Racial and ethnic differences in the association of low-carbohydrate diet with mortality in the Multi-Ethnic Study of Atherosclerosis

Authors: OH, SEUNG - Seoul National University; WOOD, ALEXIS - Children'S Nutrition Research Center (CNRC); HWANG, SEUNG - Seoul National University; ALLISON, MATTHEW - University Of California, San Diego

Submitted to: JAMA Network Open
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2022
Publication Date: 10/20/2022
Citation: Oh, S.W., Wood, A.C., Hwang, S.S., Allison, M. 2022. Racial and ethnic differences in the association of low-carbohydrate diet with mortality in the Multi-Ethnic Study of Atherosclerosis. JAMA Network Open. 5(10). Article e2237552. https://doi.org/10.1001/jamanetworkopen.2022.37552.
DOI: https://doi.org/10.1001/jamanetworkopen.2022.37552

Interpretive Summary: Reducing carbohydrate intake is often recommended for improving health, preventing chronic diseases and so extending the lifespan. However, questions still remain: firstly, the extent to which carbohydrates are replaced with foods from animal vs. plant sources is not well established; and secondly, it is not clear whether the benefits of lower carbohydrate diets on lifespan are equal across people from different racial/ethnic groups. To answer these questions, this study examined the diet and health outcomes among 6,000 older US adults who reported their race/ethnicity as either non-Hispanic white, Hispanic white, African-American or Asian. Over 17 years of observations, carbohydrate intake was not associated with time to death in the population as a whole, but both very high and a very low carbohydrate intake was associated with earlier death in non-Hispanic whites, if the remainder of the diet was composed of mostly animal based foods, as compared to mostly plant based foods. These findings suggest that the relationship between carbohydrate intake and mortality may differ according to the composition of a person's diet, as well as their race/ethnicity.

Technical Abstract: Evidence linking low-carbohydrate diets (LCDs) to mortality is limited among multiethnic populations. The objective of this study was to evaluate the association between LCDs and mortality by race and ethnicity. The Multi-Ethnic Study of Atherosclerosis is a large, population-based prospective cohort study of adults aged 45 to 84 years recruited from 6 US communities. A total of 6109 participants without baseline cardiovascular disease were included in this analysis. Baseline data were collected from July 2000 to August 2002, with follow-up completed by December 2017. The data were analyzed between May 2021 and April 2022. Food frequency questionnaires were used to assess dietary intake. From these data, overall LCD scores were calculated from the percentages of energy intake from carbohydrates, fats, and proteins. Animal-based (emphasizing saturated fat and animal protein) and vegetable-based (emphasizing monounsaturated fat and vegetable protein) LCD scores were also calculated. All-cause and cause-specific mortality were measured over a median follow-up of 15.9 years (IQR, 14.3-16.6 years). Among the 6109 participants (mean [SD] age, 62.3 [10.3] years; 3190 women [52.2%]; 1623 African American [26.6%], 701 Chinese American [11.5%], 1350 Hispanic [22.1%], and 2435 non-Hispanic White [39.8%]), there were 1391 deaths. Overall, LCD scores were not associated with mortality, but when analyses were stratified by race and ethnicity, a lower risk of all-cause and non-CV mortality was observed among Hispanic participants with moderate carbohydrate intake. Specifically, the hazard ratios for total mortality for overall LCD scores were 0.58 (95% CI, 0.40-0.84) for quintile 2, 0.67 (95% CI, 0.45-0.98) for quintile 3, 0.60 (95% CI, 0.41-0.87) for quintile 4, and 0.83 (95% CI, 0.57-1.21) for quintile 5, with quintile 1 as the reference group. A similar association was observed for animal-based (but not vegetable-based) LCD scores. In contrast, no significant associations were found between LCD scores and mortality risk in the other racial and ethnic groups. In this cohort study of multiethnic US adults, LCD score was not associated with mortality in the whole population. However, moderate carbohydrate intake was associated with a lower risk of mortality among Hispanic participants. These findings suggest that the association between carbohydrate intake and mortality may differ according to race and ethnicity. Dietary guidelines considering these differences may be necessary.