Does soy decrease testosterone?
The lie of the soy boy
Many ancestral health nutjobs demonize soy for various reasons.
The concern can come from a few places such as case studies of gynecomastia from soy consumption and how prevalent soy is in food production.
But outside of singular case studies and worries about the food supply… does soy decrease testosterone in men or “feminize” men?
Many people going plant-based are going to use soy protein probably. Soy is used in a variety of different food products in general.
Thus the increased intake of soy can be a cause for concern. Soybeans contain Isoflavones which are similar in chemical structure to estrogen. Therefore, eating soy is compared to consuming estrogen which is dubbed “the female hormone”.
Is soy turning men into women? Obviously not, a meta-analysis of clinical trials showed soy protein consumption and Isoflavones had no impact on testosterone, free testosterone, SHBG, Estradiol, and Estrone.
Another meta-analysis confirmed this with similar results showing no impact on testosterone, free testosterone, SHBG, and the free androgen index for men.
While the meta-analyses cited are not perfect we can use some logic. The mean intake of isoflavone among Japanese older adults is about 30-50 mg/day, the mean intake in the USA is less than 3 mg a day.
Therefore, Japanese older adults should have higher rates of gynecomastia, decreased testosterone, and reduced sperm count compared to the USA... there is no data from my knowledge indicating this is the case.
This means that soy consumption probably doesn’t decrease or impact testosterone levels in men.
Latest Research
Main Points: This was a large cross-sectional study with 3678 males and females (age range: 40-70 years) with chronic diseases. A food frequency questionnaire was used to create an index of unhealthy versus healthy plant based diets. Lipid profile, fasting blood sugar (FBS), blood pressure, and anthropometric indices were measured. Researchers also looked at the association between plant based diets and CVD risk factors. High adherence to a plant based and healthy plant based diet was inversely associated with numerous CVD risk factors.
Main Points: This is a large meta analysis of cohort studies or case-control studies that reported a relationship between plant-based diets and cancers of the digestive system. The overall analysis concluded that plant-based diets played a protective role in the risk of digestive system neoplasms. Subgroup analysis found plant-based diets in reduced both risk and odds of numerous forms of cancer including pancreatic, colon, rectal, and colorectal.
Study 3: Plant-based diets and long-term health: findings from the EPIC-Oxford study
Main Points: EPIC-Oxford is a large cohort study in the UK following 65,000 men and women living throughout the UK, many of which are vegetarian. This study was initially conducted to look the connection between diet and cancer, plus other chronic diseases. Vegans in EPIC-Oxford have a lower risk of diabetes, diverticular disease and cataracts and a higher risk of fractures, but there are insufficient data for other conditions to draw conclusions
Latest News & Interesting Stuff
Fellow vegan John Schlimm just released a book called “The Cheesy Vegan”, its a cookbook with many yummy vegan cheese recipes.
Here is an interesting video and blog on the connection between veganism and Buddhism.
My good friend Danny from Lifting Vegan Logic released a new video on vegan arguments.
Plant-Based Recipes
This is a solid tofu scramble recipe.
You can find the video here.
These are the ingredients:
(3-4 servings, 10min prep time)
400g tofu
1 Tbsp tahini
1/2 cup (120ml) plant milk
salt to taste or kala namak
1/4 Tsp turmeric
1/2 Tsp paprika and garlic powder
Here is how to make it:
Mix up the tahini, plant milk, salt, paprika, and garlic powder into a mixture.
Put oil in a frying pan, Crumble, and fry in that oil until browned.
Put the initial mixture into the scrambled tofu and mix in.