Revival Soy Doctor
Is it ok to take soy when you have a thyroid condition? I am on levothyroxoid and am interested in soy for perimenopause.
Thank you for your question.
Before we get started, please read the following: We do not give medical advice. We provide nutritional information regarding Revival Soy products and information available in the public domain for the uses of soy. We advise you to discuss your personal medical issues with your physician. I hope our information will be helpful to you.
If you have never tried Revival Soy, give us a call. The taste is excellent.
Will soy protein interfere with any of my prescription medications?
The FDA has not issued any drug interaction warnings for soy protein. No interactions in humans with common prescription medications have been shown. In fact, soy may enhance the benefits of many prescriptions. For instance, soy may help cholesterol lowering medications lower cholesterol even further. Soy may also reduce breast and endometrial stimulation caused by prescription hormones.
>>Some doctors suggest that thyroid medications be taken at a different time of the day than soy protein to maximize absorption of the medication - about 4 hours apart. You should consult your own doctor if you taking prescription medications.
Revival Soy is not a replacement for prescription medication, but can be excellent nutritional support for your dietary health plan. We call this SIS™ (which stands for ‘Soy Integrative Support’™). Revival Soy can be integrated into your current health plan to help you achieve better health.
Will soy protein affect my thyroid function?
Multiple HUMAN studies published in 1999 and 2000 have shown that soy protein DOES NOT harm thyroid function (see References 1, 2 and 3 below). Please pass this information along to your family/friends). The FDA rejected earlier claims that soy adversely affected the thyroid due to lack of evidence (Reference 4). Most importantly, in Asian countries where consumption of soy is 10 to 100 times higher than in America, no higher occurrence occurs. We have not had problems in tens of thousands of regular Revival customers. If you are taking thyroid medication, simply monitor your levels as normal with your own physician. Some doctors suggest that thyroid medications be taken at a different time of the day than soy protein to maximize absorption of the medication. Hypothyroidism is very common among women simply due to aging, therefore your physician should check your thyroid levels yearly regardless if you eat soy protein or not.
The American Foundation of Thyroid Patients has reviewed the current medical literature on soy and thyroid health and now recommends Revival Soy for all members. To learn more, visit http://www.thyroidfoundation.org
Hundreds of human studies have shown soy's benefits to menopause,
endometrial, breast, heart and bone health. Hypothyroidism has not been a
concern in these studies that we have seen.
Studies in athletes have also not shown any detrimental effects of soy
to thyroid health. The FDA has not issued a consumer warning, or stopped
infant formula from being used, or stopped soy foods from being sold and
consumed by hundreds of food manufacturers. If the FDA found evidence that
soy was dangerous, they would act on it. They reviewed the medical literature for 2 years and found no compelling, proven evidence that soy would harm the thyroid or cause cancer (Reference 4)!
Tens of thousands of customers from all over America use Revival daily
and have achieved excellent health. We haven't had any significant problems in tens of thousands of Revival users. Animal studies have shown that soy may actually increase thyroid hormone levels slightly which could help reduce cholesterol levels.
You should avoid isoflavone pills. Isoflavone pills are chemically-extracted and don't have the safety data that whole soy products have. A lot of our questions come from an in vitro study, using single, highly purified isoflavones, that in high concentrations, inhibited in vitro thyroid cells. Purified chemicals from potato skins have also been shown to be potent neurotoxins. New studies show that the isoflavone pills don't work as good as the whole soy products either. We can't expect a chemically-isolated pill to produce the same benefit and have the same
safety as soy foods.
The Japanese consume 100 times more isoflavones daily than Americans in
their diet. They have the best health and longest lifespan in the world
according to data from this summer (1999). If someone claims that they became hypothyroid after they started eating soy protein or soy isoflavones, it does not mean that soy caused it. Auto-immune diseases are the number one cause of thyroid problems followed by iodine deficient diets. They could have had a genetic predisposition for hypothyroidism.
Personal Note from Dr. Tabor: On a personal note, my entire family and many, many colleagues and friends consume Revival and other soy products daily. I talk to hundreds of Revival customers regularly that have wonderful health and great results.
My own grandmother is on Synthroid and enjoys Revival daily. The makers of Synthroid simply recommend not taking the medication at the same time during the day when eating soy products. She has not had any problems. She takes her Synthroid in the morning and the soy later during the day. No significant human data has ever shown this. It is just speculation. But, the SOLUTION is simple - monitor your Synthroid levels as you normally do with your medical doctor. He or she can adjust your Synthroid levels as needed up or down IF needed. It's that simple. You can also take your medication and soy at different times of the day to minimize any absorption problems. I doubt you will have any problems though because we haven't received any reports here.
Earlier claims that soy harmed the thyroid were based on PURIFIED CHEMICAL STUDIES (even by one of the FDA’s own scientists), which are irrelevant for whole soy products like Revival. As stated above, recent HUMAN STUDIES have disproved this theory, and the FDA’s other more senior scientists rejected any claims that whole soy protein harmed the thyroid. PLEASE READ CLEARLY: As you will see from the additional references below (References 5, 6, 7 and 8), purified chemicals from ANY vegetable or fruit, INCLUDING broccoli, potatoes, tomatoes, eggplant, brussel sprouts, cabbage, alfalfa, oats, carrots, cauliflower, turnips, etc. are very toxic (i.e. they cause cancer) to human cells if ISOLATED from the rest of the plant!! Of course, no one is saying that you shouldn’t eat vegetables and fruits!! That’s silly. The reason is that PURIFIED CHEMICALS from plants are NOT THE SAME as the whole plant, so to assert that soy causes hypothyroidism BASED ON PURIFIED CHEMICAL STUDIES is simply not correct or factual, particularly when the newest HUMAN studies show that soy is safe. Earlier preliminary human/soy/thyroid studies didn’t control for iodine deficiency, thus making them irrelevant, given the fact that 3 recent, well-designed, controlled studies have shown that soy does not harm the thyroid.
Additionally, as you will see from the last reference, the milk industry is suing the soy milk industry to stop using the word “soy milk” (Reference 9). The web sites promoting these “anti-thyroid” soy materials are funded/supported by the dairy industry. We are not against the dairy industry. We don’t even sell soy milk. Many of our customers mix their Revival with a big glass of regular milk daily! The groups/people against soy feel strongly that there is a vast “FDA conspiracy” and that the soy industry is blinded to this, which is not the case. They want to ignore the hundreds of medical studies showing that soy protein produces great benefits.
SOY ISOFLAVONES DO NOT HAVE AN ANTI-THYROID EFFECT IN POSTMENOPAUSAL WOMEN OVER 64 YEARS OF AGE. B. Bruce. G. A. Spiller and L. Holloway. Health Research and Studies Center, Los Altos, CA 94022 and Palo Alto V.A. Health Care System, Palo Alto, CA 94034. Experimental Biology 2000, San Diego, CA April 15-18, 2000.
Studies in animals, in vitro, and infants using soy-based formulas have suggested a possible anti-thyroid effect of soy. In a randomized, double blind, placebo-controlled study, we investigated the effect on thyroid function of a concentrate supplying 90 mg of soy isoflavones in 38 postmenopausal women, aged 64-83 years old, not on hormone replacement therapy (HRT). Thyroid stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3) were measured before supplementation (BS) and after 90 and 180 days.
These results suggest that there appears to be no anti-thyroid effect of soy isoflavones over six months in postmenopausal women not on HRT. Supported by a grant from Archer Daniels Midland Company.
Soy isoflavones exert modest hormonal effects in premenopausal women. Duncan AM, Merz BE, Xu X, Nagel TC, Phipps WR, Kurzer MS.
Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108, USA. J Clin Endocrinol Metab 1999 Jan;84(1):192-7
Soy isoflavones are hypothesized to be responsible for changes in hormone action associated with reduced breast cancer risk. To test this hypothesis, we studied the effects of isoflavone consumption in 14 premenopausal women. Isoflavones were consumed in soy protein powders and provided relative to body weight (control diet, 10 +/- 1.1; low isoflavone diet, 64 +/- 9.2; high isoflavone diet, 128 +/- 16 mg/day) for three menstrual cycles plus 9 days in a randomized cross-over design. During the last 6 weeks of each diet period, plasma was collected every other day for analysis of estrogens, progesterone, LH, and FSH. Diet effects were assessed during each of four distinctly defined menstrual cycle phases. Plasma from the early follicular phase was analyzed for androgens, cortisol, thyroid hormones, insulin, PRL, and sex hormone-binding globulin. The low isoflavone diet decreased LH (P = 0.009) and FSH (P = 0.04) levels during the periovulatory phase. The high isoflavone diet decreased free T3 (P = 0.02) and dehydroepiandrosterone sulfate (P = 0.02) levels during the early follicular phase and estrone levels during the midfollicular phase (P = 0.02). No other significant changes were observed in hormone concentrations or in the length of the menstrual cycle, follicular phase, or luteal phase. Endometrial biopsies performed in the luteal phase of cycle 3 of each diet period revealed no effect of isoflavone consumption on histological dating. These data suggest that effects on plasma hormones and the menstrual cycle are not likely to be the primary mechanisms by which isoflavones may prevent cancer in premenopausal women.
* Clinical trial
* Randomized controlled trial
PMID: 9920082 [PubMed - indexed for MEDLINE]
Modest hormonal effects of soy isoflavones in postmenopausal women. Duncan AM, Underhill KE, Xu X, Lavalleur J, Phipps WR, Kurzer MS.
Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108, USA. J Clin Endocrinol Metab 1999 Oct;84(10):3479-84
Soy isoflavones have been hypothesized to exert hormonal effects in postmenopausal women. To test this hypothesis, we studied the effects of three soy powders containing different levels of isoflavones in 18 postmenopausal women. Isoflavones were consumed relative to bodyweight [control: 0.11 +/- 0.01; low isoflavone (low-iso): 1.00 +/- 0.01; high isoflavone (high-iso): 2.00 +/- 0.02 mg/kg/day] for 93 days each in a randomized crossover design. Blood was collected on day 1 of the study (baseline) and days 36-38, 64-66, and 92-94 of each diet period, for analysis of estrogens, androgens, gonadotropins, sex hormone binding globulin (SHBG), prolactin, insulin, cortisol, and thyroid hormones. Vaginal cytology specimens were obtained at baseline and at the end of each diet period, and endometrial biopsies were performed at baseline and at the end of the high-iso diet period, to provide additional measures of estrogen action. Overall, compared with the control diet, the effects of the low-iso and high-iso diets were modest in degree. The high-iso diet resulted in a small but significant decrease in estrone-sulfate (E1-S), a trend toward lower estradiol (E2) and estrone (E1), and a small but significant increase in SHBG. For the other hormones, the few significant changes noted were also small and probably not of physiological importance. There were no significant effects of the low-iso or high-iso diets on vaginal cytology or endometrial biopsy results. These data suggest that effects of isoflavones on plasma hormones per se are not significant mechanisms by which soy consumption may exert estrogen-like effects in postmenopausal women. These data also show that neither isoflavones nor soy exert clinically important estrogenic effects on vaginal epithelium or endometrium.
* Clinical trial
* Randomized controlled trial
PMID: 10522983 [PubMed - indexed for MEDLINE]
FDA STATEMENT from AUGUST 14, 2000 that soy protein is safe:
US FDA says it weighed soy concerns versus benefits
By Lisa Richwine
WASHINGTON (Reuters) - U.S. health regulators weighed concerns that soy
products might be harmful but decided soy's positive effects justified
touting its benefits to consumers, a Food and Drug Administration official
The agency comment came in response to published remarks from two FDA
scientists that eating soy might cause health problems, particularly if given
daily to infants in soy milk formulas.
Drs. Daniel Doerge and Daniel Sheehan, the FDA scientists, have spoken to
media organizations to warn that infants given soy formula might grow up to
develop fertility problems.
They also worry that eating soy regularly might increase the risk of breast
cancer in women and brain damage in men. Their most recent comments were
published in Britain's Observer newspaper Sunday.
FDA officials considered the scientists' views and those of other critics
before announcing last October that they would permit manufacturers to
advertise that eating soy could help adults cut their risk of heart disease.
``We are well aware of the concerns, but we did balance those concerns with
the other positive effects,'' an FDA official said in an interview Monday.
The FDA reviewed scientific studies on soy before concluding that adults who
consume 25 grams of soy protein per day could see a ``significant'' lowering
of cholesterol, which would lower their risk of heart disease. High
cholesterol is a major risk factor for heart disease, the leading killer of
Critics told the FDA soy could cause harm because it contains a chemical
similar to the female hormone, estrogen, that might disrupt normal hormone
levels and impair development. Some warned about the possibility of cancer,
impaired fertility or thyroid problems.
The FDA said the concerns were not supported by conclusive scientific
research. While chemicals in soy do exert hormonal effects, the impact is
``very limited'' and much lower than that of natural or synthetic estrogens,
the FDA said when it announced it would permit the soy health claim.
Concerns that soy infant formula could be harmful were ''speculative''
pending the outcome of definitive research, the agency said.
Critics who worry about the effects of soy infant formula recommend that it
be used only when no alternatives exist.
A farmer-supported group said Monday concerns about soy's health effects
were not new but were not widely held.
``The overwhelming body of published peer-reviewed scientific evidence shows
soy has numerous health benefits,'' said Michael Orso, a spokesman for the
United Soybean Board. ^ REUTERS@
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redistribution of Reuters content, including by framing or similar means, is
expressly prohibited without the prior written consent of Reuters. Reuters
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* Read Dr. Tabor's last guest transcript
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