Soy Protein

Q: What is your opinion of Soy Protein?

Soy is an excellent protein source. For vegetarians, its amino acid ratios are pretty close to the complete proteins obtained through animal sources. 

If that's all you wanted, I can leave it at that. If you want my opinion on soy as it's being marketed today, sit back, here goes . . . . 

I'd caution people against believing that since soy has been touted as having hormonal and health benefits (based on partial research information rather than "whole picture" science), that more is better and better. Excesses in soy intake have been linked to irregularities in thyroid hormone production. It's suspected that high amounts of soy affect iodine levels. If soy based foods and soy protein supplements amount to less than 1/3 of daily protein intake, I don't see any reason for concern. Assuming it is consumed with a variety of carb sources, I wouldn’t worry too much about the thyroid being affected. I would strongly advise anyone against making soy their exclusive source of protein or putting soy protein alone in the digestive tract more than once or twice a day. Supplement manufacturers have done a wonderful job of confusing the fitness wanting public. For the last five years the bodybuilding community has gobbled up whey protein. Recent researched suggested that due to its quick gastric emptying properties, many of the amino acids get metabolized by liver enzymes, making it a less than ideal protein source if consumed alone. The whey manufacturers first responded by increasing the number of grams per serving. Why not? More protein would have to be consumed, thus more protein is sold.

Soy found its popularity primarily among vegetarians. The Soy industry watched as whey protein sales skyrocketed, thus, in order to grab their own position, they capitalized within a "health" marketplace, primarily targeting women. Many of the referenced studies are valid, but as I mentioned earlier, are not representative of "the whole picture."

In one particular study published in France, two groups of apparently healthy men were fed isocaloric diets with one group using soy protein, the other using animal products as a protein source. The goal was to see if there was a reduced propensity for gallstones if animal proteins are replaced by soy. Since gallstone accumulation can be linked with crystallization of cholesterol, at its conclusion the study examined cholesterol levels. The study showed that cholesterol crystallization was slightly retarded in the soy group extrapolating that soy can aid in preventing gallstones. Here’s what the study neglected to address. There wasn’t any control over fruit and vegetable intake. Soy is a vegetable, and it does happen to fall into the group of veggies that are high in isoflavones. Isoflavones have been closely linked to health benefits including a lowering of cholesterol. We’ve known for years that a predominance of animal meats can have adverse affects on cholesterol, but that doesn’t mean that someone consuming soy would have better cholesterol levels than someone eating combinations of chicken breast, turkey breast, fish, and egg whites and a variety of natural vegetables.

You can see how the conclusions drawn from studies can be misconstrued and over-emphasized in significance. While a great number of scientific studies can be held up to show the cancer resistive benefits of a diet rich in vegetable foods (soy included), we can not extrapolate from those studies that someone consuming soy instead of milk proteins, egg proteins, and lean animal proteins will exhibit better health, and if an exercise component is included, the conclusions in non-exercising individuals are almost invalidated. Most of the research information promoted specific to soy is publicized by organizations with a vested interest in Soy Protein sales, such as The United Soybean Board. I don’t mean to suggest that soy is not a good source of protein, but rather that the health benefits, as is commonplace, have been taken out of context and overblown to sell products. From a metabolic benefit standpoint, it appears based on the most recent and applicable studies, that you are best off getting your supplemental protein from a mix of whey and casein or egg. Watch as the newest protein supplements to hit the market feature a whey & casein blend quoting research that invalidates the research the same manufacturers used to promote pure whey products only 12 months earlier.

With that said, (whew, that was exhausting), soy is a very good and adequate protein source.

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