Eskimos, Heart Disease, and Omega-3s: The Plot Thickens
David Marcus made the following comment on an earlier post:
It’s a myth that Eskimos have low rates of heart disease. Actually, recent studies have shown they have high rates of cardiovascular disease (50% higher than western populations) despite diets that are very high in fatty fish.
Mr. Marcus makes a very good point (and it is wonderful to get such informative feedback). Myth is wrong. A Greenland doctor’s casual observation — Eskimos almost never died of heart attacks — was confirmed by a detailed study, published in Acta Medica Scandinavica in 1980. A recent study, however, found this:
OBJECTIVES: The thirty-year-old hypothesis that omega-3 fatty acid (FA) may “reduce the development of thrombosis and atherosclerosis in the Western World” still needs to be tested. Dyerberg-Bang based their supposition on casual observations that coronary atherosclerosis in Greenlandic Inuit was ‘almost unknown’ and that they consumed large amounts of omega-3 FAs. However, no association was demonstrated with data. STUDY DESIGN: Cross-sectional study. METHODS: 454 Alaskan Eskimos were screened for coronary heart disease (CHD), using a protocol that included ECG, medical history, Rose questionnaire, blood chemistries, including plasma FA concentrations, and a 24-hour recall and a food frequency questionnaire assessment of omega-3 FA consumption. RESULTS: CHD was found in 6% of the cohort under 55 years of age and in 26% of those > or = 55 years of age. Eskimos with CHD consume as much omega-3 FAs as those without CHD, and the plasma concentrations confirm that dietary assessment. CONCLUSIONS: Average daily consumption of omega-3 FAs among Eskimos was high, with about 3-4 g/d reported, compared with 1-2 g/d used in intervention studies and the average consumption of 0.2 g/d by the American population. There was no association between current omega-3 FA consumption/blood concentrations and the presence of CHD.
A well-written abstract, by the way.
Science is like a game of telephone. It would be truly weird if the initial observation was wrong, given that it was later confirmed in detail and productively followed up — and no one doubts that omega-3 increases clotting time. But “replications” are never exact. This study, for example, measured “in vivo” CHD, whereas the initial observation was about causes of death. The group of Eskimos studied is probably different; and their lifestyle, especially their diet, may have changed substantially in the last 30 years. On the other hand, these new observations are consistent with the great difficulty there has been in confirming the idea that omega-3 fats reduce heart disease.
December 1st, 2007 at 12:05 pm
Eskimos’ fish consumption with consequent high protein intake is also responsible for their high rates of osteoporosis.
December 2nd, 2007 at 4:41 am
I also noticed that in another post you mentioned the Israeli Paradox, where Jewish Israelis who consume polyunsaturated fats are supposed to have higher coronary disease rates than Non-Jewish Israelis who consume monounsaturated fats. A few recent studies have actually found that Arab Israelis have much higher heart disease risk than Jewish Israelis - among the highest rates in the world in fact - despite the fact that they drown their food in olive oil. See, for instance,
http://ije.oxfordjournals.org/cgi/content/full/35/2/448
December 2nd, 2007 at 9:33 pm
marcus’s authority re high rates of heart disease in Palestinians is consistent with Kendrick explanation, i.e., that extreme stress is the cause of heart disease (altho i tend to think that no single factor is absolutely controlling.
December 8th, 2007 at 9:40 pm
Seth, I think there is more to be done in testing polyunsaturates vs monounsaturates and saturates. Do you think you can perform some more tests on flax vs butter and flax vs coconut oil (for cognitive tasks). This might give us more light on if the weston a price crew was on to something. Also, are you familiar was ray peats work on the subject. If the weston price crew is correct that saturates allow for better functioning of omega 3 and 6 - and this is said on both weston a prices website and ray peats- then your test of flax vs butter and flax vs coconut oil- should show the saturates coming on top- or at least being better over time. There main argument is that saturates promote better brain functioning- lets look at this! Your tests vs olive oil didn’t say much because both the above camps say that monounsaturate consumption doesn’t nessasarily lead to better brain function.