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Low-Carbohydrate Diets and All-Cause and Cause-Specific

MortalityTwo Cohort Studies

Fung T et al.

Ann Intern Med 2010;153:289-298

Page 1 Fung T et al. Ann Intern Med 2010;153:289-298

Page 2

Background• Several studies have demonstrated that a low-

carbohydrate diet is at least as effective as a calorie-restricted, high-carbohydrate, low-fat diet for weight loss

• However, effects on blood lipid profiles for low-carbohydrate diets are mixed– low-carbohydrate diets resulting in greater improvements in

high-density lipoprotein cholesterol and triglyserides– but less favorable changes in low-density lipoprotein

cholesterol levels than higher carbohydrate diets

• Different types of low carb diets may impact health differently

• Long-term data on low-carbohydrate diets and mortality are insufficient (Yancy et al. 2010)

Fung T et al. Ann Intern Med 2010;153:289-298 www.pronutritionist.net

Methods (1/2)

• Two prospective cohort studies• n = 85 168 women from Nurses’ Health Study

• aged 34 to 59 years at baseline• follow-up 26 years

• n = 44 548 men from Health Professionals’ Follow-up Study• aged 40 to 75 years at baseline• follow-up 20 years

• food intake was followed with food-frequency questionnaires

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Methods (2/2)

• low-carbohydrate scores was calculated to characterize low-carbohydrate diets on the basis of the 1. proportion of carbohydrate, fat, and protein in the diet

2. the contribution to these macronutrients from animal or vegetable sources

• scores:– overall low-carbohydrate score– animal low-carbohydrate score– vegetable low-carbohydrate score

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Results

• Both men and women who had higher overall and animal low-carbohydrate scores had – higher BMI– were more likely to be current smokers– had lower intakes of fruits and vegetables

• those with higher vegetable low-carbohydrate score tended to have higher alcohol and whole grain intake

• In the extreme low decile of carbohydrate intake, daily intake was 152 g for women and 166 g for men

• In extreme high decile of carbohydrate intake, daily intake was 275 g for women and 305 g for men

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Results

• overall low-carbohydrate diet score was only weakly associated with all-cause mortality (HR 1,12)

• a higher animal low-carbohydrate diet score was associated with – higher all-cause mortality in men and women

– cancer and cardiovascular mortality in men

• a higher vegetable low-carbohydrate score was associated with lower mortality and particularly CVD mortality

• When cancers were broken into subclasses, it was found that colorectal and lung cancers were more common in low carb animal based group (Appendix material) than in high carb animal based group

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Hazard ratio comparing low carbohydrate intake to high intake: all-cause mortality (pooled)

www.pronutritionist.netFung T et al. Ann Intern Med 2010;153:289-2987

*p < 0.001

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Multivariate-adjusted hazard ratio comparing extreme deciles: cardiovascular mortality (pooled)

p < 0.001

P =0,029

Multivariate-adjusted hazard ratio comparing extreme deciles: cancer mortality (pooled)

www.pronutritionist.netFung T et al. Ann Intern Med 2010;153:289-2989

None of the pooled comparisons is statistically significant. However, in separate analyses both in women and men the differences in animal based became significant

P =0,089 P =0,23

Discussion (1/2)

• Classification of carbohydrate diets in the study does not match with current thinking of low carbohydrate diet. In the lowest decile of intake, participants still had carbohydrate intake of c. 150-170 grams per day

• “A low-carbohydrate diet” based on animal sources was associated with modestly higher (12 %) all-cause mortality in both men and women

• Vegetable-based “low-carbohydrate diet” was associated with 15 % lower all-cause and 21 % lower cardiovascular disease mortality vs respective high carbohydrate diets

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Discussion (2/2)

• Results suggest that the health effects of a low-carbohydrate diet may depend on the type of protein and fat, and a diet that includes mostly vegetable sources of protein and fat is preferable to a diet with mostly animal sources of protein and fat

• The study results are in line with another large cohort study from US ( Halton et al. 2006 ), and with European cohort studies (Lagiou et al 2007 and Trichopoulou et al. 2007 )

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