A study among Yup’ik Eskimos in Alaska suggests that diets high in omega-3 fats helps prevent obesity-related chronic diseases such as diabetes and heart disease.
On average, Yup’ik Eskimos consume 20 times more omega-3 fats from fish than people in the lower 48 states.
The study was led by researchers at Seattle’s Fred Hutchinson Cancer Research Center and the University of Alaska-Fairbanks (Makhoul Z et al. 2011).
“Because Yup’ik Eskimos have a traditional diet that includes large amounts of fatty fish and have a prevalence of overweight or obesity that is similar to that of the general U.S. population, this offered a unique opportunity to study whether omega-3 fats change the association between obesity and chronic disease risk,” said lead author Zeina Makhoul, Ph.D.
As Makhoul noted, “Residents of Yup’ik villages joined this research because they were interested in their communities’ health and were particularly concerned about the health effects of moving away from their traditional ways and adopting lifestyle patterns similar to those of residents in the lower 48 states.” (FHCRC 2011)
What the study showed
The researchers analyzed data collected from 330 people living in the Yukon Kuskokwim Delta region of southwest Alaska, 70 percent of whom were overweight or obese.
The participants provided blood samples and diet and health information via in-person interviews and questionnaires. Their height, weight, percent body fat, blood pressure, and physical activity were also measured.
The median age of the participants was 45 and slightly more than half were female. The women were more likely than the men to be overweight or obese, and body mass index (height-to-weight ratio) for all increased with age.
The omega-3s the researchers measured in participants’ blood were the long-chain kind (DHA and EPA) found only in seafood … especially in fatty fish like salmon, sardines, sablefish, and tuna.
As expected, the obese participants with low blood levels of DHA and EPA had undesirably high levels of blood triglycerides and C-reactive protein (CRP), a measure of inflammation, which raise the risk of heart disease and, possibly, diabetes.
“These results mimic those found in populations living in the Lower 48 who have similarly low blood levels of EPA and DHA,” said senior author Alan Kristal, Dr. P.H. “However, the new finding was that obesity did not increase these risk factors among study participants with high blood levels of omega-3 fats.” (FHCRC 2011)
“Interestingly, we found that obese persons with high blood levels of omega-3 fats had triglyceride and CRP concentrations that did not differ from those of normal-weight persons,” Makhoul noted. “It appeared that high intakes of omega-3-rich seafood protected Yup'ik Eskimos from some of the harmful effects of obesity.” (FHCRC 2011)
We should note in human clinical studies, omega-3s do not lower CRP levels very much, even though they do reduce other markers of inflammation (Chan EJ, Cho L 2009).
It may be that in obese people, omega-3 rich diets simply limit the rise in CRP levels seen in obese people with low omega-3 intakes.
Even though Yup’ik Eskimos have overweight/obesity levels similar to those in the U.S. overall, their prevalence of type 2 diabetes is significantly lower – 3.3 percent versus 7.7 percent.
“While genetic, lifestyle and dietary factors may account for this difference,” Makhoul said, “it is reasonable to ask, based on our findings, whether the lower prevalence of diabetes in this population might be attributed, at least in part, to their high consumption of omega-3-rich fish.” (FHCRC 2011)
Based on these findings, should overweight and obese people concerned about their chronic disease risk start popping fish oil supplements or eat more fatty fish?
“There are good reasons to increase intake of fatty fish, such as the well-established association of fish intake with reduced heart disease risk,” Makhoul added. (FHCRC 2011)
Before making a public health recommendation, the researchers said that a randomized clinical trial is needed to test whether increasing omega-3 fat intake significantly reduces the bad effects of obesity on inflammation and blood triglycerides.
As Dr. Makhoul said, “If the results of such a trial were positive, it would strongly suggest that omega-3 fats could help prevent obesity-related diseases such as heart disease and diabetes.” (FHCRC 2011)
Chan EJ, Cho L. What can we expect from omega-3 fatty acids? Cleve Clin J Med. 2009 Apr;76(4):245-51. Review.
Fred Hutchinson Cancer Research Center (FHCRC). Eskimo study suggests high consumption of omega-3s reduces obesity-related disease risk. March 24, 2011. Accessed at http://www.fhcrc.org/about/ne/news/2011/03/24/omega-3-fats-study.html
Makhoul Z, Kristal AR, Gulati R, Luick B, Bersamin A, Boyer B, Mohatt GV. Associations of very high intakes of eicosapentaenoic and docosahexaenoic acids with biomarkers of chronic disease risk among Yup'ik Eskimos. Am J Clin Nutr. 2010 Mar;91(3):777-85. Epub 2010 Jan 20.
Makhoul Z, Kristal AR, Gulati R, Luick B, Bersamin A, O'Brien D, Hopkins SE, Stephensen CB, Stanhope KL, Havel PJ, Boyer B. Associations of obesity with triglycerides and C-reactive protein are attenuated in adults with high red blood cell eicosapentaenoic and docosahexaenoic acids. Eur J Clin Nutr. 2011 Mar 23. [Epub ahead of print]
McEwen B, Morel-Kopp MC, Tofler G, Ward C. Effect of omega-3 fish oil on cardiovascular risk in diabetes. Diabetes Educ. 2010 Jul-Aug;36(4):565-84. Epub 2010 Jun 9.
Roth EM, Harris WS. Fish oil for primary and secondary prevention of coronary heart disease. Curr Atheroscler Rep. 2010 Jan;12(1):66-72. Review.
Mori TA, Beilin LJ. Omega-3 fatty acids and inflammation. Curr Atheroscler Rep. 2004 Nov;6(6):461-7. Review.