Two grams (2,000 mg) of DHA (docosahexaenoic acid) plus 400 mg of EPA (eicosapentaenoic acid) per day for 16 weeks led to significant improvements in arterial stiffness, heart rate, and some blood lipid levels, according to findings published in Nutrition, Metabolism and Cardiovascular Diseases.
However, daily curcumin doses of 160 mg alone or in combination with fish oil did not have any effect on these measures, reported scientists from the University of Newcastle and the University of Southern Queensland. The study was sponsored by Blackmores Institute.
“Supplementation with fish oil lowered heart rate and serum triglyceride levels and increased HDL cholesterol, all of which are well-recognized cardiovascular benefits of fish oil,” they wrote. “The improvement of HDL cholesterol and slight reduction in systolic blood pressure translate to a 12% reduction of Framingham Cardiovascular Disease Risk Score in the fish oil group […] relative to baseline.”
The researchers recruited 152 older sedentary overweight/obese people (aged between 50 and 80) to participate in their 16-week double-blind, randomized placebo-controlled trial. Participants were randomly assigned to one of four groups: Placebo, fish oil only, curcumin only, or a combination of fish oil and curcumin.
The results showed that while none of the groups displayed improvements in measure of cerebrovascular responsiveness (CVR), but the fish oil group did experience significant improvements in heart rate (3% reduction, compared to no fish oil) and triglycerides (reduced by 24%), while serum HDL cholesterol levels increased by 8%.
Contrary to expectations, no changes in CRP (C-reactive protein – a marker of inflammation) were observed for any of the groups, compared to placebo, although there was a non-statistically significant improvement in men in the fish oil group.
In addition, “[t]he combination of fish oil and curcumin did not, as hypothesized, result in additional or synergistic effects. While our trial was ongoing, another study examining the combined effects of fish oil and curcumin on glycaemic indices and blood lipids also failed to find any synergistic effects [Thota et al., 2019, Lipids Health Dis., Vol. 18, pp.31],” wrote the researchers.
“It is important to note that investigations into the combined effects of fish oil and curcumin in humans are novel and limited with our study being the first to examine effects on cerebrovascular function and cardiovascular risk factors.”
They concluded: “Further investigations are needed to elucidate underlying mechanisms of interaction between fish oil and curcumin, identify optimal doses when combining these bioactives and characterize those individuals who would benefit most from either intervention.”
Source: Nutrition, Metabolism and Cardiovascular Diseases
Published online ahead of print, doi: 10.1016/j.numecd.2019.12.010
“Effects of fish oil and curcumin supplementation on cerebrovascular function in older adults: a randomized controlled trial”
Authors: J.C. Kuszewski, et al.