The review, published in The Journal of Nutritional Biochemistry, suggests that omega-3 fatty acids promote changes in fat tissue (adipose tissue) metabolism, which may bring about changes in cellular signaling and secretion, contributing to improvements in glucose and lipid metabolism.
“It has been well established that adipose tissue not only is an inert storage organ but also secretes many bioactive substances,” said the authors, led by Dr Michael Puglisi from Vanderbilt University, USA.
“Various reports indicate that improved adipose (AT) tissue storage and secretory functions and a reduction in AT-specific inflammation have a central role in mediating the beneficial effects of fish oil against the risk factors of metabolic syndrome” added the reviewers.
Commenting independently, Harry Rice, PhD, V.P regulatory & scientific affairs for the omega-3 trade association GOED (Global Organization for EPA and DHA Omega-3s) told NutraIngredients that the study provided a “well-done, not to mention, much needed review of the existing gaps in the area.”
Rice explained that although there is still a lot that is unknown with regard to the mechanisms of the omega-3 response; based on the information in the current review, he “can’t help but believe that we will likely see some beneficial pharmacological agents emerge in the very near future.”
The authors said that obesity has led to “alarming increases in the incidence of many chronic diseases, including type 2 diabetes and cardiovascular disease.”
They added that because over nutrition leads to obesity, the manipulation of dietary nutrient content “is a logical means of alleviating this problem.”
Along with lowering of plasma triglycerides, omega-3 rich fish oils have been found to improve insulin sensitivity and reduce blood pressure, inflammation, thrombosis and arrhythmia – contributing to a role in lowering the risk of cardiovascular disease (CVD) and diabetes.
The authors said that the liver mediated (hepatocentric) and blood lipid mediated (hypolipidemic) effects of fish oil have been extensively evaluated, “and undoubtedly play a major part in the reduction of risk for chronic disease.”
But they noted that the potential adipose mediated (adipocentric) beneficial effects of fish oil have not been fully explored.
“Evidence points to the role of adipose tissue (AT) in fish oil-mediated improvements on features of metabolic syndrome, such as insulin resistance,” said Dr Puglisi and his colleagues.
The new review focused on the mechanistic details of the cellular signaling process that modulates AT storage, and the responses to omega-3 fatty acids that modulate a response to metabolic syndrome.
Adipose tissue plays an important role in regulating lipid homeostasis by storing excess energy in the form of triglycerides.
“Thus, the lipid storage function of AT is critical in buffering the daily influx of dietary fatty acids entering the circulation,” said the authors.
Adipose tissue secretes a variety of immune cell modulating molecules – known as adipokines. Fish oil has been associated “with remarkable changes in the plasma levels of two key adipokines, adiponectin and leptin,” they added.
Puglisi and co-workers explained that recent attention has been focused on the contribution of adiponectin in omega-3 mediated improvements in markers of metabolic syndromes. However, they added that emerging evidence has indicated a potential role of leptin in modulating metabolic syndrome from omega-3 intake.
“In addition to improving the storage and secretory functions of adipose tissue, fish oil, and the omega–3 fatty acids found in fish oil, have been shown to reduce inflammation in adipose tissue,” said the authors.
They explained that there is evidence to suggest such effects may be (at least in part) a result of modulation of signaling receptors such the peroxisome proliferator-activated receptor gamma (PPAR-gamma) or the inhibition of the Toll-like receptor 4 (TLR4)
Puglisi and his colleagues said there is “compelling evidence that fish oil mediates its beneficial effects on metabolic syndrome by improving adipose tissue storage and secretory functions and by reducing inflammation.”
Future studies are needed “to understand the mechanisms, in particular the role of PPAR-gamma, in modulating leptin signaling upon fish oil feeding,” said the authors.
Source: The Journal of Nutritional Biochemistry
Volume 22, Issue 2, Pages 101-108, doi: 10.1016/j.jnutbio.2010.07.003
“The role of adipose tissue in mediating the beneficial effects of dietary fish oil”
Authors: M.J. Puglisi, A.H. Hasty, V. Saraswathi