Adding confusion to the already-confusing world of dietary supplements, a new study published in the British Medical Journal compared the incidence of strokes in people who ate fish with those who took fish oil supplements.
Surprisingly, there was a small, but statistically significant difference between the two groups. Those who ate at least two servings of fish per week reduced their risk of stroke by between about 6 to 12 percent while people taking omega-3 fatty acid supplement experienced no benefit. The 12 percent reduction was seen in people who ate five or more servings of fish per week.
The researchers, from the University of Cambridge in the U.K., analyzed data from 38 different trials comprised of nearly 800,000 participants. Twelve of the trials were randomized controlled studies of supplemental fish oil consumption, with an average follow-up time of three years. These studies found no decrease in primary prevention of strokes, nor improved outcomes following a cerebrovascular event for those taking the supplemental fish oil.
The authors speculated that there may be other factors involved to explain the reduction in strokes among fish eaters but not among those who took the supplement. One possibility mentioned was that regular fish eaters might live a healthier lifestyle, or have a higher socioeconomic status both of which are associated with a lower risk of stroke.
An accompanying editorial from a group at Wageningen University in the Netherlands concluded, "It seems that the additional benefit of supplementation in patients who are optimally managed may be small.
ACSH s Dr. Gilbert Ross agrees with that assessment wholeheartedly. The modest benefit found in this large meta-analysis is somewhat discouraging, given the benefits found in prior studies of both fish consumption and omega-3 fish oil.