Soybeans and the hidden risk – Phytic Acid

Soybean is a legume that is commonly consumed among Asians, especially among vegans and vegetarians. It is normally served as foods that include soy milk, tofu (or bean curd) and fermented products such as soy sauce, fermented bean paste, natto and tempeh.

In 1999, the United States Food and Drug Administration (FDA) established the correlation between diets that are low in saturated fat and cholesterol (which includes soy protein) in reducing the risk of cardiovascular diseases. Since then, the consumption of soybeans has been increasing. Coupled with the fact that soybeans are also a rich source of protein, this has led many consumers to believe that soybeans are a miracle health food without any health risks. However, there is a hidden danger in over-consumption of soybeans due to its content.

Soybeans contain a high amount of phytic acid, as this is the major form of phosphorus storage in the plant (1 – 2% of the grain’s dry weight). Recent studies have provided evidence that phytic acid impairs the absorption of essential minerals, including iron, calcium and zinc in the digestive system. This interaction reduces the bioavailability of essential minerals and electrolytes in the body.

The content of phytic acid in soybeans is not reduced by usual preparation methods such as slow cooking. As a consequence, long term and high consumption of soybeans as well as soy products may lead to mineral deficiency, especially in those with grain-based diets. Hence, vegans or vegetarians are advised to consume foods that are fortified with these nutrients or take supplements.

So, are soybeans good for health? While there are nutritional benefits associated with soybean consumption, phytic acid represents the anti-nutritional component in soybeans that can cause a negative impact on mineral absorption. It can be a concern for those who consume disproportionately high amounts of soybeans and soy products for the long term. So do plan your diet with a moderate intake of soybeans and balance your diet with several healthy foods with or without supplements in order to obtain the maximum health benefits from your diet.

References:

  1. Hurrell RF, Juillerat MA, Reddy MB, Lynch SR, Dassenko SA, Cook JD. Soy protein, phytate, and iron absorption in humans. Am J Clin Nutr. 1992;56(3):573-8.
  2. Deak, N.A. & Johnson, L.A. Fate of Phytic Acid in Producing Soy Protein Ingredients. J Amer Oil Chem Soc. 2007;84: 369.
  3. Karkle ENL, & Beleia, A. Effect of soaking and cooking on phytate concentration, minerals, and texture of food-type soybeans. Food Science and Technology (Campinas), 2010;30(4): 1056-1060.
  4. Thacher TD, Aliu O, Griffin IJ, et al. Meals and Dephytinization Affect Calcium and Zinc Absorption in Nigerian Children with Rickets. Journal of Nutrition. 2009;139(5):926-932.
  5. Crag WJ. Health effects of vegan diets. Am J Clin Nutr. 2009;89(5): 1627S-1633S.
Hui Yin Yow
Hui Yin Yow

Co-Founder

A Doctor of Philosophy (Ph.D.) in Pharmacology from Universiti Kebangsaan Malaysia currently lecturing in Taylor’s University

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