Vitamins and Minerals (Oral Session 19)

(OR19-03-25) Diet and Microbiome Predictors of Plasma Vitamin B12 in Healthy U.S. Adults

Tuesday, June 3, 2025

8:56 AM – 9:06 AM ET

Location: S220 E-G

Emerging Leaders in Nutrition Science Poster Competition

Presenting Author(s)

Margaret A. Hilliard, PhD (she/her/hers)

Postdoctoral Scholar
University of California Davis
Davis, California, United States

Disclosure(s): No relevant financial relationship(s) with ineligible companies to disclose.

Co-Author(s)

AO

Andrew Oliver, PhD

U.S. Department of Agriculture
Oakland, California, United States
SS

Setareh Shahab-Ferdows, PhD

Nutritionist
USDA
Davis, California, United States
DH

Daniela Hampel

USDA-ARS Western Human Nutrition Research Center; University of California, Davis, United States
Stephanie MG Wilson, PhD (she/her/hers)

Postdoctoral Fellow
Texas A&M IHA; USDA ARS WHNRC; Montana State University
Sacramento, California, United States
Charles B. Stephensen, PhD

Research Leader
USDA-ARS Western Human Nutrition Research Center
Davis, California, United States
Lindsay H. Allen, PhD

Research Scientist
USDA, ARS-Western Human Nutrition Research Center
Davis, California, United States
Danielle G. Lemay, PhD

Research Molecular Biologist
USDA-ARS Western Human Nutrition Research Center
Davis, California, United States

Objectives: Vitamin B₁₂ is an essential cofactor produced by prokaryotes and acquired through animal-source foods. Gut microbes synthesize and consume B₁₂, but their contribution to host B₁₂ status is unknown. This study examines the contribution of dietary B₁₂ on B₁₂ status and its relationship with the gut microbiome in healthy adults.

Methods: Vitamin B₁₂ was quantified from plasma using a competitive chemiluminescent enzyme immunoassay, and the gut microbiome was profiled using shotgun metagenomics from 186 healthy adults that completed an observational, cross-sectional study balanced for age, sex, and BMI. Diet was assessed using 24-hour dietary recalls (ASA24) and the Block 2014 Food Frequency Questionnaire. The relationship between diet, B₁₂ status, and the gut microbiome was examined using hierarchical feature engineering and random forest regressions. Top model features were identified using SHapley Additive exPlanations analysis.

Results: The median intake (μg/d) of B₁₂ was 13.4 for supplement users (n = 88) and 5.5 for supplement non-users (n = 98). Accordingly, plasma B₁₂ was higher in participants who used supplements (Mann-Whitney U test, W = 2657.5, p < 0.001). A model predicting plasma B₁₂ from diet, clinical markers, and person-specific factors revealed renal function (estimated glomerular filtration rate), supplemented B₁₂, and BMI as top features in supplement users (R² = 0.47). Conversely, natural and fortified sources of dietary B₁₂ and age were the top features in a model specific to supplement non-users (R² = 0.03). Models built using microbiome data, processed with taxonomy-aware algorithms, were more predictive of B₁₂ status for supplement non-users (R² = 0.66) than supplement users (R²= 0.23). Important features in supplement user models included Ruminococcus torques, while supplement non-user models included Blautia massiliensis and an unspecified species of Intestinimonas.

Conclusions: Supplement use is predictive of B₁₂ status, but in excess may promote pathobiont taxa in the microbiome. In supplement non-users, B₁₂ status is associated with dietary sources of B₁₂ and gut microbes capable of synthesizing B₁₂.

Funding Sources: USDA-ARS