Soy Protein vs Whey Protein | Are Soybeans a Good Protein Source

A common question here at fitFLEX is with regards to soy. Just how much should we have in our daily diet? Some bodybuilding supplements contain soy but there is also conflicting information out there that states that soy is not the best protein choice, so what is the deal with soy?

As with almost any other aspect of nutrition, there's conflicting research on soy. In previous fitFLEX articles studies, we ran a balanced item on soy to present some of the positives and some of the negatives. Additional research will help further clarify what soy does and does not do, but nutrition is a complex subject and sometimes there are no definitive answers. That being said, here's some information to help you decide how much or how little soy you want to use in your bodybuilding diet.

To build muscle the body needs protein, and soy has a high concentration of it for a vegetable source. A half-cup of boiled soybeans has 11 grams of protein and only 120 calories, or about 36% of its calories from protein. Soy protein, derived from soybeans, has high BCAA and glutamine content but it is low in methionine, an essential amino acid. As noted, soy is often used in bodybuilding protein powders.

Nonetheless, there's growing evidence that there may be a downside to a diet that's too heavily based on soy products. Recently, two Food and Drug Administration (FDA) scientists, Daniel Doerge, PHD, and Daniel Sheehan, PHD, said on record that eating soy regularly might cause such health problems as increased risk of breast cancer in women, brain damage in men, and that infants given soy formulas daily may develop infertility problems later in life.

According to Reuters (August 14, 2000), "FDA officials considered the scientists' views and those of other critics before announcing last October that they would permit manufacturers to advertise that eating soy could help adults cut their risk of heart disease. 'We are well aware of the concerns, but we did balance those concerns with the other positive effects,' an FDA official said FLEX Science Editor Jim Wright pointed out that the FDA did not go on record with its awareness of these concerns when it released its glowing endorsement of soy.

So, why might soy cause problems? The key to both its risks and some of its benefits may lie in the fact that soy contains isoflavonoids that have similar action to the female hormone estrogen. These isoflavonoids may disrupt normal hormone levels and impair development Soy's reputation with bodybuilders has taken a hit recently because they seek to reduce production of female hormones and promote levels of male hormones, which create an anabolic (muscle-building) condition.

Reuters reports that the FDA says fears about the effects of chemicals in soy are overblown. "While chemicals in soy do exert hormonal effects, the impact is 'very limited' and much lower than that of natural or synthetic estrogens, the FDA said when it announced it would permit the soy health claims."

We agree and continue to believe that getting an adequate amount of protein - regardless of the source - outweighs all other factors when it comes to recovery and growth.