USA: The associations of low-carbohydrate and low-fat diets with mortality may depend on the quality and food sources of macronutrients, a recent study in the journal JAMA Internal Medicine has suggested.
According to the study, neither low-carb or low-fat diet is associated with total mortality. In fact, it is the unhealthy low-carb and low-fat diet that is associated with higher total mortality. healthy low-carb and low-fat diet were associated with lower total mortality.
Low-carbohydrate diets are often used for weight loss and management, and low-fat diets are recommended by some dietary guidelines to help prevent chronic diseases. However, there has been confusion for several years over the link between carbohydrate restriction and mortality. Some studies said that a low-carb diet leads to premature death risks; while the others stated the opposite.
Zhilei Shan, Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, and colleagues conducted the study to investigate the associations of low-carbohydrate and low-fat diets with total and cause-specific mortality among US adults.
This prospective cohort study used data from the US National Health and Nutrition Examination Survey from 1999 to 2014 from 37 233 adults 20 years or older with 24-hour dietary recall data. Data were analyzed from July 5 to August 27, 2019.
They were exposed to overall, unhealthy, and healthy low-carbohydrate-diet and low-fat-diet scores based on the percentage of energy as total and subtypes of carbohydrate, fat, and protein.
The primary outcome of the study was all-cause mortality from baseline until December 31, 2015, linked to the National Death Index mortality data.
Key findings of the study include:
During 297 768 person-years of follow-up, 4866 total deaths occurred.
Overall low-carbohydrate-diet and low-fat-diet scores were not associated with total mortality.
The multivariable-adjusted hazard ratios for total mortality per 20-percentile increase in dietary scores were 1.07 for unhealthy low-carbohydrate-diet score, 0.91 for healthy low-carbohydrate-diet score, 1.06 for unhealthy low-fat-diet score, and 0.89 for healthy low-fat-diet score.
The associations remained similar in the stratification and sensitivity analyses.
The bottom line of the study is --> low-carbohydrate and low-fat diets maybe associated with mortality, depending on the "quality and food sources of macronutrients".
The study, "Association of Low-Carbohydrate and Low-Fat Diets With Mortality Among US Adults," is published in the journal JAMA Internal Medicine.
DOI: 10.1001/jamainternmed.2019.6980