There is convincing scientific evidence that type of fat have a more important role in determining the risk of coronary heart disease(CHD) than total amount of fat in the diet.(1) However, because of misleading presentation of epidemiological data by some authors(1), the readers might be left with the impression that low-fat, high- carbohydrate diet is the best option for patients with CHD risk.
In fact, high- carbohydrate diets, in the absence of weight loss, can lead to both elevated triglyceride and reduced HDL cholesterol, effects that may be associated with increased risk for CHD.(2) Although these effects may be lessened with dietary fiber and moderate physical activity, they appear to be worse among individuals with insulin resistance.(3)
As reviewed by Kris-Etherton(4) adverse metabolic effects of low fat diet do not occur with substitution of monounsaturated (MUFA) or polyunsaturated (PUFA) fatty acids for saturated and trans-fatty acids. This is also the case for individuals with diabetes, with the added benefit of better glycaemic control.(5)
As predicted by metabolic studies, replacement of saturated fat, and even more so trans fatty acids with either PUFA or MUFA was associated with a larger reduction in risk of CHD than simple reduction of total fat consumption.(6) With respect to weight control, a moderate-fat diet can be as, or even more, effective that lower-fat diet. (6)
References
1. Hu FB, Manson JE, Willet WC. Types of dietary fat and risk of coronary heart disease: a critical review. J Am Coll Nutr 2001;20:5-19.
2. Fung MA, Frohlich JJ. Common problems in the management of hypertriglyceridemia. CMAJ 2002;167:1261-6.
3. Jeppesen J, Schaaf P, Jones G, Zhou MY, Chen YD, Reaven GM. Effects of low-fat, high-carbohydrate diets on risk factors for ischemic heart disease in postmenopausal women. Am J Clin Nutr 1997;65:1027-33.
4. Kris-Etherton PM, Kris-Etherton PM, Binkoski AE, Zhao G, Coval SM, Clemmer KF, et al. Dietary fat: assessing the evidence in support of a moderate-fat diet; the benchmark based on lipoprotein metabolism. Proc Nutr Soc 2002;61:287-98.
5. Rivellese AA, De Natale C, Lilli S. Type of dietary fat and insulin resistance. Ann N Y Acad Sci 2002;967:329-35.
6. Krauss RM, Eckel RH, Howard B, Appel LJ, Daniels SR, Deckelbaum RJ et al. AHA Dietary Guidelines: revision 2000: A statement for healthcare professionals from the Nutrition Committee of the American Heart Association. Circulation. 2000;102:2284-99.



About the author:
Dr. Michal R. Pijak is a consultant in rheumatology, allergy and clinical immunology at the University Hospital in Bratislava, Slovakia