Is your protein supplement suppressing testosterone and leaving you deficient in vital minerals?

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There is a huge amount of discussion about the benefits of the different proteins for muscle building and health. Soy, once only found in cheap protein products has now become a key ingredient in many premium brands, appearing in shakes, meal replacements and bars. But is there real scientific evidence to support the use of soy in these products? This article reviews the latest evidence, giving you the hard facts both positive and negative- that could change the way you eat for ever…

What are the health benefits of soy?
Foods and dietary supplements containing soy protein can be beneficial to health and soy has gained widespread popularity in mainstream nutrition and sports products. Possible health benefits include cancer prevention, lower blood cholesterol, reduced osteoporosis and relief of menopausal symptoms in women [6]. These effects are thought to be caused by compounds naturally present in soy beans called isoflavones and in post menopausal women can act as a natural estrogen replacement therapy.

In pre-menupausal women soyprotein supplements also produced hormonal changes and alter menstrual cycle phases, partially as a consequence of their estrogenic actions [13, 20]. Although such nutritional hormone replacement therapy can be of benefit to post menopausal women [12], the benefits and safety of such soy in pre-menopausal women and men must be questioned.

Studies in animals and humans show that although isoflavones can reduce the risk of disease, they also produce unwanted effects. In humans, these include anti-thyroid effects, increased reproductive organ cancer and hormonal imbalances [6].

Soy protein is a rich in phytic acid which reduces mineral and trace element absorption [16]. Studies assessing markers of iron status show that supplementing isoflavone rich soy protein isolate reduces iron status by more than 7% [19]. In contrast, the same study also showed that a whey protein supplement actually increased iron status by more than 9%. Iron is essential for oxygen transport and to maintain muscle performance, yet many athletes suffer with low iron stores. Symptoms include shortness of breath, poor exercise performance and slow recovery after exercise. It is clear that supplements containing soy proteins could bring about iron deficiency and impair exercise performance. In any event, heavy use of soya protein, will require an Iron supplement.

Is a protein that is used as a natural estrogen therapy for post-menopausal women really the best choice to build muscle?
There's no doubt that adding extra protein to your diet results in faster gains in strength and muscle size when training [2, 4], increases the rate of fat loss [14] and maintains muscle mass more effectively when dieting [14]. Soy has been promoted as the only complete vegetable protein that supplies all the essential amino acids.

However soy protein still requires enrichment with specific amino acids to improve its nutritional value [3]. Relative to whey, casein or meat, soy provides comparatively low levels of the branched chain amino acids (BCAA), especially leucine. The BCAAs reduce infections [1] and muscle damage [5], while leucine has anabolic effects on muscle [17] and can help prevent muscle breakdown after training. These differences suggest that soy could be less effective at building muscle than whey casein or meat - but what does the actual research show?

A recent study conducted at The Department of Human Nutrition at Kansas Sate University specifically addressed this issue [11]. The investigators compared the muscle building effects of animal derived protein and soy and showed that subjects given animal protein experienced 30% greater increases in muscle cross sectional area than subjects who took soy [11].

Research conducted at Ohio State University shows that both whey and soy can contribute to gains in muscle size [2]. In the study, a group of men received protein bars (3 bars per day, providing 33 grams of protein per day) containing soy or whey protein for nine weeks. All subjects followed the same strength-training program.

Muscle growth was slightly greater in the men given whey, who gained approximately 2% lean body mass (about 1.3 pounds) compared to the soy group, who gained only 1.6% lean body mass (about 1 pound).

Although the authors of this study conclude that "soy and whey protein bar products both promoted exercise training-induced lean body mass gain," it's important to note that one of the co-authors of this study invented the soy bars used in the research and also owns the company that sells them!

The fact that a study involves someone with a vested interest in the outcome doesn’t mean you should ignore it. However, we do need to treat these results with some caution, especially when you consider the recent studies that highlight adverse hormonal changes arising from soy intake.

Soy lowers your testosterone levels
Researchers at the Department of Medicine, University Hospital Wales have found that soy supplements significantly reduce serum testosterone in men [8]. We know that testosterone plays an important role in supporting muscle growth. But few people realise that testosterone plays a key role in almost everything. Testosterone builds emotional well-being and self-confidence. It affects how fat, fit or strong you are. Because the human brain is filled with testosterone receptors (the parts of the brain that respond to testosterone), your mood is affected if testosterone levels drop too low.

Testosterone is also very important when it comes to losing fat. Testosterone affects fat loss in one of two ways [21]. Just like a car, your fat cells have a series of brakes and accelerators. The parts of a fat cell that accelerate the release of fat are called beta-receptors. The parts of a fat cell that put the brakes on fat loss are known as alpha- receptors.

The distribution of brakes and accelerators on each fat cell is one reason why certain parts of your body shed fat faster than others. Women, for example, often have a hard time losing fat from their hips. That’s because the fat cells in that area have a higher ratio of alpha- to beta-receptors.

If a fat cell has more beta-receptors, it will release stored fat more quickly than one with fewer beta-receptors. That’s where testosterone appears to help. By increasing the number of beta-receptors, testosterone makes it easier to lose stored fat. Testosterone can also limit the storage of fat. When fat cells are exposed to testosterone in a test tube, the activity of lipoprotein lipase (an enzyme that promotes fat storage) is dramatically reduced.

To see whether the same thing happens in the human body, researchers from Sweden gave a group of overweight older men supplemental testosterone (in the form of a pill or an injection) for six weeks [22]. When it was measured after just one week, lipoprotein lipase activity in abdominal fat tissue dropped. Even more dramatic changes were seen six weeks later. Waist size also dropped in nine of the 11 men.

Canadian researchers found that testosterone levels were unaffected by milk protein supplementation, but discovered that testosterone levels were significantly reduced by soy protein intake [7]. Similar results are seen when tofu is used to replace meat in the diet [24]. Forty-two healthy adult males aged 35-62 years were studied during two diets, with each diet lasting four weeks. Both provided an equal number of calories. The only difference between the two was that subjects consumed either 150 grams of lean meat or 290 grams of tofu daily. Free testosterone levels dropped significantly after the diet containing the tofu.

A study of the eating habits of Japanese men shows that as the intake of products containing soy protein increases, free testosterone levels drop [23]. Testosterone travels around your bloodstream in two forms - free testosterone or bound testosterone. Roughly two percent of total testosterone is made up of free testosterone, which is the most “active” form. So, not only does soy reduce total testosterone, it's also having a negative impact on the free testosterone that would normally have the biggest impact on muscle growth.

Soy processing and forgotten lessons from the ancients
Soy beans have been eaten as a source of protein in the far east for thousands of years, however populations from China and Japan realised that soy required specific preparation prior to eating to minimise its anti-nutritional effects. It is no co-incidence that the most popular traditional method of soy preparation is fermentation. This process although destroying some of the anti-nutritional factors does not denature soy proteins and is used in the preparation of tempeh, miso and soy sauce.

In the quest to produce commercial soy proteins many western manufacturers have discarded traditional preparation techniques in favour of heat treatment. Although this may reduce some of soy's anti-nutritional effects [10], it also reduces the levels of digestible protein and bioavailable amino acids [18], effectively reducing protein quality…. all in the quest to boost production, quantities and profit.

Arguments for using or including soy protein for the purpose of muscle building and recovery products don't bear up to scrutiny. But if you are looking to get the health benefits such as reducing cholesterol, osteoporosis, cancer prevention, or relief of menopausal symptoms, isoflavone content is what you should be looking for… so which product should you choose?

Independent research studies by the Department of Pharmacology at the University of Milan, have investigated the active constituents of different soy proteins. They found considerable variability in the isoflavone content of soy proteins from different manufacturers and even from different batches from the same manufacturer [9]. Unless the content of specific isoflavones is declared on the product, consumers simply have no idea if they stand a chance of getting the claimed health benefits. Soy manufacturers are probably unwilling to declare the levels of the active isoflavones as poor quality control of manufacturing processes results in variable levels in each batch. For consumer this makes soy proteins health benefits little more than a nutritional lottery.

There are so many commercial interests dependent on the continued appetite for soy across the globe.
Because of this, most of the adverse effects linked with soy is heavily censored. But, there a few people brave enough to take on the giant soy industry. In a highly unusual move, US scientists Dr Daniel Sheehan and Dr Daniel Doerge wrote a letter of protest to the department of Health and Human Services at the FDA, concerned that the problems of soya consumption were being ignored.

"We oppose this health claim because there is abundant evidence that some of the isoflavones [phytoestrogens] found in soy demonstrate toxicity in oestrogen-sensitive tissues and in the thyroid. This is true for a number of species, including humans. Additionally, the adverse effects in humans occur in several tissues and, apparently, by several distinct mechanisms…Thus, during pregnancy in humans, isoflavones per se could be a risk factor for abnormal brain and reproductive tract development.″

It's not just across the Atlantic that the increased consumption of soya has concerned authorities. In Britain, the Food Standards Agency commissioned a report from its Committee on Toxicity of Chemicals in Food to look at the issue.

Professor Frank Woods, chairman of the working group that produced the 400-page report Phytoestrogens and Health, is one of the country’s leading toxologists and has been a key government adviser. If anybody can be called an expert on soya, it is him. But Woods refuses to be drawn on whether the increase in soya in Western diets is good or bad.

"We still have a lot to learn,″ he says in an article published in the Observer Food Monthly (Sunday November 7, 2004). There is, however, one area where his mind is made up. "If my daughter ever asked me advice on whether she should feed her baby on soya formula, I would say no, unless her doctor had specifically advised her to do so.″

One argument put forward by the soy industry, and by companies including soy protein in their protein bars, is that the amount of soy found in these products is relatively small. Unfortunately, nobody is really sure at what level of intake soy exerts its negative effects.

Soy has found its way into so many of the foods you eat on a regular basis. It's used in many types of bread and ready-made-meals, especially the low-carb varieties, as a cheap way to boost protein content and reduce carbs. Check the label of your protein bar, and I bet you that nearly all the popular and flashy looking US bars are using soy protein high up in their ingredient list.

The bottom line
The review of the very latest scientific data on soy protein supplements highlights a number of important issues. When considering the additional requirements for branched chain amino acids, leucine and minerals when training, it is clear that soya protein is not as applicable to meeting these needs as dairy proteins. Furthermore, the undesired hormonal changes that arise from taking soy supplements make muscle-building more difficult. With so much scientific evidence to show that soy is not the ideal protein source for the sportsman, why has soy found its way into so many sports nutrition and muscle building products? The simple answer is profit and mass-market requirements. Soy is much cheaper than quality whey protein or even casein and helps produce foods that can be labelled high in protein.

The problem is that sports nutrition brands that used to care about making high-quality products, have quietly amended their formulas to include soya, or in several cases, completely replaced the whey in the products with soya. These companies then dig an even deeper credibility hole for themselves by producing some outdated 'protein quality' table that shows that soy protein is top of the list of bioavailable proteins, far better than whey! The truth is they don't care about your gym results as much as their profits. But as someone who has spent nearly 15 years in the game, there's another reason to all of this - mass market requirements. As sports nutrition becomes more mainstream there is pressure from the retailers to make the bars more 'confectionary-like' in taste and texture. This is very hard when using only premium-grade whey. But by using soya protein you can increase the protein content to good ‘headline figures’ and still make the bar tasty and edible.

It's the same with ready-to-make drinks (RTD's). Years ago, no respectable sports nutrition brand would ever have launched a soya protein drink, as they would have been laughed out of the gym. Every knowledgeable bodybuilder knows that dairy (if you can tolerate it) or whey protein is king for building muscle. The problem with 100% whey RTD's is that current technology makes them very difficult to make and their shelf life is very poor (often only a few months) unless you use tons of preservatives. This is the reason US whey-only RTD's taste so bitter. Soya is also used as it allows a high protein content that is nearly impossible to achieve with whey-only bars.

As the founder of Maximuscle, I have watched our competitors secretly change their 'whey only' RTD's so they now contain soya, without telling the consumer, or creeping in evermore soya protein to their bars. These are the same companies that vowed never to touch soya protein in the early days. As the founder of Maximuscle, my job is to ensure that only the finest products reach the market. Giving customers the results they are after is what motivates me and allows the brand to grow. For this reason NO Maximuscle products contain soy protein. With my contacts, I could have produce a soya protein Promax powder within a month, but I haven't. It would have produced higher protein figures on the label and lowered our cost price, but we didn't, what does that tell you….soy doesn't work anything like whey for building muscle and anyone that tells you otherwise is a scam merchant.

Before you spend your hard earned money on testrogen raising, testosterone lowering' protein powders, weight gainers, protein bars, meal replacements and RTD's (ready made drinks) check out the ingredients list. You will amazed at how many of the well-known brands are replacing whey with soya in their formulas to boost their profits and reduce your gym results.

If you're interested in learning more about whey-only sports nutrition products, click here.

A special thanks to Dr Rob Child for help in researching this report

Scientific references
1. Bassit et al. (2000) The effect of BCAA supplementation upon the immune response of triathletes. Med Sci Sports Exerc. 32, 1214-1219.
2. Brown et al. (2004) Soy versus whey protein bars: Effects on exercise training impact on lean body mass and antioxidant status. Nutrition Journal http://www.nutritionj.com/content/3/1/22
3. Calderon de la Barca et al. (2000) Enzymatic modification of the functional, nutritional and sensorial properties of soybeans for special feeding. Arch Latinam Nutr. 50, 26-34.
4. Colker et al. (2000) Effects of supplemental protein on body composition and muscular strength in healthy athletic male adults. Current Therapeutic Research 61, 19-28.
5. Coombes and McNaughton (2000) Effect of branched chain amino acid supplementation on serum Creatine kinase and lactate dehydrogenase after prolonged exercise. J Sports Med Phys Fitness. 40, 240-246.
6. Doerge and Chang (2002) Inactivation of thyroid peroxidase by soy isoflavones, in vitro and in vivo. J Chromatogr B Analyt Technol Biomed Life Sci. 25, 269-279.
7. Dillingham et al. (2005) Soy protein isolates of varying isoflavone content exert minor effects on serum reproductive hormones in healthy young men. J Nutr. 135, 584-591.
8. Gardner-Thorpe et al. (2003) Dietary supplements of soya flour lower serum testosterone concentrations and improve markers of oxidative stress in men. Eur J Clin Nutr. 57, 100-106.
9. Gianazza et al. (2003) A proteomic investigation of isolated soy proteins with variable effects in experimental and clinical studies. J Nutr 133, 9-14.
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11. Haub et al. (2002) Effect of protein source on resistive-training-induced changes in body composition and muscle size in older men. Am J Clin Nutr 76, 511-517.
12. Kronenberg and Fuch-Berman (2002) Complementary and alternative medicine for menopausal symptoms: a review of randomised controlled trials. Ann Intern Med 19, 805-813.
13. Kumar et al. (2002) The specific role of isoflavones on estrogen metabolism in pre-menopausal women. Cancer 94, 1166-1174.
14. Layman (2004)
15. Liener (2002) A trail of research revisited. J Agric Food Chem. 50, 6580-6582.
16. Lonnerdal (1994) Nutritional aspects of soy formula. Acta Paediatr Suppl. 402, 105-108.
17. Meijer (2003) Amino acids as regulators and components of nonproteinogenic pathways. J Nutr 133, 2057S-2062S.
18. Sarwar (1991) Amino acid ratings of different forms of infant formulas based on varying degrees of processing. Adv Exp Med Biol 289, 389-402.
19. Swain et al. (2002) Iron indexes and total antioxidant status in response to soy protein intake in perimenopausal women. Am J Clin Nutr. 76, 165-171.
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21. De Pergola, G. (2000). The adipose tissue metabolism: role of testosterone and dehydroepiandrosterone. International Journal of Obesity and Related Metabolic Disorders, 24, S59-63
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24. Habito, R.C., Montalto, J., Leslie, E., & Ball, M.J. (2000). Effects of replacing meat with soyabean in the diet on sex hormone concentrations in healthy adult males. British Journal of Nutrition, 84, 557-563

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