Myth busting: Soy supplements are not an issue for bodybuilders, say researchers

By Annie-Rose Harrison-Dunn

- Last updated on GMT

Reasearcher bust myths surrounding soy protein and strength training
Reasearcher bust myths surrounding soy protein and strength training

Related tags Whey protein

Short-term supplementation with soy and whey protein does not lead to pro-estrogenic or anti-anabolic effects in bodybuilders, according to new research.

The study, published in Journal of the American College of Nutrition​, reviewed the effects of soy and whey protein supplementation on testosterone, sex hormone binding globulin (SHBG), and cortisol responses to an acute bout of resistance exercise like weight lifting.

The team behind the study noted that there is a common belief among fitness enthusiasts that soy-based products differ from animal-based protein products - with concerns over the potentially pro-estrogenic or anti-anabolic effects of soy protein.

"Although such fears may largely stem from bodybuilding mythologies, there is limited research on soy protein supplementation and its acute effects on hormonal responses to heavy resistance exercise,"​ explained the authors - led by William Kraemer from the University of Connecticut, USA.

The team revealed that while 14 days of supplementation with soy protein does appear to partially blunt serum testosterone, it does not have pro-estrogenic or anti-anabolic effects. In addition, they reported that whey protein influences the response of cortisol (a steroid hormone) following an acute bout of resistance exercise by blunting its increase during recovery. 

"Contrary to popular misconceptions, soy protein supplementation does not appear to hinder anabolic signaling postexercise by means of eliciting increases in estradiol concentrations​," wrote the researchers.

“This study starts to unravel and provide some insights into one of the real urban myths about soy protein and resistance exercise in men,”​ said Kraemer.


The study used a sample of ten resistance-trained men in their early 20s. The participants where split between three protein supplementation groups: whey protein isolate, soy protein isolate, or a maltrodextrin placebo control.

For a period of 14 days participants consumed 20g of their assigned supplement at the same time each morning. No other supplements were allowed during the trial. After which the participants would perform six sets of heavy resistance squats at ten reps each using 80% of their maximum lifting weight.

Source: Journal of the American College of Nutrition

Published online ahead of print, doi:abs/10.1080/07315724.2013.770648
“The Effects of Soy and Whey Protein Supplementation on Acute Hormonal Reponses to Resistance Exercise in Men”
Authors: W.J. Kraemer, G. Solomon-Hill, B. M. Volk, B.R. Kupchak, D.P. Looney, C. Dunn-Lewis, B. A. Comstock, T. K. Szivak, D. R. Hooper, S.D. Flanagan, C. M. Mares, and J.S. 

Related news

Show more

Related products

show more

Full Vegan Protein Ingredients Solution

Full Vegan Protein Ingredients Solution

Content provided by Ingredients4u AG | 24-Jul-2023 | Product Brochure

Plant-based products have always been a hot topic in the market, the plant-based food market was valued at $29.4 billion in 2020.

Solutions of Amino Acids-Based Infant Formula

Solutions of Amino Acids-Based Infant Formula

Content provided by INNOBIO Corporation Limited | 22-Jun-2023 | White Paper

Many infants who are born with nutritional defects often need specifically developed infant formulas to maintain their growth and development. Amino acids-based...

Lactium® unique bioactive ingredient for poor sleepers

Lactium® unique bioactive ingredient for poor sleepers

Content provided by Ingredia SA | 13-Jun-2023 | Product Presentation

4 out of 10 people experience difficulties getting to sleep while the recommended average night’s sleep is estimated at seven hours. Children are also...

Robuvit® for Natural Energy and Mitochondrial Support

Robuvit® for Natural Energy and Mitochondrial Support

Content provided by Horphag Research | 01-May-2023 | Clinical Study

Robuvit® French oak extract is a caffeine-free natural energizer that provides support for managing fatigue and improving energy levels. Learn how this...


So it is!!!

Posted by bg,

I did the research and found numerous articles on the benefits of soy in addition to whey for bodybuilders. So the articles appears to be accurate according to my research.

Report abuse

not quite so

Posted by N G C,

that's not what the paper says. at all. your title is hugely misleading. i am a bit disappointed.

Report abuse

Follow us


View more