December 5, 2011 (Copenhagen, Denmark) — The first large prospective study to examine fish consumption among young women has shown that even moderate intake of fish, just once a week, can be cardioprotective . The findings are important for a number of reasons, says lead author Dr Marin Str ø m (Statens Serum Institut, Copenhagen, Denmark), who reports the results together with colleagues online December 5, 2011 in Hypertension.
First of all, they illustrate that the benefits of a healthy lifestyle can be obtained at a relatively young age. "We saw quite strong associations with cardiovascular diseases occurring in the study participants when they were in their late 30s," Strøm told heartwire . "The biggest challenge in getting health messages like this across to younger populations is that usually the benefits may not be evident for 30 or 40 years, but our study shows that this is not the case." By demonstrating that the benefits of eating fish are immediate, she and her colleagues believe it will be easier to convince people to make healthy choices."This is one of the things that makes our study stand out from most of the previous work in the field," she observes.
The research is also among the first to be conducted in women of childbearing age and examines primary prevention, she says. Most prior studies of this nature have been conducted in men, in the context of secondary prevention after a cardiovascular event. Studying women separately is important, Strøm says, because there is evidence that certain risk factors that can be influenced by fish consumption, such as triglyceride levels, "may have a more negative influence on cardiovascular risk in women than in men."
Never-Eaters Have Triple the Risk of CVD Compared With Fish Consumers
Strøm and colleagues used the Danish National Birth Cohort to identify young women and examine whether or not eating fish rich in omega-3 fatty acids might reduce cardiovascular risk, by linking to CV events as recorded in the Danish National Patients Registry.
Almost 50 000 women, with a median age of 30, were interviewed in early pregnancy by telephone or answered food frequency questionnaires about how much and how often they ate fish and what types. They were also questioned about other lifestyle choices and family history. Individuals taking fish-oil capsules (less than 5% of the population) were excluded from the analysis because it was not possible to calculate the actual intake of n-3 fatty acids from this source, said Strøm.
There were 577 cardiovascular events during the follow-up period (1996–2008; median eight years). Specifically, there were 328 events due to hypertensive disease, 146 due to cerebrovascular causes, and 103 from ischemic heart disease.
Those women who never or very rarely ate fish had an almost doubling of cardiovascular disease risk compared with those who ate fish every week (corresponding to 10 g of fish per day or higher; adjusted hazard ratio for lowest vs highest intake 1.91).
And in a subset of women who consistently reported the same frequency of fish intake on three different occasions during a period of 30 weeks, there was a threefold higher CVD risk for those women who never ate fish compared with those eating it every week (adjusted hazard ratio for lowest vs highest intake 2.91).
The women in this study mainly ate cod, plaice, salmon, herring, and mackerel, says Strøm.
The results, she says, are in line with previous observational studies based on older women that suggest that the potential cardiovascular benefits of fish can be obtained with relatively moderate intake of even just a couple of times a month.
However, she stresses that to obtain the greatest gain from fish, it should be consumed as a main meal at least twice a week. "There are other health benefits that are obtained only at high intakes," she observes.
Nutrients in Fish Essential for Fetal Brain Development
In answer to a question about the risk/benefit of fish for pregnant women, particularly with regard to mercury content, Strøm noted that species with high mercury contents, such as shark, "are not commonly consumed in Denmark." Nevertheless, she notes, most developed countries have now developed dietary guidelines for pregnant women advising that they should not eat predator fish in large amounts.
Fish is the most important dietary source for the fetus to ensure optimal brain development.
But she also observes that there have been studies that have shown that the gains from the particular nutrients found in fish, such as long-chain n-3 polyunsaturated fatty acids and selenium, outweigh the risks from contaminants such as mercury in pregnant women. "Fish is the most important dietary source for the fetus to obtain the long-chain fatty acids that we believe are necessary to ensure optimal brain development," she says. And a recent US review concluded that despite the risk of environmental contaminants with some fish types, the benefits of eating fish still outweigh the risks, she notes.
The authors report no conflicts of interest.
Heartwire from Medscape © 2011 Medscape, LLC
Cite this: Eating Fish Provides Immediate CVD Benefits for Young Women - Medscape - Dec 05, 2011.