To understand Soy protein, let us start from where we get Soya?

Soy comes from the soybean pods that are in the soy plant. All soy products are made from soybean which is a very rich source of high-quality protein. Soy protein is a protein found in soybean, it is cholesterol-free and low in saturated fats. It is also a good and rich source of protein for the people who are pure vegetarians. Soy protein is the highest quality plant-based protein option, especially for vegans.

Soy protein is a complete protein as it contains all essential amino acids i.e. histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. It is also rich in fiber, iron, calcium, zinc, and B vitamins.

  • Isoflavone – It is a plant-based chemical called phytoestrogen which generally acts as an estrogen in the body. Genistein and daidzein are the most common isoflavones are found in soy products.
  • Phytoestrogen – They are found in plants and plays the same role as estrogen plays in the body.

Let us understand are estrogen and testosterone, before understanding soy effect on them.

  • Estrogen is a female sex hormone that regulates the menstrual cycle, maintains pregnancy and keeping bones strong, keeps cholesterol in control.
  • Testosterone is responsible for the development of male sexual characteristics, it maintains muscle bulk, adequate levels of red blood cells, bone growth, a sense of well-being and sexual function

Health benefit- As soya contains antioxidants, they protect cells from damage which is caused by free radicals. Free radicals are responsible for cancer and premature aging.

Prevent osteoporosis – Osteoporosis is a bone disease that occurs when the body loses too much bone, makes too little bone which causes bones to become weak and brittle. As soy is rich in calcium and protein it promotes good health to bones, and it prevents osteoporosis. It increases bone mineral density which helps to decrease calcium loss in aging women. In pregnancy, some women cannot get sunlight exposure so there are chances of lacking vitamin D as it requires in pregnancy like a woman. So fortified milk and fortified soy milk are the best options to fulfill requirements of vitamin D

Soy for infants– Sometimes breastfeeding is not possible for different reasons; soy-based formulas are advised as in case of lactose intolerance infants cannot tolerate cow milk or casein or whey-based formula. But, according to ADA American dietetic association and dieticians of Canada 2000, soy-based formula is not recommended for preterm infants who are weighing less than 1000 grams for preventing or managing colic and gastroenteritis. Soy protein is a complete protein as it contains all essential amino acids which require to support growth and development in infants and young children

Obesity – Obesity is a metabolic disorder that is caused by an imbalance of energy intake and its expenditure which leads to excess accumulation of fat in adipose tissue and organs. Obesity is associated with hyperinsulinemia, insulin resistance which causes abnormal blood sugar levels, and abnormal lipid metabolism which leads to increase risk of cardiovascular diseases. As soya is rich in protein at suppress appetite and give satiety which helps individuals to reduce weight

Insulin resistance and blood pressure – Insulin resistance is when cells in your muscles, fat, and liver do not respond well to insulin and cannot easily take up glucose from your blood. then the pancreas makes more insulin to help glucose enter your cells. Insulin resistance is associated with obesity, high blood pressure, high cholesterol, and type 2 diabetes.

Soy protein improves glycemic control – Soy protein helps to control high blood sugar levels, reduced body weight, lowers hyperlipidemia, hyperinsulinemia.

Cancer – Genistein is an isoflavone (soya contains isoflavone) which helps to reduce the risk of cancer. It prevents tumors from creating blood vessels that are nourishing for cancer growth and hence it blocks cancer development.

Heart and cardiovascular health – The American Heart Association says choosing soy protein over animal protein will improve cardiovascular health lowering LDL cholesterol and lowers blood pressure. Soybean helps to lower cholesterol they decrease the LDL and increases the HDL. Soya foods are naturally cholesterol-free and low in saturated fat. Soy products are also rich in fiber that also helps in improving gastrointestinal function, reduces cholesterol, and ultimately improves heart function. In cardiac diseases, like we said earlier soybean contains no cholesterol and has a very low level of saturated fats which is healthy for the heart by keeping low levels of total cholesterol, LDL, and triglycerides. Soy food is also rich in polyunsaturated fatty acids

Hot flashes and night sweat in females – When estrogen levels go low menopause symptoms may start to appear, Soya food contains isoflavones which is a type of phytoestrogen. Phytoestrogen works as estrogen which helps to relieve menopause symptoms such as hot flashes and night sweat.

Breast cancer in females – It is a myth that soy food increases the risk of breast cancer rather it reduces the risk of breast cancer. The above myth is created and people are pouring water into it because soy contains isoflavones which are generally known as plant estrogen and high level of estrogen associated with increased risk of breast cancer. soya food does not contain a high level of isoflavones which is required to increase the risk of breast cancer. Soya foods are always good and healthy options rather than soya or isoflavones supplements. During cancer, treatment patient needs extra calories for which they can choose soy-rich foods or rather opt for soy pills or isoflavones rich formulas.

Memory and cognitive function for males and females – Estrogen helps to improve memory in both males and females. Menopausal symptoms-In females, there are changes happening with the mood and memory impairment at the menopausal stage. Eating soy food can help to reduce the risk of memory loss.

Prostate cancer in males – Prostate cancer is mostly seen in men. Soy foods reduced the risk of prostate cancer, fermented soya food, isoflavone intake not associated with prostate cancer risk.

Vegetarian bodybuilders – Soya is as good as whey for people who are into bodybuilding. Soya protein is advantageous to people who are working out to gain lean muscle mass and reduce body fat.

Soy and vegetarians – As soy is rich in protein, vitamin B 12, Vitamin D vegetarian can choose to eat blindly. Soy protein is also effective at promoting muscle formation. There are some amino acids are present in soy which promotes healthy growth and repair of muscle and improves immunity as well. When it comes to bodybuilding or muscle gaining protein plays a crucial role along with the exercise or workout. Proteins are required to repair and rebuild muscle after the workout. Soya is a complete protein that is enough and no need to combine with any other sources as other plant-based proteins are almost incomplete protein as they do not contain all essential amino acids. Soya contains arginine which improves blood supply to muscle and it also helps to increase muscle strength and improves endurance. Soya improves thyroid function output which is helpful for bodybuilders trying to reduce fats. Soy protein also has nitric oxide which helps bodybuilders to maintain a healthy level of muscle cells. And they help to maintain a healthy level of salt in the body which is important for blood vessels to relax and to maintain healthy blood flow. Soy also contains muscle weight gain properties so it helps bodybuilders to opt for vegan lean protein.

Men boobs and erectile dysfunction – Soya does not raise or lower testosterone levels in men. Many people are concerned about lower levels of testosterone with the soy intake as isoflavones which are phytoestrogen acts as estrogen which is highly involved in women’s reproductive functions. Men body also produces estrogen in very small amounts. People are concerned about low estrogen levels as it is associated with diminishing sexual functions, erectile dysfunction, reduced muscle mass, depression, fatigue, and osteoporosis. Gynecomastia is a condition that makes breast tissue swell in boys and men. It can happen when the balance of two hormones in your body is thrown off. Although breasts do not develop in men the way they do in women, all boys are born with a small amount of breast tissue. So Soy protein is not responsible for breast enlargement in men, moderate soy intake is very safe as it doesn’t lead to feminization in males.

Hypothyroidism medication interference – Soya may interfere with thyroid hormone medication used to treat hypothyroidism as it affects hormonal balance and restricts the absorption of thyroid hormone medicine.

In this article dietician, Prachi Velhal has elaborated and helped to understand Soy protein and its benefits.


Article authored by

Prachi Velhal, Clinical Dietitian and research associate