Oh soy!

The humble soyabean is one of the best protein sources for muscle-building activities

Eisha Sarkar

Posted on Hello Wellness on Sep 9 2010 3:08PM

Once used as for preparing fire-fighting foam, paper coatings and making Henry Ford's 'silk' suits, isolated soy protein has come a long way back into our diet as one of the best protein sources available to us.

What is soy protein isolate?
By removing most of the fats and carbohydrates in soy meal, you get a product with a very neutral flavor and with 90 per cent protein. Pure soy protein isolate is difficult to find. It is mainly found combined with flavours, minerals and vitamins e.g. Protis Power 90%, Mega-Pro Pure Veg Soy Protein, etc. in select health stores or pharmacies.  

Soy protein isolate can be added to juices, milk shakes or smoothies, or can be sprinkled on cereal to boost the protein content.  Soy helps in many ways:

Muscle formation
Soy protein contains higher amounts of arginine than whey, casein and egg white. Arginine stimulates the release of anabolic hormones that promote muscle formation, helps reduce physiological stress and boosts immunity.

For high-intensity exercise
Soy consumption over a four-month period can help improve the maximal oxygen uptake for exercising under a set of defined conditions, thus a greater capacity to sustain high-intensity exercise for longer than four to five minutes.

For endurance
Soy protein isolate contains branched chain amino acids such as Leucine, Isoleucine, Valine, Glutamine and Arginine that are used as energy source during exercise after the body utilizes the muscle glycogen in the first 20 minutes of exercise.

Glutamine boosts protein synthesis, helps buffer lactic acid build-up that occurs during exercising and reduces central nervous system fatigue.

Muscle recovery
Athletes training hard produce free radicals which contribute to upper-respiratory infections and muscle inflammation, therefore increasing recovery time. Studies have found that male subjects fed soy protein showed a rise in plasma total antioxidants, associated with the reduction of muscle enzymes in the blood indicating less oxidative stress and damage occurring in the muscle tissues. Thus, soy may help to reduce muscle injury and inflammation, hence shortening recovery time. Athletes can then train sooner and harder.

Reducing fatigue
Studies with the Romanian Olympic Rowing Team showed that an intake of soy protein at 1.5 g per kg body weight in addition to the regular intake of protein in the diet (2 g/kg body weight) may be responsible for reduced fatigue post exercise.

Essential proteins
Soy protein meets or exceeds the essential amino acid requirements of both children and adults. It is highly digestible, readily absorbable, and maintains positive nitrogen balance when fed as the sole protein source, even at minimum intake levels.

Kidney function
Experts are often concerned whether high protein intake will negatively affect kidney function. Many athletes consume a higher protein intake in order to facilitate muscle building and re-synthesis of muscle after a long endurance event. A soy protein diet (1.5 g/kg body weight) helps decrease glomerular filtration rate, reducing the workload of the kidneys.

Stronger bones
Soy protein is an excellent source of calcium, which represents 50 per cent of the daily value of this important nutrient per serving.

Low heart risks
In men, the isoflavones in soy lower risk of cardiovascular disease, atherosclerosis, promote prostate health, and protect colon tissues.

Soy protein isolate may have less health benefits than whole soybeans or soy protein concentrates. During the production of soy protein isolate the protein is washed with alcohol, removing most of the isoflavones.

Does soy have feminising effects on men?
Soy isoflavones are said to exert estrogen-like effects in some conditions. Researchers have demonstrated how isoflavone genistin inhibits enzyme 3b-hydroxysteroid dehydrogenase, which is involved in reactions that convert cholesterol into testosterone.

This does not mean you avoid soy altogether. Studies have found that isoflavone exposure to levels greatly exceeding dietary intake doesn’t affect blood testosterone or estrogen levels in men or sperm and semen parameters. Erectile dysfunction in rats may be due to excessive isoflavone exposure and different isoflavone metabolism in rodents.

While scientists debate on whether soy can make you sorry, you can’t ignore the benefits it offers. It is the dose that makes the poison. Don’t overdo it and you’ll be just fine.