High dose of an n-3 polyunsaturated fatty acid diet lowers activity of C57BL/6 mice

January 1, 2011 Human Health and Nutrition Data 0 Comments

High dose of an n-3 polyunsaturated fatty acid diet lowers activity of C57BL/6 mice

Year: 2011
Authors: Rockett, B.D. Harris, M. Shaikh, S.R.
Publication Name: Prostaglandins,
Publication Details: doi:10.1016/j.plefa.2011.12.001


n3 Polyunsaturated fatty acids (PUFA) are increasingly consumed as food additives and supplements; however, the side effects of these fatty acids, especially at high doses , remain unclear. We previously discovered a high fat n3 PUFA diet made of fish/flaxseed oils promoted significant weight gain in C57BL/ 6 mice, relative to a control, without changes in food consumption. Therefore, here we tested the effects of fee ding m ice high fat (HF) and low fat (LF) n-3 PUFA diets, relative to a purified control diet (CD), on locomotor activity using metabolic cages. Relative to CD, the HF n3 PUFA diet, but not the LF n3 PUF A diet, dramatically reduced ambulatory, rearing, and running wheel activities. Furthermore, the HF n3 PUF A diet lowered the respiratory exchange ratio. The data suggest mixed fish /flaxseed oil diets at high doses could exert some negative side effects and likely have limited therapeutic applications. (Authors abstract)
Generally, dietary studies evaluating n3 PUFA efficacy in differing model systems have relied on low doses of n3 PUFAs. With animal studies, investigators have commonly used  about 5% (weight/weight) fish or flaxseed oil as intervention, corresponding to approximately 2 to 6% of total energy as n3 PUFAs. Overall, very little is known about the effects of high doses of n3 PUFAs, which could have a unique therapeutic niche or could exert negative side effects. Therefore, the objective of this study was to determine if short term dietary consumption of a high dose of n3 PUFAs could lower energy expenditure prior to any large differences in body weight. Studies were conducted in comparison to a low fat (LF) purified mouse control diet (CD) and a LF n3 PUFA diet. A high dose of n3 PUFAs lowered mouse activity. The reduction in activity with the HF n3 PUFA diet was consistent with a previous study demonstrating this diet promoted significant body weight gain in mice. The LF n3 PUFA diet also had a tendency to reduce energy expenditure in some of the measurements. This raises the question of whether mixing fish and flaxseed oils has some potential effect that does not promote body weight loss and perhaps even increase body weight gain after long-term feeding due to a reduction in activity.  Overall, the potential therapeutic value of high n3 PUFA doses appears very limited. The data did suggest high doses of n3 PUFAs are effective in their accepted role of lowering triglycerides (TG) even when they lower activity. There are a few cases where an increase in body fat mass due to lower activity could have some value. Perhaps short-term intervention with a high dose of fish/flaxseed oils would assist in lowering TGs and lowering energy expenditure. Further functional and mechanistic studies in animals and eventually humans would be required to address at what specific dose, composition of n3 PUFAs, and duration could these fatty acids be utilized for these cohorts. (Editors comments)

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