The scientists at the Harvard School of Public Health studied the relationship between omega-3 fatty acids and heart disease rates… AGAIN! They found that people who ate more omega-3s AND had higher levels of omega-3s in their blood had lower rates of heart disease. This kind of study is not new, however, it is important for a number of reasons.
- People from different ethnic groups were in the study. The research was conducted in the Multi-Ethnic Study of Atherosclerosis (MESA) Study that includes whites, Hispanics, African- and Chinese-Americans. Much of the science that guides our nutrition recommendations comes from studies that primarily include white study subjects. The genetic variability between ethnic groups affects how an individual may respond to a nutrition or drug intervention so conducting studies in multi-ethnic populations is very important.
- They measured omega-3s in both blood and diet. The relationship between heart disease and omega-3s was found when measuring omega-3s in people’s diets and by directly measuring omega-3s in their blood. Having both measures of omega-3s show the same relationship with heart disease strengthens the findings. It also demonstrates (again) how omega-3s in the diet are directly linked to levels in our blood.
- Omega-3s affected heart disease, not just risk factors for heart disease. This research showed a reduction in rates of heart disease, which included diagnosed coronary heart disease and stroke. These “hard endpoints” are actual disease states that affect quality of life. “Soft endpoints” are risk factors for disease, like high blood pressure, but not the disease itself. These risk factors are helpful, but ultimately they are a less meaningful measure of disease.
- Many other studies have come to the same answer about heart disease and omega-3s. Repeating studies with a similar question may seem boring, but it is very, very important! Finding the same answer to the same question in multiple studies strengthens our confidence in the findings.
- BUT…This study cannot determine cause-and-effect relationship. While there are many strengths to this study, it is a cross-sectional study. This means we cannot assume that the omega-3s in the blood or diet caused the reduction in heart disease rates. What we do know is that they are strongly related and worth studying more.
We should note that the way that omega-3 fatty acids were measured in this study was not the same as how we measure blood levels of omega-3s at OmegaQuant. We measure EPA and DHA from red blood cells and these researchers measured omega-3s in all cells found in plasma (the part of blood that doesn’t include red blood cells). These two measures (red blood cell vs. plasma) are not the same, but they are related. In the end, the overall message that omega-3s are important for heart health is consistent!
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