A study of the metabolic effects of omega-3 fatty acids, especially DHA, concludes that these compounds may have an even wider range of biological impacts than previously considered, and suggests they could be of significant value in the prevention of fatty liver disease.
The research, done by scientists at Oregon State University (OSU) and several other institutions, was one of the first of its type to use “metabolomics,” an analysis of metabolites that reflect the many biological effects of omega-3 fatty acids on the liver. It also explored the challenges this organ faces from the “Western diet” that increasingly is linked to liver inflammation, fibrosis, cirrhosis and sometimes liver failure.
The results were surprising, researchers say.
Effects of DHA Omega-3 Studied
Researchers studied the effects of DHA in the livers of mice in which nonalcoholic steatohepatitis (NASH), commonly called fatty-liver disease, was induced by a standard Western diet consumed for 16 weeks. Some of the animals received EPA and/or DHA along with the diet and others received olive oil.
Supplementation with DHA partially or totally prevented metabolic damage through those pathways often linked to the Western diet – excessive consumption of red meat, sugar, saturated fat and processed grains.
Supplementation with DHA was more effective than EPA at normalizing NASH gene expression markers and other factors altered by the western diet. The team found that DHA affected all major metabolic pathways to exert a protective effect against the diet’s ability to induce the disease. The researchers observed changes in vitamin, carbohydrate and lipid metabolism, as well as protein function.
The findings were published last month in PLOS One, an online professional journal.
“We were shocked to find so many biological pathways being affected by omega-3 fatty acids,” remarked study coauthor Donald Jump, who is a professor at the Oregon State University College of Public Health and Human Sciences. “Most studies on these nutrients find effects on lipid metabolism and inflammation. Our metabolomics analysis indicates that the effects of omega-3 fatty acids extend beyond that, and include carbohydrate, amino acid and vitamin metabolism.”
“A lot of work has been done on fatty liver disease, and we are just beginning to explore the potential for DHA in preventing or slowing disease progression,” Dr Jump noted.
“Fish oils, a common supplement used to provide omega-3, are also not prescribed to regulate blood glucose levels in diabetic patients,” he added. “But our studies suggest that DHA may reduce the formation of harmful glucose metabolites linked to diabetic complications.”
DHA Omega-3 Effects Targeted
Omega-3 fatty acids have been the subject of much recent research, often with conflicting results and claims. Possible reasons for contradictory findings, OSU researchers say, are the amount of supplements used and the relative abundance of two common omega-3s – DHA and EPA. Studies at OSU have concluded that DHA has far more ability than EPA to prevent the formation of harmful metabolites. In one study, it was found that DHA supplementation reduced the proteins involved in liver fibrosis by more than 65 percent.
The American Liver Foundation has estimated that about 25 percent of the nation’s population, and 75 percent of those who are obese, have nonalcoholic fatty liver disease. This can progress to nonalcoholic steatohepatitis, cirrhosis and cancer.
This study established that the main target of DHA in the liver is the control of inflammation, oxidative stress and fibrosis, which are the characteristics of more progressively serious liver problems. Omega-3 fatty acids appear to keep cells from responding to and being damaged by whatever is causing inflammation.
These research efforts, done with laboratory animals, used a level of DHA supplementation that would equate to about 2-4 grams per day for an average person. In the diet, the most common source of DHA is fatty fish, such as salmon, mackerel or sardines, which along with calamari are the sources typically used for omega-3 fatty acid supplements as well.