In the last decades, soy cultivation has increased very strongly on a global level - but with it also the criticism. More than 330 million tons of soy are produced worldwide - 80% for animal feed, which is why the associated ecological impacts are often the subject of sustainable discourse. In this article, we get a better overview of the sustainable balance of soy.
What is soy
The soybean, scientifically also called Glycine max or simply soybean, is a well-known crop plant of the legume family. Already since 3050 BC one could prove a cultivation as a food plant in Japan - almost 5000 years later - since 1875 the bean is also cultivated regionally in Austria.
A total of 6 % 6% of the world's agricultural land is used for soybean cultivation. Since the 1970s, this has also recorded the greatest growth in cultivation area of all crops. In 1960, approximately 17 million tons of soy were produced, while in 2019 this figure had already risen to 338 million tons.
Estrogens in soy
It should be noted at the outset that soy does not contain estrogen. However, soybeans do contain so-called phytoestrogens. These are plant hormones that contain a significantly weakened form of estrogens and could even possibly block the estrogens present in the human body - which is why they are also receiving attention in cancer research. Isoflavones (also phytoestrogens) as antioxidants could minimize oxidative stress in human cells and in this context also have a positive effect on gene mutations. However, further randomized clinical studies are necessary to establish a clear causality.
A meta-analysis published in 2003 in the journal Cancer Investigation investigated the relationship between genistein, an isoflavone from soybeans, and biological and molecular effects associated with cancer cells. The study was motivated by statistical data showing that the incidence of breast and prostate cancer is significantly higher in the United States and Europe than in Asian countries such as Japan and China. The reason for this, according to the analysis, could be the Eastern eating habits - which traditionally contain more soy products than in Western countries. According to studies, genistein could inhibit carcinogenesis in animal cells. Through certain modulation of human genes related to cell cycle control and apoptosis (i.e. pre-programmed cell death), the phytoestrogen in soy could be responsible for a certain balance between cell survival and cell death.
Soy isoflavones and male reproductive hormones
A clinical study published in 2010 in the journal Fertility and Sterility investigated whether the isoflavones found in soy cause estrogen-like effects in men, such as lowering testosterone levels or sperm quality. For this purpose, the researchers searched PubMed and CAB databases since July 2008 and analyzed studies dealing with soy, isoflavones, genistein, phystoestrogens, androgens or testosterone. The primary outcome from 15 placebo-controlled intervention groups and 32 reports, which included 36 study groups, was as follows: No significant effects of soy protein or isoflavone intake were found. According to the result of the meta-analysis, soy and isoflavone foods do not alter testosterone levels or sperm quality.
The Okinawa Centenarian Study is the largest study of the elderly population in Okinawa, Japan, funded by the Japanese Ministry of Health. The background is the long life span of the people on the island - researchers had contact with more than 1000 centenarian citizens during the study period. In addition to probably having the longest life expectancy globally, the remarkable health of people in old age is significant: coronary heart disease, stroke and cancer - causes of death with the highest mortality rates in the West - record the lowest incidence in Okinawa anywhere in the world. The primary end goal of the study was to investigate the cause of this.
The results of the study show that the islanders age more slowly and have an 80% lower risk of developing heart disease compared to people in the western population. They are also 50% less likely to develop colon cancer and 25% less likely to develop breast or prostate disease. In addition, the incidence of dementia is lower than in the West.
An important result of this - in addition to social lifestyle and genetic predisposition - was the traditional diet, which consisted of an abundance of vegetables and legumes with low calorie density, including soy products and tofu.
Deforestation due to soy cultivation
While it is well known that the cultivation of mass-produced crops such as soy plantations in indispensable geological standpoints such as the rainforest has a significant impact on the global ecosystem, it should be noted that about 5% of soy grown globally is intended for consumption by humans. About 80% is used as animal feed for factory farms.
The largest cultivation countries are the USA, Brazil and Argentina, whereby genetically modified soy plants are mostly produced with the help of forest clearing, destruction of grassland and savannahs. The global area under soy production is about three times the size of Germany. These genetic modifications make soybean monocultures specifically immune to applied pesticides and able to survive large-scale spraying of weed killers.
Consequently, the EU imports low-cost soy as feed for livestock and is now dependent on soy imports from the growing countries. Most of the import is genetically modified soy, which ends up on the steak plate via the detour of animal intake. As a result, a Central European who consumes meat consumes an average of 60 kg of genetically modified soy per year, which was previously used as crushed animal feed.
According to studies, this would not even be necessary to this extent, since 65% of the imported soy in Europe could be replaced by regional feed.
Beef or tofu
Soy as feed for animal food shows no added value in the sustainability balance. To produce one serving of beef (i.e. 200 g each), you need 9 kg of vegetable protein suppliers such as soy. With this amount, one could produce 68 servings of tofu (i.e. 200 g each).
While corn removes valuable finely decomposing organic substances from the soil, the soybean plant enriches the soil with them. As a result, the soil can be prepared for future plants, the arable land remains fertile and can be worked better. The background to this is the release of the important nitrogen into the soil - only a small proportion is used for protein formation.
Soybean cultivation in Austria
In Austria, only GMO-free seeds are used for domestic soy production. The country uses large amounts of soy production for the human food sector compared to other European countries, as around 50% is used for this purpose in these latitudes. More than one third of the soy production in Austria complies with the organic guidelines for cultivation.
In summary, vegetable milk from soy does not contain estrogens and the contained phytoestrogens did not record any negative properties or changes in the human hormone balance or sperm quality in men. Soy is grown on a large scale as a monoculture, but up to 80% of it is used for animal feed. Comparing the added value of beef and tofu production, 9 kg of soy can produce either 5 servings of beef or 68 servings of tofu.
Environmentally friendly grown soy has positive effects for biodiversity in the farmland and sustainable effects for the ecological condition of the soil. A conscious examination of soy and its production reveals the importance of a sustainable diet.