Low carbohydrate-high protein diet and mortality in a cohort of Swedish women

Objective. The long-term health consequences of diets used for weight control are not established. We have evaluated the association of the frequently recommended low carbohydrate diets - usually characterized by concomitant increase in protein intake - with long-term mortality. Design. The Women's Lifestyle and Health cohort study initiated in Sweden during 1991-1992, with a 12-year almost complete follow up. Setting. The Uppsala Health Care Region. Subjects. 42 237 women, 30-49 years old at baseline, volunteers from a random sample, who completed an extensive questionnaire and were traced through linkages to national registries until 2003. Main Outcome Measures. We evaluated the association of mortality with: decreasing carbohydrate intake (in deciles); increasing protein intake (in deciles) and an additive combination of these variables (low carbohydrate-high protein score from 2 to 20), in Cox models controlling for energy intake, saturated fat intake and several nondietary covariates. Results. Decreasing carbohydrate or increasing protein intake by one decile were associated with increase in total mortality by 6% (95% CI: 0-12%) and 2% (95% CI: -1 to 5%), respectively. For cardiovascular mortality, amongst women 40-49 years old at enrolment, the corresponding increases were, respectively, 13% (95% CI: -4 to 32%) and 16% (95% CI: 5-29%), with the additive score being even more predictive. Conclusions. A diet characterized by low carbohydrate and high protein intake was associated with increased total and particularly cardiovascular mortality amongst women. Vigilance with respect to long-term adherence to such weight control regimes is advisable.