The impact of soybean products and probiotics on calcium bioaccessibility from organic and inorganic calcium salts in an in vitro digestion model

Probiotics and isoflavones have a promising therapeutic effect on calcium status and bone health, but there are only limited studies focusing on these products. The present study aimed to 1) determine the potential bioaccessibility of calcium from soybean products (raw soybean and tempeh) and a probiotic strain (Lactobacillus acidophilus) and to 2) evaluate whether the studied products and strain have an impact on the potential bioaccessibility of calcium from inorganic and organic calcium salts. The bioaccessibility of calcium was determined based on enzymatic in vitro digestion, and calcium content by flame atomic absorption spectrometry. The average potential calcium bioaccessibility from tempeh was 10% and from raw soybean was 2%, while probiotics could release over 85% of potential bioaccessible calcium during enzymatic digestion. In conclusion, the potential bioaccessibility of calcium from tempeh and soybeans is low. Soybean products decrease the bioaccessibility of calcium from organic and inorganic calcium salts, while probiotics could improve the bioavailability of calcium from these salts.