Correspondence

Low-Carbohydrate Diet and Coronary Heart Disease in Women

N Engl J Med 2007; 356:750-752February 15, 2007

Article

To the Editor:

Halton and colleagues (Nov. 9 issue)1 report that low-carbohydrate diets are not associated with an increased risk of coronary heart disease in women. We pooled data from our own studies2-4 evaluating the effect of lifestyle changes (Mediterranean-style diet and exercise) on body weight, lipid levels, and vascular inflammatory markers in 190 overweight women who were followed for up to 2 years. The women were advised to increase their consumption of fruits, vegetables, nuts, whole grains, and olive oil. The 115 women who had a dietary intake of carbohydrate that exceeded 50% of energy were compared with the 75 who had a carbohydrate intake equal to or below 50%. The mean (±SD) values for the macronutrient composition of the diets in the two groups were as follows: high-carbohydrate intake — 58±3.1% carbohydrate, 14±2.5% protein, and 28±4.8% fat (9±1.5% animal and 19±3.5% vegetable fat); low-carbohydrate intake — 45±3.3% carbohydrate, 19±2.9% protein, and 36±4.3% fat (12±1.9% animal fat and 24±4.1% vegetable fat).

Women consuming a low-carbohydrate diet lost more weight than did those consuming a high-carbohydrate diet and had better lipid and inflammatory profiles (Figure 1Figure 1Changes in Body Weight and Lipid and Inflammatory Profiles in 190 Women, According to Dietary Intake of Carbohydrate.). Restriction of carbohydrates within a Mediterranean-style diet may be advantageous for weight loss.

Katherine Esposito, M.D., Ph.D.
Miryam Ciotola, M.D.
Dario Giugliano, M.D., Ph.D.
Second University of Naples, 80138 Naples, Italy

4 References

1. 1

   Halton TL, Willett WC, Liu S, et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women. N Engl J Med 2006;355:1991-2002
   Full Text | Web of Science | Medline

2. 2

   Ziccardi P, Nappo F, Giugliano G, et al. Reduction of inflammatory cytokine concentrations and improvement of endothelial functions in obese women after weight loss over one year. Circulation 2002;105:804-809
   CrossRef | Web of Science | Medline

3. 3

   Esposito K, Pontillo A, Di Palo C, et al. Effect of weight loss and lifestyle changes on vascular inflammatory markers in obese women: a randomized trial. JAMA 2003;289:1799-1804
   CrossRef | Web of Science | Medline

4. 4

   Esposito K, Marfella R, Ciotola M, et al. Effect of a Mediterranean-style diet on endothelial dysfunction and markers of vascular inflammation in the metabolic syndrome: a randomized trial. JAMA 2004;292:1440-1446
   CrossRef | Web of Science | Medline

To the Editor:

Halton et al. conclude that “vegetable sources of fat and protein . . . may moderately reduce the risk of coronary heart disease.” They do not provide details of the sources of these vegetable fats and proteins, but it would be important to learn which foods are most correlated with a decreased risk. Specifically, what portion of the decreased risk is due to the consumption of nuts, which have been shown to be strongly negatively correlated with coronary heart disease?1

Daniel B. Hrdy, M.D., Ph.D.
Citrona Farms, Winters, CA 95694

Dr. Hrdy reports being a walnut grower.

1 References

1. 1

   Hu FB, Stampfer MJ, Manson JE, et al. Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. BMJ 1998;317:1341-1345
   CrossRef | Web of Science | Medline

Author/Editor Response

We are gratified to know that the findings of Esposito and colleagues regarding a low-carbohydrate dietary pattern in relation to weight loss and cardiovascular risk factors during their 2-year intervention using a Mediterranean diet are consistent with ours. These findings suggest that the restriction of refined carbohydrates in a Mediterranean diet can be beneficial in reducing the risk of cardiovascular disease.

Regarding Hrdy's question about the sources of vegetable fat and vegetable protein in the diet of our cohort, we focused on the macronutrient composition of the diet, rather than on individual food sources. In our cohort, the foods that most contributed to vegetable-fat intake were vegetable oils (e.g., soybean, corn, and canola), olive oil, mayonnaise, peanut butter, and nuts. The oils included a mixture of monounsaturated and polyunsaturated fatty acids. Because an adjustment was made for the trans fatty acid content of foods in the analyses, the inverse association observed between vegetable fat and coronary heart disease was independent of trans fat intake.1 The foods that most contributed to vegetable-protein intake were whole-grain foods (e.g., dark bread and cold cereals), legumes (beans and peas), peanut butter, and nuts. Some foods high in carbohydrate such as pasta and potatoes also contributed to vegetable-protein intake in the overall cohort. It is not possible to estimate the contribution of each individual food to the lower risk of coronary heart disease associated with the low-carbohydrate dietary pattern, because each food contains many nutrients. However, we believe that the benefit of the vegetable-based, low-carbohydrate-diet score in our cohort was due not only to the inclusion of vegetable fat and vegetable protein but also to the lower glycemic load of this dietary pattern, since the glycemic load was strongly related to the risk of coronary heart disease. Thus, a heart-healthy dietary pattern should emphasize healthful sources of fat and protein and low amounts of refined carbohydrates and added sugar.

Thomas L. Halton, Sc.D.
Walter Willett, M.D., Dr.P.H.
Frank B. Hu, M.D., Ph.D.
Harvard School of Public Health, Boston, MA 02115
frank.hu@channing.harvard.edu

We also want to report that while conducting this research, Dr. Halton was a full-time doctoral student at Harvard School of Public Health. Since graduation, he has founded an exercise- and nutrition-counseling business (Fitness Plus).

1 References

1. 1

   Hu FB, Stampfer MJ, Manson JE, et al. Dietary fat intake and the risk of coronary heart disease in women. N Engl J Med 1997;337:1491-1499
   Full Text | Web of Science | Medline

Citing Articles (5)

Citing Articles

1. 1

   K. Esposito, M. Maiorino, D. Giugliano. (2009) Which diet is best for diabetes?. Diabetologia 52:5, 988-989
   CrossRef

2. 2

   Katherine Esposito, Miryam Ciotola, Maria Ida Maiorino, Dario Giugliano. (2008) Lifestyle approach for type 2 diabetes and metabolic syndrome. Current Atherosclerosis Reports 10:6, 523-528
   CrossRef

3. 3

   Dario Giugliano, Katherine Esposito. (2008) Mediterranean diet and metabolic diseases. Current Opinion in Internal Medicine 7:2, 149-154
   CrossRef

4. 4

   Katherine Esposito, Antonio Ceriello, Dario Giugliano. (2007) Diet and the Metabolic Syndrome. Metabolic Syndrome and Related Disorders 5:4, 291-296
   CrossRef

5. 5

   Katherine Esposito, Miryam Ciotola, Dario Giugliano. (2007) Mediterranean diet and the metabolic syndrome. Molecular Nutrition & Food Research
   CrossRef