Soy

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When you want to follow a vegetarian diet or simply replace your meat products with plant-based foods, soy is often a great alternative. Soy, in the form of soybeans, soy milk, or tofu, can serve as excellent meat substitutes. The origin of these products is the soybean. In this article, you’ll learn about the benefits of soy products as meat substitutes and the positive effects they can have on overall health.

What is Soy

Soy originates from soybeans and originally comes from the Far East. There is evidence that as early as 2838 BC, soybeans were used as food in the Chinese empire. Besides wheat, rice, millet, and barley, soy was considered one of the 5 sacred crops. Examples of soy products produced with soybeans as a base include: soy butter, soy milk, soy burgers, and of course, tofu.

Benefits of Soy

The benefits of soy as a meat substitute are mainly due to the fact that it is a source of protein. Protein is mainly found in meat or dairy products. If you are a vegetarian, or perhaps want to consume less meat, soy is an ideal meat substitute. Because it contains the complete chain of amino acids, soy proteins are equivalent to the proteins found in meat. These proteins can significantly lower LDL cholesterol levels by almost 5 percent. This can reduce the risk of heart disease.

In addition to protein, soybeans also contain other benefits. This legume contains a lot of iron in the form of ferritin. Furthermore, soybeans contain many good fats in the form of omega-6 and omega-3 fats.

Furthermore, soybeans may have a preventive effect on osteoporosis, or decreased bone mass. This is a phenomenon that frequently occurs in the elderly, increasing the risk of bone fractures. Soy may alleviate this by the presence of isoflavones in the bean. These isoflavones are molecularly similar to estrogen. Estrogen is the female hormone, which also plays a role in bone formation. When consuming more soy, the risk of bone fractures decreases due to an increased amount of estrogen.

Positive Effects of Soy

Various studies have shown that men who regularly consume soy have a lower risk of prostate enlargement as well as prostate cancer. Administering soy is said to prevent calcification in the veins. In addition to prostate cancer, consuming soybeans may have a positive effect in preventing breast cancer and specific forms of colon cancer. This is an outcome that scientists are further investigating. Because the studies were conducted in specific areas of Asia where soy consumption in the form of tofu is higher than in Western countries.

In conclusion, soybeans and soy products have a preventive effect on many common conditions. So, soybeans are a good meat substitute and a wise choice when you want to replace meat products with plant-based alternatives.

A recent study of the University of North Carolina at Chapel Hill showed that men eating whopping amounts of soy experienced breast enlargement and even some nipple discharge

Jim Rutz

It’s important to note that Jim Rutz is a religious fanatic who warns that eating soy can make you gay. However, if you actually read the study, the opposite seems to be true! Here’s what the researchers themselves say:

No estrogenic or antiestrogenic symptoms (eg, gynecomastia and weight loss) were observed after administration of the isoflavone preparation.

I’ve emphasized “No” to highlight that they indicate there were no cases of gynecomastia or other (anti-)estrogenic symptoms. Moreover, the men did not eat “whopping amounts” of soy; rather, they were administered the isoflavones. So, it’s not like they had been eating a lot of soy their whole lives. The researchers gave 30 healthy men a single, high dose of a solution containing isoflavones. Both solutions contained more genistein than ever previously administered to humans and more than one would normally get from soy in regular diet. The researchers also refer in their conclusion to two other studies that do not show soy can have negative effects (A. Cassidy, L.J.W. Lu et al.)

Lower testosterone and libido from soy?

Another mentioned adverse effect of soy is once again an attack on masculinity. Several studies have looked at the effect of soy on testosterone, erectile dysfunction, sperm production, and reduced libido. For anyone striving for muscle growth, the first point is crucial. For those (whether consciously or not) striving to improve their chances with the female gender, the latter two points are much more important. After all, if you’ve put in a lot of effort to get the ball to the goal, you have to be able to get it in.

For practical and medical reasons, many of these studies have been conducted on animals. Since soy is a major part of baby food and children’s food in many countries, these studies have also often looked at the influence of soy on young animals of various ages to see what the effects are, now and later in life.

In Europe, in most countries, soy accounts for less than 2% of baby food. In the U.S., however, this is as high as 36% [Merrit and Jenks]. In some cases, soy is used from birth through the toddler years [Pollack et al]. The results of some of these studies have led to regulations on soy in (baby) food in, among others, Israel, Australia, England, France, and New Zealand. Because many of these studies must look at certain cells in the testes involved in reproduction, this can be significant when conducted on men. Therefore, many of these studies have been conducted on animals.

Studies on soy effect on testosterone and reproduction: Rats and apes

Where the researcher from AMC started a study by chance on the effect of soy in food on rats, this was intentional for Polish researchers. They looked at the influence of soy on testosterone before and after reproduction. They gave the females and males soy-rich food during breeding and also to the rats born from the females that ate the soy-rich food. They wanted to see the effects on newborns at different times and on the male hormonal balance in adult men.

They saw no significant decrease in testosterone in adult men due to the diet with soy-rich food. In fact, after 160 days, testosterone was much higher in the rats that ate soy-rich food (see right image: Dark is soy, PND=number of days after birth). Strangely enough, this difference is not specifically mentioned in their conclusion other than that soy can influence male sex hormones depending on the duration of the diet. However, they did see a decrease in testicular size after eating soy.

Soy lowers testosterone in Marmoset monkeys

English researchers used not rats, but Marmoset monkeys. They were particularly interested in the effects on newborns. Because the development of sex hormones in newborn Marmoset monkeys is more similar to that of humans than in rats, they hoped to gain more insight than previous studies with rodents.

These monkeys can show a lot of variation among each other, so you would need to use a lot of them for good information if it weren’t for the fact that they are usually born in pairs (although triplets and quadruplets also occur). Here, one of the two can serve as a control, allowing for comparison. The researchers used 7 pairs, one of which was given soy milk for 30-40 days and the other regular milk (both from the supermarket). In weeks 120-138, they looked at the effect of the diet after birth on puberty (week 40-60) and later.

the increase in Leydig cell numbers was most marked in males with consistently lownormal testosterone levels…….Unexpectedly,our findings show that testicular weight and somatic cell numbers are significantly increased in animals that have been fed with SFM as infants. The latter changes did not result in any values in SFM-fed males that lay outside of the control range of values, and these differences would not have been detectable if the present study had not used a paired, co-twin design. However, there is some concern that these changes may reflect a degree of ‘compensated Leydig cell failure’, which merits further investigation

K. Tan – University of Edinburgh

To understand what they mean, you need to know that testosterone is made in the Leydig cells in the testes (from cholesterol). The researchers observed that in the monkeys that drank soy milk, the number of Leydig cells increased. They suspect that, in compensation, the Leydig cells produce less testosterone (“Compensated Leydig cell failure”). The lower testosterone levels in soy milk-drinking monkeys lie between normal values and would not have been noticeable if they had not been compared to their twin brother.

Soy has no effect on testosterone in Macaque monkeys and does not cause gynecomastia

American researchers also used monkeys, but macaques this time. They were curious about the long-term effects of isoflavones. They divided 91 macaques into three groups: a diet without soy, a diet with low soy, and a diet with high soy.

The American researchers observed no influence on testosterone and estradiol. They also did not see gynecomastia occur.

Serum estradiol, testosterone, or androstenedione did not differ among the 3 groups at baseline or following the 31-mo dietary soy protein treatment period (table 3)

D.L. Perry – Wake Forest University School of Medicine, Winston-Salem

Soy does not lower testosterone, but does lower risk of prostate cancer

Researchers from the University of Hawaii came to this conclusion when they had 23 men eat soy twice a day for a month. After a month, they switched to a low-soy diet. The results were then compared. They saw no difference in testosterone, but a decrease in Prostate-Specific Antigen (PSA). PSA is also called the “prostate cancer protein” because higher amounts in the blood can indicate prostate cancer, but also other conditions such as an enlarged prostate or inflammation.

No significant between-group and within-group differences were detected. During the high soy diet, dietary isoflavone intake and urinary isoflavone excretion increased significantly as compared to the low soy diet. A 14% decline in serum PSA levels (P=0.10), but no change in testosterone (P=0.70), was observed during the high soy diet in contrast to the low soy diet.

G. Maskarinec. University of Hawaii

Soy does not lead to a decline, but actually an increase in testosterone long-term!

At least, according to researchers from the University of Ottawa. They tested 6 groups of rats, all of which received different amounts of phytoestrogens ranging from no phytoestrogens to the amount in normal food and ultimately also the amount that is thirty times higher.

Where the Poles looked up to 280 days after birth, the Canadians looked up to day 360 (from day 28 when they no longer received mother’s milk). The 360 days should show what lifelong exposure means. In the left image, you can see the thick line indicating the testosterone level on the soy-free diet. It is clear that from day 120 onwards, all diets with soy result in a higher testosterone level.

If we look here after 280 days as the Poles did, we also see in this case that the differences are small, whereas they are much higher after 160 days. In essence (very simplistically), the only difference is that they mention this increase in their conclusion while the Poles did not.

By the way, the difference in the androgenic dihydrotestosterone was even greater (not shown).

However, rats on diets 5 and 6 demonstrated altered serum testosterone profiles such that at days 120, testosterone levels remained significantly elevated at approximately 3 ng/ml (P < 0.05). Serum dihydrotestosterone levels exhibited similar profiles and the levels in PND 120 rats on diet 5 or 6 were also significantly elevated (two to threefold, P < 0.05).

J. McVey. University of Ottawa

Soy cheaper, but lower quality than other proteins?

There are many different types of protein. The most popular protein is whey protein because of its high biological availability and fast absorption. The biological value of whey is calculated at 97. The highest biological value in this table is whey concentrate with 104. For the slower-acting casein, this is 77, and according to wiki, this is 74 for soy. Researchers from the University of Amsterdam (which is of course the best university in the world, judging by the brilliant students who study there;) compared the effects of protein from soy and casein. They describe the value of protein as the speed at which it is digested, the speed at which amino acids are absorbed, and how long they remain in the intestines as newly synthesized protein (new protein built from amino acids).

The researchers found that more protein was synthesized from casein, while more was broken down from soy. This confirmed that soy has a lower biological value than casein (and therefore also than whey).

In conclusion, a significantly larger portion of soy protein is degraded to urea, whereas casein protein likely contributes to splanchnic utilization (probably protein synthesis) to a greater extent. The biological value of soy protein must be considered inferior to that of casein protein in humans.

Y. Luiking – Universiteit van Amsterdam.

References

1. AMC Magazine. 2012, December
2. J. Martinez, J.E. Lewi. An unusual case of gynecomastia associated with soy product consumption. Endocr Pract. 2008 May-Jun;14(4):415-8.
3. M.G. Busby et al. Clinical characteristics and pharmacokinetics of purified soy isoflavones: single-dose administration to healthy men. Am J Clin Nutr. 2002 Jan;75(1):126-36.
4. A. Cassidy. Physiological effects of phyto-estrogens in relation to cancer and other human health risks. Proc Nutr Soc 1996;55:399–417.
5. L.J.W. Lu et al. Altered time course of urinary daidzein and genistein excretion during chronic soya diet in healthy male subjects. Nutr Cancer 1995; 24:311–23.
6. R.J. Merritt and B.H. Jenks Safety of soy-based infant formulas containing isoflavones: the clinical evidence. 2004. J Nutr 134,1220S–1224S.
7. F.P. Polack et al. Changing partners: the dance of infant formula changes. 1999. Clin Pediatr38,703–708.
8. Gorski K. et al. Differential effects of soy-containing diets on the reproductive tissues growth and reproductive hormone secretion in male rats. Reprod Biol. 2006 Nov;6(3):275-90.
9. K. Tan et al. Infant feeding with soy formula milk: effects on puberty progression, reproductive function and testicular cell numbers in marmoset monkeys in adulthood. Human Reproduction Vol.21, No.4 pp. 896–904, 2006
10. D.L. Perry et al. Dietary soy protein containing isoflavonoids does not adversely affect the reproductive tract of male cynomolgus macaques (Macaca fascicularis). J Nutr. 2007 Jun;137(6):1390-4.
11. Protein Quality Evaluation: Report of the Joint FAO/WHO Expert Consultation. Bethesda, MD (USA): Food and Agriculture Organization of the United Nations (Food and Nutrition Paper No. 51). December 1989. ISBN 92-5-103097-9.
12. Y. Luiking et al. Casein and Soy Protein Meals Differentially Affect Whole-Body and Splanchnic Protein Metabolism in Healthy Humans. 2005 The American Society for Nutritional Sciences
13. M. McVey et al. Increased serum and testicular androgen levels in F1 rats with lifetime exposure to soy isoflavones. Reproductive Toxicology (impact factor: 3.23). 07/2004; 18(5):677-85. DOI:10.1016/j.reprotox.2004.04.005
14. G. Maskarinec. Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men. Eur J Clin Nutr. 2006 Dec;60(12):1423-9. Epub 2006 Jun 14.