In the course of the vegan hype, legumes and in particular beans are often touted as a complete source of protein. For several reasons, however, legumes are not suitable for meeting protein requirements as an exerciser with the aim of optimizing muscle building, strength building and body fat loss, in contrast to high-quality animal protein. In addition to the problem of the lack of rotation of the protein source and thus the variation of amino acids and micronutrients, covering the protein requirement with beans has numerous other disadvantages. The following points about beans are often not mentioned by advocates of a vegetarian or vegan diet:
1. Lectins
Lectins are plant-specific defense proteins/anti-eating poisons or anti-nutrients whose purpose is to protect the plants and seeds they contain from predators such as insects, birds and mammals. Not only kidney beans, but also all other types of beans of the genus Phaseolus vulgaris (haricot beans) contain a lectin called phytohemagglutinin (PHA). Both PHA and other lectins have been shown in experiments on both animal and human tissue to produce what is known as “leaky gut ” and thus enter the bloodstream, where they can cause low-level inflammation. These are a necessary step for the development of, among other things, atherosclerosis. Leaky Gut Syndrome can also be one of the first steps towards an autoimmune disease.
2. Carbohydrate content
For the same amount of protein, beans provide significantly more carbohydrates than animal protein sources. For this reason, beans are less suitable as a protein source in a low-carbohydrate diet. Getting your protein needs from beans while maintaining/reducing your body fat percentage would only work for very carb tolerant people anyway, all other downsides of beans aside.
3. Phytates
Phytates are also anti-nutrients, which also prevent the absorption of minerals. This puts legumes, often cited as an excellent source of iron, in a different light as only up to 25% of the iron in legumes can be digested as it is bound to phytate. Compared to animal foods, legumes are a much poorer source of iron. The same applies to zinc, a very important mineral that many people who do not eat animal products lack anyway. Incidentally, cooking and roasting legumes does not appear to have any reducing effect on phytates. While in fermentation can moderately reduce the percentage of phytates.
4. Phytoestrogens
Phytoestrogens are secondary plant substances. They can mainly be divided into three classes. isoflavones, lignans and coumestans. Lignans and isoflavones are of the greatest importance for human metabolism, while coumestane is only found in minor amounts in the human diet. In their structure and function, these groups of substances are similar to the female sex hormone estrogen. Their concentration in the body exceeds the endogenously caused estrogen concentration by a factor of 100 to 10,000. Soybeans and their products are particularly rich in the precursors of the isoflavones that are active in the human body. In the case of hormone-dependent diseases in particular, excessive intake of soy foods should be avoided for reasons of precaution.
5. Less and more incomplete protein
On average, beans, peas and other legumes contain over 60% less protein per 100g than 100g of meat or fish. The Protein Digestibility-Corrected Amino Acid Score (PDCAAS) developed by the Food and Agricultural Organization (FAO)/World Health Organization (WHO) of the United Nations is an index that clarifies protein quality. Legumes rank on average 20-25% lower than animal protein sources on the PDCAAS Index due to the anti-nutrients they contain and their low content of the two essential amino acids cysteine and methionine. Thus, even beans such as kidney beans, which contain more protein than other beans, are not an equivalent alternative to animal protein sources, as their protein is less digested and less complete than protein from meat, fish or eggs.
6. A combination with grain is nonsense
The frequently used argument that a PDCAAS of 1.0 can be achieved by combining grain products and legumes, which corresponds to the value of whey protein powder and eggs, is nonsensical. Cereals contain the inflammation-promoting gluten protein and have a high carbohydrate content. You can find out more about gluten here .
Combining an inferior and digestive protein source with a potentially inflammatory carbohydrate source to achieve the same PDCAA level as animal products makes no sense from both a performance-enhancing and health perspective. And would also stand in the way of many trainees in terms of body fat reduction due to the carbohydrate content.
7. Food volume
Even if kidney beans were easy to digest and had a complete amino acid profile, the nutritional volume of 1kg of beans alone speaks against a one-time and, above all, daily intake. Eating 1kg of beans throughout the day is work, even for someone who trains hard and has a healthy appetite. Eating 1kg of meat or fish throughout the day is relatively easy. Three 180g burger patties alone are more than half of it.
8. Poor digestion from FODMAPs
The name FODMAP stands for "fermentable oligo-, di- and monosaccharides and polyols". These are a category of various carbohydrates and polyhydric alcohols found in many foods that are poorly absorbed by the small intestine. This allows the FODMAPs to get to the large intestine instead of being digested in the small intestine. Gut bacteria in the large intestine then ferment the carbohydrates, producing gas, an effect that many people feel in the form of gas and bloating after eating legumes. Diarrhea due to an osmotic effect can also be a consequence.
A FODMAP intolerance is not the cause of small bowel overgrowth like irritable bowel syndrome, but can worsen their symptoms or be triggered by these diseases. If you type the term FODMAP list into a search engine, you will find several lists of high and low FODMAP foods. Foods high in FODMAP include kidney beans, broad beans, peas and lentils.
In a factual, emotion-free perspective, it becomes clear that beans are neither a good food nor a substitute for animal products. If you manage to cover your protein requirements with beans in the long term and without any negative side effects, you can of course do so. However, at YPSI we recommend high quality animal protein sources to our customers for the reasons detailed in this article, among others.
However, beans and other legumes can be part of the diet as they offer some benefits. In terms of content and taste. However, we advise against beans and other legumes as a relevant or even primary protein source for the reasons mentioned above.
Good luck with covering your protein needs!
Image: Kidney beans.