Soy: a complete source of protein

Am Fam Physician. 2009 Jan 1;79(1):43-7.


Soybeans contain all of the essential amino acids necessary for human nutrition and have been grown and harvested for thousands of years. Populations with diets high in soy protein and low in animal protein have lower risks of prostate and breast cancers than other populations. Increasing dietary whole soy protein lowers levels of total cholesterol, low-density lipoproteins, and triglycerides; may improve menopausal hot flashes; and may help maintain bone density and decrease fractures in postmenopausal women. There are not enough data to make recommendations concerning soy intake in women with a history of breast cancer. The refined soy isoflavone components, when given as supplements, have not yielded the same results as increasing dietary whole soy protein. Overall, soy is well tolerated, and because it is a complete source of protein shown to lower cholesterol, it is recommended as a dietary substitution for higher-fat animal products.

MeSH terms

  • Complementary Therapies*
  • Female
  • Hot Flashes / drug therapy
  • Humans
  • Hyperlipidemias / drug therapy*
  • Isoflavones / metabolism*
  • Isoflavones / pharmacology
  • Neoplasms / prevention & control*
  • Nutritive Value
  • Osteoporosis, Postmenopausal / prevention & control*
  • Plant Proteins, Dietary / administration & dosage
  • Plant Proteins, Dietary / adverse effects
  • Plant Proteins, Dietary / therapeutic use*
  • Soybean Proteins / administration & dosage
  • Soybean Proteins / adverse effects
  • Soybean Proteins / therapeutic use*


  • Isoflavones
  • Plant Proteins, Dietary
  • Soybean Proteins