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Can Adding Soy To Your Protein Mix Lead To More Growth?

New research has found that adding soy to a casein and whey blend could help increase the length and total impact of your anabolic response to protein powder.

You've probably heard that you should drink whey protein after your workouts to boost muscle growth and increase protein synthesis. As it turns out, the best "whey" to go actually involves using a combination of fast- and slow-digesting post-workout proteins—typically whey (fast) plus casein (slow).

One type of protein you'll seldom hear mentioned in this conversation is soy, which is usually not associated with muscle growth and bodybuilding. Yet if you look more closely at the evidence, you'll find that adding soy to the mix won't detract from you gains—and it might even enhance them.

The Whey-Casein Combo ///

That's right, a growing body of research suggests that including both whey (fast-digesting) and casein (slow-digesting) proteins in your post-workout shake boosts and prolongs your body's anabolic response.

You can make a bigger impact on overall and long-term muscle protein synthesis by consuming whey and casein after a workout, compared to consuming whey protein alone. Research also shows that, over time, this combination leads to greater muscle growth.

Don't get me wrong, whey is still the protein king. It's the richest source of branched chain amino acids (BCAAs) and is the fastest-digesting protein you can throw down your gullet. That means it rushes its amino acids, including the critical BCAAs, to your muscle fibers to kickstart muscle protein synthesis.

But if you take whey by itself, that blip in muscle protein synthesis may be too quick to maximize muscle growth. By adding slower-digesting proteins to the mix, you keep muscle protein synthesis jacked up for longer. That means more muscle is built for a longer period of time.

Casein and Whey and Soy—Oh Boy! ///

While the whey-casein combo is a great post-workout choice, a brand-new study published in the Journal of Nutrition suggests that a combination of whey, casein, and soy proteins may be even better. While whey has a fast digestion rate and casein has a slow digestion rate, soy digests at a rate somewhere in between the two. From a timing standpoint, a casein-whey-soy blend theoretically could help your body sustain a higher level of protein synthesis for a longer period.

To test the theory, researchers from the University of Texas Medical Branch in Galveston had men consume 20 grams of whey protein or 20 grams of a whey-soy-casein combo one hour after a leg workout. Researchers found that both the whey protein and the mixed protein increased muscle protein synthesis to a similar degree. However, the mixed protein, with its differing rates of digestion, maintained a higher rate of protein synthesis for hours longer.

It could be argued that the same response would have been seen with a whey and casein combination. After all, other studies have shown the exact same result with only the dairy proteins. Keeping this in mind, my advice is to combine at least whey and casein to your post-workout shake. For best results, though, I recommend adding soy to the mix. I've been recommending a blend of whey, casein, and soy for almost a decade now.

The Soy Story ///

Because soy digests slower than whey, but faster than casein, it makes a nice bridge between the two and keeps a steady flow of aminos to your muscles. In addition to its speed of digestion, soy offers numerous other benefits that only improve the power of the dairy proteins to promote muscle growth. Many argue that soy protein does not promote muscle growth as well as the dairy proteins, as some studies have suggested. However, these studies either looked at a snapshot of the rate of muscle protein synthesis, or were conducted on animals.

The two studies that provided weight-training humans whey or soy over a long period showed similar results between the two proteins. One 2006 study from Canada, performed on untrained subjects, showed that weight training for six weeks while supplementing with an equivalent dose of whey or soy resulted in similar gains in muscle mass and strength.

And a 2007 study done by Douglas S. Kalman, Ph.D., R.D., found that trained male lifters who supplemented twice daily with either soy protein concentrate powder, soy protein isolate powder, a soy-whey protein powder blend, or a whey protein isolate all increased muscle mass to a similar degree during the 12-week training period.

Soy also has benefits that whey, casein, and other protein powders do not. First, soy has the ability to raise growth hormone (GH) levels. This appears to be due to its high arginine and lysine content. Research has also found that soy can boost nitric oxide (NO) levels. Virginia Polytechnic Institute and State University (Blacksburg) researchers found that the soy phytoestrogen, genistein, increased NO levels by increasing the amount of nitric oxide synthase (NOS), which is the enzyme that catalyzes the conversion of arginine into NO.

A 2004 Ohio State study comparing soy and whey protein bars on muscle growth reported that the men taking soy had better antioxidant protection following exercise. Another 2004 study, published in the International Journal of Sports Nutrition and Exercise Metabolism, found that trained men who consumed 40 grams of soy protein before lifting weights for four weeks had better antioxidant protection following a weight workout compared to men who consumed whey protein.

A 2005 study published in the Journal of Sports Medicine and Physical Fitness found that women consuming soy protein for four weeks had less oxidative muscle damage following exercise than those consuming only whey.

But, My Testosterone! ///

If you've been doing a little protein "research" on the Internet, you probably came across those dire soy protein warnings: Don't have soy or it will increase your estrogen levels and lower your testosterone. "Oh, no," you think, "I just had some soy milk and I can already feel my penis shrinking!"

These fears have been perpetuated by a couple of old and poorly conducted studies. The most recent review study analyzed 15 quality studies done on soy and testosterone levels in men and concluded that soy does not alter testosterone concentrations in men.

I'm not suggesting that you take soy and soy alone. I'm suggesting that you add some to your whey-casein blend. Some of you might think it will be too expensive to buy three kinds of protein.

Honestly, I think it will save you money in the long run. Casein and whey protein powders have been getting more and more expensive. Soy, on the other hand, remains fairly inexpensive. By "cutting" your whey and casein with soy, you'll get more bang for your buck.

I typically mix whey, casein, and soy at 2:1:1 ratio. So a post-workout shake for me means about 20 grams of whey, 10 grams of casein, and 10 grams of soy. As for brands, I prefer Dymatize ISO-100 Whey, Dymatize Elite Casein, and Optimum Nutrition Soy Isolate.

Jim Stoppani


References:

  1. Boirie, Y., et al. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc. Natl. Acad. Sci. USA 94:14930-14935, 1997.
  2. Candow, D. G., et al. Effect of whey and soy protein supplementation combined with resistance training in young adults. IJSNEM 16:233-244, 2006.
  3. Hamilton-Reeves, J.M., et al. "Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis." Fertil Steril. 2009 Jun 11.
  4. Isidori, A., et al.1981 A study of growth hormone release in man after oral administration of amino acids. Curr Med Res Opin 7:475-481.
  5. Kalman, D., et al. Effect of protein source and resistance training on body composition and sex hormones. JISSN 4:4, 2007.
  6. Kerksick, CM, et al. The effect of protein and amino acid supplementation in performance and training adaptations during ten weeks of resistance training. Journal of Strength and Conditioning Research 20(3), 643-653, 2006.
  7. Paul, G. L., et al. The rationale for consuming protein blends in sports nutrition. Journal of the American College of Nutrition 28 (4):464S-472S, 2009.
  8. Reidy, P. T., et al. Protein Blend Ingestion Following Resistance Exercise Promotes Human Muscle Protein Synthesis. J Nutr., in press, 2013.
  9. Si, H. and Liu, D. Genistein, a Soy Phytoestrogen, Upregulates the Expression of Human Endothelial Nitric Oxide Synthase and Lowers Blood Pressure in Spontaneously Hypertensive Rats. Journal of Nutrition138:297-304, 2008.
  10. Soop, M., et al. Coingestion of whey protein and casein in a mixed meal: demonstration of a more sustained anabolic effect of casein. Am J Physiol Endocrinol Metab. 2012 Jul 1;303(1):E152-62.
  11. Suminski RR, Robertson RJ, Goss FL, et al. Acute effect of amino acid ingestion and resistance exercise on plasma growth hormone concentration in young men. Int J Sport Nutr. Mar 1997;7(1):48-60.
  12. Tipton KD, Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise. Med Sci Sports Exerc. 2004 Dec;36(12):2073-81.
  13. van Vught, A.J., et al. "Effects of Oral Ingestion of Amino Acids and Proteins on the Somatotropic Axis." J Clin Endocrinol Metab. February 2008, 93(2):584-590.

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About The Author

Jim holds a doctorate in exercise physiology and has been the personal nutrition and health consultant for numerous celebrity clients...

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lgerry

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lgerry

interesting article. i found this one as well:

http://www.menshealth.com/nutrition/soys-negative-effects

Mar 20, 2013 6:36pm | report
 
JimmyHimself

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JimmyHimself

Why did you have to post this now I'm scared haha

May 25, 2013 10:04am | report
Kovenant

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Kovenant

That was a retarted talking bullcrap in mens health, theres no study or evidence, theres no research that certify the bullcrap of that article, by the way read menshealth is like grab a cosmopolitan, worst magazine ever

Jun 1, 2013 4:22pm | report
psych107

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psych107

Three quarts of soy milk a DAY? Good grief.

Jul 22, 2013 3:47pm | report
craigreid92

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craigreid92

I currently take whey after a workout and casein before bed. Is that just as effective as if I was taking whey-casein in one? Kind of new to this stuff

Mar 20, 2013 7:22pm | report
 
northcuttnm

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northcuttnm

I take whey in the morning when I wake up, whey before my workout, whey after my workout, and caesin before I go to sleep. Eat clean, get your protein shakes in, and train dirty. You will see results.

Mar 21, 2013 9:23am | report
BatteryBackup

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BatteryBackup

I take a zero hour weight training class in the morning, and have about half an hour to eat breakfast which usually consists of about 30 grams of protein from a whey shake and a V8 drink, then proceed to lift about 25 minutes later. Is having whey protein at that time beneficial to me at all or does it not make much of a difference in that time-frame?

Mar 20, 2013 8:35pm | report
 
JFort93

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JFort93

Thank you for citing your sources Dr. Stoppani, however I'm a bit confused by the study done by UT. They compared a whey PWO shake to a whey, casein, and soy PWO shake. We already know that whey casein is better than just whey alone. I don't see how one can jump to the assumption that Soy is the variable causing the longer duration of protein synthesis, or that it makes a good "bridge" between the two proteins. Sounds like bro science to me.

Mar 21, 2013 12:31am | report
 
jayhead000

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jayhead000

Glad to see the UTMB study referenced! I was wondering about this study as I stopped seeing the researcher in the gym. Wish I could have gotten some free protein, but i didn't qualify. :(

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Mar 21, 2013 8:13am | report
 
slainrush

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slainrush

I have a doubt, when you say 20g of whey protein post workout, you mean 20g of the whole product like Dymatize Iso Whey or you mean 20g of "protein" only of this product ?

Mar 21, 2013 8:24am | report
 
vkartikv

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vkartikv

I've been consuming mhp's up your mass which lists soy as a significant protein source and yet ive seen nothing but gains and no 'shrinkage'. the fear surrounding soy has little basis.

Mar 21, 2013 9:23am | report
 
dajunglebrotha

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dajunglebrotha

love soy!

Mar 21, 2013 9:41am | report
 
robwein83

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robwein83

I'm going to be paraphrasing and may hack up the exact science, but I believe it is Layne Norton which had done some studies regarding Leucine being a primary activator of protein syntheses. More important in regards to this article, is his conversations about not needing to sustain elevated amino acid levels at all times. In fact, they were finding that your body is more efficient with muscle synthesis by getting the "adequate" levels of protein with the threshold level of Luecine and to allow your amino levels to taper down until your next feeding to encourage protein syntheses. Keeping amino acid levels elevated at all times does not equate to higher protein syntheses, in fact it is the opposite.

The only time that maintaining a relatively level amount of amino acids at a sustained level might be helpful would be with a casein p[protein before bed when you are fasting.

In simplest terms.... Throughout the day you will benefit from spikes of protein with the correct threshold of Leucine more than keeping amino acid levels elevated at a sustained level all day.

http://www.musculardevelopment.com/articles/supplements/2827-investigating-optimal-protein-frequency-the-nemesis-of-high-protein-meals-has-a-name-and-its-name-is-refractory-by-layne-norton.html#.UUtJYzddy9M

Mar 21, 2013 11:55am | report
 
Sabeque

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Sabeque

I know this is a bit off topic but what if you can't handle the lactose in casein? Can you sub that with egg protein instead? I've read egg protein is the slowest digesting protein of all. thanks for the article, by the way...interesting read on soy

Mar 21, 2013 12:00pm | report
 
El_ganso

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El_ganso

Thanks for this article. I�m actually using a product with a blend of proteins (Dymatize Elite XT), and I wasn�t so sure this was the correct choice !

Mar 21, 2013 12:22pm | report
 
robwein83

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robwein83

I'm going to be paraphrasing and may hack up the exact science, but I believe it is Layne Norton which had done some studies regarding Leucine being a primary activator of protein syntheses. More important in regards to this article, is his conversations about not needing to sustain elevated amino acid levels at all times. In fact, they were finding that your body is more efficient with muscle synthesis by getting the "adequate" levels of protein with the threshold level of Luecine and to allow your amino levels to taper down until your next feeding to encourage protein syntheses. Keeping amino acid levels elevated at all times does not equate to higher protein syntheses, in fact it is the opposite.

The only time that maintaining a relatively level amount of amino acids at a sustained level might be helpful would be with a casein p[protein before bed when you are fasting.

In simplest terms.... Throughout the day you will benefit from spikes of protein with the correct threshold of Leucine more than keeping amino acid levels elevated at a sustained level all day.

Mar 21, 2013 4:40pm | report
 
ashleyhorner

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ashleyhorner

this is great. I actually get a lot of people asking me about SOY proteins. I will have to share this with them.

Apr 30, 2013 2:35pm | report
 
charlievanriper

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charlievanriper

Not to mention the Fact that there are good and Bad types of Estrogen and the Estrogen increased by Soy Isoflavones actually blocks the bad estradiol allowing the flow of more Free testosterone in your system. Yes this is a true and great Artical Dr Stoppani

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May 2, 2013 4:20pm | report
 
lkjkaol

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lkjkaol

Approximately 90% of all Soy in the U.S.A. is GMO. IMHO I think it is wise to eliminate the "bio-engineered" foods.

May 24, 2013 5:39pm | report
 
lkjkaol

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lkjkaol

Approximately 90% of all Soy in the U.S.A. is GMO. IMHO I think it is wise to eliminate the "bio-engineered" foods.

May 24, 2013 5:39pm | report
 
AJG1991

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AJG1991

Thanks for this article Dr. Stoppani. Really appreciate all the info I've learned from you alone in the last few months that I've really gotten into body building. Going to give the soy a shot at the 2:1:1 ratio you stated.

May 30, 2013 10:51am | report
 
Kovenant

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Kovenant

Dr. Stoppani, is the man, and he knows what he talking btw im MD and Cyclist and I use Soy protein before my runs because it make a lot less Uric Acid then less cramping less latic acid on the road. And my ***** works perfectly, and other research i read before about bodybuilding lot ppl when do cycles of any kind of hormone have fear of estrogen and start using aromatase inhibitors and anti estrogens you know what your body need estrogen also when your testosterone is high and if you block it fast you decrease your gains.

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Jun 1, 2013 4:17pm | report
 
tastyanimalsnom

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tastyanimalsnom

interesting article, I'll have to test this out.

Jun 8, 2013 9:45pm | report
 
aLinux

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aLinux

body stats: ht (height) displays wrong and soy is great.. just make sure it's "fermented non-GMO and perhaps organic" else cook or boil it to break it down a little bit so it's more digestible.

Oct 27, 2013 6:00pm | report
 
CalebGr

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CalebGr

Soy is bad for you i don't care what people say. Fermented soy is the only way to eat it safe. Just look up soy under the FDA and it will come up as Poisonous Plant Database.

Oct 27, 2013 6:22pm | report
 
Showing 1 - 25 of 27 Comments

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