Supplements of DHA may reduce clot formation (platelet aggregation) in woman by about 18%, while similar risk reductions were observed in men only for EPA supplements, according to findings published in the Journal of Nutrition.
“These novel findings allow for optimal cardio-protection that is tailored for both gender groups and offers a safe and non-pharmacological approach,” wrote the researchers, led by Manohar Garg from the University of Newcastle in Australia.
“With respect to thrombotic disease risk, men would likely benefit more from supplementation with EPA, whereas women are more responsive to DHA.”
The study adds to an earlier report from the same researchers, published in 2011 in The Journal of Nutritional Biochemistry.
The heart health benefits of fish oil, and the omega-3 fatty acids it contains, are well-documented, being first reported in the early 1970s by Dr Jorn Dyerberg and his co-workers in The Lancet and The American Journal of Clinical Nutrition.
To date, the polyunsaturated fatty acids (PUFAs) have been linked to improvements in blood lipid levels, a reduced tendency of thrombosis, blood pressure and heart rate improvements, and improved vascular function.
“Despite the fact that fish and fish oils contain EPA and DHA in variable amounts, few well-designed studies in humans have assessed their individual effects,” explained Dr Garg and his co-workers.
“In the available fish oil and platelet aggregation literature, a wide variability in terms of dosages and concentration ratios of EPA:DHA is apparent. This variable, coupled with the nonmodifiable factor of gender, may likely explain the inconsistent results in the fish oil and platelet aggregation literature.”
The Newcastle, Australia-based researchers recruited 94 healthy men and women to participate in their double-blinded, randomized, placebo controlled trial. Participants were randomly assigned to receive EPA-rich (1000 mg EPA:200 mg DHA, EPAX 5510 TG/N) or DHA-rich (200 mg EPA:1000 mg DHA, EPAX 1050 TG/N) oil capsules daily, or placebo for four weeks.
Results showed that, in men and women combined, both EPA and DHA were associated with a reduction in platelet aggregation of 12 and 15%, respectively, compared with placebo.
When the researchers considered men and women independently, men were seen to benefit more from EPA, while women benefited more from DHA.
Dr Garg and his co-workers report that gender is known to affect the metabolism of omega-3. Indeed, it’s well established that women of child-bearing age have higher DHA and lower EPA levels than men.
“This is in line with our findings where plasma DHA concentrations increased to a greater extent in women than in men (148 vs. 64%, respectively) following supplementation with DHA-rich capsules, demonstrating a significant sex 3 treatment interaction,” they said.
“Considering that plasma fatty acid composition following chronic n3 PUFA supplementation reflects that of platelets, our data are consistent with the previously published in vitro study showing slower movement of DHA into platelet phospholipids in men.”
“Our findings suggest effects of EPA and DHA on platelet aggregation their effects are not shared or complementary, rather they are sex-specific,” they concluded.
Too early to draw conclusions?
Commenting independently on the study, Harry Rice, PhD, VP of regulatory & scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED), said: "I commend the investigators for being systematic in that this is the group's fourth study related to the association among EPA & DHA supplementation and sex-dependent platelet responses.
"While the present results may be real, I think it's too early to conclude for thrombotic disease risk that men would benefit more from EPA and women from DHA. It's too early because the power associated with the sex subgroup analyses is low and low power reduces the likelihood that a statistically significant result reflects a true effect."
Source: Journal of Nutrition
2013 Volume 143, Pages 457-463, doi:10.3945/jn.112.171249
“Eicosapentaenoic and Docosahexaenoic Acid Supplementations Reduce Platelet Aggregation and Hemostatic Markers Differentially in Men and Women”
Authors: M. Phang, L.F. Lincz, M.L. Garg