relatively healthy Americans one Lovaza capsule a day (about 850 mg EPA plus DHA). It missed its primary endpoint but showed roughly 20% fewer heart attacks, including fatal ones. Harris says that with low-risk participants and about a fifth of the REDUCE-IT dose, the two trials can't be directly compared.

• 08

  Harris doesn't think omega-6 is the villain

  He dislikes the omega-6 to omega-3 ratio, because the same ratio can mean very high or very low levels of both, and it assumes omega-6 is bad. Americans eat about 15 g of LA a day but only about 0.1 g of arachidonic acid. Tissue arachidonic acid barely shifts with intake, which Attia calls a buffer or 'capacitor'. Harris is sorry to see oils bred to be low in LA (safflower went from 77% to about 15%) because evidence suggests higher LA is linked to lower risk. Attia pushes back, pointing out that humans ate little seed oil for most of history.