May 25, 2011 (Chicago, Illinois) — Eating baked or broiled dark fish such as salmon five times a week may prevent heart failure in older women, whereas having fried fish only once a week may increase this risk, a new study reports . The findings are based on a 10-year follow-up of more than 84 000 postmenopausal women who participated in the Women's Health Initiative--Observational Study (WHI-OS).
Compared with the women who rarely ate broiled or baked fish, those who consumed five or more servings a week had a 30% lower risk of developing heart failure. Conversely, women who had at least one serving a week of fried fish had an almost 50% increased risk of incident heart failure, compared with those who rarely ate fried fish.
"How you prepared the fish was maybe just as important as eating the fish itself," senior author Dr Donald Lloyd-Jones (Northwestern University, Chicago, IL) told heartwire , adding that the magnitude of the increased risk of heart failure associated with eating fried fish was "unexpected."
Other key findings were that most of the reduction in heart-failure risk with frequent consumption of broiled or baked fish was due to eating dark fish (salmon, mackerel, or bluefish) as opposed to white fish (sole, snapper, or cod) or tuna. Fish consumption also predicted future heart failure independent of MI, a common cause of heart failure.
Lloyd-Jones also cautioned that people should not interpret these findings to mean that they could just take a capsule of fish oil and obtain the same benefits as were seen here, because there may be other constituents in the fish that are contributing, he noted.
The study, by Dr Rashad J Belin (Northwestern University, Chicago, IL) and colleagues, is reported online May 24, 2011 in Circulation: Heart Failure.
Data Adjusted for Multiple Confounders
Heart failure affects one in five people, the authors write, adding that postmenopausal women are at higher risk. Previous studies have shown that omega-3 fatty acids found in fish may reduce the risk of CVD, probably because they decrease inflammation, oxidative stress, and blood pressure, but research assessing diet and nutrient intake and their role in the risk of HF in postmenopausal women is lacking, they note.
To determine whether heart failure in postmenopausal women is affected by dietary fish intake, the team analyzed data from 84 493 women in the WHI-OS aged 50 to 79 (average age 63). Detailed information about fish consumption and preparation was obtained from food frequency questionnaires (FFQs) administered at baseline. Women with a history of MI were excluded from the study.
Based on their replies to the FFQ, women were divided into five categories of broiled or baked fish consumption--from less than once a month (reference group) to five or more times a week--and three categories of fried fish consumption--from less than once a month to one or more times a week.
Women who ate the most broiled or baked fish tended to be younger and more physically fit and to follow a healthier diet. Women who ate the most fried fish were more likely to smoke and to have a higher body-mass index (BMI), higher systolic BP, diabetes, atrial fibrillation (AF), and CAD.
During an average follow-up of 10 years, until August 2008, there were 1858 cases of heart failure.
The researchers adjusted the results for potential confounders including age, ethnicity, education, physical activity, smoking, alcohol, diabetes, hypertension, BMI, AF, MI/CABG/PTCA, time-dependent MI, and dietary intake of fiber, fruit and vegetables, fried food, sodium, omega-3 fatty acid, and trans-fatty acid.
Fish Is Only "Part of the Equation"
"Eating baked or broiled fish frequently . . . is part of the equation, it's not the whole equation," Lloyd-Jones stressed. The women who frequently ate broiled or baked fish also had a healthier diet and were more physically fit, he pointed out.
"Trying to condense the healthful benefits of a good diet pattern into taking a pill with omega-3 fatty acids in it would be a very poor take-home message from this study," he cautioned.
Clearly there may be many other things in baked or broiled fish that are also providing benefit and are part of a healthy diet, which you will never get in a supplement"
"Clearly there may be many other things in baked or broiled fish that are also providing benefit and are part of a healthy diet, which you will never get in a supplement."
The data did not provide information about raw fish such as sushi, but Lloyd-Jones expects that it would also be linked with a reduced risk of heart failure. Frying fish, on the other hand, likely introduces saturated fat and trans fats, which is probably why it more than offsets the benefits of eating fish, he explained. However, this study did not find an increased risk of heart failure with increased consumption of trans-fatty acids.
Strong Study, Reinforces "Eat-Fish" Message
Asked to comment on the study, Dr Rachel Johnson (University of Vermont, Burlington), a member of the nutrition committee of the AHA, said the study had a strong design, since it was a large, longitudinal cohort study that used a "rich database."
"The take-home message is that if you are not already regularly eating fish, try to add it to your diet, and have it in a preparation method retaining the beneficial aspects of fish," she said, noting the AHA recommends at least two servings of fish a week. "There is certainly no harm in eating more than two servings a week, particularly if you have risk factors," she added.
Heartwire from Medscape © 2011 Medscape, LLC
Cite this: Baked/Broiled Fish Reduces HF, Fried Fish Ups Risk - Medscape - May 26, 2011.