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Soy Protein: The Truth Behind The Myths

Updated: Nov 30, 2022

Have you heard the warnings: "Soy may increase the risk of breast cancer!" Or "Women with breast cancer shouldn’t use soy!"


Or one of the craziest myths, "Men will get man-boobs"!

Science says these myths were never true. Soy is actually one of the most nutrient-dense foods.


In fact, soy protein has been in the food chain for over 5,000 years. Soy contains all of the essential amino acids in the right ratios needed to support growth and development.

Results from more than 50 studies have provided scientific evidence of the cholesterol-lowering benefits of soy protein in the diet.


Yet soy is the subject of several popular myths starting in 1999.


Let's bust some of these myths, shall we?

  • Soy may increase the risk of cancer, including breast cancer. Much of the concern about soy is based on the estrogen-like effects of isoflavones, a group of naturally-occurring plant chemicals found in large amounts in soybeans. Since many breast cancers need estrogen to grow, some believe that soy could increase breast cancer risk. However, numerous clinical studies have proved these claims wrong. In fact, soy is associated with a reduced risk of breast and prostate cancer.

  • Soy lowers testosterone levels in men Concerns have been raised that soy affects estrogen levels in men, along with other female-like effects, such as lower testosterone levels, reduced sperm count, and fertility. A review of 41 clinical studies on the feminizing effects of soy shows that there are no significant effects of soy protein or isoflavone intake on testosterone or estrogen levels in men, regardless of dose or study duration.

  • Soy interferes with thyroid metabolism There are some concerns that soy can interfere with thyroid function. However, a recent study found that consumption of soy protein has no effect on thyroid hormones.

  • Soy is hard on the kidneys Animal protein is much harder to digest than vegetable protein. Since many people have digestive difficulties, protein that is not thoroughly digested is very challenging to the kidneys. Powdered protein is in a pre-digested state, and is the BEST protein source to choose!

We encourage a skeptical approach because the internet is full of unsupported, unreliable data and opinions.


For more on soy issues, we recommend reputable sites such as: The American Council for Science and Health The National Library of Medicine PUBMED Shaklee Health Sciences Bulletins

Now that we've busted these soy myths, here are some of the benefits of soy based on the best science we know.

Soy protein may:

  • Help prevent breast cancer

  • Help prevent prostate cancer

  • Reduce LDL cholesterol

  • Increase T-cell activity (Increased immunity)

  • Act as a powerful anti-oxidant against “trans fatty acids”

  • Improve heart health

  • Strengthen aging bones

  • Slow menopause

Thanks for reading!


Jody on behalf of Your Shaklee Team

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