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, which increasingly is linked to liver inflammation, fibrosis, cirrhosis and even liver failure.
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.
Supplements of DHA, used at levels that are sometimes prescribed to reduce blood triglycerides, appeared to have many unanticipated effects. There were observable changes in vitamin and carbohydrate metabolism, protein and amino acid function, as well as lipid metabolism.
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.
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,” says Donald Jump, a professor in the OSU 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,” he added.
Omega-3 fatty acids have been the subject of much recent research, often with conflicting results and claims. Possible reasons for contradictory findings, researchers say, are the amount of supplements used and the relative abundance of two common omega-3s: DHA and EPA. Previous studies 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.
Where to Find Your Omega-3s
DHA and EPA omega-3 fatty acids are naturally found in egg yolks (amounts vary depending on the chicken feed), as well as in cold-water fish and shellfish like tuna, salmon, mackerel, cod, crab, shrimp, and oysters. ALA is prevalent in many plant oils.
These research efforts, done with laboratory animals, used a level of DHA supplementation that would equate to about 2 to 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.
The most recent research is beginning to break down the specific processes by which these metabolic changes take place. If anything, the results suggest that DHA may have even more health value than previously thought.
“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,” says Jump, who is also a principal investigator in OSU’s Linus Pauling Institute.
“Fish oils, a common supplement used to provide omega-3, are also not prescribed to regulate blood glucose levels in diabetic patients,” he says. “But our studies suggest that DHA may reduce the formation of harmful glucose metabolites linked to diabetic complications.”
Both diabetes and liver disease are increasing steadily in the United States.
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.
How to Apply the Research
The benefits of DHA (as well as ALA and EPA, which are other forms of the omega-3 fatty acids) are pronounced and extend beyond the findings of this study, says Dr. Natalie Digate Muth, Healthcare Solutions Director for the American Council on Exercise. “Overall,” explains Digate Muth, “omega-3s reduce blood clotting, dilate blood vessels, reduce inflammation, and act to reduce cholesterol and triglyceride levels. They are important for eye and brain development and are especially important for a growing fetus in the late stages of pregnancy. Omega-3s may also help to preserve brain function and reduce the risk of mental illness and attention deficit.”
The Institute of Medicine (IOM) considers 1.1 grams per day of ALA to be the minimal amount necessary for normal growth and neural development. The IOM suggests that 10% of the needed ALA could come from EPA or DHA, which suggests a daily intake of about 100 milligrams per day. This amount could be obtained by consuming one serving of canned tuna. Some expert panels have recommended much higher intakes of 250 and 500 milligrams per day due to the significant health benefits.
Notably, most Americans tend not to consume enough omega-3 fatty acids, although this recommendation can be met through the consumption of approximately 8 ounces of a fatty fish per week. Though natural food sources are best, people who do not meet this recommendation or do not like fish may benefit from supplementation or from fortified foods.