The Cooper Institute
 

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH

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Yet Another Reason to Eat Fish

Posted in
Eat better

Thursday, Sep 11, 2014

In a previous post we discussed the relationship between cardiorespiratory fitness (CRF) level and future risk of dying from heart failure (HF)1. Specifically, higher levels of CRF significantly decreased the risk of HF death in a group of nearly 45,000 men who were followed for an average of 20 years. In two other posts, one in 2013 and one earlier this year, we wrote about some of the cardiovascular and mental health benefits of increased dietary intake of omega-3 fatty acids. Omega-3’s are commonly known as fish oils, but are also found in plant-based foods such as walnuts. The most beneficial of the fish oils are EPA and DHA, which are only found in fatty fish and supplements. A recent large study has reviewed the relationship between fish intake and risk of developing HF. Before we talk about this study, let’s review some basic facts about HF.

HF is a type of cardiovascular disease where the heart’s pumping ability is decreased. Typically, HF develops slowly over a period of several years, but it can develop quickly following a heart attack. Some of the strongest predictors of HF are age, hypertension, heart valve disease, obesity, diabetes, low fitness level, and smoking. It might surprise you to learn that HF is the leading cause of hospitalization for Americans over the age of 65, and that more than 5 million people in the U.S. are living with congestive heart failure (CHF). Because our population is aging and the prevalence of diabetes, obesity, and sedentary lifestyle are very high, the prevalence of HF is expected to rise over the coming years.

In a recent paper published in Clinical Nutrition2, Djousee and colleagues examined several of the best studies that had previously looked at the relationship between fish consumption and future risk of developing HF. The studies were combined using a technique called a meta-analysis; this technique results essentially in one large mega-study. In the Djousee paper, a total of 176,441 adult men and women were included. At baseline, data on fish intake and EPA/DHA intake were obtained by using food frequency questionnaires. During an average follow-up period of 13 years, 5480 subjects developed HF. The key finding in the paper was that individuals who reported the highest intake of fish and/or EPA/DHA had a 15% reduction in risk of developing HF. For each 3.5 ounce serving of fish consumed per week, the risk of HF was decreased by 5%. These results were statistically significant, meaning that it was very unlikely that the findings were due to chance alone.

Some individuals have expressed concern regarding the presence of contaminants such as mercury that might be present in fish. According to the FDA and EPA, there are only four species of fish that contain significant levels of mercury. These include shark, swordfish, king mackerel, and golden bass (tilefish). Pregnant and nursing mothers, as well as young children are strongly advised to avoid consuming these types of fish. However, these same individuals can safely consume 12-16 ounces of other fish per week.

While all types of fish are a great source of protein and are low in saturated fat, there are varying amounts of omega-3’s in different species of fish. Among the best sources are anchovy, herring, salmon, mackerel, bluefish, sardines, trout, albacore tuna, and striped bass.

As mentioned previously, the risk of developing HF increases with age. However, there are many things under our control that can decrease our risk of developing HF. These are summarized below:

  • Maintain a normal blood pressure. If you have high blood pressure, follow your doctor’s recommendations closely.
  • Maintain a reasonable body weight
  • Avoid a sedentary lifestyle. Try to accumulate at least 150 minutes per week of moderate intensity aerobic exercise, and perform moderate resistance training at least two days each week.
  • Avoid tobacco in all forms
  • Maintain a normal blood glucose level. If you have prediabetes or diabetes, follow your doctor’s recommendations closely.
  • Finally, eat more fatty fish or take a fish oil supplement!!
To learn more about how diet affects the risk of developing chronic health conditions, consider taking Nutrition for Health and Fitness either live or online. You need not be a fitness professional to take this course; the general public is invited as well!

 

References

1Farrell, S.W., et al. Cardiorespiratory fitness, body mass index, and heart failure mortality in men: the CCLS. (2013). Circulation: Heart Failure.  6(5):898-905.

2Djousse, L., et al. (2012). Fish consumption, omega-3 fatty acids and risk of heart failure: a meta-analysis. Clinical Nutrition 31(6):846-853.