Every once in a while, I meet people who ask me how much soy (tofu, edamame, soy milk, etc.) is safe to eat in a day. Some people say they do not eat soy products at all because it is known to be unhealthy and to increase estrogen levels.
So let's talk about it.
The study which found that soy contains phytoestrogens was done somewhere in the 1970s. It was then speculated that phytoestrogen raises estrogen levels in the body. The publication of these "findings" throughout the Western world in the early 1990s was financed (you guessed it) by dairy companies who saw that soy products were beginning to bite into the market share of dairy products.
In the meantime, these findings have already been refuted by many other studies showing that phytoestrogens actually balance estrogen levels in the body by temporarily clinging to estrogen receptors. It has also been shown that soy products (organic non-GMO) are healthy and nutritious and contain a good amount of protein, fat, fiber, and vitamins.
Soy can help lower blood pressure and cholesterol, menopause symptoms, infertility, osteoporosis, risk of breast cancer and prostate cancer.
So how much should you eat?
Like anything healthy - as much as you want within a balanced and healthy diet.
What should you be careful of?
Xenoestrogen.
Xenoestrogens are chemicals which look like estrogen but, unlike the phytoestrogen that balances estrogen levels in the body, xenoestrogens cause the body to produce excess estrogen and thus promote overweight, hormonal imbalance and diseases such as hypothyroidism and cancer.
What contains xenoestrogens?
Most plastic products, conventional cosmetics and hygiene products, detergents, synthetic hormonal drugs.
As a side note, I will add that dairy products, especially milk and soft cheeses, contain sex and growth hormones (yes, organic milk, even hormone-free milk) and other chemicals that are endocrine disruptors, reduce calcium and magnesium absorption, promote inflammation and intestinal permeability.
References:
https://onlinelibrary.wiley.com/doi/full/10.1111/cas.12268
https://www.mdpi.com/2072-6643/9/2/179/htm
https://academic.oup.com/jn/article/140/12/2289S/4630696
https://www.tandfonline.com/doi/full/10.3109/13697137.2014.966241
https://www.hindawi.com/journals/jeph/2012/713696/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4453601/