Vitamins are natural substances that the human being cannot synthesize, that is, he must take them from external sources. People need 13 vitamins. First, the nine water-soluble (water-soluble) covering C and those of group B (B1, B2, B3, B5, B6, B7, B9 and B12). According to place, the four fat-soluble (insoluble in water), which include the A, E, K and D.
A balanced diet provides us with the necessary amounts since they are present in a wide variety of foods, especially of vegetable origin. An important exception is vitamin B12, which is present in foods of animal origin. For this reason, vegan diets should consume this vitamin as a nutritional supplement.
Vitamin deficiency (hypovitaminosis) is the cause of various diseases. However, the pathologies associated with hypovitaminosis are rare, since the daily requirements of vitamins are minimal (of the order of micrograms to milligrams).
Jacques Cartier portrayed by Theophile Hamel.
Wikimedia Commons
First diseases due to vitamin deficiency
Scurvy was the first disease whose dependence on nutritional factors was known. It was the French navigator Jacques Cartier who described the disease in some Indigenous people in Canada and in part of his crew.
Later, scottish physician James Lind published a treatise on scurvy and suggested the use of lime juice for its treatment. We currently know that such a pathology is due to a deficit of vitamin C, also called ascorbic acid (which means “anti scurvy”). That is why they recommended such treatments.
Since then, arguably, the study of vitamins and their role in preventing certain diseases has been the biggest milestone in biomedical nutrition research.
Apart from scurvy, there are other diseases directly associated with vitamin deficiencies. For example, beriberi (vitamin B1), pellagra (vitamin B2), anemia (vitamin B9 or vitamin B12, regardless), xerophthalemia (vitamin A, which leads to blindness) and rickets in children or osteomalacia in adults (both associated with vitamin D deficiency).
Overdose can also be of vitamins
Due to its nature as a natural substance and the well-known beneficial effect on health, many people are indiscriminately using large amounts of vitamins and vitamin complexes without a prescription.
However, this practice is not without risks. On the one hand, vitamins are very biologically active chemical compounds that have various roles in our body. It is well known that active substances exert their action at a certain concentration and that what can be beneficial at physiological concentration can be toxic in greater quantity.
Some reasons why a beneficial compound can become toxic when overused are:
The amount of the unused bioactive substance can accumulate in certain tissues – for example, lipophilic substances accumulate in adipose tissue and liver, and hydrophilic substances are stored in some organs such as the kidneys and liver – which causes long-term harmful effects.
It is also possible (and not exclusive with the above explanation) that the excess bioactive compound is metabolised to toxic substances. This is especially important in the substances that accumulate in the liver, which is the “chemical factory” of our organism.
The excess of bioactive compound can interact with other substances present in our body. It is well known that some vitamins interact with some drugs decreasing the activity of these, which can be harmful to our health.
For these reasons, bioactive substances should always be consumed in the indicated doses, based on the scientific method.
Vitamin A and the peculiar case of the supposed vitamin D
In general, there are few known side effects of water-soluble vitamins, as they are excreted relatively easily, even in the case of hypervitaminosis (with some exceptions). On the contrary, excess fat-soluble vitamins produces more and more serious pernicious effects. Remember that these are the A, E, K and D, which we will see in detail.
Vitamin A is present in numerous fruits and vegetables and, if a balanced diet is followed, its supplementation is not necessary. From the physiological point of view, its main function is in the process of vision. It is also known to be an immune system stimulant.
Those ofVitamin A deficiencies usually arise from a chronic disease that affects its absorption. It manifests itself in some symptoms related to vision problems, an increased frequency in infections in the skin, respiratory tract and mucous membranes.
But excessive consumption of vitamin A has also been associated with certain diseases and ailments, among which we can mention headache, fatigue, nystagmus (involuntary and uncontrollable movement of the eyes), peeling of the skin, increased lymph node and various bone problems.
Vitamin D, really, is not a vitamin but a hormone. In the diet we consume precursors of vitamin D, which are transformed into it in our body through photochemical reactions, for this reason it is necessary to sunbathe to have good levels of vitamin D.
It is necessary to sunbathe to have good levels of vitamin D.
Shutterstock / Vitalinka
Currently, it is common to find, through blood tests, that the amount of vitamin D is less than the standard. This deficiency can be caused by two factors. On the one hand, by inadequate exposure to sunlight. On the other, by the tendency to lower the level of cholesterol (either through medication or diet), since this is a precursor of vitamin D in the body.
Vitamin D deficiency has serious consequences on our health. It causes rickets in children and osteomalacia – softening of the bones – in adults.
In addition, vitamin D dietary supplements do not usually alleviate this deficit, perhaps due to ineffective absorption or, more frequently, the poor quality of preparations sold without a prescription.
In some situations – such as in pregnancy, breastfeeding and in people with problems in the metabolic pathway of vitamin D – there is an increased need for vitamin D. In these cases you always have to follow the instructions of the doctors, because you have to remember that it is a hormone and that imbalances in the endocrine system have serious consequences on health.
On the one hand, some recent publications have analyzed the poisonings caused by hypervitaminosis D, which show alarming growths for a decade.
Vitamin D has been found to cause high concentration of calcium ions in plasma, leading to excitability in the central, autonomic and somatic nervous systems. It has also been associated with cognitive delay.
Other symptoms caused by excessive doses of vitamin D are headache, fatigue, stunted growth (which can be reversed with medical treatment), diarrhea and failures in various organs (kidneys, lung, heart, blood vessels and skin).
In addition, from the biochemical and physiological point of view, hypervitaminosis can cause irreversible effects on the production of calcitonin, which is the hormone that controls the way the body uses calcium.
Other fat-soluble vitamins: E and K
The physiological role of vitamin E in humans is not fully elucidated, although it has an important role in blood clotting. Its main activity acts as an antioxidant. On the effects caused by its deficit there are still no results in humans. But it does about hypervitaminosis E, and these indicate that it does not produce serious pernicious effects. For this reason, it is also used as a food additive (E-306, E-307, E-308 and E-309).
Finally, regarding its toxicity due to overdose, type K1 can cause some mild effects such as transient facial flushing, or a more serious one such as dyspnea, which can cause death.
On the other hand, excess vitamin K2 can cause kernicterus (a type of cerebral palsy in newborns), hemolytic problems in children, jaundice, damage to mucous membranes and liver problems. In addition, due to its chemical (oxidant) characteristics, vitamin K can interfere with some antioxidants.
That is why it is necessary not to take these supplements lightly and, in case of observing any anomaly, consult with the professionals of your health center.
Bernardo Herradón, Scientific researcher in organic chemistry, scientific communicator, Institute of General Organic Chemistry (IQOG – CSIC)
This article was originally published on The Conversation. Read the original.
