The use of high doses of vitamin C can cause hemolysis and increase the formation of free radicals. Excess vitamin C may also lead to insomnia, kidney stones, and decreased insulin secretion.
Vitamins are essential substances for human life, but the body cannot synthesize them and must obtain them from external sources. Vitamin deficiency (due to insufficient supply or reduced absorption) often manifests as various diseases, typically requiring treatment with vitamins. However, excessive supplementation or using vitamins when not deficient can lead to toxicity, which can often be very dangerous.
Vitamin A: Plays a role in the formation of retinal pigments, epithelial cell differentiation, and bone regeneration; it is indicated for the treatment of eye, bone, and skin diseases.
High doses can cause vitamin A toxicity; in children, it may increase intracranial pressure, cause bone pain, dermatitis, optic nerve atrophy, and blindness. In adults, excess vitamin A can lead to headaches, menstrual disorders, liver dysfunction, hypercalcemia, psychiatric disturbances, and fetal malformation in pregnant women.
Vitamin B6: Acts as a coenzyme in amino acid metabolism, participates in blood formation, and tissue regeneration; it also aids in the conversion of tryptophan to serotonin, an important neurotransmitter.
High doses or prolonged use over months can lead to vitamin B6 toxicity, manifested by peripheral neuropathy, memory loss, and elevated liver enzymes.
Vitamin B12: Functions as a coenzyme in nucleic acid and myelin synthesis, playing a role in the structure and function of the nervous system, blood formation, and liver tissue regeneration.
Excess vitamin B12 (often from high-dose injections) can activate the coagulation system, increasing the risk of thrombosis.
Vitamin C: Plays a role in the structure of connective tissues, synthesizes catecholamines, neutralizes free radicals, and enhances the body’s resistance.
High doses can lead to hemolysis, especially in individuals with glucose-6-phosphate dehydrogenase deficiency or those with elevated serum iron levels. This condition may also increase free radical formation, cause insomnia, agitation, kidney stones, decrease insulin secretion, and reduce coagulation time.
Vitamin D: Involved in bone regeneration, increases calcium absorption from the intestine, and regulates blood calcium levels.
Excess vitamin D can elevate blood calcium levels; in infants under one year, it may cause irritability, seizures, and early cartilage ossification. In adults, high doses can lead to anorexia, vomiting, diarrhea, psychiatric disturbances, and even death.
Vitamin E: Participates in preventing lipid oxidation in cell membranes and provides antioxidant protection.
Excess vitamin E can cause digestive disorders, headaches, visual disturbances, inhibit reproductive function, and cause kidney damage.
Many other vitamins, when in excess, can also pose health risks. Therefore, it should be understood that vitamins, like other medications, should not be used without indication. When using vitamins, one should avoid causing excessive states.
If there is no vitamin deficiency, supplementation through food is sufficient. If using supplements, oral administration is preferred, unless the digestive tract cannot absorb vitamins or nutritional support is needed outside of the digestive system. The dosage of vitamins should be tailored to the individual’s condition (children, adults, pregnant women, and pathological states…). It is advisable not to use complex supplements containing multiple oil-soluble vitamins, as this can easily lead to vitamin accumulation.
