A new study at the University of Oxford evaluated if omega-3 supplements help in reducing the risk of cardiovascular disease in individuals with diabetes.
Diabetes and cardiovascular disease are leading causes of morbidity and mortality worldwide. People with diabetes are at a higher risk of cardiovascular disease. Unquestionably, diet has a substantial effect on the progression of these diseases. In recent years, the consumption of omega-3 supplements has been attributed to the maintenance of good health. The claimed benefits associated with omega-3 consumption have been widespread from heart health to vision improvement and brain health.
The AHA does not recommend omega-3 supplements for preventing coronary heart disease
In spite of the growing popularity of omega-3 supplements, the American Heart Association does not recommend taking omega-3 supplements for the prevention of coronary heart disease. They also do not recommend omega-3 supplements for reducing the risk of cardiovascular events in patients with diabetes.
However, the American Heart Association does recommend eating fish once or twice a week for primary prevention of coronary heart disease and sudden cardiac death and omega-3 supplements for secondary prevention of coronary heart disease.
Although several observational studies have shown the benefits of eating fish to reduce the risk of heart disease, most randomized trials on omega-3 supplementation have shown inconclusive results. Since the omega-3 supplements are being consumed by a lot of people, it is important for researchers to find conclusive evidence to corroborate the association between omega-3 supplements and cardiovascular disease.
A study of cardiovascular events in diabetes
Patients with diabetes have two-to-three times higher risk of heart disease compared with the general population. Therefore, omega-3 supplements are of greater significance for diabetic patients, even if they provide a small protective effect against adverse cardiovascular events.
A study of cardiovascular events in diabetes, called ASCEND, published in the New England Journal of Medicine, assessed the effectiveness and safety of omega-3 supplements in patients with diabetes who had no evidence of cardiovascular disease at the start of the study.
A total of 15,341 men and women, 40 years and above were included in the study. The researchers at the University of Oxford, UK, randomly assigned participants to receive either 1g of omega-3 supplement or a placebo containing olive oil. The participants were followed up for a period of 7.4 years during which the researchers sent them questionnaires regarding adherence to the supplement regimen, any adverse events, and use of any antiplatelet or anticoagulation therapy.
The researchers considered the occurrence of the first serious vascular event, defined as nonfatal myocardial infarction, stroke, transient ischemic attack, or vascular death as the primary consequence of the study. Any serious vascular event or arterial revascularization procedure was the secondary consequence studied.
No significant difference observed between groups receiving omega-3 or placebo
A total of 689 patients in the omega-3 supplement group and 712 patients in the placebo group experienced a serious vascular event. Based on the results, the researchers concluded that the difference in cardiovascular events between the two groups was statistically not significant. Furthermore, the researchers observed no significant difference between mortality from all causes between the two groups. There was no difference noted between the two groups for any serious vascular events or revascularization.
Omega-3 supplements failed to prevent heart disease
Patients with diabetes have an increased risk of heart disease. Prevention, by any means or to any degree, is crucial for diabetic patients. However, this study showed that omega-3 supplements failed to prevent heart disease compared to placebo.
Although the result of this study is disappointing, they resonate with the results of previous randomized trials. While the consumption of the omega-3 supplements continues, the evidence of benefit from this supplement is getting thinner. The expert groups may need to revisit the data from current studies before continuing to promote the omega-3 supplements. In patients with diabetes, these results prove to be of little help.
Is it time to move on from omega-3 supplements?
Despite increasing evidence from trials that suggest little or no beneficial effect of omega-3 supplements on cardiovascular health, some clinical guidelines still recommend the use of these supplements for the secondary prevention of coronary heart disease. The researchers conclude that based on the result of the present trial, there is no significant difference in the occurrence of cardiovascular events between diabetic patients who received omega-3 supplements and those who received placebo. These results, therefore, do not support the current recommendations of routine omega-3 supplements for prevention of vascular events in patients with diabetes.
Eating fish and other seafood rich in omega-3 fatty acids is a proven strategy for good health. Taking omega-3 supplements clearly does not substitute for nutrient-rich foods but it is best to talk to the healthcare provider before making a decision on starting or discontinuing the use of omega-3 supplements.
Written by Preeti Paul, MS Biochemistry
Reference: Louise Bowman et al., Effects of n-3 Fatty Acid Supplements in Diabetes Mellitus. The ASCED Study Collaborative Group. N Engl J Med 2018;379:1540-50 DOI:10.1056/NEJMoa1804989