Soy & Health

Hi Guys :))

Since soy products have recently enjoyed increasing popularity i wanted to point out some important informations about soy. 🙂

Here is a post where you can read about soy, including lots of medical research & studies which i’ll link below. Don’t hesitate to contact my at any time, I LOVE CHATTING with you guys ❤

I know that this post seems really long, but i wanted to provide you informations about the individual topics as well as a brief summary 🙂


Soy products include soybeans (also called edamame) and any other items made from soybeans, including soymilk, tofu, tempeh, miso, and vegetarian meat and dairy substitutes like soy meats and soy cheeses.

Evidence indicates that Soy products may reduce the risk of breast cancer and breast cancer recurrence as well as lung cancer & lung cancer recurrence.

They are not bad for your thyroid gland (Schilddrüse) but may reduce the absorption of thyroid medications. The benefits of soy products appear to relate to traditional soy products, like Tempeh, Miso & Edamame, not the concentrated soy protein isolates. (Protein Powders).  🙂

Soy & Cancer

Epidemiological studies have found that soy protein may reduce the risk for cancers including breast, colon and prostate1.

In addition Soy products can improve survival from lung cancer. Researchers examined the women’s diets before and after their cancer diagnosis. Those who ate the most soy products cut their risk of dying by nearly half, compared with women who ate the least amount of soy. Previous studies have shown that soy products reduce the risk of developing lung cancer, and have a similar ability to reduce the risk of breast and prostate cancer22, 23

Studies show that women who include soy products in their routine are less likely to develop breast cancer, compared with other women. In January 2008, researchers found that women averaging one cup of soymilk or about one-half cup of tofu daily have about 30 percent less risk of developing breast cancer, compared with women who have little or no soy products in their diets.2, 27 However, to be effective, the soy consumption may have to occur early in life, as breast tissue is forming during adolescence.3,4

What about women who have been previously diagnosed with breast cancer?

Several studies showed that women who regularly consumed soy products, such as soymilk, tofu, or edamame, had a 32 percent lower risk of recurrence and a 29 percent decreased risk of death, compared with women who consumed little or no soy.Women who avoid soy products get no advantage at all compared to those who include soy products in their diets appear to cut their risk of cancer recurrence.

Soy & Reproductive Health

Other concerns include whether soy has a negative effect on reproductive health. However, studies in both men and women have shown that soy did not hinder reproduction. 7,8    

Also, adults who had been fed soy infant formula as infants were found to have no difference in their reproductive health when compared with adults who had been fed cow’s milk formula.9

Soy & Men Health

Soy products have no adverse effects on men health or hormones and may help prevent cancer in men. A meta-analysis published in Fertility and Sterility, based on more than 50 treatment groups, showed that neither soy products nor isoflavone supplements from soy affect testosterone levels in men.10 An analysis of 14 studies published in the American Journal of Clinical Nutrition showed that increased intake of soy resulted in a 26 percent reduction in prostate cancer risk.11 Researchers found a 30 percent risk reduction with non-fermented soy products such as soymilk and tofu.

Soy & Fibroids

Fibroids are the most frequently seen tumors of the female reproductive system, also known as uterine myomas (99% bening -> non – cancerous).

A study of Japanese women found that the more soy women ate, the less likely they were to need a surgical removal of the uterus (hysterectomy)  suggesting that fibroids were less frequent.12

In a study of women in Washington State, soy did not seem to help or hurt, probably because American women eat very little soy, compared with their Japanese counterparts.13  What did have a big effect in this study were lignans, a type of phytoestrogens found in flaxseed and whole grains. The women consuming the highest amounts of these foods had less than half the risk of fibroids, compared with the women who generally skipped these foods. So, again, phytoestrogens (phyto = plant) seem beneficial.

Soy & Thyroid Health (Schilddrüse)

Clinical studies show that soy products do not cause low thyroid function (hypothyroidism)14. However, soy isoflavones may take up some of the iodine that the body would normally use to make thyroid hormones.15 The same is true of fiber supplements and some medications. Theoretically indicating that people who consume soy might need slightly more iodine in their diets. (Iodine is found in many plant foods, especially in seaweed and iodized salt.) Soy products can also reduce the absorption of medicines used to treat hypothyroidism.14 People who take these medications should check with their health care providers to see if their doses need to be adjusted.

Soy & abdominal fat

There was a study done in 2007 by some scientists where People fed the exact same diet, but just had the dairy protein replaced with soy, and there was a significant drop in abdominal fat. Same calories, but instead of the abdominal fat growing, it seemed to melt away. We’re finally understanding some of the biology behind this.  26

In 2009 in the Journal of Nutritional Biochemistry, scientists found that soy helps prevent human fat cells from taking up fat in the first place. They put a layer of human fat cells in a Petri dish, and as the concentration of the soy isoflavone was increased, the fat accumulation within the fat cells dropped. And these are the kinds of blood levels we can get incorporating soy into our diet.  The actual effective phytoestrogens here are called Genistein – with 50 micrograms— fat uptake in a meal was almost completely blocked. 27

These phytoestrogens are so amazing that the meat industry bragged in their trade journals that phytoestrogens have been found in animal products, too. Which is not too much of a suprise since animals are eating primarily plants. What is a big note here is how much of the isoflavones are found in the foods? Beef or chicken have about 4 for these isoflavones. Veggie burgers have 4,000. Dairy milk has 6. But soy milk has 6,000.

Other Health Effects of Soy

A study looking at the diets and measures of inflammation (Entzündungen) showed that the more soy products the women consumed, the less inflammation they experienced. Inflammation is linked to cancer, type 2 diabetes, and cardiovascular disease.16 Soy products appear to reduce low-density lipoprotein (“bad”) cholesterol.17 They may also reduce the risk of osteoporosis-related hip fractures. In a study published in the American Journal of Epidemiology, women who consumed at least one-fourth cup of tofu per day averaged a 30 percent reduction in fracture risk.18 A study in the journal of Menopause found that women taking soy isoflavone supplements for six weeks to 12 months reduced the frequency of hot flashes by 21 percent, compared with women taking a placebo.19 . 


It has long been known that cow’s milk increases the amount of insulin-like growth factor in the bloodstream,20 and this compound is linked to higher cancer risk. Some evidence suggests that highly concentrated soy proteins (indicated as “soy protein isolate” on food labels) can do the same.21  Simple soy products, such as tempeh, edamame, or miso, are probably the best choices.

Since high protein intake is associated with increased IGF1 levels (insulin-like growth factor), and soy products are generally high in protein, excessive consumption (more than 5 servings per day) and intensive consumption of Soy Protein Isolates should be avoided for best possible health outcomes. 25 

Is there anyone who should avoid soy?

People having soy allergies should avoid all sorts of soy products. 🙂  A national survey found that only about 1 in 2,000 people report a soy allergy. This might seem a lot but that’s 40 times less than the most common allergen—dairy milk—and about ten times less than all the other common allergens—like fish, eggs, shellfish, nuts, wheat, or peanuts.


Evidence (till now) indicates that soy products may reduce the risk of breast cancer and breast cancer recurrence. They do not appear to have adverse effects on the thyroid gland, but may reduce the absorption of thyroid medications.  As mentioned already, most of the benefits of soy products appear to relate to traditional soy products, like Tempeh, Miso, Edamame and other whole food sources. Not to the concentrated soy protein isolates. 🙂

Studys & Infos:

This is a really nice infographic you can download for free summing up all things you can read here and send to anyone who is ever concerned about the health effects of eating soy 🙂

Check out Physicians Committee for responsible medicine for great information!!

Klicke, um auf pv_soy_and_your_health.pdf zuzugreifen

How much soy is too much?

Read more about Milk & Prostate Cancer:

Not convinced yet? check out to read more about this topic.


1. Badger TM, Ronis MJ, Simmen RC, Simmen FA. Soy protein isolate and protection against cancer. J Am Coll Nutr. 2005;24:146S-149S.

2. Wu AH, Yu MC, Tseng CC, Pike MC. Epidemiology of soy exposures and breast cancer risk. Br J Cancer. 2008;98:9-14.

3. Korde LA, Wu AH, Fears T, et al. Childhood soy intake and breast cancer risk in Asian American women. Cancer Epidemiol Biomarkers Prev. 2009;18:1050-1059.

4. Shu XO, Jin F, Dai Q, et al. Soyfood intake during adolescence and subsequent risk of breast cancer among Chinese women. Cancer Epidemiol Biomarkers Prev. 2001;10:483-488.

5. Shu XO, Zheng Y, Cai H, et al. Soy food intake and breast cancer survival. JAMA. 2009;302:2437-2443.

6. Guha N, Kwan ML, Quesenberry CP Jr, Weltzien EK, Castillo AL, Caan BJ. Soy isoflavones and risk of cancer recurrence in a cohort of breast cancer survivors: the Life After Cancer Epidemiology study. Breast Cancer Res Treat. 2009;118:395-405

7. Mitchell JH, Cawood E, Kinniburgh D, Provan A, Collins AR, Irvine DS. Effect of a phytoestrogen food supplement on reproductive health in normal males. Clin Sci (Lond). 2001;100:613-618.

8. Kurzer MS. Hormonal effects of soy in premenopausal women and men. J Nutr. 2002;132:570S-573S.

9. Strom BL, Schinnar R, Ziegler EE, et al. Exposure to soy-based formula in infancy and endocrinological and reproductive outcomes in young adulthood. JAMA. 2001;286:807-814.

10. Hamilton-Reeves JM, Vazquez G, Duval SJ, Phipps WR, Kurzer MS, Messina MJ. Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. Fertil Steril. 2010;94:997-1007.

11. Yan L, Spitznagel EL. Soy consumption and prostate cancer risk in men: a revisit of a meta-analysis. Am J Clin Nutr. 2009;89:1155-1163

12. Nagata C, Takatsuka N, Kawakami N, Shimizu H. Soy product intake and premenopausal hysterectomy in a follow-up study of Japanese women. Eur J Clin Nutr. 2001;55:773-777.

13. Atkinson C, Lampe JW, Scholes D, Chen C, Wahala K, Schwartz SM. Lignan and isoflavone excretion in relation to uterine fibroids: a case-control study of young to middle-aged women in the United States. Am J Clin Nutr. 2006;84:587-593.

14. 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. Thyroid. 2006;16:249-258.

15. Divi RL, Chang HC, Doerge DR. Anti-thyroid isoflavones from soybean: isolation, characterization, and mechanisms of action. Biochem Pharmacol. 1997;54:1087-1096.

16. Wu SH, Shu XO, Chow WH, et al. Soy food intake and circulating levels of inflammatory markers in Chinese Women. J Acad Nutr Diet. 2012;112:996- 1004.

17. Pipe EA, Gobert CP, Capes SE, Darlington GA, Lampe JW, Duncan AM. Soy protein reduces serum LDL cholesterol and the LDL cholesterol:HDL cholesterol and apolipoprotein B:apolipoprotein A-I ratios in adults with type 2 diabetes. J Nutr. 2009;139:1700-1706.

18. Koh WP, Wu AH, Wang R, et al. Gender-specific associations between soy and risk of hip fracture in the Singapore Chinese Health Study. Am J Epidemiol. 2009;170:901-909.

19. Taku K, Melby MK, Kronenberg F, Kurzer MS, Messina M. Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials. Menopause. 2012;19:776-790

20. Heaney RP, McCarron DA, Dawson-Hughes B, et al. Dietary changes favorably affect bone remodeling in older adults. J Am Diet Assoc. 1999;99:1228-1233.

21. Dewell A, Weidner G, Sumner MD, et al. Relationship of dietary protein and soy isoflavones to serum IGF-1 and IGF binding proteins in the Prostate Cancer Lifestyle Trial. Nutr Cancer. 2007;58:35-42.

22. Yang G, Shu XO, Li HL, et al. Prediagnosis Soy Food Consumption and Lung Cancer Survival in Women. J Clin Oncol. Published online on March 25, 2013.

23. Yang G, Shu XO, Chow WH, et al. Soy food intake and risk of lung cancer: evidence from the Shanghai Women’s Health Study and a meta-analysis. Am J Epidemiol. 2012;176:846-855.

25. Nutr Cancer. 2007;58(1):35-42. Relationship of dietary protein and soy isoflavones to serum IGF-1 and IGF binding proteins in the Prostate Cancer Lifestyle Trial. Dewell A1Weidner GSumner MDBarnard RJMarlin RODaubenmier JJChi CCarroll PROrnish D.

26. Int J Obes (Lond). 2006 Sep;30(9):1389-96. Epub 2006 Mar 14.Weight gain over 5 years in 21,966 meat-eating, fish-eating, vegetarian, and vegan men and women in EPIC-Oxford. Rosell M1Appleby PSpencer EKey T.


  • Nomura SJO, Hwang YT, Gomez SL, et al. Dietary intake of soy and cruciferous vegetables and treatment-related symptoms in Chinese-American and non-Hispanic White breast cancer survivors. Breast Cancer Res Treat. 2018;168:467-479.

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