Associations of Low-Carbohydrate and Low-Fat Diets With Mortality Among Individuals With Hypertension: A Prospective Cohort Study.

Objective: Low-carbohydrate diets (LCDs) and low-fat diets (LFDs) have shown short-term metabolic improvements. However, the associations of different types of LCDs and LFDs with mortality among individuals with hypertension remain unclear when considering the quality of macronutrients and food sources.

Method: The prospective cohort study included 16,379 adults (≥20 years) with hypertension from the National Health and Nutrition Examination Survey from 1999 to 2016 in the United States. Data with at least one dietary recall were utilized to construct overall, healthy, and unhealthy LCD and LFD scores. Mortality outcomes were linked to National Death Index mortality data until December 31, 2019. Cox proportional hazard regression models were used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of mortality.

Results: Elevated healthy LCD scores were associated with favorable levels of blood triglycerides, high-density lipoprotein cholesterol, and blood pressure, while increased healthy LFD scores were linked to reduced levels of blood insulin, Homeostasis Model Assessment of Insulin Resistance, low-density lipoprotein cholesterol, and diastolic blood pressure at baseline (all p_trend < 0.05). During 167,213 person-years of follow-up, a total of 5010 deaths occurred. The multivariable-adjusted HRs of all-cause mortality for per 25-percentile increment in dietary scores were 0.91 (95% CI, 0.87-0.95; p_trend < 0.05) for healthy LCD scores, 0.95 (95% CI, 0.91-0.98; p_trend < 0.05) for healthy LFD scores, 0.99 (95% CI, 0.95-1.03; p_trend = 0.71) for unhealthy LCD scores, and 1.06 (95% CI, 1.02-1.10; p_trend < 0.05) for unhealthy LFD scores. Isocalorically replacing 5% energy of low-quality carbohydrate or saturated fat with high-quality carbohydrate, plant protein, or unsaturated fat was associated with a 9% to 45% reduced risk of all-cause mortality.

Conclusions: Among individuals with hypertension, healthy LCDs and LFDs are significantly associated with a lower risk of all-cause mortality, whereas unhealthy LFDs scores are notably associated with a higher risk of all-cause mortality.