Some studies show that fish oil protects humans against type-2 diabetes [J Am Diet Assoc. 2010 Jul; 110(7): 1018-26.], others show that a diet that is rich in fish fatty acids actually raises the chance of diabetes developing [Diabetes Care. 2012 Apr; 35(4): 918-29.]. Epidemiologists at the University of Pittsburgh in the US have probably discovered the reason why different studies come to different conclusions. A diet that is rich in fish fatty acids only protects against diabetes if you also do large amounts of exercise.
Some studies show that fish oil protects humans against type-2 diabetes [J Am Diet Assoc. 2010 Jul; 110(7): 1018-26.], others show that a diet that is rich in fish fatty acids actually raises the chance of diabetes developing [Diabetes Care. 2012 Apr; 35(4): 918-29.]. Epidemiologists at the University of Pittsburgh in the US have probably discovered the reason why different studies come to different conclusions. A diet that is rich in fish fatty acids only protects against diabetes if you also do large amounts of exercise.
Some studies show that fish oil protects humans against type-2 diabetes [J Am Diet Assoc. 2010 Jul;110(7):1018-26.], others show that a diet that is rich in fish fatty acids actually raises the chance of diabetes developing [Diabetes Care. 2012 Apr;35(4):918-29.]. Epidemiologists at the University of Pittsburgh in the US have probably discovered the reason why different studies come to different conclusions. A diet that is rich in fish fatty acids only protects against diabetes if you also do large amounts of exercise.
Ten years ago, articles on the health benefits of fish oil appeared every week in the media. Now in 2014 the same fish oil is regarded with disdain. This is the result of a couple of large studies in which the health effects of fish fatty acids have been shown to be disappointing or downright negative. The same is also the case for epidemiological studies on the effects of fish fatty acids such as DHA and EPA [structural formulas shown above] on the body’s glucose-insulin management and the likelihood of developing type-2 diabetes.
Some studies show that fish oil protects humans against type-2 diabetes [J Am Diet Assoc. 2010 Jul; 110(7): 1018-26.], others show that a diet that is rich in fish fatty acids actually raises the chance of diabetes developing [Diabetes Care. 2012 Apr; 35(4): 918-29.]. Epidemiologists at the University of Pittsburgh in the US have probably discovered the reason why different studies come to different conclusions. A diet that is rich in fish fatty acids only protects against diabetes if you also do large amounts of exercise.
Nevertheless, there are animal studies and human lab studies that have shown that fish oil supplementation can improve the functioning of insulin in the body. The indications that fish oil enhances the effect of insulin are just as strong as the indications that physical exercise enhances the functioning of insulin.
The effects of exercise and fish-oil supplementation resemble each other, but work through different mechanisms. Exercise stimulates the muscle cells’ glucose uptake because it activates the glucose transporter GLUT4; fish fatty acids oxidise in the body into substances that activate the PPAR proteins. PPAR is a molecular sensor that cells use to sense fat. Activating PPAR boosts cells’ burning of fatty acids and their insulin sensitivity.
If your insulin system is working well your cholesterol levels will be ok, and you will be less likely to develop cardiovascular disease.
That’s why the epidemiologists at the University of Pittsburgh examined 344 Americans aged between 30 and 54 to see whether there was a link between a high fish-oil intake and a lifestyle that included lots of exercise on the one hand, and insulin sensitivity and cardiovascular health on the other.
The researchers discovered that in half of the participants who got relatively large amounts of exercise [and burned more than 2093 kcal per week as a result of exercise] the cardiovascular health was better the more fish fatty acids they had in their blood. The same was the case for insulin sensitivity. Among the participants who exercised a lot, their insulin sensitivity was higher the more fish fatty acids they had in their body.
The researchers suspect that fish oil not only makes cells more sensitive to insulin, but that it also reduces the secretion of insulin. It may be that the latter effect also weighs heavier in obese, non-active people than the previous, and that it therefore can cause a kind of pseudo-diabetes. But in people who are active, and who make their cells more sensitive to insulin through exercising more, a diet that is rich in fish oil has a positive effect.
Concurrent physical activity modifies the association between n3 long-chain fatty acids and cardiometabolic risk in midlife adults.
Muldoon MF, Erickson KI, Goodpaster BH, Jakicic JM, Conklin SM, Sekikawa A, Yao JK, Manuck SB.
Abstract
Greater consumption of n3 (?3) polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can reduce risk for cardiovascular disease events, yet their effects on metabolic risk factors and diabetes remain unclear. This cross-sectional study used a community volunteer sample to test whether the associations between n3 fatty acids and cardiometabolic risk vary as a function of physical activity. Participants were 344 generally healthy adults, 30-54 y of age, not taking fish oil supplements or confounding medications. Serum phospholipid EPA and DHA were used together (EPA+DHA) as a biomarker of n3 fatty acid exposure. Cardiometabolic risk was calculated as a continuous measure based on standardized distributions of blood pressure, waist circumference, HDL cholesterol, triglycerides, glucose, and a simple count of risk factors. Insulin resistance was estimated from the homeostatic model assessment. Physical activity was found to predict cardiometabolic risk (P ? 0.02) and insulin resistance (P ? 0.02) and to moderate the association between EPA+DHA and both cardiometabolic risk (P-interaction ? 0.02) and insulin resistance (P-interaction ? 0.02). Specifically, higher EPA+DHA was associated with lower cardiometabolic risk and insulin resistance in persons engaged in regular physical activity but not in relatively inactive individuals. These findings were noted in several components of cardiometabolic risk, in men and women separately, and in models adjusted for overall diet quality. In midlife adults, habitual physical activity may be necessary to unmask the salutary effects of n3 fatty acids on cardiometabolic risk and insulin resistance.
PMID: 23884386 [PubMed – indexed for MEDLINE] PMCID: PMC3743273 [Available on 2014/9/1]
