A problem with much nutritional epidemiology, as I blogged earlier, is “the narrow range of intakes within a given population”. For this reason Ernst Wynder thought it better to make between-country comparisons. Of course different countries differ in many ways other than the ones you care about. A solution to both problems is to study an unusual country — a country with a wide range of intakes of the nutrient you care about — in depth.
This is what a new paper about omega-3 has done. The researchers measured the blood of about 400 Eskimos, who had a much larger range of omega-3 levels in their blood than Americans or Europeans. The results aren’t easy to sum up because there were plenty of non-linear associations. Here’s what I think is their most interesting result:
Associations of EPA and DHA with C-reactive protein were inverse and nonlinear: for EPA, the association appeared stronger at concentrations >3% of total fatty acids; for DHA, it was observed only at concentrations >7% of total fatty acids.
C-reactive protein is a marker of inflammation. Notice that, due to the details, the combination of (a) high intakes and (b) a wide range of intakes makes this correlation much easier to see. This result suggests that EPA and DHA (or something correlated with them) indeed reduce inflammation, as is often proposed. Perfectly consistent with my dentist’s observation that my gums looked a lot better (less inflamed) right after I started drinking 4 T/day flaxseed oil. Plus a reader’s observation that his sports injuries healed much faster after he started drinking 4 T/day flaxseed oil. (And here.)
Previous epidemiology had had a hard time detecting the anti-inflammatory correlation of omega-3s. My self-experimentation plus other people’s observations made it obvious there was something to it (and provided experimental evidence for causality: more omega-3, less inflammation). Better epidemiology has now supported this.
Thanks to Dave Lull.
I drink about three large cups of coffee per day. My dental hygienist has always remarked about the large amount of staining that she finds on my teeth (hence, I get my teeth cleaned four times per year, instead of the more-usual two). Since I started taking 3 1/2 tablespoons of flax oil every day, my teeth have become much less stained than usual. I haven’t made any other changes in my oral hygiene. The last time I went to the dentist, the hygienist was amazed at the difference. I wonder if the staining is related to some sort of inflammatory response?
By the way, Seth — what’s your view on taking DHA supplements (in addition to the flax oil)?
I don’t have an opinion about DHA supplements. Haven’t tried them.
Your story about teeth staining is very interesting. Recently I noticed my teeth stained, which surprised me. I assumed it was due to drinking ice tea, but this doesn’t make much sense since I had drunken lots of ice tea in the past without teeth staining. I had been continuing to take 3 T flaxseed oil every day — but the flaxseed oil is old (I was in China) and possibly degraded. I had other reasons to suspect degradation and now you’ve given me another one.
Seth,
Do you take lignan added Flaxseed oil? As I’ve heard (from Dr. Weil) that without the lignan it could be problematic for men in particular and could increase likelihood of prostate cancer.
I’ve found there to be a high correlation between omega3 intake and my acne. First thing I did was stop eating omega6 foods, which reduced the acne significantly. Eating lots of sardines in olive oil helped, olive oil alone was inflammatory. Using flax was OK, but I don’t want to take tablespoons of flax per day. Ordinary cod liver oil didn’t help at all, not that I could tell. The fermented cod liver oil, using gummi fish, was the most effective of all.
I don’t consume much omega-3 because I hate the smell and taste of fish (and fish oil), but I do consume tons of nuts and seeds (some walnuts that have ALA omega-3, but also lots of omega-6, and no flax) that are rich in omega-6 and my most recent CRP was .18 mg/L. The reference range is less than 3 mg/L.
Chris, no I don’t take the version with lignans. Thanks for alerting me.
vic, everyone else says omega-6 is proinflammatory. You seem to be saying the opposite. Am I misunderstanding?
I’ve never seen good evidence that omega-6 are pro-inflammatory in people. Almost every epidemiologic study I’ve seen that looks at nuts and linoleic acid (the primary omega-6 fatty acid in vegetable oil) finds a robust inverse association between consumption of nuts (and/or linoleic acid) and coronary disease, cancer, and mortality.