Whether in its original form or processed into tofu and soy milk: Soy has become an integral part of vegetarian and vegan cuisine. For years, there have been more and more soy-based meat and milk alternatives in supermarkets.
So much good is in soy
Quite apart from the protein content, the list of healthy components in soy is long: vitamin B, minerals such as magnesium, trace elements such as iron and unsaturated fatty acids, including omega-3 fatty acids.
Real protein bomb: The bean is known for its high protein content. According to the Federal Center for Nutrition, this is around 40 percent in the dried beans. Ready-to-eat soy products contain around eleven percent protein.
For a balanced diet, the legume is a very good way to replace the animal protein that is so important, says Stefan Kabisch, study doctor at the Medical Clinic for Endocrinology and Metabolic Medicine at the Berlin Charité.
Is soy really that healthy?
Anyone who eats different vegetable proteins can at least eat a balanced diet as a vegetarian. Vegans would need to add vitamin B12 though.
However, the bean also contains substances that nutritionists consider in a more differentiated way. This includes isoflavones, which are similar to the female sex hormone estrogen.
For this reason, they are suspected of having a “hormonally activating effect”, as physician Stefan Kabisch says. This means they can bind to the same estrogen receptors in the body and set in motion the same processes as estrogens.
So is soy not as healthy as you think?
Healthy people don’t have to worry about normal consumption, says Kabisch. Due to their regulatory form, isoflavones are “very probably harmless, maybe even useful”.
This was also shown by long-term studies from Asia, where soy has been on the menu for much longer. Incidentally, isoflavones are also found in smaller amounts in other legumes such as chickpeas, lentils and beans.
Does soy affect the thyroid negatively?
And yet soy is suspected of affecting the thyroid. According to physicians Kabisch, isoflavones are able to block a specific enzyme in the thyroid gland.
This enzyme is responsible for building active hormones from inactive precursors.
According to Kabisch, if this enzyme is inactivated, hypothyroidism can develop. Because this effect is so small and not yet clinically relevant, he sees normal soy consumption for healthy people no health risk.
In addition, the amount of isoflavones in soy is reduced by about a fifth when it is processed into tofu.
When to avoid soy
However, the legume is not suitable for everyone. People with hormonal diseases such as breast cancer and metabolic disorders should have their diet checked by a doctor, says Nicole Schlaeger, team leader for healthy eating and nutritional education at the consumer center in North Rhine-Westphalia.
Basically, she advises not to replace dairy products and meat exclusively with soy products.
It is important to pay attention to variety – and sometimes to reach for oat or almond milk, ideally enriched with calcium.
In other cases, too, most nutrition experts urge caution when it comes to soy. Soy milk is not suitable for babies and small children because it has less calcium than cow’s milk and the interactions with other hormones are still unclear.
The same applies to pregnant and breastfeeding women.
Beware of allergies
On the other hand, allergy sufferers should be careful, which also applies to other legumes. According to the consumer advocate, people who are allergic to birch, for example, can also overreact to soy.
According to the doctor Kabisch, a soy-containing diet is also not suitable for gout diseases because of the purine it contains – a metabolic precursor of uric acid. This also applies to other legumes.
If you still don’t want to do without soy, you should only eat it in moderation, according to the recommendations of consumer protection groups.
Little researched as a dietary supplement
Incidentally, soy does not only play a role in food. The hormonal effect of isoflavones is also used in dietary supplements intended to help with menopause symptoms.
Because the artificial dosage of 40 to 5000 mg is often many times higher than in the natural form (in Western Europe 1-3 mg), according to doctor Stefan Kabisch, the risk of hormonal side effects could also increase.
In his opinion, women in particular who are prone to thyroid disorders should consult their doctor first before taking it.
Stefan Kabisch advises against self-medication. In addition, there was still a lack of reliable long-term scientific data.
Note the organic seal
According to the NRW consumer advice center, anyone who not only wants to look after their own well-being but also that of the environment should look out for the organic seal. This is the only way to control the growing conditions.
It becomes more difficult when it comes to the place of origin of the small legume. According to consumer advocates, the soy used for food comes mainly from Europe.
Incidentally, most of the soy does not end up on the plate, but is processed to 80 percent into animal feed.
According to the World Wide Fund For Nature (WWF), it mostly comes from the USA, Brazil or Argentina.
German Press Agency (dpa)
World Wide Fund for Nature (WWF) https://www.wwf.de/themen-projekte/landwirtschaft/produkte-aus-der-landwirtschaft/soja
Federal Center for Nutrition https://www.bzfe.de/lebensmittel/vom-acker-bis-zum-teller/huelsenfruechte/huelsenfruechte-gesund-essen/#:~:text=Soybeans%20are%20the%20%20highest%20protein%20legumes, fat content %20of%20around%2018%20percent