Antivitamins

Essence of the problem and biological role

Antivitamins (antivitamina) are a specific group of chemical agents whose presence in biological systems serves to counteract vitamins. From the perspective of pathophysiological processes, they are fully fledged participants in metabolism. A crucial fact has been established: these compounds are normally found in the human body at absolutely any age, from the neonatal period to extreme old age.

The key effect of these substances lies in the partial or complete elimination of the specific action of vitamins. This means that even with an adequate intake of beneficial nutrients from food, their real effectiveness may approach zero if the activity of their antagonists prevails in the tissues. Such molecular antagonism forms the basis for the development of a wide spectrum of metabolic disorders.

Pathogenesis: receptor and enzymatic levels

The mechanisms of action of antivitamins are realized through several well-defined pathways, which can be divided into cellular and biochemical blockades.

The first mechanism is the blockade of cell receptors intended for binding with vitamins. For a vitamin to exert its effect, it must bind to a specific target. Antivitamins occupy these receptors, with the result that the true vitamin circulates in the tissues but cannot transmit its signal inside the cell.

The second, equally significant pathway is the blockade of the active sites of enzymes. It is known that many vitamins work in conjunction with enzymes. The antivitor interferes with this process, causing a severe disruption in the interaction between the vitamin molecule and the enzyme. The active site becomes blocked, and the biochemical reaction halts completely.

Pathogenesis: effect on the molecule and metabolism

If an antivitamin does not block a receptor or an enzyme, it may attack the vitamin molecule itself or disrupt the processes of its intracellular transformation. Three such mechanisms are distinguished:

• Destruction of the vitamin molecule. The chemical substance acts as a destructive agent. It enters into a direct reaction with the vitamin, leading to the cleavage of its structure. The vitamin physically ceases to exist.
• Modification of the vitamin molecule. The antivitamin does not destroy the molecule completely, but alters its chemical structure or spatial configuration. Such a modified molecule loses its biological value.
• Blockade of intracellular metabolism. Once inside the cell, vitamins must undergo a series of transformations. Antivitamins are capable of interrupting this intracellular cycle, making the ultimate utilization of the substance impossible.

Pathological consequences

Whichever path an antivitamin takes — whether destruction, modification, or blockade of receptors, enzymes, or metabolism — the pathophysiological outcome is always the same. Absolutely all of the above mechanisms inevitably lead to the development of hypovitaminosis.

Depending on the degree of suppression of vitamin activity, various forms of severe disorders can develop in the body:

1. Avitaminoses — conditions in which the action of a vitamin is completely eliminated.
2. Hypovitaminoses — conditions of partial elimination of effects, characterized by functional deficiency.
3. Dysvitaminoses — complex forms of disorders in which a profound imbalance arises throughout the entire vitamin metabolism system.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Types of avitaminoses and hypovitaminoses in clinical practice
• The concept of dysvitaminosis: causes and mechanisms of development
• Competitive and non-competitive blockade of vitamin receptors
• The role of vitamins as coenzymes and the consequences of their blockade
• Intracellular metabolism of vitamins: stages and points of vulnerability

Other topics in "Chapter 14. Vitamin Metabolism Disorders"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.