Researchers find only vegetarian low-carb diet is associated with lower risk of heart disease

Advocates of low-carbohydrate diets, such as the popular Atkins diet, claim that those diets may help prevent obesity and coronary heart disease (CHD). However, the long-term safety of those diets has been debated, particularly because they encourage the consumption of animal products, which are high in saturated fats and cholesterol and could potentially increase the risk of CHD. Prevailing dietary recommendations have advocated a contrary approach, recommending diets that are low in fat and high in carbohydrates as the best way to manage weight and reduce the risk of cardiovascular disease.

In the first study to look at the long-term effects of low-carbohydrate diets, researchers from the Harvard School of Public Health (HSPH) found no evidence of an association between low-carb diets and an increased risk of CHD in women. Their findings did suggest, however, an association between low-carb diets high in vegetable sources of fat and protein and a low risk of CHD.

“This study suggests that neither a low-fat dietary pattern nor a typical low-carbohydrate dietary pattern is ideal with regards to risk of CHD; both have similar risks. However, if a diet moderately lower in carbohydrates is followed, with a focus on vegetable sources of fat and protein, there may be a benefit for heart disease,” said Tom Halton, a former doctoral student in the Department of Nutrition at HSPH.

The study appears in the November 9, 2006, issue of The New England Journal of Medicine.

The researchers, Halton, senior author Frank Hu, associate professor of nutrition and epidemiology at HSPH, and colleagues, looked at data collected over a 20-year period from 82,802 women in the Nurses’ Health Study, a long-term study that began in 1976. Study participants were divided into 10 categories according to their overall diet score, which was measured by calculating fat, protein and carbohydrate intake as a percentage of energy. The scores ranged from 0 (the lowest fat and protein intake and highest carbohydrate intake) to 30 (the highest fat and protein intake and lowest carbohydrate intake). A higher score meant a person followed a low-carbohydrate diet more closely; that score was called the “low-carbohydrate-diet score.”

Halton and his colleagues also created two additional low-carbohydrate-diet scores. The first calculated percentages of energy from carbohydrate, animal protein and animal fat. The second calculated percentages of energy from carbohydrate, vegetable protein and vegetable fat.

The researchers documented 1,994 cases of coronary heart disease over the study period.

The results showed that a low-carbohydrate score was not associated with risk of CHD in women. There was no evidence that the relationship was modified as a result of physical activity levels, body-mass index, or the presence or absence of hypertension, diabetes, or hypercholesterolemia.

Total amounts of fat or carbohydrate did not appear to have an appreciable relationship with risk of CHD. However, types of fat and carbohydrates do make a difference. Vegetable fat was associated a lower risk of risk of CHD, whereas higher dietary glycemic load (reflecting the amount of refined carbohydrates that can rapidly elevate blood sugar levels)–typical of a high-carb diet–was strongly associated with increased risk. The authors found that, when vegetable sources of fat and protein were chosen instead of animal sources, the low-carbohydrate-diet score was associated with a 30% lower risk of CHD.

“This study doesn’t mean that you should load your plate with steak and bacon,” said Hu. “One likely explanation that we did not see increased risk of CHD with low-carbohydrate diets is that the adverse effects of animal products might be counterbalanced by reducing refined carbohydrates. The quality of fat and carbohydrate is more important than quantity. A heart-healthy diet should embrace healthy types of fat and carbohydrates.”

Source: Harvard School of Public Health

8 thoughts on “Researchers find only vegetarian low-carb diet is associated with lower risk of heart disease

  1. Well, I don’t think any sane person would think that a diet high in animal protein and fat will be beneficial. Glad to see the Atkins diet debunked and the benefits of vegetarian low-carb diets confirmed.

  2. Maybe “Only vegetarian low-carb diet associated with lower risk of heart disease”?

    The most relevant sentence to the reader seems to be “The authors found that, when vegetable sources of fat and protein were chosen instead of animal sources, the low-carbohydrate-diet score was associated with a 30% lower risk of CHD.”

  3. PE

    In a review of 32 cohort and case-control studies investigating the association of saturated fat and heart disease, Ravnskov found that 22 of the cohort studies and all 6 case-control studies conducted found NO correlation between development of heart disease and level of saturated fat intake. In three of the cohort studies, a positive correlation between saturated fat and heart disease was shown, and in one cohort study a *negative* correlation was shown. (Ravnskov, U., “The questionable role of saturated and polyunsaturated fastty acids in cardiovascular disease,” J Clin Epidemiol 1998;51: 443-460). In other words, the evidence indicates that saturated fat does not cause heart disease. The whole premise that it does is based on a hypotheses that has never been substantiated. If you wish to read about how America and the health profession was pushed into adopting this unproven dietary dictum, I suggest you read Gary Taubes’s illuminating article, “The Soft Science of Dietary Fat” (Science, Vol. 291, March 30, 2001). Atkins wasn’t totally right, but he wasn’t as wrong as the low-fat zealots.

  4. what is the truth among all of these studies; now we find some studies told us diet is useful;tomorrow we find another told us diet is harmful; sometimes we hear the two opposites in the same time;now we are confused;by whome we trust ;in my opinion ; we must trust ourselves ; i ask myself ? what my grandfather do to live 78 years with a good body?
    note: he died before i ask him!

  5. gary dempster

    this is crap man, they just manipulate statistics and then say they conclude whatever it is they see in the data. only proper clinical studies have any real meaning or validity. better yet real life experience from actual people. this just looks like another attempt to salvage mainstream nutritional theory vis a vis diets that “threaten” it.

    low carb diets have been shown beyond any shadow of a doubt in real clinical studies to be healthful, and to reverse many serious diseases (obesity, diabetes, digestive disorders, etc etc.) also, there are no meaningful studies that show animal fat/saturated fat to be unhealthy, this is just a very popular mis-conception — does not make it true. read gary taubes or dr. james carlson for proof galore…

  6. John McAuliffe

    I have been a partial vegan for two years.
    When I consumed a meat diet, I found that I was not as able to endure prolonged exercise without feeling exhausted rather quickly.

    I also noticed that I was developing numbness in my hands, as if my circulation was effected by that diet.
    The main reason I am partial vegan is that I actually enjoy the larger variety of fruits/nuts/vegetables that I eat now, which I tended not to eat on the old diet.
    Finally; apart from the tendency towards over eating, which the consumption of meat, and or meat/dairy products seems to encourage; I am not too thrilled with the fact that nearly all of the animals, and chickens are injected with growth hormones, and are given man made up feed which also has chemicals added.

    I wonder whether the deterioration in the quality of life and health in the West, has more to do with corruption of healthy organic farming of yester year, to the “modern” farming methods of today; which I suspect is contributing to the pollution of all of the food we eat, with the over reliance on antibiotics, chemical fertilizers, additives, hormones, genetic engineering, and unnatural feeding conditions.

    The sooner genuine “organic” farming becomes the rule rather than the exception, the better in my book.
    Iin the meantime, I will continue to cut down my risks of becoming contaminated by poor farming practices, and stay with vegetarianism, which seems for a growing number of people; the much lesser of the two evils.

    John McAuliffe

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