Fermented Foods and Bone Health: Investigating the Gut-Bone Axis in Premenopausal Vegan Women

Plant-based diets are increasingly adopted for health and environmental reasons, but they are associated with lower bone mineral density, higher fracture risk, and elevated bone turnover markers, particularly in women. These effects are partly explained by lower intakes of calcium and zinc, and higher concentrations of phytates and oxalates, substances that inhibit mineral absorption from plant foods. Evidence-based dietary strategies to support bone health in vegan populations beyond supplementation remain limited.

Fermented plant-based foods may help address this gap through two complementary mechanisms: first, by delivering live microorganisms that beneficially modulate gut microbiota and promote the production of short-chain fatty acids, which support mineral absorption and reduce bone resorption, and second, by reducing antinutritional factors such as phytates during microbial fermentation, thereby improving mineral bioavailability.

This study investigates whether the daily consumption of fermented plant-based foods, specifically lacto-fermented vegetables, calcium-fortified plant-based yogurt alternatives with live cultures, and Rhizopus-fermented tempeh, reduces bone resorption and improves calcium metabolism in premenopausal women following a vegan diet. Participants will follow each dietary condition (fermented or matched non-fermented control foods) for 12 weeks in randomized order, separated by an 8-week washout period. Blood, urine, and stool samples are collected at each study visit to assess bone turnover markers, gut microbiota composition, short-chain fatty acid production, inflammatory markers, and a range of metabolic and nutritional parameters.