Vitamin C

Biochemical significance: Vitamin C is important for many metabolic processes. It participates in protein metabolism, is important in the synthesis of collagen and L-carnitine, as well as certain neurotransmitters. Collagen is an essential component of connective tissue, which participates in the wound healing process. Vitamin C is a powerful antioxidant and regenerates other antioxidants in the human body, such as vitamin E (tocopherol). In addition to its biosynthetic and antioxidant functions, vitamin C plays an important role in stimulating the immune system and improves iron absorption. Current evidence suggests that regular intake of vitamin C does not reduce the incidence of colds and flu, but such intake may be significant in people who are exposed to heavy physical exertion, the elderly and smokers. Regular intake of vitamin C contributes to shortening the duration of the common cold and alleviates the severity of symptoms, which is attributed to its antihistamine effect. Epidemiological evidence confirms that the consumption of fruits and vegetables, which are a rich source of vitamin C, is associated with a lower risk of most types of cancer. This vitamin limits the creation of free radicals, modifies the immune response, but also through its antioxidant potential neutralizes free radicals, which are the cause of many diseases in the body, including cancer. Evidence from many studies suggests that a high intake of vitamin C is associated with a reduced risk of cardiovascular disease. This connection can be attributed to the antioxidant effect, because vitamin C reduces the adhesion of monocytes to the endothelium, improves the production of nitric oxide, which results in vasodilation (expansion of blood vessels), decreases apoptosis (death) of smooth muscle cells of blood vessels, which prevents the formation of atherosclerotic plaques.

Vitamin C deficiency leads to a disease called scurvy. The time it takes for scurvy to develop varies depending on the vitamin C depot in the body. It usually occurs in a month from little or almost no intake of this vitamin, below 10mg/day. The initial symptoms of scurvy are fatigue, weakness, inflammation of the gums. As vitamin C deficiency progresses, collagen synthesis is disrupted, connective tissue weakens, which leads to the appearance of petechiae, joint pain, and difficult wound healing. Additional signs of this disease are depression, bleeding gums, tooth loss. Anemia can also occur due to bleeding and poor absorption of iron, caused by low intake of vitamin C. Children may develop bone disease. If left untreated, scurvy is fatal. Today, vitamin C deficiency and scurvy are very rare in developed countries.

Vitamin C excess: Vitamin C has low toxicity and does not cause serious adverse effects at high doses. The most common symptoms in case of overdose are diarrhea, nausea, stomach cramps and other gastrointestinal disorders. A high intake of vitamin C also has the potential to increase the excretion of oxalate and uric acid, which contributes to the formation of kidney stones, especially in people with chronic kidney disease. In some people, large doses of ascorbic acid have led to a breakdown of simultaneously ingested vitamin B12 and excessive absorption of iron.