Omega-3 helps reduce weight in obese mice

A diet high in fat but enriched with EPA (eicosapentaenoic acid) supplements has been shown to decrease the weight of obese laboratory mice. In addition, this omega-3 appears to reduce both the size of adipose tissue cells and its inflammation

This was revealed by researchers at Texas Tech University in Lubbock, USA, in a study published in the Journal of Nutrition. 

Obesity: not just a weight problem

Obesity is a major global public health problem: its prevalence is steadily and alarmingly increasing in Western and low- and middle-income countries. Obesity is associated with an increase in adipose tissue, the main repository of lipids in humans, consisting of the 'collection of numerous cells called adipocytes. The condition is characterized by 'increased blood pressure, blood sugar, and inflammation. So it is an important risk factor for various chronic diseases, such as type 2 diabetes mellitus, cardiovascular disease, and cancer. Research to develop nutritional interventions to prevent or treat obesity and its associated diseases is therefore badly needed. The same Texas scientists have previously demonstrated the ability of omega-3 EPA to reduce insulin resistance and inflammation, in obese laboratory mice.

EPA reduces macrophages, cells of inflammation

The study analyzed adipose tissue taken from animals subjected to different types of feeding for eleven weeks: one group had been on a low-fat diet, another on a high-fat diet, and a third on a high-fat but EPA-containing diet. Finally, one group of animals was fed a high-fat diet for six weeks followed by the 'addition of EPA for only five weeks. When the data were analyzed, it was found that, compared with the mice that had been on a high-fat diet of fat alone, the diet combined with EPA caused a decrease in body weight, amount of fat, adipocyte size, and also was evident to be less infiltration into the adipose tissue of macrophages, the cells of the immune system a sign of inflammation. 

In contrast, there were no significant differences between mice fed a high-fat diet and those that had been fed the same diet followed by EPA supplementation for six weeks. This second group, however, showed a reduction in mean adipocyte size and macrophage infiltration, suggesting that EPA might prevent adipose tissue inflammation and growth, which are typical features of feeding excess lipid. Metabolomic analyses conducted on adipose tissue and bioenergetic tests also showed that EPA could also regulate the function of mitochondria, the cellular organelles that produce energy.

EPA counteracts the effects of a high-fat diet 

According to the researchers who conducted the study, these data demonstrate that EPA supplements can ameliorate the damaging effects of excess lipids through their ability to increase oxygen consumption and 'fatty acid oxidation, reduce adipocyte size, and adipose tissue inflammation. Future studies will still be needed to elucidate the mechanisms of cell signaling and those mediating the effects of EPA. 

 Source: Monique J LeMieux, Nishan S Kalupahana, Shane Scoggin, and Naima Moustaid-Moussa "Eicosapentaenoic Acid Reduces Adipocyte Hypertrophy and Inflammation in Diet-Induced Obese Mice in an Adiposity-Independent Manner" J. Nutr. 2015 jn.114.202952; first published online December 31, 2014.