Soy superfood – soy superhealth?

Soy milk, soy schnitzel, soy yoghurt, soy sausage – soy is becoming increasingly popular as a plant-based alternative to animal products, and not always as obvious as you might think. The legume is also behind tofu, tempeh and miso. The product, which has been increasingly appearing on our grocery shelves in recent years and is also in the spotlight as animal feed and because of its ecological footprint, has been present in some Asian cuisines for thousands of years – see the famous soy sauce, which comes in so many different varieties that it's easy to lose track. But what is soy anyway, how is it processed, how does it affect our health and especially our longevity?

Origin far from Europe

Soy is a plant from the legume family. Depending on the species, it grows up to 180 cm tall and develops legumes. Do you know edamame, the green bean-like dish that is often served salted as a small appetizer in Japanese restaurants? These are unripe soybeans. The ripe soybeans later have a slightly darker yellow to brown color.

The ingredients of various soy products vary greatly, depending on how they are grown and processed. We often consume soy as a fermented product in the form of tempeh, soy sauce or miso. During fermentation, the soybean is fermented by microorganisms. This creates a different composition of ingredients, characteristic tastes and special consistencies. Soy products are fermented by very different microorganisms - the ingredients of the fermentation product natto (contains the enzyme nattokinase, which is a potential candidate in longevity research) are therefore not comparable with tempeh. In addition, the protein profile of soy varies greatly depending on the variety and food, which is why many studies are carried out with pure soy protein. When it comes to nutrition, however, it is important to also consider the interactions between the ingredients and the method of preparation, which is why studies with pure soy protein are not representative of a soy-rich diet. Let's take a look at the ingredients of the legume anyway.

Soya as a source of protein

Do you know soy as a popular source of protein? It's quite possible, because soy has the highest proportion of plant proteins at over 30% and therefore also covers all essential amino acids. And if that's not enough, the quality of the proteins is very close to that of animal proteins and is the most balanced compared to other plant protein sources. So if you want to use soy as a plant protein source, that's a very good decision, because there is no longer any need to supplement individual amino acids.

Fats

With around 15% fat, soybeans may sound quite fatty at first. However, it is worth taking a closer look at the fats, because it all depends on which fats are contained. The majority are polyunsaturated fats, and with both saturated and unsaturated fatty acids, the legume covers all essential fats. Soy is therefore not only a great source of the majority of amino acids, but also of the important fatty acids.

carbohydrates

The fact that soy is so popular as a fitness food is probably not only due to the high protein content, but also to the low amount of carbohydrates. At only around 14%, this proportion is very low. In addition, the carbohydrates in soy are long-chain - so-called oligosaccharides. The advantage of oligosaccharides is that they are not processed quite as quickly by the body and therefore do not have such a strong effect on blood sugar levels. However, most of them are only processed in the intestines by the bacteria there, which leads to the formation of gases.

So do soy products automatically lead to flatulence? - No, it's not quite that simple. Because the work that your intestinal bacteria do to break down the carbohydrates is already done by other bacteria or processing mechanisms in most soy products. So it really depends on the soy product and the processing method.

isoflavones

Soya is known for its ingredients from the group of isoflavones. Isoflavones are substances that are produced in the plant itself, for example as a defense against pests. Daidzein is an isoflavone that can be metabolized in the intestines to equol. The isoflavone is processed by certain bacteria that are only found in the intestines of 50-60% of Asian people and 30-40% of people from non-Asian regions. Perhaps you have heard something about telomeres and their connection to health and aging? According to a study from 2017, equol can increase the length of telomeres in skin cells. Equol also acts as a powerful antioxidant. antioxidants protect cells and thus our entire body from rapid aging and thus contribute to a healthy lifestyle.

Have you ever heard that soy contains estrogen and that men should therefore avoid it? This is a myth that persists, but is anything but true. But this half-truth must come from somewhere, because some isoflavones in soy have a similar structure to estrogen - they are so-called phytohormones, i.e. plant hormones. Due to their structural similarity to estrogen, they can also bind to human estrogen receptors. The concern that the consumption of soy products leads to increased activity of the estrogen receptor mechanisms and thus estrogen-like effects is unfounded. Because, as with many products, it is the dose that makes the poison and the amount of phytoestrogens in soy is comparatively small. In people who consume a lot of soy, the risk of cancer even decreases (more on this in the section on cancer risk).

Effects of soy on cardiovascular disease

The effects of a diet rich in soy on the risk of cardiovascular disease are controversial. On the one hand, nutritional studies in this field are very difficult to conduct, and on the other hand, many people with a diet rich in soy are vegetarians or vegans. So it is not just the effect of soy that is important, but also the effect of the lack of animal products. However, some studies assume that the consumption of soy products reduces the risk of cardiovascular disease by lowering LDL cholesterol levels and the blood pressure-lowering effect. This is supported by a meta-study from 2019, where the consumption of soy reduced overall mortality and the risk of death from cardiovascular disease.

Soy and the risk of cancer

If you look at the rates of breast cancer in soy-consuming countries compared to Western countries, the risk is significantly higher in the latter. True, this may not only be due to soy, but also to various other dietary and living conditions. Nevertheless, studies on the effects of soy on breast cancer and other types of cancer are constantly being carried out on the basis of this information. A meta-study from 2019 summarized these and came to the conclusion that while soy does not significantly reduce the risk of cancer, it certainly does not increase it. The meta-study also analyzed studies with soy isoflavones. According to this, the risk of dying from breast and prostate cancer is significantly reduced when supplementing with soy isoflavones.

''Quo vadis?''

The study results on whether soy reduces the risk of certain diseases are ambivalent, but there are no published studies that show that soy has a negative effect when consumed in normal amounts. Quite the opposite! There is evidence that soy has very positive effects on our health and longevity. If you look at soy from a nutritional perspective, it is undoubtedly an excellent way to cover many needs and, thanks to the variety of soy products, avoid falling into a simplistic diet.