There is no other natural food that is so controversial than soy. Soy is a healthy food that is rich in antioxidants, protein and minerals. It may help improve your heart health, reduce your risk of certain cancer and alleviate menopausal symptoms. But others claim that soy is unhealthy and should not be eaten unless in fermented form. Two well known soy bashers are Dr. Mercola and Dr. Fallon. They have written many anti-soy articles which have been widely circulated. They claim that soy is full of toxins, promotes cancer, causes Alzheimer and lets your brain shrink! Their cases are mainly built on a few animal studies in which rodents were fed extremely large amounts of soy isoflavones.
About 0.5% of the population is allergic to soy and should avoid its consumption. Luckily, symptoms of soy allergy
are mild and life-threatening allergic reactions, as can happen with peanuts, are extremely rare.
Soy and cancer
Some experimental studies using rodents or cultured cells show that soy components may increase the risk of cancer. But all epidemiological and clinical studies involving humans demonstrate a protective effect of soy.
Countries with a high consumption of soyfoods have a far lower cancer rate than in those countries where their use is less. Especially the effect of soy on breast cancer risk
is still an ongoing debate, but more recent studies show that soy is safe and actually reduces this risk.
Soy and the thyroid function
Soy contains compounds called goitrogens that interfere with thyroid function
. Around 1950 there were indeed several cases of goiter in infants fed with soy flour based formulas which were not fortified with iodine. Today formulas are always fortified with iodine and no cases of goiter have been reported in babies fed with these formulas. After a review of medical literature the FDA found no proven evidence that soy would harm the thyroid.
Soy and acne
There is only one scientific study that mentions a link between soy and acne: a study at The Chinese University of Hong Kong found that "the intake of dairy and soy products was significantly associated with a lower incidence of acne". But why do some people write on our forum that their acne gets worse during periods when they eat more soy products? Maybe they belong to the small group of persons that are allergic to soy and develop acne-like conditions.
Soy and gout
Is soy safe for gout
patients? In 1998, a Japanese study by Yamakita and co-workers of Hyogo College of Medicine found that eating tofu is a safe for gout patients. One 2004 study by Hyon K and co-workers found that a moderate intake of purine rich vegetables is not associated with increased risk of gout. Protein rich foods tend to contain higher levels of purines but the proteins seems to lower the serum uric level, especially vegetable protein. The Mayo Clinic recommends eating more plant-based proteins, such as beans and legumes.