Soy and Gastrointestinal Health: A Review

Area of Science:

• Nutrition Science
• Gastroenterology
• Microbiome Research

Background:

• Soybean is a globally significant legume, a primary protein source, and a key ingredient in plant-based alternatives.
• Soy's health benefits are linked to phytoestrogens, and its consumption may influence gastrointestinal (GI) health and colorectal cancer risk through the gut microbiome.
• Emerging evidence suggests a connection between soy intake and the gut microbiome's composition and activity.

Purpose of the Study:

• To critically evaluate current evidence on the effects of soybean consumption on GI health.
• To assess the impact of soy foods, soy constituents (isoflavones, soy proteins, oligosaccharides), and soy-based products on GI health measures.
• To review data from clinical, observational, and animal studies.

Main Methods:

• Narrative review of existing scientific literature.
• Inclusion of data from clinical trials, observational studies, and animal trials.
• Focus on effects of whole soybeans, soy-based products, and key soy constituents.

Main Results:

• Consistent favorable changes in GI health measures observed with certain soy foods, like fermented soy milk.
• Individuals with an equol-metabolizing microbiome showed positive responses.
• Evidence suggests varied effects depending on the type of soy product consumed.

Conclusions:

• Specific soy foods, particularly fermented options, demonstrate beneficial effects on gastrointestinal health.
• The ability of an individual's microbiome to metabolize equol influences the positive outcomes of soy consumption.
• Further clinical investigation is required for soy protein isolates and textured soy proteins to ascertain their functional GI health effects.