Is Soy Protein Bad For Men? Testosterone Affects.

Is Soy Protein Bad For Males?

What's the catch? Can I consume Soy without growing breast!?

Soy protein highly supports a healthy lifestyle as a source of cholesterol-free, lean and lactose-free protein. Easy for diabetics and those with kidney issues. Soy has been in consumption for several years in the East Asia where it is popularly eaten as whole soy. Over the years, soy has been repackaged into new products such as soy isolates, soy concentrates and other texturized products.

Does soy affect hormone testosterone? No, At least not unless you consume A LOT of soy. This has been one of the most controversial topics in the recent past about soy. This article discusses everything you need to know about soy. If you want to look into some low carb vegan protein solutions check the reviews out below.

 Nutrients found in soybeans

100 grams of whole soybeans contains 180 calories, 9 grams of fat, 10 grams of carbs and 18 grams of proteins. The same amount of soybeans includes a proper amount of magnesium, folate, iron, calcium, potassium, phosphorus, copper and vitamin K.

Omega- 6 polyunsaturated fats are found in soybeans in large quantities. Research has shown that omega-6, when taken in excess, may lead to diseases and inflammation of body tissues.

  Isoflavones in Soy protein are endocrine disruptors

Estrogens are hormones steroid in nature found in females. The hormones are responsible for regulating the female reproductive system and sexual development.

The hormone estrogen is also found in men but in low quantity. The estrogen receptor lacks powers to select the type of substance that can activate it at any particular time. When estrogen receptors are activated,   a physiological effect occurs as a result of gene expression.

 Let us talk about how soy protein comes in…

Soy protein contains large quantities of a compound called isoflavones. Isoflavones are plant-based estrogens that are capable of activating estrogen receptors in the body.

An endocrine disruptor is any chemical that interferes with the normal hormonal functions in the human body. The soy estrogens can lead to reduced estrogen activity due to the isoflavones blocking the real estrogen from attaching itself on the cell receptor or cause an increased estrogen activity due to successful activation of the receptors by the isoflavones.

 Soy and male reproductive health

An elevated amount of estrogen in males is not healthy. This is to say that an increased amount of isoflavones could lead to significant changes in hormonal composition in men.

One particular research showed that men who eat soy protein daily had a lower sperm count within a duration of 3 months. While another conflicting study found that   50 milligrams of soy protein for four months had no effect on sperm count.

There are several studies that show adverse effects of soy on male sperm count and quality while others find no cause for alarm. This is to say that most studies being conducted about the impact of soy protein in males are not conclusive.

  Soy protein and Erectile Dysfunction

There are a number of studies suggesting that large amounts of soy proteins may decrease penile function.  A research conducted on rats to determine the effects of daidzein( a type of isoflavones found in soy protein) on erectile function, suggested that the rats that consumed a high amount of daidzein could not maintain their erection for long.  However, the levels of testosterone remained the same.

Even though rats have been used in recent studies to reflect the effects of some substances in humans, it is worthwhile to note that rats metabolize soy. Differently, we cannot compare the two.

Soy protein and the thyroid function in males.

The isoflavones in soy proteins are goitrogens, meaning that they disrupt the normal functioning of the thyroid gland. The isoflavones are said to inhibit production of the enzyme thyroid peroxidase that is responsible for the production of thyroid hormones.

  • A study in which some adults took 30 grams of soy protein for three months significantly raised levels of Thyroid stimulating hormone.

Majority of participants in the same study experienced symptoms of hypothyroidism such as fatigue, constipation, and thyroid enlargement. Even though, there are some studies showing that soy protein has no effects on thyroid functioning. Generally, there is no enough evidence to show that isoflavones are inhibitors of the primary thyroid enzyme. Evidence also shows a more managed filter of protein in the kidneys.

 Soy may not affect everyone the same way

Men with higher body fat have high levels of estradiol since it is converted from testosterone in body fat. Men prone to high estrogen levels can decrease their estrogen levels by eating a moderate amount of soy. Too much of soy protein will increase the levels of estrogen, especially in men with higher body fat.

  Soy protein is not bad after all

Fermenting soy has shown to decrease phytic acid even though it doesn’t get rid of isoflavones. Some brands of soy protein like Natto contain vitamin K2 which is vital for cardiovascular health.

  • Always keep in mind that the dose makes the poison. The plant-based estrogens are excellent sources of proteins. Always choose fermented soy and eat in a reasonable amount.

 How much soy should you eat?

Diet variation is the key to attaining the balanced nutrients as recommended. It is therefore vital to derive your protein from other sources apart from soy.  Two to three servings of soy are recommended to keep you within the healthy amount. The recommended amount of soy per day is 56 mg a day which you can easily subdivide into two servings.

 The Bottom line?

It is not easy to review soy protein because, for every study showing harm, there is another one showing its benefits. We can’t deny the fact that soy has several advantages including reducing one’s risk of developing prostate cancer. This makes it obvious that men should not fear soy but incorporate it into their diets in the recommended amount.

We go over other vegan diet tips on another review as well. Be sure to check it out and learn more! It’s important to do your OWN research. ASCVS is here to help as much we can.

Brice Mansa - ISSA Certified Personal Trainer & Nutrition Coach

Brice Mansa is a certified personal trainer from the ISSA. He took his knowledge from college to provide a more broad education method (blogging) to enhance the lives of thousands of people. Tired of being limited as a personal trainer in a gym with a single client, he stepped up his game. is proud to host him and the team of 4 other certified personal trainers and kinesiologists. When Brice isn't training or writing he likes long walks on the beach, puppos & motorcycles. We hope you enjoy his content, tips & stories!