Investigation of the diet-gut-muscle axis in the Osteoporotic Fractures in Men study

Authors: BARGER, KATHRYN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; LANGSETMO, LISA - University Of Minnesota; ORWOLL, ERIC - Oregon Health & Science University; LUSTGARTEN, MICHAEL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Journal of Nutrition Health and Aging
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2020
Publication Date: 3/12/2020
Citation: Barger, K., Langsetmo, L., Orwoll, E.S., Lustgarten, M.S. 2020. Investigation of the diet-gut-muscle axis in the Osteoporotic Fractures in Men study. Journal of Nutrition Health and Aging. https://doi.org/10.1007/s12603-020-1344-1.
DOI: https://doi.org/10.1007/s12603-020-1344-1

Interpretive Summary: The primary goal of the study was to investigate the association between dietary fiber intake with gut bacterial composition and functions in older men that had either high or low levels of whole-body lean mass. We found that older men that had a relatively higher intake of dietary fiber and that had higher levels of lean mass also had higher levels of butyrate-producing bacteria and butyrate producing-functions. Additionally, measures of physical function were relatively higher in older men that had a higher intake of dietary fiber and that had increased amounts of whole-body lean mass. Collectively, these data suggest that a high-fiber diet may positively impact butyrate-producing bacteria, which may be involved in mechanisms related to the maintenance of whole-body lean mass and physical functioning in older adult men. Future studies aimed at testing the causative role of this hypothesis are of interest.

Technical Abstract: Objectives: To investigate the association between dietary fiber density (grams of fiber consumed per 100 kcal) with the gut-muscle axis in older adult men. Design: Cross-sectional study. Setting: Osteoporotic Fractures in Men (MrOS) cohort participants at Visit 4 (2014-16). Participants: Older adult men (average age, 85y) from the MrOS study. Measurements: Men who were in the highest tertiles for dietary fiber density and the percentage of whole body lean mass were defined as T3T3 (n=42), whereas men who were in the lowest and intermediate tertiles for these variables were defined as T1T1 (n=32), T1T3 (n=24), and T3T1 (n=13), respectively. Additionally, measures of physical function, including the short physical performance battery (SPPB) score and grip strength were higher in T3T3 when compared with T1T1. Gut bacterial abundance was quantified with use of 16S v4 rRNA sequencing, and the bacterial functional potential was derived from the 16S data with PICRUSt. Chao1, ACE, Shannon, Simpson, and Fisher indices were used as measures of a -diversity. Weighted and unweighted Unifrac, and Bray-Curtis were used as measures of b-diversity. Age, physical activity score, smoking, and number of medications-adjusted DESeq2 models were used to identify bacteria and functions that were different when comparing T3T3 with T1T1, but that were not also different when comparing T3T3 with T1T3 or T3T1. Results: alpha-diversity was not different, but significant differences for b-diversity (unweighted UniFrac, Bray-Curtis) were identified when comparing T3T3 with T1T1. Known butyrate-producing bacteria, including Ruminococcus, Lachnospira, and Clostridia, and gene counts for butyrate production (KEGG IDs: K01034, K01035) were higher in T3T3, when compared with T1T1. Conclusion: These data suggest that a high-fiber diet may positively impact butyrate-producing genera and gene counts, which collectively may be involved in mechanisms related to the percentage of whole body lean mass and physical functioning in older adult men. Future studies aimed at testing the causative role of this hypothesis are of interest.