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Feedzone Q&A: What’s the difference between whey protein and soy protein?

  • By Monique Ryan
  • Published Jan. 28, 2010
  • Updated Dec. 17, 2012 at 4:12 PM EDT
Whey and soy proteins provide different amino acid profiles, and the available forms vary as well.

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Differentiating protein

Hi Monique,
I am lactose intolerant and would love to know where to buy lactose-free whey protein, as I have not found it in any store (or the associates are uninformed). Also, are there any differences between whey protein and soy protein isolate? I know soy is a complete protein, but still think there may be differences.

Thank You!
— Jason

Hi Jason,
It sounds like you are focusing on some strength and muscle building during this time of the season and are interested in using a high quality protein supplement to support your efforts. Research shows that consuming 20 grams of high quality protein with 25 grams of carbohydrate in the hour before weight training can enhance your muscle building efforts. Consuming this protein and carbohydrate combination in the hour after weight training is also beneficial. If you combine any weight training workout with a cardio or cycling workout, you can increase the amount of carbohydrate that you consume to provide fuel for endurance training (before) or recovery nutrition (after).

You are correct in that both whey and soy protein powders can provide high quality protein though their amino acid profiles can differ. It is also important to know if both these protein sources have positive effects on muscle building.

Whey protein is made from cow’s milk and is isolated from whey, a by-product of cheese manufacturing. Whey protein typically comes in three major forms: concentrate, isolate, and hydrolysate. Concentrate contains some lactose, while isolates have had the lactose removed. Hyrolysates are partially broken down and may be more easily absorbed, but is usually more expensive than the other two forms.

Whey protein has long been considered the “Gold Standard” protein for muscle building because it is such an excellent source of the branched chain amino acids (BCAAs). BCAAs are metabolized directly into the muscle and used during periods of exercise and resistance training. One of these BCAAs, leucine, which is about 50-percent higher in whey protein than soy protein, plays a particularly important role in firing up protein synthesis.

Soy protein can also be a little controversial in that is contains phytoestrogens and there is concern that is may produce the unwanted effect of decreases in testosterone and increases in estrogen in men. Soy in general is controversial regarding its long-term effect on the health of both men and women, particularly in relationship to whether it increases or decreases risk of hormone related cancers, as well as its relationship to other health concerns.

In contrast to whey protein, soy protein has high amounts of the amino acids arginine, which has a role in protein synthesis, and in glutamine, which supports the immune system. Soy protein is available in concentrate form and also in the most pure form as an isolate. Of course all forms are lactose free.

Proper use of whey protein does clearly support muscle building efforts, and a few recent studies have shown that soy protein may as well. One study compared intact proteins form both milk and soy and found that soy was an effective post-workout beverage, supporting muscle building. Another study supported the muscle building results of soy protein, and also found that it had no negative effect on testosterone or estrogen levels in men. This same study also found comparable muscle building results from soy protein isolate, or concentrate, whey protein isolate or concentrate, or a combination of soy and whey protein.

Whey protein is digested quickly, while soy protein is digested more slowly, so a combination may in theory provide a more sustained release of amino acids for optimal protein synthesis.

So, if you are going to use whey protein, look for the isolate form which does not contain lactose. Soy protein also presents as an alternative which is lactose-free, or you can even use both protein sources. You can simply search on the internet for whey protein isolate and come up with some brands that are lactose-free — many of them state this on the container. Also, real food sources such as poultry, fish, and lean meat, and lactose free milk also provide viable protein sources that can be consumed after strength training exercises.

Thanks,
— Monique

Monique Ryan, MS, RD, LDN is a nationally-recognized nutritionist with over 22 years of experience and is owner of Personal Nutrition Designs, a Chicago based nutrition consulting company that provides nutrition programs for endurance athletes across North America.

Any information or advice offered by the members of the Coaches’ Panel should not in any way be viewed as personal medical advice. The recommendations made in this column are offered as general information for healthy, physically fit amateur and professional athletes. None of the information provided by members of the Coaches’ Panel should be viewed as a replacement for personalized, professional medical treatment or to replace the advice or services of your physician. While some members of the Coaches’ Panel are Licensed Medical Doctors, Licensed healthcare professionals, and certified coaches, their advice in no way establishes a doctor-patient relationship between the writer and readers of this column. If you are beginning or resuming a vigorous exercise program, it is important to visit your health care provider for a complete physical examination in order to identify and treat any potential risks you might face.

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