Legumes: Beans, Peas, Lentils, Soy and Peanuts
Legumes contain Phytic Acid which binds to nutrients in food preventing their absorption, earning them the label ‘anti-nutrients’, the knock on effects of this is highly dependent on intake quantity. Legumes also contain galaco-ligosaccharides which are associated with digestive issues. However, the main issue with legumes is their lectin content.
Lectins are known to damage the intestinal wall by reducing the speed of cell renewal, which leads to ‘leaky gut’, this causes digestive issues, specifically with vitamin and mineral absorption and autoimmune problems. Lectins are a plant form of defence that are resistant to digestion and lead to antibody production to them, which means certain lectin containing foods can literally be intolerable to a body, stimulating an immune response i.e. allergic reaction, and too much lectin consumption leads to vomiting, cramping and diarrhoea. Immune responses include skin rashes, joint pain and general inflammation, thankfully these will stop, as soon as consumption stops.
Peanuts (unless you’ve picked them yourself) contain the FDA declared “unavoidable contaminant” aflatoxins, long-term consumption of which are linked to cancer and other diseases.
Soy, ignoring the fact that 93% of soy produced is GMO, as well as containing lectins and phytic acid which inhibit calcium, magnesium, copper, iron and zinc absorption, also contain phytoestrogens, which are hormone disruptors linked with infertility and some forms of cancer. Soy also contains trypsin inhibitors which have a negative effect on protein digestion and increase the bodies need for vitamins B12 and D, as well as a clot-promoting substance called Haemagglutin, which causes red blood cells to clump together, that can be painful and lead to health issues. Its isoflavones have been shown to stimulate growth of cancer cells, its aluminium content is connected to kidney and nervous system issues and soys high levels of goitrogens block the production of thyroid hormone.
Unfortunately the pet food industry have adopted a number of legumes as ‘protein sources’ instead of the species appropriate protein source meat. i.e. soy in ‘cat food’ (those meaty pieces) and ‘pea protein’ in kibble, also peanut husks are used as a source of fibre.
There are a number of ways that lectins can be processed that reduce the negative effects, such as sprouting and fermenting, however these processes are costly and not normally utilised in ‘pet food’ or even in home preparation.
Bearing all of this in mind you can possibly see why personally I recommend against feeding legumes, and in fact other than the odd handful of peanuts or spoonful of hummus, I don’t eat them myself (thankfully coffee beans are not legumes lol).