A new study of over 19,000 adults found a 15 percent higher likelihood of diabetes or history of stroke or heart disease among Americans restricting carbohydrates to less than 45 percent of energy compared with those eating a diet balanced in carbohydrate, fat and protein. The risk was even higher (40%) among those eating a carbohydrate restricted diet that was also high in fat.
Public health is strongly affected by suboptimal diet patterns. They represent the leading risk factor for death from all causes and account for approximately one-half of all deaths from cardiometabolic disease, the authors say. Heart disease, diabetes and stroke accounted for about 30 percent of the mortality burden in U.S. adults in 2019. Just to the north, heart disease remains the 2nd leading cause of death in Canada.
When carbohydrates are restricted, energy from protein and fat increase as a percent of total calories ingested. When some or all of the carbohydrate calories are replaced with other macronutrients, this can lead to increased intake of fat. Therefore, researchers at William & Mary considered whether the amount and type of fat in the diet mattered. High dietary fat in a carbohydrate restricted diet was associated with higher prevalence of cardiometabolic disease. This occurred even for high polyunsaturated fat, which have been shown to be support heart health.
So what was the diet associated with lowest prevalence of cardiometabolic health? “Our findings showed that recommended carbohydrate intake plus high monounsaturated fatty acid intake presented the strongest protective association with cardiometabolic outcomes of any dietary pattern we investigated in this study,” the authors say.
The first-of-its-kind, nationally-representative study was led by William & Mary’s Zach Conrad and student Corina Kowalski and was supported by the Institute for the Advancement of Food and Nutrition Sciences. The researchers looked at health information cross-sectionally from a nationally representative U.S. NHANES database on 19,078 people over a 20-year period.
The study, titled “Fat Intake Modifies the Association between Restricted Carbohydrate Diets and Prevalent Cardiometabolic Diseases among Adults in the United States: National Health and Nutrition Examination Survey, 1999–2018,” appears in the peer-reviewed journal Current Developments in Nutrition.
According to Conrad, “a restricted carbohydrate diet is associated with elevated prevalence of cardiometabolic disease in adult Americans, and even more so if dietary fat intake is high. Because the association is cross-sectional, causality cannot be determined; it is possible that people with cardiometabolic disease start to restrict carbohydrate intake as a consequence of their health status. However, a diet pattern meeting recommended intakes for carbohydrates (45-65% of energy), fat (20-35% of energy) and protein (10-35% of energy) is supported by this research from a cardiometabolic perspective. ”
The study can be found by clicking here.
The Institute for the Advancement of Food and Nutrition Sciences (IAFNS) is a 501(c)(3) science-focused nonprofit uniquely positioned to mobilize government, industry and academia to drive, fund and lead actionable research. This work was supported by IAFNS Dietary Lipids and Carbohydrates Committees. For more information, visit iafns.org.