Soy Side Effects Researchers Think You Should Be Aware Of


Although often considered a healthy addition to the diet, the side effects of soy products are of increasing concern to many researchers.

Natural Toxins

Soy contains a large amount of what nutritionists call anti-nutrients. This is just a fancy name for toxins. There are several natural substances that are found in soy that are actually toxic to various systems in the body.

Enzyme Inhibitors

Enzyme inhibitors block the action of enzymes that are needed to digest proteins. Cooking does not negate the effects of these enzyme inhibitors and when ingested they can produce a series of problems like:

  • Gastric pain
  • Reduced protein digestion
  • Amino acid deficiencies

In research that was carried out on various lab animals these anti-nutrients were found to cause unusual symptoms in the pancreas, including enlargement and cancer.

The substance that inhibits the action of Trypsin in the body is also a growth inhibitor. Ingesting large amounts of soy, especially in a non-fermented form such as edamame, can cause abnormal and stunted growth patterns in children. The fermented forms such as tofu seem to have less of an impact on the body.

Other Side Effects of Soy

As more research is done there are more concerns coming to light about soy in the diet. Other side effects of soy that result from the toxins it contains are:

  • Abnormal clotting of the blood
  • Abnormal thyroid function leading to hypothyroidism
  • Mineral deficiencies
    • Calcium
    • Zinc
    • Magnesium
    • Copper
  • Increased instances of breast cancer in women who have had their ovaries removed


Phytoestrogens are simply an estrogen like chemical that is produced by plants. Soy is high in phytoestrogens and there is some concern that large amounts of this substance can be detrimental to human health, especially that of babies and young children. One study estimates that a baby being fed a soy based formula is getting the equivalent of the amount of estrogen in five birth control pills a day. This concentrated amount of phytoestrogens may be responsible for some of the following:

  • As the number of infants fed soy based formula has increased since it became popular in the early 1970s so have the instances of learning disabilities, and attention disorders.
  • Girls are entering puberty earlier than in the past, some as early as eight or nine.

Drug Interactions

Soy can inhibit the action of certain drugs. If you are on medication you may want to stay away from soy products all together. Some of the pharmaceuticals that soy interferes with are:

  • Warfarin
  • Thyroid medications
  • Estrogen supplements
  • Atrovent
  • Primatene, or other dual action brochodilator drugs

Caution with Soy Isoflavones

Soy isoflavones are an isolated soy product. This product is found in everything from diet bars to protein shakes. You should discuss your use of isoflavones with your doctor, especially in the following cases:

  • Prostate cancer
  • Breast feeding
  • Pregnancy or trying to get pregnant
  • Peanut allergies
  • Kidney disease
  • Difficulty urinating

More Information About the Side Effects of Soy

If you are interested in more information about the possible side effects and health risks of soy in your diet you may want to take a look at the following:

Use Soy Cautiously

While there are conflicting statements about soy products it seems clear that moderation is a good idea. Always check with your health care provider before you add soy or soy isoflavones to your diet. Monitor yourself for changes in the way that you feel, and if you have any of the symptoms above you should discontinue the soy immediately.It may be a good idea to use other forms of protein in your child's diet in most cases, until more is known about the effects of soy on a child's developing system.

If you choose to continue using soy products be sure to stay abreast of the newest research and information available to you.

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Soy Side Effects Researchers Think You Should Be Aware Of