i so this :
The Facts They Don't Want You To Hear About Soy Protein
Monday, 31 October 2011 13:24:43 Europe/London
So what is the problem with Soy Protein?
Quite simply, soy toxins. Soy beans contain a number of naturally occurring toxins that are both toxic to humans and animals. Soy protein contains even more toxins. During the chemical manufacturing process extra toxins develop including residues of one of the chemicals (Hexane) used to extract the protein. So what are the main soy toxins?
Trypsin inhibitors
This is perhaps the worst culprit. It is literally unbelievable that sports nutrition companies are happy to use soy protein with trypsin inhibitors as one its components.
Trypsin inhibitors, as the name suggests, inhibit the action of your digestive systems trypsin and protease enzymes. These are two essential enzymes responsible for digesting protein. Yes you read correctly. They inhibit protein digestion. To add Soy Protein to a protein powder or weight gainer contradicts logic? It gets worse; monkeys were fed a diet based on soy concentrate and subsequently developed chronic pancreatitis, a condition that leaves the pancreas susceptible to pancreatic cancer.
Phytates
These have the ability to chelate minerals which means they are able to bind to minerals in the digestive system. Unfortunately the process is quite specific to essential minerals such as zinc, calcium, copper, manganese and iron. Sports people in particular have higher requirements for certain minerals, especially zinc & iron, so adding soy protein is totally counter intuitive.
If you are a male wanting to optimise testosterone levels, forget soy.
If you want to build and maintain a lean physique soy protein could hamper your results. Unfortunately soy protein has recently been scientifically proven to lower testosterone levels in men by 19%. It’s hard enough to maintain peak levels of testosterone whilst training hard, so once again the use of soy seems confounding.
Is soy protein in your protein powder?
It is an established fact that whey protein is unmatched for building muscle so why would supplement companies use soy protein in their products? Given the arguments above, the only obvious reason is a financial one. If you make a protein powder with whey protein and combine it with soy protein the potential increase in profits can be substantial. Great for the company, but potentially not so great for athletes trying to optimise their dietary regime.
Soy protein is an inferior protein compared to whey, egg and milk protein.
If lowering testosterone and interfering with the digestion of protein digestion wasn’t bad enough, soy protein also has a lower biological value compared to whey, milk and egg proteins giving even more reason to avoid it's use. Listed below are the biological values of whey, egg, milk and soy. The biological value is a measure that shows the amount of protein utilised by the body. In simple terms the higher the score the better the protein.
Whey Protein 104
Milk Protein 88
Egg White Protein 85
Soy Protein 75
The other reason that whey, milk and egg proteins are superior to soy protein is the higher content of branch chain amino acids. Whey protein has the highest content of branch chain amino acids of any food. Branch chain amino acids (L-Leucine, L-Isoleucine, L-Valine) are scientifically proven to boost protein synthesis aiding the formation of lean muscle tissue. They are by far the most important amino acids for athletes.