Soybeans are one of the most versatile legumes when we look at the forms in which they are consumed, as they have been for thousands of years. Soybeans were first cultivated over 7,000 years ago in China, and have been a staple in Asian cuisine for at least the last 2,500 years1. In the last 30 years global consumption of soybeans has hugely increased, driven by more interest in vegetarian protein options, dairy alternatives, as well as a number of other factors.
So, what comes under the umbrella of soy products?
We eat soybeans in their immature form as edamame, still in their pods and green. We also use soybeans to make minimally processed products such as soy milk and tofu, both commonly unfermented, as well as fermented soy products, including soy sauce, fermented whole soybeans, miso and tempeh. Fermenting soy adds to the flavour, often giving it the distinct umami or savoury flavour we taste in miso or soy sauce. Studies have shown the fermentation process can also give rise to antioxidant properties of soy, as well as improve the nutritional quality and bioactivity of the food products, especially in relation to our gut microbiota and the bioavailability of vitamins and minerals2.
Soybeans are a nutrient-dense food, rich in protein, containing all 9 essential amino acids. Just 100g of soybeans provide us with 121% of our recommended daily intake (RDI) for iron, 120% for manganese and many of the B vitamins, including 94% of our RDI for folate. Soybeans are also rich in dietary fibre, zinc, potassium, magnesium and vitamin K3.
There’s often talk about soy in relation to isoflavones, or phytoestrogens, which are able to bind to our estrogen receptors, and link to certain diseases, in particular breast cancer. However, it has been shown that normal consumption of foods that contain these phytoestrogens should not provide sufficient amounts to elicit a physiological response in humans. As well, a number of studies determine there is no link between the consumption of soy products and breast cancer4, while others have shown an inverse association, or reduced incidence of breast cancer following a diet high in soy5.
- Shurtluff W., Aoyagil A. (2009). History of Edamame, Green Vegetable Soybeans, and Vegetable-Type Soybeans.
- https://www.sciencedirect.com/science/article/pii/S073497501830199X?via%3Dihub
- https://fdc.nal.usda.gov/fdc-app.html#/?query=ndbNumber:16108
- Oseni, T., Patel, R., Pyle, J., & Jordan, V. C. (2008). Selective estrogen receptor modulators and phytoestrogens. Planta medica, 74(13), 1656–1665. doi:10.1055/s-0028-1088304
- https://www.ncbi.nlm.nih.gov/pubmed/11352858
