One of the best-known vegan proteins is soy protein. Many plant-based protein powders are based entirely or largely on soy. You can also find many vegan products on store shelves that use soy protein as an additive or main ingredient to add vital proteins to vegan dishes.

The reason for its frequent use in vegan products is the low price of soy protein. This is often advertised as a very good source of protein because it is low in calories. The idea is to mix a lot of protein into the diet for as few calories as possible. This is fundamentally not a bad thing.

But does it work that simply?

Unfortunately, not everything is high-quality protein that shines, because you should be aware of the possible disadvantages of soy proteins and soy protein powders for your health.

The most well-known disadvantages of soy protein

Disadvantage 1: Inferior amino acid profile of soy protein

You can read about the importance of amino acids here .

In order for the body to actually use the protein consumed through food, the amino acid profile of the protein sources is crucial. Unfortunately, soy protein is one of the vegan proteins that, on its own, does not have an optimized amino acid profile. Soy protein is not suitable on its own to cover the majority of your protein needs.

You could compensate for this deficiency by simply consuming more soy protein - for example, integrating additional soy protein powder into your plant-based diet. Nevertheless: The amount of essential amino acids in soy protein is comparatively poor.

In order to get enough protein from soy protein every day, you always have to charge an extra portion surcharge. For example, compared to high-quality whey protein, you would need 40g soy protein instead of 25g whey protein to get the same amount of essential amino acids. Pea protein, as a comparable vegan protein, would achieve this effect at 38g.

Even if the 2g difference to soy protein sounds manageable at first glance, you still need protein every day. Depending on the situation, your individual daily requirement can be well over 100g. The small difference of 2 grams quickly adds up over several months - both in terms of costs and quantity.

Do you have your protein needs on track? In our article about your daily protein amount you will find out everything you need to have full control over your daily protein consumption for your health!

Especially when building muscle or maintaining muscle (diet), soy protein can only be a good alternative in significantly increased quantities. The “good” price-performance ratio is quickly history. You can almost call it a marketing trick. Because in this case you get less quality for less money!

So it's better to choose a high-quality pea protein or, even better, a plant-based protein with more components. The combination of different plant amino acids increases the biological value . This helps meet your protein needs and your health!

You can find out more about biological value in our detailed Lykaia Protein Guide for 2023.

Disadvantage 2: Lectins in soy protein

It is claimed that the processing process of soy leaves an insignificant amount of lectins in the soy protein powder. That is fundamentally correct. However, reality shows that many people with lectin intolerance still react to it.

The consequences are inflammation in the intestines. This results in gastrointestinal problems that can manifest themselves in a variety of ways. If you had various complaints in the gastrointestinal tract (even mild ones) after a meal rich in soy, the soy may be responsible. The practice of nutritionists shows that amateur athletes or people in general who cover their protein needs with vegan protein powders talk about better digestibility after changing their protein preparation and that gastrointestinal complaints often subside.

The quantity makes the poison here. As described, you need a lot of soy protein to cover your daily needs due to the sub-optimal amino acid profile. This also increases the intake of lectins through the consumption of soy products. A possible lectin intolerance becomes more likely to become noticeable.

So always keep an eye on your intestines when consuming soy products. This is especially true for protein powders made from soy.

Since quite a few people report this condition, it makes sense to use an alternative or only consume soy protein in small quantities. Good alternatives are pea protein, hemp protein, pumpkin seed protein or rice protein (if you value an exclusively plant-based diet). Unfortunately, the taste of most of the protein powders available on this basis is debatable.
That's why we've spent the last six months creating an optimal vegan protein powder. The result will soon be available in our shop!

If animal protein sources are an option for you, whey protein and casein hold their own still as the undefeated leaders!

Disadvantage 3: Phytoestrogens in soy protein

Do you know secondary plant substances? To this day, science continues to update itself on a daily basis about the number, mode of action, dosage levels and dosage form. Various secondary plant substances are said to have a positive effect on our health in a balanced ratio and, for example, have anti-carcinogenic and antioxidant effects in our body. This applies as long as you consume them from whole plant-based foods and not from dietary supplements (which also include soy protein powder).

Phytoestrogens found in soy protein as representatives of secondary plant substances are considered particularly controversial. On the one hand, there are studies that claim that the low intake of soy products is irrelevant for us humans. Others, however, reveal that the phytoestrogens in soy protein can have negative effects on the hormonal balance of women and men. The studies suggest that hormone levels can shift through the intake of phytoestrogens. Testosterone and estrogen are said to become imbalanced, which can have countless disadvantages for your well-being.

Science is currently coming to the conclusion that further (long-term) studies on humans are necessary to make a statement about the effect of phytoestrogens in soy protein. Personally, I don't want to rely on unclear studies that can swing in one direction or the other.

Phytoestrogens should be consumed through normal, whole foods. This means that meeting your daily protein requirements allows you to consume products containing soy. Protein powders containing soy should be used to a very limited extent or avoided until the studies become clearer.

Recommendation: It is better to use small amounts of soy protein per day or, to be on the safe side, choose other, higher quality protein powders.

Disadvantage 4: Allergens in soy and soy allergy

What many people don't know is that soy is the most common cause of food allergy, especially in children and adults. The proportion of the German population across all age groups who suffers from a soy allergy is around 0.3%. It should be noted that children are represented more frequently at around 1%.

Possible symptoms include rashes such as hives or swelling in the mouth and throat area. Some complain of digestive problems and diarrhea. In other cases, breathing problems and coughing are common reactions to soy products.

Even though many soy products have a lower proportion of allergens due to the manufacturing process, this unfortunately does not apply to soy protein powder. It is precisely here that the highest amounts of allergens have been found in various studies and random samples. For example, 10% of people who are allergic to cow's milk also have a reaction to soy products. Soy milk is generally not recommended for children up to the age of one.

If you already have a known allergy or are considering soy protein for your children, it is not advisable to consume it. If in doubt, you should definitely talk to your doctor to check for a soy intolerance.

So it’s better to turn to other vegan protein sources.

Our conclusion on the questionable soy protein

As a manufacturer of high-quality products based on natural raw materials that primarily focus on your individual health, we have decided against using soy proteins. The arguments are too broad and too serious. With a clear conscience, we could not offer you high-quality products that contain soy protein. Many manufacturers try to present the unclear study situation in a positive way and thereby justify the cost-effective use of soy protein. We don't do that. We rely on proven components.

Even with careful control of soy cultivation and production, there are too many disadvantages for people with possible intolerances.

If you definitely don't want to go without your soy protein, enjoy it in manageable quantities. If you don't have an intolerance, we still recommend a combination with other plant-based protein sources. This increases the amino acid profile.

Have you been looking for a healthy alternative to soy protein for a long time?

Try our high-quality vegan multi-component protein. This consists of pea protein, hemp protein and pumpkin seed protein. We have also added high-quality mushrooms, which have many benefits for your health in everyday life and during sport.

You can read about the benefits of our chosen vegan protein sources here .

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