Lectins

Humans have long been omnivorous animals. Throughout evolution, our digestive system has specialised in digesting and assimilating many green plants, wild fruits (especially berries and nuts) and animal products (meat, eggs and fish), as these foods were what we could mainly gather or hunt. For millions of years our digestive system has had very little contact with cereals or leguminous plants. Although we sometimes found "wild" cereals or legumes that we ate, they were far from being our main source of food. However, with the arrival of the Neolithic revolution, where man learned to cultivate the land and domesticate animals, our eating style changed completely. This was about 8,000 to 10,000 years ago. From that time onwards, the consumption of cereals and cereal flours increased dramatically, and to a lesser extent that of pulses, because they were foods that could be easily preserved. And since then, this has only increased. Our digestive system, despite its adaptability and flexibility, has not been able to adapt to such a drastic change in such a short time (yes, yes, 10 000 years is a very short time in the history of evolution). As a result, over-consumption of these foods has put "stress" on our gut and its guardians, the cells of the immune system. 

     One of the reasons why grains and legumes promote inflammation is the presence of substances called lectins. Lectins are proteins found in many plants. Most cereals except rice, millet, teff and little else contain them. In fact, gluten is one type of lectin, although other non-gluten cereals, such as maize or oats, contain similar lectins. All legumes also contain lectins, as do solanaceous plants such as tomatoes, potatoes and aubergines. Lectins are chemical substances that allow plants to defend themselves against predators, as they do not have claws or teeth like animals, nor can they flee when attacked. On the one hand, they produce a certain toxicity and cause intestinal inflammation, so many animals and insects avoid eating them. On the other hand, lectins allow plants to survive, favouring the expansion of their seeds, as the animal gut often has no mechanism to digest them. Thus, the seed ingested by an animal will pass through its digestive tract and come out intact in the faeces a few hours later, while the animal will probably have moved on. In this way the seed will be "planted" elsewhere, surrounded by the wonderful fertiliser that is faeces. Lectins are therefore a very clever and effective form of plant defence. In small doses, they are not a problem for our organism, as our digestive tract can tolerate them. But the problem comes when we ingest too much. And this is what has been happening more and more. From the invention of agriculture to the present day, the consumption of lectin-laden foods has risen sharply, especially since the mid-20th century. It should not be forgotten that, back in the 1960s-70s, health authorities began to recommend the consumption of cereals, milk, cheese, margarine and potatoes as the basis of our diet. These recommendations were later transformed into the famous "nutritional pyramid", which first appeared in Sweden in 1974 and was later exported to the rest of the world, recommending the percentage of each type of food that we should eat for good health. According to this nutritional pyramid, which varied little from country to country, products such as cereals, bread, rice, pasta and dairy products should be at the base of our diet. Today, these recommendations have been more than contested by many scientists, and it has even been demonstrated that the high consumption of carbohydrates has a harmful effect on health and is linked to many chronic diseases such as diabetes and cardiovascular disease. However, this way of eating has become established in Western societies and most people today still think that healthy eating is just a matter of eating this way. This is not to say that these foods should not be eaten, but they should be eaten in moderation and, preferably, with the knowledge of how to prepare them in order to inactivate some of the effect of their anti-nutrients.

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