[Creative Cultivation Program] Will eating soy cause early puberty or cancer? Don’t worry, eating more soy has “billions” of benefits!

Author: Xue Qingxin

Reviewer: Zhang Jiguo

Many people are familiar with soy isoflavones. After all, people say that it "makes men effeminate, causes children to have early puberty, and causes breast hyperplasia."

This has led to many people being afraid to eat soybeans, or even drink soy milk.

Are soy isoflavones really that powerful? In this article, we will talk about soy isoflavones and finally see which soy products have the highest content of soy isoflavones.

Soy isoflavones are really wronged

There are often rumors among the people that bean products contain estrogen and that neither men nor children should eat them, otherwise men will become "feminine", children will experience precocious puberty, and may even get breast cancer.

In fact, we don’t have to worry about eating soy causing the rumored problems.

Because the "estrogen" contained in soybeans and their products is soy isoflavones, which are secondary metabolites formed during the growth of leguminous plants such as cereals and soybeans. They are also called phytoestrogens and are one of the biologically active ingredients in soy products. There is a certain difference between soy isoflavones and so-called estrogens. Excessive intake of exogenous estrogens will increase the risk of endometrial cancer and breast cancer, while soy isoflavones are easy to decompose and will not accumulate in the body. They do not have the toxic side effects of exogenous estrogens.

Soy isoflavones can help regulate the body's hormone balance and can bind to estrogen receptors in different tissues and organs to play the role of estrogen or antagonize endogenous estrogen. For example, when the body's estrogen level is low, soy isoflavones can help increase estrogen; when the body's estrogen level is high, it can play a role in lowering the estrogen level.

In general, soy isoflavones are a player that can “replenish when the level is low and resist when the level is high”, and can help us maintain the balance of estrogen levels in the body.

The Many Benefits of Soy Isoflavones

Regular consumption of foods containing soy isoflavones will not cause cancer, precocious puberty, or make you effeminate. Instead, it will help prevent many diseases in the body.

Anti-tumor: Domestic and foreign researchers have studied soy isoflavones and found that they can inhibit the proliferation of cancer cells, induce cancer cell apoptosis, resist oxidation, inhibit the formation of new blood vessels, and prevent and reduce the risk of many cancers, such as breast cancer, prostate cancer, breast cancer, skin cancer and other cancers.

In addition, a number of research results show that health evidence analysis has found that soy and its products can reduce the risk of breast cancer and osteoporosis in women. [1]

Prevention and improvement of postmenopausal osteoporosis: Especially for postmenopausal women, because of the significant decrease in estrogen levels, bone mass decreases, bone microstructure is damaged, and osteoporosis is prone to occur. Soy isoflavones have a chemical structure similar to that of the endogenous hormone estradiol, and can bind to receptors, have a mimetic estrogen effect, reduce bone resorption rate, increase bone formation rate, regulate osteoclasts, osteoblasts and osteocytes, and play a role in preventing osteoporosis. [2, 3]

Health evidence analysis found that soybeans and their products can reduce the risk of osteoporosis in women.

Protect cardiovascular system: The conversion products of soy isoflavones in the body can reduce serum total cholesterol. They can also improve the function of vascular endothelial cells, reduce oxidative damage, reduce vascular permeability, and inhibit inflammatory factors by reducing the level of inflammatory factors and the generation of reactive oxygen species. They have a positive effect on cardiovascular health, reduce the risk of cardiovascular disease, and prevent atherosclerosis. [2, 3]

Anti-Alzheimer's effect: Prevention of senile dementia: Alzheimer's disease is also known as senile dementia, which is a neurodegenerative disease that is common in the elderly. Animal experiments have found that this disease can cause neuronal degeneration and necrosis in patients. This change is related to oxidative stress response, and genistein in soy isoflavones can improve this oxidative stress response. Supplementation of soy isoflavones can also promote the expression of cerebellar neurotrophic factor and improve the function of neural information transmission. In addition, the anti-inflammatory and antioxidant functions of soy isoflavones have a positive effect on improving Alzheimer's disease. [3]

Who is more reliable when it comes to supplementing soy isoflavones?

Soy isoflavones are commonly found in the soy products we often eat, such as soybeans, tofu, tofu brain, soy milk, dried tofu... So, among so many soy products, which one is more suitable for supplementing soy isoflavones?

A study has tested the content of soy isoflavones in the soy products we often eat. The results found that the processing technology of soybeans will directly affect the content of soy isoflavones in the final food. The content of soy isoflavones will decrease to varying degrees after soybean processing. [4]

In a comparison of soy isoflavone content among different beans, soybeans contain the highest amount of isoflavones, at approximately 97 mg/100 g. [4]

In the comparison of soy isoflavone content among different soy products, yuba > dried tofu > tofu skin > tofu > fermented bean paste > soy milk > soy milk > fermented tofu > spicy noodles > soy sauce. [4]

In addition, bean sprouts made from soybeans also contain soy isoflavones, but the content is not much, only 14.2 mg/100 g, which is between soy milk and soy milk.

Therefore, if you want to supplement soy isoflavones more effectively, in addition to eating soybeans, it is also recommended to eat bean curd sticks, dried tofu, bean skin, and tofu.

How much to eat?

Currently, Japanese people have the highest average life expectancy in the world. Their average daily intake of soy isoflavones is 17.96 mg. The average daily intake of soy isoflavones in Okinawa Prefecture, a famous place for longevity, is 32 mg. [5]

The University of Tokyo in Japan recommends that adults consume 40 to 50 mg of soy isoflavones per day. If this amount is consumed every day, it can effectively prevent prostate cancer in men and breast cancer in women. [5]

Statistics show that the current average daily intake of soy isoflavones by Chinese residents may not exceed 15 mg/day.[5] This amount is still relatively low, equivalent to a maximum daily intake of about 16 grams of soy per person.

my country's "Dietary Guidelines for Chinese Residents" recommends that adults consume 105-175 grams of soybeans per week, averaging 15-25 grams per day. If you can eat 25 grams of soybeans every day, you can consume nearly 25 grams of soy isoflavones. Although it does not meet the recommendations of the University of Tokyo in Japan, it is already a good improvement for Chinese residents.

25 grams of soybeans is equivalent to about 100 grams of northern tofu or a fist of tofu skin/shreds.

▲Photo: 100g northern tofu

Summarize:

Soybeans are not only a source of soy isoflavones, but also provide us with high-quality protein. It is recommended that healthy people eat more soybeans and their products every day. Stewed tofu, fried tofu, stir-fried tofu skin, cold tofu shreds, etc. are all very delicious dishes, don't miss them!

References:

[1]. Chinese Nutrition Society. Dietary Guidelines for Chinese Residents[M]. People's Medical Publishing House, 2016, 81.82

[2] Chen Jiaxu, Chen Ruyang, Lian Yuan, Yao Xinshuo, Huang Yuxin, Gao Yao, Xiao Yu. Research progress on biotransformation and functional activity of soybean isoflavones[J]. Food Research and Development, 2021, 42(09): 176-182.

[3] Li Shuo, Wang Jian. Research progress on clinical application of soybean isoflavones[J]. Soybean Science, 2020, 39(04): 633-640.

[4] Liu Liting, Shi Fei, Liu Ye, Chen Shanshan. Analysis of types and contents of soy isoflavones in different soy products[J]. Food Safety Guide, 2022(19):100-102.DOI:10.16043/j.cnki.cfs.2022.19.050.

[5] Gu Jingfan, Du Shouyin, Guo Changjiang. Modern Clinical Nutrition, 2nd Edition[M]. Science and Technology Press, 2009

This article is produced by the Science Popularization China-Creation Cultivation Program. Please indicate the source when reprinting