Vitamin B12 Associated to Total Body Fat in Healthy Non-Obese Adults According to Insulin Resistance Status

Abstract

Background: Vitamin B12 level and body fat are known “markers” associated with insulin resistance. While it has been reported that Vit B12 levels are correlated to bodyfat, in healthy, non-obese adults is still unclear. Thus, we aim to determine the association between low vitamin B12 and high body fat in healthy, non-obese adults, according to insulin resistance status. Methods: Secondary analysis of outpatient healthy adults attending a private clinic, from 2012 to 2018. We included adults with BMI from 18.5 to 29.9 Kg/m2, without diagnosed chronic diseases, and with normal levels in glucose, blood pressure, and thyroid profile. Older adults were excluded. Sex-adjusted high body fat measured through bioimpedance. Vitamin-B12 levels were classified in tertiles and the lower tertile was used for the analyses. HOMA-IR was used to define insulin resistance (Cut-off 2.8). We used Poisson regression models to estimate PR adjusted to age, sex, and ferritin levels, and subgroup analysis according to insulin resistance status. Results: 794 healthy adults were included in the analysis. 88.8% were females and were 18 to 39 years old (69.4%). 49.0% were overweight, 23.2% had insulin resistance, 33.0% had low vitamin-B12 levels, and 64.7% had high body fat. Low vitamin-B12 levels increase the prevalence of high body fat by 13% (95%CI: 2-25%). This association increases by 2% in those with insulin resistance, without interaction. Conclusion: Low vitamin-B12 levels are associated with a high level of body fat in healthy non- obese adults, particularly in those adults with insulin resistance.