Fermentation of calcium-fortified soya milk does not appear to enhance acute calcium absorption in osteopenic post-menopausal women

Ageing women may choose to drink soya milk to reduce menopausal symptoms. As fermentation enriches soya milk with isoflavone aglycones, its beneficial qualities may improve. To reduce osteoporotic risk, however, soya milk must be Ca enriched, and it is not known how fermentation affects Ca bioavailability. A randomised crossover pilot study was undertaken to compare the Ca absorption of fortified soya milk with that of fermented and fortified soya milk in twelve Australian osteopenic post-menopausal women. The fortified soya milk was inoculated with Lactobacillus acidophilus American Type Culture Collection (ATCC) 4962 and fermented for 24h at 37C. Ca absorption from soya milk samples was measured using a single isotope radiocalcium method. Participants had a mean age of 548 (sd 123)years, with mean BMI of 265 (sd 55)kg/m² and subnormal to normal serum 25-hydroxyvitamin D (mean 625 (sd 191)nmol/l). Participants consumed 185kBq of ⁴⁵Ca in 44mg of Ca carrier. The mean fractional Ca absorption () from soya milk and fermented soya milk was 064 (sd 023) and 071 (sd 029), respectively, a difference not of statistical significance (P=0122). Although fermentation of soya milk may provide other health benefits, fermentation had little effect on acute Ca absorption.