Associations of Lower-Carbohydrate and Lower-Fat Diets with Mortality among People with Cardiovascular Disease.

BACKGROUND: Although low-carbohydrate and low-fat diets have been shown to have short-term metabolic benefits, the associations of these dietary patterns, particularly different food sources and macronutrient quality, with mortality in people with cardiovascular disease (CVD) remain unclear. OBJECTIVES: To examine the associations of different types of lower-carbohydrate diets (LCDs) and lower-fat diets (LFDs) with mortality in individuals with CVD. METHODS: This study included 3971 adults with CVD from the NHANES 1999-2014. Mortality status was linked to National Death Index mortality data through 31 December 2019. Overall, unhealthy and healthy LCD and LFD scores were determined based on the percentages of energy from total and subtypes of carbohydrate, fat, and protein. Cox proportional hazards regression models were applied to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Higher healthy LCD score was associated with favorable blood lipids and higher homeostasis model assessment of insulin resistance, whereas higher unhealthy LFD score was associated with lower high-density lipoprotein and higher C-reactive protein at baseline (all P-trend < 0.05). During 35,150 person-years of follow-up, 2163 deaths occurred. For per 20-percentile increment in dietary scores, the multivariate-adjusted HRs of all-cause mortality were 0.91 (95% CI: 0.86, 0.96) for healthy LCD score (P < 0.001), 0.94 (95% CI: 0.89, 1.00) for healthy LFD score (P = 0.04), and 1.07 (95% CI: 1.00, 1.14) for unhealthy LFD score (P = 0.04). CONCLUSIONS: Overall LCD and LFD scores are not associated with total mortality. Unhealthy LFD scores are associated with higher total mortality, whereas healthy LCD and LFD scores are associated with lower mortality in people with CVD.

Associations of lower-carbohydrate and lower-fat diets with mortality among people with prediabetes.

BACKGROUND: Although low-carbohydrate and low-fat diets are beneficial in short-term metabolic improvement, the associations of these dietary patterns, particularly with different food sources and quality of macronutrients, with mortality remain unclear among people with prediabetes. OBJECTIVES: We aimed to examine the associations of different types of lower-carbohydrate diets (LCDs) and lower-fat diets (LFDs) with mortality among individuals with prediabetes. METHODS: This study included 9793 adults with prediabetes from the NHANES 1999-2014. Mortality status was linked to National Death Index mortality data through 31 December, 2015. Overall, unhealthy, and healthy LCD and LFD scores were determined based on the percentages of energy from total and subtypes of carbohydrate, fat, and protein. Cox proportional hazards regression models were applied to calculate HRs and 95% CIs. RESULTS: Higher healthy LCD score was associated with favorable blood glucose, insulin, HOMA-IR, C-reactive protein (CRP), and blood lipids, whereas higher healthy LFD score was associated with lower blood glucose and CRP at baseline (all P-trend < 0.05). During 72,054 person-years of follow-up, 1352 deaths occurred. The multivariate-adjusted HRs (95% CIs) of all-cause mortality per 20-percentile increment in dietary scores were 0.88 (0.80, 0.96) for healthy LCD score (P = 0.003), 0.85 (0.78, 0.93) for healthy LFD score (P < 0.001), 1.09 (0.99, 1.21) for unhealthy LCD score (P = 0.08), and 1.11 (1.00, 1.22) for unhealthy LFD score (P = 0.05). Isocalorically replacing 3%-5% energy of low-quality carbohydrate or saturated fat with high-quality carbohydrate, plant-based protein, or unsaturated fat was associated with a 14%-37% reduced all-cause mortality. CONCLUSIONS: Healthy LCD and LFD scores were significantly associated with lower all-cause mortality, whereas unhealthy LCD and LFD scores tended to be associated with higher all-cause mortality, among people with prediabetes.