A new study by Siri-Tarino of the Children’s Hospital Oakland Research Institute in California,concluded in the American Journal of Clinical Nutrition that we are missing lower cardiovascular disease targets when we urge the obese to lower dietary fats. The emphasis on reducing dietary saturated fat isn’t preventing cardiovascular disease (CVD) in the obesity epidemic and associated metabolic disturbances, the authors concluded.
Limiting carbohydrates, particularly refined carbohydrates, offers the best hope for reducing the CVD burden associated with fats clogging the arteries.
Siri-Tarino and her colleagues cited evidence to support their views and conclusions:
- Clinical trials and prospective-cohort studies have not consistently shown that reducing dietary saturated fat lowers CVD risk.
- Replacing saturated fat with carbohydrate has not been shown to reduce CVD risk.
- Interest in the relationship between glycemic load or index and CVD risk has insufficient evidence to develop prevention programs.
- The effect of saturated fat on LDL may be modulated by the amount of polyunsaturated fatty acids.
- Substituting mono- and polyunsaturated fats for carbohydrate effectively reduces LDL.
- Both overweight and increased carbohydrate intake have been linked to the poor lipid profile associated with metabolic syndrome.
- Reducing carbohydrate intake has been shown to lower the concentration of artery-clogging small, dense LDL particles.
- Relationships between dietary fats and other CVD risk factors, such as blood pressure, insulin sensitivity, and inflammation, are unclear.
In a meta-analysis published in the same issue of the journal, Siri-Tarino and colleagues concluded that the evidence does not support “the conventional wisdom that reduced dietary saturated fat intake is beneficial for cardiovascular health.” No additional benefit has been seen by lowering saturated fat below 9%.
Interestingly although this line of reasoning has years of research supporting it, the article was considered so controversial that an opposing editorial was place on the facing page. Apparently the challenge to conventional wisdom isn’t appreciated: Jeremiah Stamler wrote, “The authors seem to be dissociating themselves from prevailing national and international dietary recommendations to the general population for primordial, primary, and secondary prevention of CHD/CVD and the established metabolic risk factors.
The problem with cutting fat, especially saturated fat, is that carbohydrates are usually used to replace the fats. In the allegedly “heart healthy” processed foods, sugar tends to be used to replace flavorful fats. And fat is well known to reduce satiety so people eat more.
The advice to the obese should be to restrict carbohydrates in the form of grains and sugars rather than lowering fats.
Medical News: Review Calls for Reevaluation of the Fat-CVD Link
American Journal of Clinical Nutrition. Siri-Tarino PW. et al “Saturated fat, carbohydrate, and cardiovascular disease” Am J Clin Nutr 2010; 91: 502-09.
American Journal of Clinical Nutrition. Stamler J “Diet-heart: a problematic revisit” Am J Clin Nutr 2010; 91: 497-99.
American Journal of Clinical Nutrition. Siri-Tarino PW, et al “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease” Am J Clin Nutr 2010; 91: 535-46.
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