Maintaining protein levels is important for all athletes. Protein is the vital source of amino acids, which build cells in the body. Soy protein is a popular source of these essential acids, especially for vegetarians because it contains a complete set, which is very rare for a plant protein. It is also easier to digest and free from cholesterol and lactose and higher in fiber than animal proteins. Soy isoflavones are found in high concentrations in soy protein.
Soy isoflavones are molecules that work in the body in several ways. They are transformed in the digestive system and lead to an increase in the amount of estrogens available to the body. These estrogens (called phytoestrogens) play a role in many hormonal activities and cause a variety of biological effects, from increasing the amount of hemoglobin in the blood (allowing for better transportation of oxygen to the body tissues) to reducing stress on the kidneys. Growth hormones are stimulated and increased and endorphin and testosterone levels also have been shown to rise. Studies show that athletes supplementing with soy protein showed an increase in lean muscle mass and a decrease in body fat along with increased strength and less muscle fatigue after a training session.
Many studies show that soy isoflavones are also beneficial for a variety of reasons related to overall health. They have been used successfully to relieve menopause symptoms in women and improve bone health. They may also protect against certain cancers, most notably prostate cancer. The antioxidants found in isoflavones are thought to help in cancer prevention, preventing free radical damage to the cells. This cellular protection is also important for athletes who make demands on the muscle cells and require greater protection from free-radical damage. Isoflavones also reduce the risk of heart attack by preventing the growth of plaques that clogs the arteries.
The most beneficial isoflavones can be found in soy foods like soy nuts and tempeh. However, supplements including pills, tablets, bars and shakes are also used to achieve higher concentrations. Red clover is another natural source of isoflavones that is used in supplementation. Care should be taken when choosing soy products, as the specific effects of ingesting more than the normal amounts of soy than you would get in your diet are not known. There is some suggestion that large amounts of soy can lead to health problems, most notably infertility. Also there some people are allergic to soy.
An active athlete requires about 0.9 grams of protein per pound of lean muscle mass. Many people find it difficult to acquire all the protein they require from the foods they eat. Athletes especially, because of their increased protein requirements during training and competition, often require supplements. Soy protein with isoflavones is often chosen because of the additional antioxidant and hormone-stimulating properties and general health benefits.
Dario Elia, KrisztiÃ¡n Stadler, ViktÃ³ria HorvÃ¡th and Judit Jakus. Effect of soy- and whey protein-isolate supplemented diet on the redox parameters of trained mice European Journal of Nutrition. Volume 45, Number 5 / August, 2006 Pg. 259-266.