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soy protein

A few years ago I spoke about why we don’t use soy protein in our products and I really wanted to expand on why it has no place in a Reflex product

I want to support our anti soy position with referenced studies. In short, deliver an article that really does make you think twice about buying another protein powder that contains soy protein. There are various articles that attempt to vindicate soy, but I’m not sure why when there are so many question marks relating to its use. Just remember there are so many significantly superior and safe alternatives without any question marks attached to them.

GMO soy, its production and hexane

Soy protein is largely derived from GMO soy crops which are used to make soy protein isolate. It’s the manufacturing of soy that is one of the real issues I have. One of the cheaper extraction methods to make soy protein uses a solvent called hexane, whilst there are other water based extraction methods that avoid the use of hexane it’s used by a minority of brands and is more expensive. In the following link you will see a news article that talks about independently tested soy products and the associated levels of hexane discovered in various soy products.


Whichever way you want to look at this, one thing is absolutely clear. Soy protein manufacturing using hexane is not the ideal. The question is how can you tell if the soy protein in your protein powder contains traces of Hexane? I’d ask the supplement company and if they say “we’ll look into it”, it’s probably because they don’t know themselves which to me is completely inexcusable. This is really just part of the story and I don’t want to spend too much time on how soy is made, suffice to say if you consume soy let’s hope is completely free from hexane.

Soy as a source of protein for sports nutrition

Assuming you are not vegan, soy really has no place in sports nutrition, pea in our opinion is a better alternative. The biological value of soy is lower than the big three, those being whey, egg and micellar casein. Soy is lower in essential amino acids and contains few branched chain amino acids, so again its use it questionable at best. The following human study quite clearly demonstrates soy’s inferior ability to stimulate protein synthesis vs milk proteins.

The authors quote “Milk-based proteins promote muscle protein accretion to a greater extent than do soy-based proteins when consumed after resistance exercise” http://ajcn.nutrition.org/content/85/4/1031.short

The next study focuses on the effect of healthy males consuming 56 grams of soy protein daily for a month. Serum testosterone dropped by 19%, absolutely the last thing you want if you are an athlete.

The authors quote “Soy protein powder decreases serum testosterone levels in healthy men and acts as an ER-β agonist.”


It’s never one sided? Over 170 negative studies might suggest otherwise

The story for and against soy is not one sided and yes I’ve cherry picked two studies above to illustrate negative aspects of soy. Many will argue a case for soy and others, like me, will argue the case against. The trouble is for me that even a handful of negative studies will worry me. The trouble is there are more than a few, here is a link to another interesting article with links to over 170 negative studies relating to soy consumption.


With such a significant number of published studies even those fanatical about soy must have nagging doubts about consuming it in even moderate amounts.

Soy protein isolate is used in significant amounts in sports nutrition

Soy in small amounts is not the issue, foods like tofu, soy sauce and natto have a long history of consumption. The issue for me is the amount of soy protein and the associated phyates, trypsin inhibitors and phytoestrogens that can be and are used in protein powders, all-in-one bodybuilding supplements and protein bars. Today it’s very easy to buy a protein blend with soy protein isolate as a main ingredient, same for the all-in-one powders and it’s the same story for protein bars. It is therefore quite possible to be consuming at least 50 grams of highly concentrated soy daily without even realising it, and that is a huge amount compared to a diet with some weekly consumption of tofu and other fermented soy foods.

If I was a cynical manufacturer I could see the attraction of it’s use in protein powders. They are a cheap source of protein and increase profits, in protein bars they can help with shelf life at reduced costs once again boosting profits. What I don’t like is the fact that certain brands then imply that the very same products are the best on the market. That’s simply not possible. If you are replacing whey/casein/egg with soy then in my book you are compromising. It can only be included to cut costs unless I’ve missed something in the last 20 years? If someone can give me a better explanation I’d love to know why.

Today, me and my family avoid soy protein containing foods as a precautionary measure; we simply don’t need it in our diets and I’m not prepared to take the risk. Nor am I prepared to sacrifice quality of Reflex products and formulate products with soy protein.

The question you need to ask yourself, are you happy to take the risk when you don’t need to??

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