Nutritional Pearls: Fish and Heart Disease

Answer: This study seems to show that fish consumption is more beneficial for those with established heart disease. Those without heart disease saw no significant cardiovascular benefit in greater consumption of fish.

The Research

You get a point in your Mediterranean diet score if you eat an average of 2 servings of fish per week. This can be almost anything that lives in the water: shellfish, including shrimp, octopus, or mussels, or fish, which are higher in omega-3 fatty acids, such as salmon, tuna, and mackerel.

Last year we covered a meta-analysis that showed a significant effect of higher fish consumption on the risk of stroke, heart failure, heart attack, and mortality.

Today we have a study that looks at the relationship between heart disease and fish consumption in 4 different cohort studies of people in 40 countries and 6 continents over 7 years.1

The more than 191,600 people included in the analysis for this research were aged about 55 years old on average. Three of the studies were in individuals with known heart disease, while the fourth and largest study had a mixture of those with and without heart disease. All 4 studies administered country-specific dietary questionnaires at the start of their respective research periods, but only 1 of the studies asked about specific types of fish.

The authors began by assessing the overall intake of fish of all kinds and classified participants into 4 levels of average intake: less than 50 grams per month (about 1.75 oz), 50 g to less than 175 g (about 6.17 oz) per week, 175 g to less than 350 g (12.35 oz) per week, and more than 350 g (about 12.3 oz) per week.

The authors considered body mass index, waist-to-hip ratio, geographic region of residence, whether the participant had been diagnosed with high blood pressure or diabetes, and other factors.

The Results

Unexpectedly, the authors found that the cohort including those both with and without a history of heart disease showed no significant association between fish intake and risk of serious cardiovascular disease or death (whether from heart disease specifically or otherwise).

The 3 smaller cohorts–– all participants with vascular diseases–– showed that, compared to those with the lowest level of fish intake, those who consumed at least 175 g of fish per week, on average, were 11% to 23% less likely to experience a serious but non-fatal cardiovascular event, 13% to 34% less likely to die of heart disease, and 14% to 23% less likely to die of any cause.

What’s the Take Home?

This study seems to show that fish consumption is more beneficial for those with established heart disease. Those without heart disease saw no significant cardiovascular benefit in greater consumption of fish.

That said, the nutritional effects of any particular food are not limited to any single benefit alone, and people do eat a variety of foods, so assessing a single food or food group must be interpreted with caution.

From a high-level perspective, this new study does not change the Mediterranean diet recommendation of 2 servings of a variety of fish twice per week. It's about more than heart disease.

Reference:

Mohan D, Mente A, Dehghan M, et al; PURE, ONTARGET, TRANSCEND, and ORIGIN Investigators. Associations of fish consumption with risk of cardiovascular disease and mortality among individuals with or without vascular disease from 58 countries. JAMA Intern Med. 2021;181(5):631-649. doi:10.1001/jamainternmed.2021.0036