Carbohydrate restriction is effective in improving atherogenic dyslipidemia even in the absence of weight loss

Department of Medicine
Duke University Medical Center
Durham, NC 27705
ewestman{at}duke.edu

Jeff S Volek

Department of Kinesiology
University of Connecticut
Storrs, CT 06269

Richard D Feinman

Department of Biochemistry
SUNY Downstate Medical Center
Brooklyn, NY 11203

Dear Sir:

Krauss et al (1) are to be congratulated on the data presented in their recent article in the Journal, one of the strongest cases for dietary carbohydrate restriction to date. At the same time, we have concerns about the misleading and confusing way in which the data were presented and interpreted and about the scarcity of citations of other publications that are supportive of these findings (2-4). Because of the significance of these data for health, careful and appropriate conclusions are extremely important.

The abstract conclusion, "Moreover, beneficial lipid changes resulting from a reduced carbohydrate intake were not significant after weight loss," is in contradiction to their data, which showed that HDL cholesterol is significantly increased by weight loss after carbohydrate restriction, and even more so in the subjects receiving a greater percentage (15%) of energy from saturated fatty acids (SFA). The negative conclusion stands in stark contrast to the data in the paper that show that carbohydrate restriction is effective for improving atherogenic dyslipidemia even in the absence of weight loss. The reason most markers were less responsive to weight loss induced by the low-carbohydrate diet was that they had been improved by carbohydrate restriction before weight loss was instituted.

Krauss et al chose not to mention their data on a comparison between the high-carbohydrate diet and the low-carbohydrate diet higher in SFA. SFA are generally considered atherogenic, but the question of whether such an effect would be manifest when carbohydrates are restricted remains unanswered (5, 6).

The increase in LDL peak particle diameter reported by Krauss et al (1) shows the substantial advantage of low carbohydrate (with or without SFA) over low fat, again a finding previously reported (2, 4, 6-9) but not cited by Krauss et al.

Given how difficult it is to lose weight, the data of Krauss et al support the notion that carbohydrate restriction is the default diet for treatment of atherogenic dyslipidemia. Because low-carbohydrate strategies are at least as effective at fat reduction as are low-fat diets, it is reasonable to conclude that carbohydrate restriction, lower or higher in SFA, is the preferred diet for most people and especially those with the complex of health markers referred to as metabolic syndrome, as we previously suggested (10).

Remarkably, despite these data on the advantages of carbohydrate restriction, the report concludes with tired "concerns" about low-carbohydrate diets and a tribute to exercise and fiber, variables not included in the study. Overall, the authors seem to have had a goal of trying to support current official health guidelines rather than a goal of trying to bring those guidelines into concordance with the scientific data. As suggested by the results of the study by Krauss et al, further research should concentrate on the lower-carbohydrate, higher-saturated fat diets as a therapy for atherogenic dyslipidemia.

ACKNOWLEDGMENTS

None of the authors had a personal or financial conflict of interest with respect to the study by Krauss et al.

REFERENCES