Another good reason to eat your fruits and vegetables

Your grandmother always told you, you couldn’t leave the table until you ate all your vegetables. She was giving you the essence of reducing your chances of dying from cardiovascular disease.

The trouble with testing any dietary hypothesis (even Grandma’s advice on vegetables) is the complexity of understanding nutrition. Unlike drugs, which are based on linear thinking (one drug affects one enzyme and that treats you), nutrition is based on non-linear thinking. That means nutrition is more like a three-dimensional chess match. Whenever you change one component (i.e. amount of fat) in the diet, there will be unintended changes as something else is automatically changed as a consequence (like either an increase in dietary protein or carbohydrate to make up the difference of the reduction of dietary fat). This secondary dietary change may totally obscure what you are trying to study. This explains why so many dietary studies appear to produce such wishy-washy results. To try to get around this constant dilemma, investigators often do extremely large epidemiological studies, using people who are initially disease-free and ask how an exposure to some dietary variable affects the development of a particular disease or more importantly death from a particular disease. These are called prospective cohort studies.

As you might imagine, there are very few of these studies since they require a very large number of subjects, and if the outcome is death, then they have to be followed for a very long time. This also means that these studies are extremely expensive. In a soon-to-be-published article in the European Heart Journal is a massive prospective cohort study (with more than 300,000 subjects and based upon an average of eight years of follow-up) that suggested if you ate more fruits and vegetables, your likelihood of dying of heart disease was reduced by 22 percent (1).

How much is more fruits and vegetables? It is about eight servings per day, and it appeared to be a dose-response effect. For each serving of fruits or vegetables, the risk of death from heart disease goes down by 4 percent. Bottom line, the more fruits and vegetables you eat, the greater the reduction in cardiovascular death.

Since you have to eat, why not eat right if your goal is reducing the risk of death from heart disease. If you are eating more fruits and vegetables, then something must be removed from the diet if the calories are to remain constant. The most logical choice would be reducing grains and starches as you increase fruits and vegetables. In the process, you reduce the glycemic load of the diet and reduce production of insulin. This will not only reduce your risk of dying from heart disease, but also help you lose excess body fat (2)

Notice that I keep emphasizing the words death and dying. The prevailing “wisdom” in the cardiovascular community is that it doesn’t matter what you eat as long as you reduce cholesterol levels. And since increased fruits and vegetables consumption has little impact on cholesterol levels, we are told that if you really want to reduce the risk of dying from heart disease, it’s imperative that you must take a statin drug for the rest of your life. Unfortunately, the research data doesn’t support such optimism. For example, if subjects are studied who have no heart disease (these are called primary prevention studies), then taking statin drugs has no impact on reducing their all-cause mortality (3). In other words, any reduction in cardiovascular death was offset by increases of death from other causes. Not such a good deal if your goal is reducing death whatever the cause. Another group of researchers came to the conclusion after analyzing a number of published trials using statin drugs for the primary prevention of developing heart disease, that there was no compelling reason for their use (4). Since the vast majority of the people taking statin drugs have no established heart disease, this would mean the continued prescription of these drugs comes close to health-care fraud.

But what if you already have heart disease? What is the best way to reduce the risk of dying from it? To answer that question, you undertake secondary prevention studies using death (it’s very easy to measure) as your clinical endpoint. In secondary prevention studies, statins will reduce cardiovascular mortality by about 20 percent in people who already have established heart disease. But if you really want to reduce the likelihood of dying from existing heart disease (like by 70 percent), then you not only have to have the patients increase their intake of fruits and vegetables, but also remove much of the omega-6 fatty acids from the diet and replace them with omega-3 fats (5).

If you do both of these dietary changes (replace grains and starches with more fruits and vegetables as well as replace omega-6 fats with omega-3 fats), then you are essentially following the anti inflammatory diet. That’s how you live longer whether you have heart disease or not.

References

1. Crowe FL, Roddam AW, Key TJ, et al. “Fruit and vegetable intake and mortality form ischaemic heart disease.” Eur Heart Journal 32: doi 10.1093 (2011)

2. Sears B. “The Zone.” Regan Books. New York, NY (1995)

3. Ray KK, Seshsai SRK, Erqou S, Sever P, Jukema JW, Ford I, and Sattar NS. “Statins and all-cause morality in high-risk primary prevention.” Arch Intern Med 170: 1024-1031 (2010)

4. Taylor F, Ward K, Moore THM, Burke M, Davey-Smith G, Casas JP, and Ebrahim S. “Statins for the primary prevention of cardiovascular disease.” The Cochrane Library Issue 1 (2011)

5. de Lorgeril M, Renaud S, Mamelle N, Salen P, Martin JL, Monjaud I, Guidollet J, Touboul P, and Delaye J. “Mediterranean alpha-linolenic acid-rich diet in secondary prevention of coronary heart disease.” Lancet 343: 1454-1459 (1994)

Nothing contained in this blog is intended to be instructional for medial diagnosis or treatment. If you have a medical concern or issue, please consult your personal physician immediately.

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About Dr. Barry Sears

Dr. Barry Sears is a leading authority on the impact of the diet on hormonal response, genetic expression, and inflammation. A former research scientist at the Boston University School of Medicine and the Massachusetts Institute of Technology, Dr. Sears has dedicated his research efforts over the past 30 years to the study of lipids. He has published more than 30 scientific articles and holds 13 U.S. patents in the areas of intravenous drug delivery systems and hormonal regulation for the treatment of cardiovascular disease. He has also written 13 books, including the New York Times #1 best-seller "The Zone". These books have sold more than 5 million copies in the U.S. and have been translated into 22 different languages.

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