“We saw a positive effect on [heart disease and stroke risk] even from relatively modest intake of fish, so this is encouraging to people who might struggle to comply with the recommended levels of daily fish intake,” study researcher Marin Strom, PhD, tells WebMD in an email.
Strom, of Statens Serum Institut in Copenhagen, Denmark, and her colleagues note that most research into omega-3 fatty acids and heart attack and stroke risk has focused on men, and even studies that did include women tended to overlook those of childbearing age.
The Danish researchers took advantage of their country’s large database of health information about pregnant women. Dietary data for about 49,000 women in the Danish National Birth Cohort was linked to information about hospitalization from the Danish National Patients Registry. At the beginning of the study, the women on average were about 30 years old.
The scientists compared the women’s intake of fatty fish, including salmon, mackerel, cod, and herring, with their risk of being hospitalized for heart disease, stroke, or high blood pressure over the next eight years or so. Compared to the women who ate the most fish, those who ate little or none were about 50% more likely be hospitalized for heart disease, stroke, and high blood pressure.
Previous research has shown that people who don’t eat fish are also more likely to have other risk factors for heart disease and stroke, such as smoking or a sedentary lifestyle, Strom and her colleagues write. But even after they accounted for those factors, the association between omega-3 fatty acid intake and heart disease and stroke risk remained significant.
Why Omega-3s Might Lower Risk
“However,” she says, “fish also contains other important nutrients, such as selenium, and I would rather emphasize the importance of eating fish … than advise people to take supplements.”
Omega-3 fatty acids from fish could reduce heart disease and stroke risk by reducing inflammation, triglycerides (blood fats), blood clotting, and irregular heart rhythms, Harvard professor JoAnn Manson, MD, DrPH, tells WebMD.
“Some of the heart attacks and [other heart and stoke-related] events that occur in younger women are due to an increased risk of clotting,” notes Manson, chief of preventive medicine at Brigham and Women’s Hospital in Boston.
She calls Strom’s study “interesting” but noted that, as an observational trial in which women decided on their own how much fish to eat, the findings could be related to unidentified factors tied to fish consumption. Also, this kind of trial just shows an association, not true cause and effect.
Strom and her colleagues published their findings in Hypertension: Journal of the American Heart Association.