Soy is good for your health in the same way smoking is good for your lungs.

The soy manufacturers have run such as successful marketing campaign that 75% of US consumers rate soy products as healthy(1).

Driving to an appointment last week, I heard an upbeat advert for soy, praising its health benefits and calling it miracle food. When I got back to my desk I did a little searching online and found a number of websites pushing Soy propaganda, which is to be expected since consumers have been bombarded in the media and online with stories about the health benefits of soy.

Here are some of the health issues of soy:

  • Soy is a potent source of phytoestrogens which mimic estrogen and can lead to infertility and may promote breast cancer in adult women
  • Drinking 2 glasses of soy milk daily for one month can alter a woman’s menstrual cycle.
  • Soy is high in goitrogens, substances which block the normal functioning of the thyroid gland
  • The processing of soy produces cancer causing nitrosamines
  • Soy foods contain high levels of aluminium which is toxic to your nervous system
  • Soy is also high in phytates, which block the absorption of vital minerals such as iron, calcium, magnesium and zinc. This is particularly bad news for vegetarians
  • As much as 90% of soy produced in the US today is genetically modified (GMO ) and as a result contains the highest possible pesticide levels
Under no circumstances should infants be given soy milk (infant formula) as this will harm the sexual and reproductive development of the infant.

Weight Loss Claims

Soy proponents claim that some studies show that people who regularly consume soy protein tend to weigh less and have less abdominal fat than those who don’t. They claim that soy isoflavones (estrogen-like substances) reduce belly fat and also protect against breast cancer.

This is rubbish!

Estrogenic compounds tend to increase belly fat and the presence of these isoflavones is one of the main reasons NOT to eat soy. As far as the breast cancer claim goes, a number of studies show that genistein (the main isoflavone) , promotes the growth of breast cancer cells and tumour growth. Here is one of the studies, there are many more. [Soy diets containing varying amounts of genistein stimulate growth of estrogen-dependent (mcf-7) tumors in a dose-dependent manner. Allred CD, Allred KF, Ju YH, Virant SM., Helferich WG. Cancer Res. 2001;61: 5045-5050.]

More Reading

If you want to read more about the dangers of soy, I suggest that you look into the book The Whole Soy Story by Kaayla T. Daniel.


(1)    2013 survey – Consumer Attitudes About Nutrition (United Soybean Board)