Soya

Studies in people

• No harm found

  Male hormone levels²

  In men, eating soy or soy isoflavones did not change testosterone or estrogen levels.

• No harm found

  Plant protein for meat-free diets³

  Well-processed soya protein can replace meat and fish protein in adults without hurting how they use dietary nitrogen.

Animal and lab studies only

• No harm found

  Gut bacteria and food additive⁶

  Soya hemicellulose is broken down by gut bacteria, and animal studies found no bad effects at high doses.

• Benefit

  Gut inflammation⁷

  In animal studies, soya isoflavones eased gut inflammation and helped the gut lining work better.

• Benefit

  Bone loss after menopause⁸

  In animal studies, soya isoflavones combined with DHA reduced bone-breaking cell formation, but scientists do not yet know if this helps people.

Study type not stated

• Benefit

  Muscle strength and size⁴

  Soya protein builds muscle strength and size just as well as whey protein when combined with weight training.

• Benefit

  Muscle building and recovery⁵

  Soya protein builds lean muscle about as well as whey and may help athletes recover after hard training.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least two findings in people. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.