Soy, as a vegetable alternative to animal protein sources is an almost complete protein source. It is low on fat and carbohydrate, while some of its properties make it particularly attractive for women or those on low-calorie diets. However, this doesn’t mean you should forget about your whey protein or casein. But you might consider making soy protein part of your diet. Believe it or not, soy contains more protein than meat, eggs or fish, along with other essential nutrients like calcium, iron, potassium, vitamin E or fiber.
soy, soya, Genistein
Where you can find soy protein
Soy is extracted from soy beans. After the oil is extracted from the beans, the remainder is the soy protein itself. In commercial products you can find it in tofu, soy milk, soy cheese, textured soy protein or soybean meal.
In general, soy can be added to soups, sauces or dressings. It can be baked, fried or mixed into other foods to boost their protein content.
In powder format, it is often added to drinks, burgers, soy noodles or even ordinary noodles.
Its impact on improving performance
Why athletes use soy protein
Its high BCAA (branched-chain amino acid), glutamine and arginine content made it popular among sport fanatics and dieters, since it does not only promote muscle gains and recovery but boosts metabolism and fat loss, too. Research involving both male and female athletes has shown that soy can support muscle gains and boost performance, while reducing body fat at the same time.
How it enhances muscle gains and recovery:
- By enhancing total protein intake, it helps you keep and increase your muscle mass.
How it promotes fat loss:
- It indirectly stimulates metabolism, which boosts the fat burning capacity of the body.
How it promotes longevity
- Thanks to its isoflavone content, it can fight free radicals and support the immune system.
- I reduces lipid and cholesterol levels in the blood, thus promoting cardiovascular health.
Symptoms of soy protein deficiency
No known deficiency symptoms.
Based on studies, soy protein may be useful in the treatment of the following symptoms:
- Cancer; especially breast and prostate cancer
- Cardiovascular diseases
Although soy was the first protein powder available as a supplement, it was considered an “inferior protein source” for decades, because it was not considered whole (compared to animal based proteins). Today – thanks to science – we have a somewhat more sophisticated view on this matter. It is actually a good, almost complete protein source. It is low on calories and fat, while some of its benefits make it particularly attractive for women or those on low-calorie diets. Furthermore – believe it or not – soy contains more useful protein than meat, eggs or fish, along with other essential nutrients like calcium, iron, potassium, vitamin E or fiber. Based on the Protein Digestibility Corrected Amino Acid Score (PDCAAS – a WHO method), soy received a maximum score out of several scores, which means, it can be considered a whole food.
A good choice for athletes?
A study involving both male and female athletes has shown that soy can help prevent muscle catabolism and boost performance while reducing body fat – the latter may be a result of the stimulating effect on hormone production and metabolism.
Soy also strengthens bones and connective tissues; plus, it reduces inflammation and shortens recovery time. Furthermore, research involving Olympic athletes demonstrated that athletes who used soy experienced less fatigue after training.
Some research has shown another unique result: soy can support or even rev up metabolism, even when the total calorie intake is lowered. And this is good news for those who aim for a “target weight” (which is lower than their present bodyweight, of course :)). As you might have experienced it, when you reduce calories, your body switches to starvation mode. As a result, your body produces less thyroid hormones. But, if you provide your system the phytochemicals (from soy protein) it apparently needs for thyroid hormone production, your metabolic rate will remain steady, so you can keep on burning calories as fuel just as before.
Although there has been some controversy on the negative impact of soy on testosterone levels, it should be noted that these studies were conducted on animals, not humans. On the other hand, human experiments have found that soy in fact reduces the level of a dangerous look-alike of testosterone, namely dihydrotestosterone, which is quite infamous for its negative effects. One study found a 13% drop of dihydrotestosterone levels, which might lead us to the conclusion that soy prevents testosterone from transforming into dihydrotestosterone. And this is a good thing, especially if muscle mass matters to you!
Of course we do not recommend that you switch to soy completely and give up all the other protein sources like whey or casein, which have already proven anabolic effects. However, it can be beneficial if you keep a balance of different protein types in your diet. Or, you should at least try to make sure about one-third of your daily protein intake comes from soy.
Benefits for women
Its isoflavones, especially daidzein make soy particularly beneficial for active women. These estrogen-like compounds are particularly useful for women at menopause: they diminish the most common symptoms like hot flashes, irritability or discomfort. It can also be useful for women who – based on their doctor’s recommendation – need an alternative to traditional estrogen supplementation.
It is important to know for both men and women that soy promotes calcium retention, thus it can help preserve bone strength and prevent osteoporosis.
For the time being, there are no official results on the anti-cancer or potential anti-carcinogenic properties of soy. But there are studies in progress. Soy provides your body 3 potential anti-cancer compounds: the powerful antioxidant phytic acid, protease inhibitors, which block enzymes that lead to cancer, and isoflavones like genistein or daidzein (we have mentioned above), which act against estrogen and minimize its harmful effects. Research has shown that soy can be particularly effective for people exposed to the risk of hormone-related cancer types like breast or prostate cancer.
For cardiovascular health
Although the exact mechanism is not known yet, it is a well-known fact that soy can effectively lower cholesterol levels. Some studies have shown that soy consumption may lower the total cholesterol level by 23 mg/dl. This can significantly reduce the risk of related diseases including heart attack or stroke.
Actually, scientists are so positive about this that the FDA (Food and Drug Administration) approved that the following sentence should be displayed on products on which the recommended dosage of soy protein appears (4 portions a day, 6,25 g each): “25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. A serving of (name of food) provides ____ grams of soy protein.”
While research keeps on producing results on the usage of soy as a vegetable-based protein alternative, potential anti-cancer or anti-heart-disease remedy or antioxidant, there are further scientific debates going on, on other potential uses of these little beans. One thing is for sure: more and more researchers and scientists recommend that we should make soy part of our everyday protein intake for our present and future health.
Indications for use
For active and healthy males, the average protein need is between 2 and 3 grams per kilogram of bodyweight, while for most of the females, the recommended daily protein intake is between 1.5 and 2 grams per kilogram of bodyweight. For example, a 90 kg male should consume 180 to 270 grams of protein each day. And, a 55 kg female should consume 90 to 115 grams of protein daily.
The necessary daily amount of isoflavones in soy proteins is between 50 and 100 mg.
Soy protein can be consumed at any time of the day to enhance protein intake. It is a common ingredient in protein powders, shakes or MRPs.
If you decide to take a soy protein supplement, you should pick a product in which soy protein isolate is the first or second in the list of ingredients. This way you can make sure you have picked a quality product, since soy protein isolate is 90% protein, unlike soy protein concentrate, which is only 70%.
Synergists of soy protein
No known synergists.
Toxicity of soy protein
No known toxicity.
Contra-indication and restrictions
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