The dangers of vitamin overdose

  • Bernardo Herradón
  • Institute of General Organic Chemistry
  • The Conversation
  • January 18/2022
  • vitaminas

FUENTE DE LA IMAGEN,GETTY

 

Vitamins are natural substances that humans cannot synthesize, that is, must take them from external sources.

People need 13 vitamins. First, the nine water-soluble (soluble in water) that comprise the 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 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 plant 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 (on the order of micrograms to milligrams).

Early vitamin deficiency diseases

Scurvy was the first disease knew its dependence on nutritional factors. He was the French navigator Jacques Cartier who described the disease in some indigenous people in Canada and in part of their crew.

Later, the Scottish physician James Lind published a treatise on scurvy and suggested the use of lime juice for its treatment. We currently know that such pathology is due to a deficiency of vitamin C, also called ascorbic acid (which means 'anti scurvy'). That is why they recommended such treatments.

Since then, possibly the study of vitamins and their role in preventing certain diseases has been the greatest milestone in biomedical research on nutrition.

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, independently), xerophthalemia (vitamin A, leading to blindness), and rickets in children or osteomalacia in adults (both associated with vitamin D deficiency).

Due to its nature as a natural substance and the 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 risk. 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 a physiological concentration can be toxic in larger amounts.

Some reasons why a beneficial compound can become toxic when used in excess are:

  1. The amount of unused bioactive ingredient can accumulate in certain tissues – for example, lipophilic substances accumulate in adipose tissue and the liver, and hydrophilic substances are stored in some organs such as the kidneys and liver – causing long-term deleterious effects.
  2. It is also possible (and not exclusive to the above explanation) that the excess bioactive compound is metabolized to toxic substances. This is especially important in substances that accumulate in the liver, which is the "chemical factory" of our body.
  3. 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 their activity, which can be detrimental 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 alleged vitamin D

In general, few side effects of water-soluble vitamins are known, since they are excreted relatively easily, even in the case of hypervitaminosis (with a few exceptions). On the contrary, the excess of fat-soluble vitamins produces more and more serious pernicious effects. Let us remember that these are 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.

Deficiencies in vitamin A usually arise from some chronic disease that affects its absorption. It manifests itself in some symptoms related to vision problems, a higher frequency of skin infections, 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, an enlarged lymph node and various bone problems.

Vitamin D is not really 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 need to sunbathe to have good levels of vitamin D.

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 2 factors. On the one hand, due to inadequate exposure to sunlight. On the other hand, due to the tendency to lower cholesterol levels (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. causes the rickets in children and osteomalacia – softening of the bones – in adults.

In addition, vitamin D dietary supplements do not usually alleviate this deficiency, perhaps due to inefficient absorption or, more frequently, to the poor quality of preparations sold without a prescription.

In some situations – such as pregnancy, lactation and in people with problems in the vitamin D metabolic pathway – there is a greater need for vitamin D. In these cases, you should always follow the doctor's instructions, because you have to remember that is a hormone and that imbalances in the endocrine system have serious health consequences.

On one side, some recent publications have analyzed intoxications caused by hypervitaminosis D, which show alarming growth for a decade.

Has found that vitamin D causes high concentration of calcium ions in the plasma, which causes 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, growth retardation (which can be reversed with medical treatment), diarrhea and failure of various organs (kidneys, lungs, heart, blood vessels and skin).

Furthermore, from a 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 coagulation. Its main activity is as an antioxidant. On the effects caused by its deficiency there are still no results in humans. But yes about hypervitaminosis E, and these indicate It does not produce serious harmful 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, that of type K1 It can cause some mild effects such as transient facial flushing, or more serious effects such as dyspnea, which can lead to death.

For its part, excess vitamin K2 can cause kernicterus (a type of cerebral palsy in newborns), hemolytic problems in children, jaundice, damage to the mucous membranes and liver problems. Also, 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 abnormality, consult the professionals at your health center.

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 2 factors. On the one hand, due to inadequate exposure to sunlight. On the other hand, due to the tendency to lower cholesterol levels (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. causes the rickets in children and osteomalacia – softening of the bones – in adults.

In addition, vitamin D dietary supplements do not usually alleviate this deficiency, perhaps due to inefficient absorption or, more frequently, to the poor quality of preparations sold without a prescription.

In some situations – such as pregnancy, lactation and in people with problems in the vitamin D metabolic pathway – there is a greater need for vitamin D. In these cases, you should always follow the doctor's instructions, because you have to remember that is a hormone and that imbalances in the endocrine system have serious health consequences.

On one side, some recent publications have analyzed intoxications caused by hypervitaminosis D, which show alarming growth for a decade.

Has found that vitamin D causes high concentration of calcium ions in the plasma, which causes 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, growth retardation (which can be reversed with medical treatment), diarrhea and failure of various organs (kidneys, lungs, heart, blood vessels and skin).

Furthermore, from a 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 coagulation. Its main activity is as an antioxidant. On the effects caused by its deficiency there are still no results in humans. But yes about hypervitaminosis E, and these indicate It does not produce serious harmful 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, that of type K1 It can cause some mild effects such as transient facial flushing, or more serious effects such as dyspnea, which can lead to death.

For its part, excess vitamin K2 can cause kernicterus (a type of cerebral palsy in newborns), hemolytic problems in children, jaundice, damage to the mucous membranes and liver problems. Also, 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 abnormality, consult the professionals at your health center.

Bernardo Herradon, Scientific researcher in organic chemistry, science communicator, Institute of General Organic Chemistry (IQOG – CSIC)

Original Version:  https://theconversation.com/los-peligros-de-la-sobredosis-de-vitaminas-174278