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.