Soy is an important food source for people who eat a plant-based diet. However, on the internet you will find a lot of contradictory information about soy. Maybe you would like to eat plant-based, but you are having doubts about soy products. This article explains why soy is, in fact, healthy.
What is soy?
Soybeans have been cultivated in China since three thousand years ago. Famous soy products from the Asian cuisine are tofu, tempeh, soy sauce and miso. Nowadays soy products are popular in the West as well. We use soy to produce meat replacements, for example. Furthermore, soy is processed in a lot of food items.
According to The Netherlands Nutrition Centre (1) and the Flemish Institute for Healthy Living (2), soy products can be a part of a healthy diet. Soybeans contain high-quality plant protein. That means that your body can use this protein well for growth and maintenance. Moreover, soy contains unsaturated fats, fibre, iron, vitamin B1 and calcium. If you eat plant-based, soy products are a good alternative to meat and dairy. Furthermore, soy can lower the bad cholesterol (LDL), which decreases your risk of cardiovascular diseases. Soy also has a beneficial effect on for people who suffer from diabetes.
Nevertheless, there are a lot of myths circulating about soy. Below are seven answers to commonly heard myths.
7 reasons to actually use soy products
1. Soy decreases breast cancer risk
Soybeans contain isoflavones or phytoestrogens. These are substances similar to estrogens, the female sex hormones.
In 2020, scientists from China compared 114 extensive studies about soy. Their conclusion was that a high soy consumption lowers the risk of breast cancer. Taking supplements with isoflavones from soy doesn’t have this effect (3).
The researchers found that besides breast cancer, a high soy intake also lowers the risk of ovarian, prostate, gastric, intestinal and lung cancer. A good reason to use soy!
Some people are worried that phytoestrogens mess up your hormones. They claim that soy does increase the risk of breast cancer. This information is outdated, according to the new Chinese study.
2. Soy is healthy for men as well
The study mentioned above also shows that soy does not have an influence on the reproductive hormones of males (3). That’s good to know, because some men worry about phytoestrogens in soy. They think that men who use a lot of soy products, will get more female hormones. According to them, that would cause breast development and impair fertility.
These effects are not proven by science. On the contrary, soy products actually lower the risk of prostate enlargement and prostate cancer (2, 3). So consuming soy is healthy for men, too.
3. Soy products are healthy for children
Soy products are healthy to consume for children and adolescents as well. Soy drink contains the same amount of protein as cow’s milk (4). Protein is important for the growth and development of children. It is important to choose a soy drink with added calcium and vitamin B12, because those nutrients are naturally absent or present in lesser amounts in soy.
In Asian countries like China and Japan, soy products are also consumed by children. There is no evidence that soy has any adverse effects on the hormonal development of children, or in puberty (5).
Soy drink is not suitable for babies up to 1 year old. Soy drink doesn’t have the same composition as breast milk. However, the same can be said for cow’s milk. It contains too much protein and too little fats and iron, compared to breast milk. Up to the age of 6 months, only breast milk is the best for a baby. If you can’t give breast milk, infant formulas are an alternative. There are infant formulas for children over 6 months as well. Soy-based infant formulas are available, and they are just as healthy as the ones based on cow’s milk (6, 7).
4. There’s no need to worry about phytic acid
Soy beans contain phytic acid, a substance which plays a role in the growth of the plant. Phytic acid impairs the absorption of the minerals zinc, iron, calcium and magnesium. However, soy itself contains all of those nutrients (8). This means that by consuming soy, you are also getting more of these minerals. If you have a complete and wholesome diet, you will get a sufficient amount of all these nutrients, and it will be no problem to use soy products.
Phytic acid actually has health benefits as well (9). It is an antioxidant, which means phytic acid protects your body cells against harmful substances. It also protects against tumors and helps to control blood sugar and cholesterol levels. Phytic acid may even have beneficial effects on Parkinson and Alzheimers.
Do you still prefer to minimize your intake of phytic acid? If you do, you can choose to use fermented soy products. Fermentation is a process which changes the taste, texture and composition of soy. Examples of fermented soy products are tempeh, soy sauce and miso.
Another way to lower the amount of phytic acid is soaking soy beans. If soy beans are stored in warm and humid conditions, the amount of phytic acid decreases. That influences the structure of tofu and soy drink. Soft tofu (known as silken tofu) contains less phytic acid than harder types of tofu (9).
5. People in Asia also consume tofu and soy drink
Some websites claim that people in Asia consume only fermented soy products. This is not true. Non-fermented tofu is also used in the Asian cuisine. Maybe you know tofu by its Indonesian name tahu, or maybe you like Japanese silken tofu. Soy drink has also been used for ages in China and other East-Asian countries (10).
6. Soy doesn’t cause thyroid issues
The thyroid gland is an organ in the neck. This gland regulates, amongst other things, how much energy you absorb from your food. It produces various hormones for this, including T3 and T4. The thyroid gland itself is controlled from the brain by means of the hormone TSH.
Research shows that supplements with isoflavones from soy don’t have any effect on T3 and T4. They can, however, slightly raise the hormone TSH (11). For healthy people, who don’t have thyroid problems, this is not an issue. However, this effect might be significant for people who have existing thyroid problems and are using thyroid medication.
Are you suffering from hypothyroidism (meaning your thyroid is working slower than it should)? Then don’t use large amounts of soy products or supplements with isoflavones without first consulting your GP and/or dietitian. Do you not have any existing thyroid issues? Then it is simply safe and healthy to use soy products.
7. For the Amazon rainforest, it’s better to use soy than meat or dairy
Ninety percent of the soy that is grown, is hidden in animal products, according to the Dutch environmental organization Milieu Centraal (12). This is due to the fact that a lot of soy is used as animal feed. The soy used as animal feed is mostly grown in South-America, for which tropical rainforest is being destroyed. Furthermore, this soy is often genetically manipulated, so that stronger pesticides can be used to grow it. These pesticides contaminate the earth and are bad for human health. By eating animal products, you are indirectly consuming a lot of this soy.
Only a small amount of soy goes to plant-based products. These products are often made from European soy. In the European Union, genetically manipulated products have to be labelled (13). Producers like Alpro use responsible soy only. The soy they use, is sourced from Europe or Canada, there are no rain forests being cut down for it and the soy is not genetically manipulated (14).
So, if you are concerned about protecting the rainforest, it is actually better to eat soy products than animal products.
No worries about soy
In conclusion, you don’t need to worry about soy. Soy products are a great part of a healthy, plant-based diet. That doesn’t mean that you have to eat soy if you are following a plant-based diet. You can also choose for other protein sources, like other beans, peas and lentils.
This article was written by Wouter Stap, intern and fourth-year Nutrition and Dietetics student.
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