Why fish oil protects against diabetes

You've heard that fish oil is good for you for a lot of reasons, but nobody ever knew exactly why. Now some scientists have discovered that omega-3 fatty acids reduce inflammation that can lead to diabetes.

By studying fat tissue in the mice consuming fish oil, researchers found that omega-3 fatty acids seem to act on a particular receptor on cells, GPR120, which, when activated, blocks inflammatory processes.
Chronic inflammation can lead to insulin resistance, a precursor to diabetes.

"If we can fix the inflammation part, it's possible that we could prevent insulin resistance or even ameliorate diabetes," said study co-author Saswata Talukdar, a post-doctoral fellow at University of California, San Diego.

Here's more of the science.

Fat tissue contains macrophages, immune system cells that gobble up bacteria, clear out cellular debris and help rid the body of infection. But macrophages found in fat can also have a downside. When macrophages "go rogue," Talukdar said, they produce cytokines and other pro-inflammatory proteins.

A build up of cytokines can result in a "signaling cascade," that eventually leads to low-grade, chronic inflammation and insulin resistance, Talukdar said. In people with insulin resistance, cells are unable to properly utilize insulin, which regulates blood sugar levels. That can lead to type 2 diabetes, which is often linked to obesity.

While studying fat tissue, researchers found that omega-3 fatty acids, especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), acted on the specific receptor, GPR120 (for G protein-coupled receptor), found on the surface of macrophages.

The GPR120 receptor is found only on pro-inflammatory macrophages in mature fat cells, according to the study. Exposure to omega-3 fatty acids activates the receptor, which reduces the runaway pro-inflammatory cascade.

This study focused on diabetes, but omega-3 fatty acids may also help with other diseases in which inflammation plays a role, including cancer and cardiovascular disease, researchers said.


Being appropriately cautious, the researchers said it is not guaranteed that the same result would be found in humans.

The National Institutes of Health has a lot of information on omega-3s here, including dosing information.

For healthy adults with no history of heart disease, the American Heart Association recommends eating fish at least two times per week. In particular, fatty fish are recommended, such as anchovies, bluefish, carp, catfish, halibut, herring, lake trout, mackerel, pompano, salmon, striped sea bass, tuna (albacore), and whitefish. It is also recommended to consume plant-derived sources of α-linolenic acid, such as tofu/soybeans, walnuts, flaxseed oil, and canola oil. The World Health Organization and governmental health agencies of several countries recommend consuming 0.3-0.5 grams of daily EPA + DHA and 0.8-1.1 grams of daily α-linolenic acid. A doctor and pharmacist should be consulted for dosing for other conditions.