Safety and tolerability of whole soybean products: A dose-escalating clinical trial in older adults with obesity

Authors: REBELLO, CANDIDA - Pennington Biomedical Research Center; Boue, Stephen; LEVY, RONALD - Louisiana State University; PUYAU, RENEE - Pennington Biomedical Research Center; BEYL, ROBBIE - Pennington Biomedical Research Center; GREENWAY, FRANK - Pennington Biomedical Research Center; HEIMAN, MARK - Scioto Biosciences; KELLER, JEFFREY - Pennington Biomedical Research Center; REYNOLDS, CHARLES - University Of Pittsburgh; KIRWAN, JOHN - Pennington Biomedical Research Center

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2023
Publication Date: 4/16/2023
Citation: Rebello, C., Boue, S.M., Levy, R., Puyau, R., Beyl, R., Greenway, F., Heiman, M., Keller, J., Reynolds, C., Kirwan, J. 2023. Safety and tolerability of whole soybean products: A dose-escalating clinical trial in older adults with obesity. Nutrients. 15(8):1920. https://doi.org/10.3390/nu15081920.
DOI: https://doi.org/10.3390/nu15081920

Interpretive Summary: Soybean products have nutrients, dietary fiber, and plant components beneficial for cardiovascular and overall health. Despite their high consumption in Asian populations, safety in Western diets is debated. We conducted a dose escalating clinical trial of the safety and tolerability of soybean products in eight older adults with obesity. Whole green soybean pods grown under controlled conditions were processed to flour (WGS) at the United States Department of Agriculture using common cooking techniques such as slicing and heating. WGS incorporated in food products was consumed at 10g, 20g, and 30g/day for one week at each dose. Gastrointestinal outcomes, clinical biomarkers, and adverse events were evaluated. We explored the stimulation of phytoalexin (glyceollin) production in live viable soybean seeds (LSS-G). We compared the compositions of WGS and LSS-G with published values of commercial soybean flour and its fermented and enzymatically hydrolyzed forms. We found that although 30g WSG was well-tolerated, it made participants feel full. Our processing produced glyceollins (267µg/g) in LSS-G. Processing soybean flour decreases iron content, but also reduces oligosaccharides which may attenuate flatulence it causes. Providing soybean flour at <30g/day in food products may be prudent to prevent exclusion of other food groups and nutrients in this population.

Technical Abstract: Soybean products have nutrients, dietary fiber, and phytoalexin components beneficial for cardiovascular and overall health. Despite their high consumption in Asian populations, safety in Western diets is debated. We conducted a dose escalating clinical trial of the safety and tolerability of soybean products in eight older adults with obesity. Whole green soybean pods grown under controlled conditions were processed to flour (WGS) at the United States Department of Agriculture using common cooking techniques such as slicing and heating. WGS incorporated in food products was consumed at 10g, 20g, and 30g/day for one week at each dose. Gastrointestinal outcomes, clinical biomarkers, and adverse events were evaluated. We explored the stimulation of phytoalexin (glyceollin) production in live viable soybean seeds (LSS-G). We compared the compositions of WGS and LSS-G with published values of commercial soybean flour and its fermented and enzymatically hydrolyzed forms. We found that although 30g WSG was well-tolerated, it made participants feel full. Our processing produced glyceollins (267µg/g) in LSS-G. Processing soybean flour decreases iron content, but also reduces oligosaccharides which may attenuate flatulence it causes. Providing soybean flour at <30g/day in food products may be prudent to prevent exclusion of other food groups and nutrients in this population.