Recently, a report from the foreign media was circulated and exploded in the WeChat circle of friends. The news said that “a middle-aged woman in Ningbo is concerned about health, drink three years of self-milled soy milk after the detection of breast cancer”, a time when people talk about soy milk changed. Many women no longer dare to drink soya bean milk, and even completely cut off relations with soya food. In fact, the so-called “soy milk contains estrogen will lead to breast cancer” argument is not based on science.
As we all know, soy products contain phytoestrogens, which are reported to be the main cause of breast cancer. First of all, we must understand the following concepts.
1. What are phytoestrogens?
Phytoestrogens are a class of non-steroidal compounds that occur naturally in plants and are named after their biological activity, which is similar to that of estrogen. Phytoestrogens are widely distributed in food, such as lignans in lentils and grains, and coumarins in soybean sprouts.
2. Phytoestrogens ≠ human estrogens
When it comes to estrogen, many people are concerned because excessive levels of estrogen can cause breast cancer, endometrial cancer, uterine fibroids and uterine bleeding. However, phytoestrogens are not the same as human estrogen. Studies have found that phytoestrogens play a two-way regulatory role on estrogen levels in women’s bodies. Phytoestrogens have a molecular structure similar to that of estrogen and can bind to estrogen receptors to produce effects similar to those of estrogen, but this effect is less than that of estrogen in the human body. When the estrogen level in the body is insufficient, its binding can play a role in replenishing estrogen; while when the estrogen level in the body is too high, its binding plays an inhibitory role because it prevents estrogen binding, which is equivalent to lowering the estrogen level. Therefore, phytohormones are also known as the regulator of female estrogen levels.
3. What are soy isoflavones? How is soy milk metabolized in the body?
Soy isoflavones are flavonoids, a class of secondary metabolites formed during the growth of soybeans, which are biologically active substances. Because they are extracted from plants and have a similar structure to estrogen, soy isoflavones are also known as phytoestrogens.
The soy isoflavones in soy milk exist mainly in the form of glycosides. When the human body ingests soy and its products, the isoflavone glycosides are decomposed in the intestine by glycosidases, releasing glycosides and glycoside ligands with bioactive blood, and these active substances are absorbed directly in the intestine or are converted into the final metabolites —– estriol (equol).
4. Estriol in relation to disease and health
Estriol is the end metabolite of the biotransformation of soy isoflavones and soy flavonoids by the action of colonic microflora and has higher pharmacological activity than soy isoflavones, especially in the prevention of cardiovascular disease, breast and prostate cancer. The biological activities of estradiol are most typically estrogenic and antioxidant.
I. Antitumor
Studies on the anticancer effects of esmolol have focused on breast cancer and prostate cancer. Epidemiological surveys have confirmed that a decrease in urinary 2 hydroxy ketone / 16α hydroxyestrone leads to an increase in the incidence of breast cancer. A case-control study showed that soy intake had no significant effect on this ratio, but the ratio was closely related to the serum and urinary levels of estradiol, suggesting that the inhibitory effect of soy isoflavones on breast cancer may be mainly attributed to its metabolite estradiol.
II. Improve menopausal symptoms, anti-cardiovascular disease
The consumption of soy isoflavones can compensate for the decrease in estrogen due to menopause, thus reducing or avoiding the menopause syndrome. Australian scientists have found that menopausal women who consume 45 grams of soy per day have a 40% reduction in the incidence of menopausal syndrome. A diet containing soy foods can relieve the symptoms of hot flashes and sweating in menopausal women. Soy isoflavones can also improve arterial elasticity throughout the body in women at or near menopause.
5. Soy isoflavones – do not cause breast cancer
Contrary to what rumors say, a large number of studies have confirmed that drinking soy milk in moderation can prevent breast cancer.
Epidemiological studies have shown that Asians have lower incidence and mortality rates of breast cancer and prostate cancer than Westerners due to their high intake of soy and soy products. The Shanghai Breast Cancer Status Survey studied 5,042 women aged 20-75 years with breast cancer in Shanghai and found that eating soy products significantly reduced the mortality rate of breast cancer patients. The results of a case-control study on diet and breast cancer in Chinese women living in Singapore also showed that soy had a significant preventive effect on the development of breast cancer. Rather, they may reduce the risk of breast cancer, especially in Asian populations where soy consumption is high.
In addition, an article published in the world’s leading medical journal “Cancer” (cancer), “International Guidelines for Breast Health and Cancer”, lists a number of ways to prevent breast cancer in countries around the world, one of which is to eat soy and its products in moderation.
6. Moderate intake of soy products is safe and will not induce breast cancer
A moderate intake of soy products is safe and will not induce breast cancer, and it also has a role in preventing and reducing menopausal syndrome, which is a good food for women.
Contrary to the rumors, numerous studies have confirmed that drinking soy milk in moderation can prevent breast cancer.
Epidemiological studies have shown that Asians have lower incidence and mortality rates of breast and prostate cancer than Westerners due to their high intake of soy and soy products. The Shanghai Breast Cancer Status Survey studied 5,042 women aged 20-75 years with breast cancer in Shanghai and found that eating soy products significantly reduced the mortality rate of breast cancer patients. The results of a case-control study on diet and breast cancer in Chinese women living in Singapore also showed that soy had a significant preventive effect on the development of breast cancer. Rather, they may reduce the risk of breast cancer, especially in Asian populations where soy consumption is high.