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Revival Products Revival Products
  • Home
  • Shop
  • Menopause 101
    • Support for Menopause
    • Menopause Hot Flash and Night Sweat Support with Soy?
    • What Causes Menopause?
    • What Can I Expect?
    • Other Health Benefits
    • Here’s What Others Are Saying
  • Revival Difference – Benefits
    • The Revival Difference
    • Our Patented Technology & Our Research
    • Our Concentration Process: Less Soy Intake, More Benefit.
    • How Our Concentration Process Works
    • Doctors Recommend It!
    • Are You Getting Enough Soy?
    • It Doesn’t Taste Like Soy.
    • When Will I See Results?
    • For Best Results
    • Learn More About Soy
  • Tips & Recipes
  • About Us
    • Necessity Is The Mother Of Invention
    • Awards & Recognition
    • In The News
  • Testimonials
  • FAQ & Customer Care
  • REVIVAL’S AUTOSHIP FAMILY MEMBER
Nov 18

Human Study Confirms Soy Does Not Impact Thyroid Function*

One of the most discussed issues of dietary soy consumption and human health over the years has been thyroid function. Animal and cell culture studies reported that soy isoflavones inhibit the activity of enzymes involved in the production of thyroid hormones [1 – 3]. However, animal and lab cell culture studies are often very different than human consumption. Despite this enzyme inhibition, consumption does not appear to actually alter thyroid function, since the hormones and the gland were unaffected in rats [2, 3].

Studies on human subjects confirmed the findings reported in the animal studies regarding the lack of any effect of dietary soy on thyroid function [4, 5]. Despite this, the concern over soy consumption and thyroid function has persisted. This appears to be due to the fact that many of the human clinical trials have been of short duration, and several internet groups selling anti-soy books have failed or refused to report the newer human studies.

A new human clinical trial addressed this issue by examining thyroid function in postmenopausal women taking a soy isoflavone supplement (54 milligrams of genistein) daily for 3 years [6]. For this study, blood levels of thyroid hormones and auto-antibodies were assessed in 40 women taking genistein daily and 37 women taking a placebo capsule daily. Additionally, changes in thyroid hormone receptors and thyroid hormone enzymes were measured in 71 postmenopausal women taking genistein daily and 67 postmenopausal women taking a placebo daily. The results of this new soy research report showed that daily consumption of genistein:

  • Had no effect on thyroid hormones, which remained within the normal range for the full duration of the study,
  • Did not alter the function of enzymes involved in thyroid hormone production,
  • Did not cause any changes in thyroid hormone auto-antibodies, and
  • Had no effect on the expression of thyroid hormone receptors.

These results continue to confirm earlier studies that soy does not appear to alter thyroid function in healthy postmenopausal women. This is an excellent study in regards to its 3-year duration; however, this study focused only on genistein, the main isoflavone present in soy protein. Additional long-term studies looking at soy protein with all the isoflavones present or looking at the other isoflavones individually will be beneficial in continuing to clear up the issue of soy and thyroid function. Individuals taking thyroid medications need to separate soy consumption and medication intake by 3 – 4 hours, so as not to interfere with absorption of the medication [7 – 9], which is also true for other foods like walnuts, calcium, and dietary fiber.

References:

[1]  Divi RL, Chang HC, Doerge DR. Anti-thyroid isoflavones from soybean: isolation, characterization, and mechanisms of action. Biochem Pharmacol 1997; 54:1087-96.

[2]  Chang HC, Doerge DR. Dietary genistein inactivates rat thyroid peroxidase in vivo without an apparent hypothyroid effect. Toxicol Appl Pharmacol 2000; 168:244-52.

[3]  Doerge DR, Sheehan DM.  Goitrogenic and estrogenic activity of soy isoflavones.  Environ Health Perspect 2002; 110 (Suppl 3):349-353.

[4]  Bruce B, Messina M, Spiller GA.  Isoflavone supplements do not affect thyroid function in iodine-replete postmenopausal women.  J Med Food 2003; 6:309-316.

[5]  Messina M, Redmond G.  Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature.

[6]  Bitto A, Polito F, Atteritano M, Altavilla D, Mazzaferro S, Marini H, Adamo EB, D’Anna R, Granese R, Corrado F, Russo S, Minutoli L, Squadrito F.  Genistein aglycone does not affect thyroid function: results from a three-year, randomized, double-blind, placebo-controlled trial.  Journal of Clinical Endocrinology & Metabolism 2010; 95:Published online ahead of print.

[7]  Jabbar MA, Larrea J, Shaw RA. Abnormal thyroid function tests in infants with congenital hypothyroidism: the influence of soy-based formula. J Am Coll Nutr 1997; 16:280-2.

[8]  Bell DS, Ovalle F: Use of soy protein supplement and resultant need for increased dose of levothyroxine. Endocr Pract 2001; 7:193–194.

[9]  Pinchera A, MacGillivray H, Crawford JD, Freeman AG. Thyroid refractiveness in an athyreotic cretin fed soybean formula. N Engl J Med 1965; 273:83-87.

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GREAT TASTE GUARANTEE Revival is the only soy brand with a Great Taste Guarantee. Your satisfaction is important to us! Revival Soy is the best-tasting way to enjoy the benefits of soy in our humble opinion. If you are not satisfied for any reason, we will exchange it for another Revival product or refund your money for the unused portion within 30 days of the order date.

*These statements have not been evaluated by the Food and Drug Administration. Revival foods and healthy foods are not intended to diagnose, treat, cure or prevent any disease. Individual results vary. Consult a doctor before starting any diet or exercise plan. Typical hot flash reduction was nearly 40% in a 12-week study. Typical weight loss was 26 - 29 pounds for dieters in a 16 week study. Studies were funded in part or in whole by Physicians Laboratories. Testimonials were compensated fairly for use of their testimonies including payment plus free products. Individual results vary. The FDA states that 25g of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce risk of heart disease. Each Revival protein shake and protein bar provides 20g of soy protein which is a good source of energy from calories. Adequate calcium throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis. (Full Disclaimer) MEDICAL DISCLAIMER - All information is intended for your general knowledge only and is not a substitute for medical advice or treatment for specific medical conditions. We cannot and do not give medical advice. (Full Disclaimer)

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