Higher blood levels of the omega-3s EPA and DHA are associated with lower coronary risks, but the overall evidence is insufficient to encourage high consumption of omega-3s, says a new meta-analysis.
Writing in the Annals of Internal Medicine, an international team of scientists report that the evidence is also inconclusive for omega-6s, and for guidelines to encourage lower consumption of saturated fats.
The conclusions appear to fly in the face of nutritional guidelines, which generally encourage low consumption of saturated fats, high consumption of omega-3 polyunsaturated fatty acids, and avoidance of trans fats for cardiovascular health.
“The pattern of findings from this analysis did not yield clearly supportive evidence for current cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of saturated fats,” they wrote.
“Nutritional guidelines on fatty acids and cardiovascular guidelines may require reappraisal to reflect the current evidence.”
‘It’s not a home run, but it shows they’re protective’
Leading supplement experts have interpreted the results differently, however, and see the data as pointing in the right direction for the omega-3 fatty acids, EPA and DHA.
Duffy MacKay, ND, Sr VP of scientific & regulatory affairs for the Council for Responsible Nutrition (CRN), told us he had some concerns that the findings of the new study contracts decades of scientific advice, and the potential effects on consumers of this back-and-forth nutritional advice.
The data is pointing in the right direction for omega-3s, he said, and shouldn’t change any advice to consumers.
When asked if the new findings have the potential to impact the discussions around the 2015 Dietary Guidelines, Dr MacKay said the authors are high level and that the dietary guidelines committee will see the publication and probably take it into consideration.
“But I don’t think they will list bacon as a nutrient of concern!”
“At the end of the day, it shows that EPA and DHA are pointed in the right direction,” he said. “It’s not a home run, but it shows they’re protective, and play a role along with exercise, a healthy lifestyle, and supplements.”
“We need to modify our expectations when they come to nutritional interventions,” he added. “The effects can be subtle and they can take a long time to manifest the benefits.”
Harry Rice, PhD, VP of regulatory & scientific affairs, for the Global Organization for EPA and DHA Omega-3s (GOED), told NutraIngredients-USA: “In contrast to the authors, I think the findings provide compelling evidence (25% decreased risk of coronary outcomes associated with circulating EPA+DHA) to support increased consumption of fatty fish (source of EPA+DHA), as well as supplementation with EPA+DHA as part of a healthy diet and lifestyle.
“Quite frankly, it's not a surprise that long-chain omega-3 supplementation in RCTs was not associated with an overall decreased risk of coronary outcomes since recent studies have been fraught with design issues, particularly being under-powered.”
For the new systematic review and meta-analysis, the researchers analysed data from 49 long-term prospective observational studies of a broad range of both dietary and biomarker fatty acid measures in coronary disease. They also examined associations with coronary outcomes in 27 randomized trials of fatty acid supplementation.
Results showed that there statistically non-significant associations between omega-3s and omega-6s and coronary disease in prospective studies. The researchers also found, “some evidence that circulating levels of eicosapentaenoic and docosahexaenoic acids (the 2 main types of long-chain omega-3 polyunsaturated fatty acids) and arachidonic acid are each associated with lower coronary risk.
“However, our meta-analysis of randomized trials of long-chain omega-3 and omega-6 polyunsaturated fatty acid supplements suggest that supplementation with these nutrients do not statistically significantly reduce the risk for coronary outcomes.”
“Current evidence does not clearly support guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats,” they concluded.
Source: Annals of Internal Medicine
2014, Volume 160
“Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk – A Systematic Review and Meta-analysis”
Authors: R. Chowdhury, S. Warnakula, S. Kunutsor, et al.