The link between diet and coronary health have been widely studied. Research focusing on fish consumption show that one meal a week or more can positively impact cardiovascular health.
Several major studies have examined the link between diet and coronary health. One of these followed 20,551 healthy male physicians, aged from 40 to 84. They completed a questionnaire on fish consumption and were checked 11 years later. The authors concluded that eating fish was associated with a reduced risk of sudden cardiac death, with the benefits detected at a consumption level of one meal a week or more.
In the Netherlands, a study that began in 1960 looked at the diet of 552 men who would be 50–69 in 1970. The incidence of stroke in this group was recorded from 1970 to 1985. Men who ate an average 20g of oily fish a day had a significantly lower risk of stroke than those who ate less.
In Italy, the GISSI trial reported the initial outcome of a study relating dietary supplements of fish oil to the incidence of heart attack. Nearly 12,000 survivors of heart attacks were randomly assigned fish oil. Three and a half years later 20% fewer of the group taking fish oil had died. The fish oil group consumed 1g per day of DHA and EPA; equivalent to two meals a week of oily fish.
The Nurses Health Study led from Harvard University brought some equivalent information in women’s health. Initiated in 1976 at Brigham and Women’s Hospital it was the longest major women’s health study ever undertaken. Around 85,000 women aged 30–55 at the outset were monitored from 1980 to 1994. One of many findings was that those who ate fish 2–4 times a week showed an incidence of stroke 48% less than those who ate fish once a month or less.
People suffering from diabetes type 2 are especially vulnerable to cardiovascular disease. Information derived from the Nurses Health Study indicates that regular consumption of fish can reduce that risk by more than half.
The above studies are a very small proportion of the many reports available. The U.S. National Library in Bethesda monitored research papers on the subject and picked up over 700 references a year on fish oils and cardiovascular disease. The wealth of information available led Professor Walter Willet of Harvard School of Public Health and Harvard Medical School, to comment, “The evidence that higher intake of omega-3 fatty acids can reduce coronary heart disease mortality due to sudden death is conclusive.”
The United States Department of Agriculture (USDA) dietary guidelines, released in April 2005, say “Choose fish more often for lunch or dinner. Look for fish rich in omega-3 fatty acids, such as salmon, trout and herring.”
The American Heart Association now specifically recommends people without documented coronary heart diseases to eat a variety of fish, preferably oily, at least twice a week.
In the UK, the Joint Health Claims Initiative (JHCI) is a collaborative group of consumer organisations, enforcement authorities and industry associations that looks at what claims can be made about products for consumers. In 2005, an expert committee of the JHCI ruled that oil rich fish can be promoted to consumers as being beneficial for the heart.
In an article published in the Journal of the American Medical Association in October 2006, Dr Zarius Mozaffarian of the Brigham and Women’s Hospital and Dr Eric Rimm of the Harvard Medical School stated that the benefits of eating fish, both finfish and shellfish, clearly outweigh the risks associated with them.
They based their statement on an extensive review of available evidence.
Top of their list of benefits of eating seafood was the clear superiority in heart health among people that frequently eat fish or take omega-3 fatty acid supplements, compared with population groups that do not. Other clear benefits relate to conditions such as ischaemic stroke, asthma, rheumatoid arthritis, depression, diabetes, prostate cancer, cognitive function and child development.
In the same week of October, the Committee on Nutrient Relationships in Seafood of the National Academies in the United States published similar conclusions.
In a report entitled “Seafood Choices: Balancing Benefits and Risks”, they stated that seafood is a nutrient-rich food that makes a positive contribution to a healthful diet. It is a good source of protein and, relative to other protein foods such as red meat, poultry and eggs, is generally lower in saturated fatty acids and higher in the omega-3 fatty acids EPA and DHA and in selenium.
The conclusions are also in line with similar risk: benefit evaluations performed by VKM, the Norwegian Scientific Committee for Food Safety, also in 2006.
Following a review of the risk: benefit balance, in 2004 the UK Food Standards Agency (FSA) revised upwards its recommendations concerning oily fish. The FSA website states, “Aim to eat at least two portions of oily fish a week because fish are a good source of protein, vitamins and minerals, and they are low in saturated fat.” It continues, “Oily fish are a healthy choice because they also contain omega-3 fatty acids.” For most sections of the population the FSA suggests they can eat up to four portions a week.
In 2004, the Dutch State Institute for Public Health and Environment (RIVM) published an extensive review of risks and benefits from a wide variety of foods. Risks and benefits were compared using the Disability Adjusted Life Years (DALYs). For fish, the heart health benefits were weighed against risks represented by contaminants such as dioxins. The conclusion was that the benefits are far greater than the risks. Consumption of oily fish once a week brings a health gain of 82,000 DALYs compared with risks which rated from “probably low” to “absent”.