In many areas of biological science and medicine, uncertainty and even controversy remains.
It has practically become common knowledge that taking fish oil is “good for you.” Many studies have confirmed diets high in omega-3 polyunsaturated fatty acids reduce risk of cardiovascular events and lower triglyceride levels. There are reports that fish oil reduces inflammation in the body and lowers the risk of many related disease such as even Alzheimer’s.
A new study in mice however leads to the surprising conclusion that regular fish oil consumption actually may reduce lifespan.
The researchers fed a special genetic variety of mice diets that either included 5% daily fish oil + 5% safflower oil or instead 10% daily safflower oil. The mice used were SAMP8 mutants that were bred to have accelerated aging and shortened lifespans. These mice are often used in longevity experiments because their average lifespans are only typically one year. They were fed these diets from 12 weeks of age on.
The researchers hypothesized since fish oil is so easily oxidized it may lead to greater oxidative stress within cells and thus actually accelerate aging, a process believed in part due to accumulative damage from oxidative stress. Safflower oil is an omega-6 fatty acid and is not readily oxidized – it could have beneficial effects without causing oxidative stress.
Sure enough, the study showed that the mice fed fish oil lived an average of 48.4 weeks while the mice fed pure safflower oil lived an average of 56.3 weeks, with all other conditions kept equal between the groups.
It was also shown that there were higher levels of oxidative stress in the fish-oil fed animals. The authors noted these levels of fish oil is equivalent to what people would be exposed to taking daily fish oil supplements, or eating a lot of fish, and caution their findings may extrapolate to humans.
The scientists conclude:
These ﬁndings suggest that intake of ﬁsh oil increases oxidative stress, decreases cellular function, and causes organ dysfunction in SAMP8 mice, thereby promoting aging and shortening the lifespan of the mice.