Low-Carbohydrate Diets (Plant- vs. Animal-Based) and Mortality
Plant-based low-carb diets were associated with lower all-cause and cardiovascular mortality.
Recent studies have shown equivalence of low-carbohydrate and low-fat diets for weight loss (JW Gen Med Aug 19 2010). In this large prospective study, researchers assessed whether type of low-carb diet — plant-based or animal-based — affects length of life. They used self-reported diet histories gathered during 20-plus years of follow-up in the observational Nurses' Health Study (85,000 women) and the Health Professionals Follow-up Study (44,000 men) to determine whether participants reported a low-carb diet pattern.
The researchers calculated a vegetable low-carbohydrate score for each participant: Compared with those in the lowest decile of vegetable protein and fat intake, those in the highest decile had lower all-cause mortality (hazard ratio, 0.80) and cardiovascular mortality (HR, 0.77) — but not lower cancer mortality (HR, 0.96). Similarly, animal low-carbohydrate scores were calculated: Compared with those in the lowest decile of animal protein and fat intake, those in the highest decile had greater overall mortality (HR, 1.23), cardiovascular mortality (HR, 1.14), and cancer mortality (HR, 1.28). Analyses were adjusted for multiple confounders.
This large prospective study suggests that not all low-carbohydrate diets are equal when considering length of life — plant-based diets appear to be superior to animal-based ones. Nonetheless, editorialists remind us of the potential hazards involved in attributing causation using data from observational studies.
Jamaluddin Moloo, MD, MPH
Published in Journal Watch General Medicine October 12, 2010
Fung TT et al. Low-carbohydrate diets and all-cause and cause-specific mortality: Two cohort studies. Ann Intern Med 2010 Sep 7; 153:289. (http://www.annals.org/content/153/5/289.abstract)
Yancy WS Jr et al. Animal, vegetable, or . . . clinical trial? Ann Intern Med 2010 Sep 7; 153:337. (http://www.annals.org/content/153/5/337.extract)