Soy Protein – Good or Bad?

Soy is fairly inexpensive protein source and has a complete amino acid profile. It is in fact regarded as the best vegetarian protein source. Then why many bodybuilders fear it?

In fact even I used to fear soy protein but not any more!! As I don’t hold any degree for nutrition I will simply lay down the results of some research and some quick facts. After reading this, I am sure that I will leave you with a clear mind to make a wise decision. In all the places I will be using whey as reference as most of us consider whey as the best protein. hy Soy? The PDCAAS score

In all the protein related stories on the net or papers, egg white protein is taken as reference(egg white protein is regarded as complete and is given a neutral score of 1 in all reference). One of the most accurate protein quality measuring factor is Protein Digestibility Corrected Amino Acid Score(PDCAAS). Having PDCAAS as a reference, in comparison to egg both soy and whey share the same score. Many people consider beef as perfect protein, but even beef scores only 0.92 in PDCAAS in comparison to “1” of Soy, which leaves us with a positive attitude towards reading further. 

Essential Amino Acids

Essential amino acids(EAA) are group of amino acids which can’t be prepared by our body and needs to be supplemented through diet. This is the reason why experts suggest us to take a gram or even more of protein per pound of bodyweight. Many of the bodybuilders consider “whey gold standard” as the best protein source in the world. But “whey” necessarily need not be the “best”. To get a clear picture of the amino acid profile look at the table below.

 EAA - Soy vs. Whey Protein

Soy Vs. Whey Protein	mg EAA per g of Protein
Amino Acid	Soy Protein	Whey Protein
Isoleucine (BCAA)	49mg	54mg
Leucine (BCAA)	82mg	89mg
Valine (BCAA)	48mg	82mg
Histidine	19mg	16mg
Lysine	64mg	88mg
Methionine	26mg	32mg
Phenylalanine	38mg	32mg
Threonine	38mg	65mg
Tryptophan	14mg	22mg
Totals	378mg	480mg

 

The Arginine Factor 

Arginine is a non-essential amino acid which helps in fighting both physical and mental fatigue. Arginine is used in the preparation of nitric oxide which relaxes the blood vessels and helps the body get rid of the toxic substances like ammonia and also used in the preparation of glutamine and creatine by our body. Studies have shown that arginine is used in the formation of protein and it also stimulates the release of growth hormone and prolactin(Prolactin (PRL) or Luteotropic hormone (LTH) is a peptide hormone primarily associated with lactation). And the list goes on and on…

This is the reason why the nitric oxide(NO) supplements evolved in the industry and claimed skin bursting pumping experience in the gym. So here instead of saying much about soy I present to you a table which establishes the amount of arginine per 100g of whey and soy.

Arginine - Soy vs. Whey Protein

Soy Vs. Whey Protein	Arginine per 100g of Protein
Soy Protein	7.6g
Whey Protein	2.9g

 

The Glutamine ratio 

Glutamine is a non-essential amino acid which acts as a cell volumizer by hydrating the muscle cells. In addition to this glutamine is also known to increase the nitric oxide balance in the body, increases the growth hormone production and also known to exhibit anti-catabolic effects.

So a bodybuilder looking to get solid gains consume 3-5g of glutamine 2-3 times a day. So here I present to you a table that shows the amount of glutamine per 100g of soy and whey. 

Glutamine - Soy vs. Whey Protein

Soy Vs. Whey Protein	Glutamine per 100g of Protein
Soy Protein Concentrate	10.5g
Whey Protein Concentrate	4.9g

 

The Estrogen connection

In addition to arginine and glutamine, soy also contains Isoflavones. Isoflavones help to reduce soreness and inflammation and thus improve recovery. They also show powerful antioxidant capabilities. But this is the compound which has given soy the ‘feminizing’ character in the bodybuilding arena. There are many scientific studies which state that isoflavones increase the female hormone count and reduce the level of testosterone and more specifically reduces muscle growth. But there are only a handful of studies which concludes about the estrogen effects but most of the studies conclude that there is no adverse effect on the levels of testosterone or muscle growth due to isoflavones. 

In a 2007 issue of the journal of international society of sports medicine, researchers reported that subjects who were fed either with soy or whey or a combination of both(while also following a resistance training program) showed no differences in free and total testosterone levels – all groups also made similar gains in lean muscle mass. The findings thus concluded that soy was in fact not an inferior source of protein as suggested by earlier studies. 

Soy is made up of three major isoflavones called fenistein, glycitein and daidzein which are also referred to as phytoestrogens (meaning plant estrogens) and are similar to the chemical make up of our body’s own natural hormones estorgen. But research has shown that they are very weak (approximately 1000 times weaker than estrogen). 

“While isoflavones do act to regulate the production and levels of estrogen within the body, for them to actually increase the body’s estrogen levels, and thus compete with the anabolic effects of testosterone, a person would have to consume incredibly large amounts for very long period of time,” says Bodybuilding nutritionist CHAD NICHOLLS (nutritionist of 8 times Mr.Olympia Ronnie Coleman) 

Since numerous people supplementing with soy got similar effects like whey, if they had negative effects on testosterone, gains wouldn’t be the case. Basically the effects of feminizing compounds were tricky with explanation: the pseudo-like estrogen may attempt to battle with testosterone, but they are not strong enough to battle with testosterone and produce a negative effect. So just as whey can build muscle, soy can also build muscle. 

References 

Kalman, D. et al.(2007)Effect of protein source and resistance training on body composition and sex hormones. Journal of the International Society of Sports Nutrition. 

Cadow, D.G. et al.(2006). Effect of Whey and Soy Protein Supplementation Combined with Resistance Training in Young Adults. International Journal of Sports Nutrition and Exercise Metabolism.