Eating fish rich in omega-3 fatty acids at least twice a week is widely recommended for people with diabetes, but getting your omega-3s in the form of fish oil supplements from the store may not provide the same benefits, according to a growing body of evidence. Here's why.
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Diabetes and Fish Goals
The American Diabetes Association (ADA) refers to salmon and other fatty fish high in omega-3s — such as herring, sardines, mackerel, trout and albacore tuna — as "diabetes super foods" and suggests eating non-fried fatty fish twice a week.
Diabetes occurs when your body no longer produces the hormone insulin or grows resistant to its effects. Insulin is tasked with helping the body use glucose for energy. If blood sugar levels remain high over time, diabetes-related complications, including heart disease, nerve damage and even blindness, can occur, according to the ADA.
However, omega-3 fats may help reduce your risk for heart disease and also cool inflammation, which may be the common denominator in many diseases, including diabetes, according to a December 2019 study in Circulation Research, cited by the American Heart Association (AHA).
The AHA recommends consumption of omega-3 for heart health, noting that adults with diabetes are two to four times more likely to die from heart disease than their peers who do not have diabetes.
Though omega-3s are good for you, fish oil supplements are another story altogether. It was previously thought that omega-3 supplements may help protect against type 2 diabetes, the form of the disease most closely linked to obesity. But a systematic review of 83 trials, comprising 121,070 people with and without diabetes, debunked this widely held theory.
The study, published in the August 2019 issue of the British Medical Journal, found that taking fish oil supplements had no benefit in preventing or treating type 2 diabetes. Omega-3s — mainly supplements — had little or no effect on the likelihood of a diabetes diagnosis, average glucose levels over time or fasting insulin (the amount of insulin in your blood after fasting), the study found.
Omega-3s From Food
Davida Kleinman, RDN, a dietitian at Eat Right Bucks County and an adjunct professor of nutrition science at Bucks County Community College in Doylestown, Pennsylvania, always encourages her patients with diabetes to get the nutrients they need from whole foods, not supplements.
Supplements drill it down to one nutrient, Kleinman says, while whole foods provide all of the nutrients and benefits. "If they don't like seafood, flax seed and plant-based oils such as flaxseed oil, soybean oil and canola oil may suffice," she says.
The U.S. Office of Dietary Supplements suggests other non-fish sources of omega-3s such as:
- Chia seeds
- Fortified foods
Read more: Top 10 Healthy Fish to Eat
It's buyer beware when it comes to over-the-counter fish oil supplements, warns Ajaykumar D. Rao, MD, an associate professor of medicine at the Lewis Katz School of Medicine at Temple University in Philadelphia. Due to regulatory issues, it is hard to know for sure what is in any over-the-counter supplement, despite what its label says.
"Prescription omega-3s can provide good benefits as it pertains to heart disease, which remains the No. 1 killer in people with diabetes," Dr. Rao says.
To that point, the Circulation Research study and the AHA did find that fish oil supplements reduced inflammatory markers, but also cautioned that store-bought supplements are not regulated and that researchers are still working to identify the right mix of fatty acids for optimal health.
If you're not getting enough omega-3s in your diet, talk to your doctor about prescription supplements. Always let your doctor know everything else you're taking as even so-called natural supplements do confer their fair share of risks and side effects, Dr. Rao cautions.
- American Diabetes Association: “Diabetes Superfoods”
- Circulation Research: “Enriched Marine Oil Supplements Increase Peripheral Blood Specialized Pro-Resolving Mediators Concentrations and Reprogram Host Immune Responses”
- American Diabetes Association: “Complications”
- American Heart Association: “Cardiovascular Disease and Diabetes”
- American Heart Association: “Could Fish Oil Fight Inflammation?”
- British Medical Journal: “Omega-3, Omega-6, and Total Dietary Polyunsaturated Fat for Prevention and Treatment of Type 2 Diabetes Mellitus: Systematic Review and Meta-Analysis of Randomized Controlled Trials”
- Davida Kleinman, RDN, registered dietitian, nutritionist, Eat Right Bucks County, adjunct professor, nutrition science, Bucks County Community College, Doylestown, Pennsylvania
- U.S. Office of Dietary Supplements: “Omega-3 Fatty Acids”
- Ajaykumar D. Rao, MD, associate professor, medicine, Lewis Katz School of Medicine at Temple University and Center for Metabolic Disease Research, Temple University Hospital, Philadelphia