The modest hormonal effects of soy isoflavones: What do we really know? A narrative review

Background: Soybean is a species of legume native to Southeast Asia. It is widely grown as it is widely used in producing foods and food additives. The categories of soy protein differ according to their production methods, which ranges from isolated to concentrated and textured soy protein. The direct effect of soy bean on health and its mechanism of work are yet unclear and is still a controversial issue that needs to be investigated. Aim: To provide an overview of existing soybean and health-related research studies and to identify the positive and negative effects if found especially for heart diseases and cancers. Materials and Methods: A search of periodical literature by the author involving dietary therapy and soybean was carried out. Items were identified initially through health-oriented indexing services such as Medline, Health STAR, and Cinahl, looking up for articles published in English language, from 2010 to 2020. Keywords included “Isoflavones,” “soybean,” “cancer,” “Tofu,” and “heart disease.”Results: Researches are still controversial, some studies acknowledged the soybean product’s efficacy in preventing diseases such as heart diseases and cancers, while others found no or negative effects on health. Conclusion: The risk/benefit status of soy products as beneficial supplements continues to be controversial. To conclude, it can be confirmed that 12–25 gm of soy with 75 gm of isoflavones daily (2–4 servings of soy foods per day) can improve the estrogen level along with lipid profile and offer benefits to the cardiovascular system and estrogen deficit symptoms. Most populations should not exceed the recommended amount and the effectiveness of using soybeans should be matched with tolerance and compliance to reach the desirable improvements.