The results of the ASCEND study published at the ESC Congress 2018 and in the New England Journal of Medicine show what many have always suspected: Fish oil preparations have absolutely no effect on patients with diabetes. According to Professor Louise Bowman, there is no justification for recommending fish oil preparations to protect against cardiovascular events. A reconsideration of the European Guidelines in this respect should, therefore, be considered.
In observational studies, higher fish consumption is associated with a lower risk of coronary heart disease and stroke. Particularly in the USA, these studies have led to an oversupply of fish oil preparations. However, previous randomized trials have not shown that taking fish oil supplements with omega-3 fatty acids reduces the risk of cardiovascular events. The ASCEND study (a study on cardiovascular events in diabetes) investigated whether fish oil preparations reduce the risk of cardiovascular events in patients with diabetes.
Between 2005 and 2011, 15,480 patients with diabetes but no history of cardiovascular disease were randomly assigned to a fish oil supplement (1g daily) or placebo. A 1g olive oil capsule was chosen as the placebo. It was believed that the British population now consumed so much olive oil that 1 gram of it a day could not falsify the result, Bowman said. The fish oil preparation chosen was not an OTC product, but a prescription product with proven quality.
The primary efficacy outcome was initially a severe vascular event, such as non-fatal heart attacks, non-fatal strokes, or transient ischemic attacks (sometimes referred to as "mini-strokes") or deaths due to a cardiovascular cause (but without intracranial bleeding in the head or brain).
During an average follow-up period of 7.4 years, the first event occurred among 689 fish oil consuming participants (8.9%) and 712 (9.2%) placebo participants. There was no significant difference between the two groups: the rate ratio was 0.97 (95% confidence interval 0.87-1.08, p = 0.55). The long-term randomized study thus shows that fish oil preparations do not reduce the risk of cardiovascular disease in patients with diabetes.
Current results show that fish oil alone has no positive effect on the health of diabetes patients. In Mrs. Bowman's words, "A fish oil capsule is not a fish." The positive results from previous observational studies may also be due to the fact that people who eat fish also consume other healthy foods, for example in the form of vegetable supplements. According to Bowman, so far there has not been a scientific study that could prove that a dietary supplement has a medically proven effect at all. As a result, the global 31 billion dollar market simply employs very good marketing staff.
Sources:
1. European Cardiology Congress 2018: Hot Line Session 2, Sunday, 26.8.2018, 16:45 to 17:45, Auditorium Munich.
2. Bowman et al. (2018). ASCEND Study Collaborative Group. ASCEND: Characteristics of a randomized trial of aspirin and of omega-3 fatty acid supplementation in 15,480 people with diabetes. At Heart J. 2018-198:135-144.