Daily yogurt consumption does not affect bone turnover markers in men and postmenopausal women of Caribbean Latino descent: a randomized controlled trial

Abstract

Background: Caribbean Latino adults are at high risk for osteoporosis yet remain underrepresented in bone research. This increased risk is attributed to genetics, diet, and lifestyle known to drive inflammation and microbial dysbiosis.

Objective: The primary objective of this study was to determine whether consuming 5 oz of yogurt daily for 8wks improves bone turnover markers (BTMs) among Caribbean Latino adults > 50 years; and secondarily to determine the impact on the gut microbiota and markers of intestinal integrity and inflammation.

Methods: Following a 4wk baseline period, participants were randomized to an 8wk whole fat yogurt intervention (n = 10) daily, containing only Streptococcus thermophilus and Lactobacillus bulgaricus, or to an untreated control group that did not consume yogurt (n = 10). Blood and stool samples collected at week-0 and week-8 were used to assess BTMs, inflammation, intestinal integrity biomarkers, and gut microbiota composition, short chain fatty acids (SCFAs), respectively. Data were evaluated for normality and statistical analyses were performed.

Results: Participants were 55% women, with a mean age of 70 ± 9 years, BMI 30 ± 6 kg/m², and serum C-reactive protein 4.8 ± 3.6 mg/L, indicating chronic low-grade inflammation. Following 8wks of yogurt intake, absolute change in BTMs did not differ significantly between groups (P = 0.06-0.78). Secondarily, absolute change in markers of inflammation, intestinal integrity, and fecal SCFAs did not differ significantly between groups (P range 0.13-1.00). Yogurt intake for 8wks was significantly associated with microbial compositional changes of rare taxa (P = 0.048); however, no significant alpha diversity changes were observed.

Conclusions: In this study, daily yogurt did not improve BTMs, inflammation, intestinal integrity, nor SCFAs. However, yogurt did influence beta diversity, or the abundance of rare taxa within the gut microbiota of the yogurt group, compared to controls. Additional research to identify dietary approaches to reduce osteoporosis risk among Caribbean Latino adults is needed.

Trial registration: This study is registered to ClinicalTrials.gov, NCT05350579 (28/04/2022).

Keywords: Aging; Bone turnover markers; Gut microbiota; Inflammation; Yogurt.

Fig. 1

Timeline of randomized controlled trial conducted among older Caribbean Latino men and women assigned to either a non-yogurt diet-control or yogurt intervention group

Fig. 2

Consort diagram of the randomized controlled trial conducted among older Caribbean Latino men and women assigned to either a non-yogurt diet-control or yogurt intervention group. ¹Per-protocol analyses exclude all participants without a blood sample collected at 8-weeks ± 7 days. ²Intention-to-treat analyses used the last observation carried forward method for all participants with a missing sample at 8-weeks ± 7 days

Fig. 3

Relative abundance of S. thermophilus and L. bulgaricus in stool as a measure of intervention compliance conducted among older Caribbean Latino men and women assigned to either a non-yogurt diet-control or yogurt intervention group

Fig. 4

The effect of the daily yogurt supplementation on the gut microbiota among older Caribbean Latino adults compared to a non-yogurt diet-control group. A Principal Coordinate Analysis (PCoA) of beta diversity during the intervention showed changes in composition of rare taxa in unweighted UniFrac distance. Analysis was performed comparing control and yogurt groups only within the intervention phase. No baseline samples were included (PERMANOVA, P = 0.047). B Alpha diversity showed no significant association with daily yogurt consumption when analyzed with linear mixed models only including the yogurt group comparing baseline vs intervention phase (Shannon index, LMM, P ≥ 0.25). Although significant differences were observed at 6.1 to 9 weeks (Kruskal–Wallis, P = 0.01). Panels A and B include per subject repeated measures