I tell you! There are some plants that contain seeds. The seeds are the bodies that make up the fruit from which a new plant emerges. This term refers to the reproductive structure in which plants reproduce, which is why they are called spermatophytes (plants that produce seeds). While it is true that a seed is the beginning from which a new plant can grow under the right conditions, it also contains a reserve of food and is wrapped in an outer layer of protection.
Well, without delving too deeply into the complex issues of plant taxonomy, there is a family that, along with cereals and some tropical fruits and roots, has been the basis of human nutrition for thousands of years, and its consumption has been an inextricable part of human development.
Do you know which family we are talking about? I am talking about legumes ( Leguminosae ) or fabaceae ( Fabaceae ), and their seeds, legumes.
Some of the most frequently consumed legumes are peas, beans (also known as kidney beans, beans or string beans), chickpeas, lentils, peanuts (or peanuts), soybeans or our protagonists in this article: fava beans ( Vicia fava ).
Broad beans are a miracle of nature. On the one hand, they are full of protein and other nutrients, and on the other they cause a lot of gas (sometimes in uncomfortable situations). But for some reason, eating fava beans can cause more than just bloating and an orchestra of flatulence. Broad beans can induce a sudden and severe breakdown of red blood cells in some people, thus worsening their general condition.
You see, red blood cells (another name for red blood cells) are especially important in transporting oxygen throughout the body. Therefore, a rapid and sudden destruction of erythrocytes (another name for red blood cells) can cause a shortage of oxygen in the body’s tissues. Basically the “truck” that was supposed to transport the oxygen has broken down, so the oxygen doesn’t get to where it should. As you can imagine, this can be very serious. What will be the symptoms of this condition? Well, now that we understand that oxygen isn’t getting where it’s supposed to, it’s easy to understand that symptoms can include shortness of breath, weakness, dizziness, and confusion. There are several things in medicine that can cause a similar picture, but a very big clue is that these symptoms begin shortly after eating beans.
By the way, scientists, who are sometimes too practical, called this condition favism (hence “the Fabaceae family”, or the scientific name for broad beans being ” Vicia faba “).
Let’s delve a little deeper into the science of this condition. You see, to transport oxygen, red blood cells are made, among other things, of a molecule called hemoglobin. And when we have low hemoglobin (perhaps because our red blood cells are losing -bleeding- or destroying -favism, for example-), we reach a condition that will sound more familiar to you: anemia.
The point is that there are several types of anemia, depending on what causes it to happen. In this case, it is a hemolytic anemia.
Hemolytic anemia is a group of blood disorders that cause a decrease in the mass of red blood cells. Unlike non-hemolytic anemias (for example, due to iron deficiency -another component of the hemoglobin structure-), in hemolytic anemias the life of red blood cells in peripheral blood (normal between 90 and 120 days) is shortened .
In other words, not only do we have fewer red blood cells, but we also have more fragile ones. And what happens is that when a red blood cell breaks, it not only releases hemoglobin and iron, it also releases the rest of its content (bilirubin, cholesterol, etc). This has many implications. For example, by releasing bilirubin, we can develop jaundice (we turn yellow), by releasing cholesterol our gallbladder will have to work extra and may generate gallstones and, of course, we will also have fatigue.
In the most serious cases, this disease can cause the death of the sufferer. The worst of all? You don’t even have to eat beans for this to happen. Some people may have this response just from breathing in plant pollen.
You see, eating beans is not the problem, the problem is having a genetic alteration that causes an enzyme deficiency. An enzyme is a molecule that helps chemical reactions take place in the body. Thus, when we do not have enough of this enzyme, our red blood cells begin to break down more quickly.
This extreme response to fava beans is called fauvism and is associated with low levels of an enzyme called glucose-6-phosphate dehydrogenase (G6PD). This enzyme protects your red blood cells from molecules called oxygen free radicals. These molecules are a natural part of life, they are produced when cells produce energy, for example. But they can also build up and be harmful. Under normal conditions, we have our protection mechanisms, such as the G6PD enzyme, but if our shields fail, we can have problems.
But this is where Medicine gets even more complicated. There are over 400 million people in the world who have low levels of this enzyme and who do NOT have favism. This is because favism is a genetic disease, and the majority of those 400 million are biologically male. Why is this important? because the gene responsible for the production of G6PD is on the X chromosome (it is an X-linked disease). And females have two of those X chromosomes (males have only one). Fortunately, mutations on both X chromosomes are usually needed to develop the disease.
Thus, G6PD deficiency is transmitted by mothers who carry one copy of the gene on one of their X chromosomes to half of their children; sons will be affected (lacking a second copy), and daughters who receive the gene are carriers.
Broad beans contain compounds that, when digested, enhance the production of free radicals. So there are even more of these molecules in your body, and without their guardian enzyme to protect them, your red blood cells are somewhat helpless and end up taking a lot of damage, breaking down and causing that hemolytic anemia we were talking about earlier.
The bad thing is that we are talking about the most common enzymatic defect that our species has and there is no specific treatment.
So, on a day like today, if you’re lucky enough not to have to avoid this nutritious treasure that the earth offers us, don’t forget to enjoy a good plate of broad beans (or one of their legume sisters).
References:
- Rozman, C. & Cardellach, F (Ed. 19). (2020). Farreras Rozman. Internal Medicine . Elsevier.
- Jameson, JL, Fauci, A., Kasper, D., Hauser, S., Longo, D. & Loscalzo, J. (Eds. 20). (2019). Harrison. Principles of internal medicine . McGraw Hill.
