In-depth analysis of B vitamins and vitamin C: metabolic hubs, hematopoietic function, and antioxidant warning signs of "rust".

Vitamin B6 is also a component of coenzymes, primarily involved in nitrogen metabolism. Its physiological functions include transamination, decarboxylation, and therapeutic effects. Vitamin B6 is a coenzyme for transaminases, removing the α-amino group from amino acids to form keto acids. Decarboxylation coenzymes participate in the formation of certain neurotransmitters, such as dopamine and serotonin with tyrosine and histidine. High doses of vitamin B6 can be used to treat epilepsy in its early stages. It can also be effective for spastic disorders in infants and young children. Vitamin B6 is widely distributed in food and is generally not deficient. Deficiency can lead to insomnia and skin inflammation in individuals; growth retardation and anemia in infants; and impaired fetal brain cell development in pregnant women.

Vitamin B12, also known as cobalamin, contains the trace element cobalt. Its physiological functions are as follows: (1) Participating in the synthesis of nucleic acids and proteins. Vitamin B12 can improve the utilization rate of folic acid and promote the development and maturation of red blood cells. Insufficient supply in food or complete gastrectomy can induce pernicious anemia. (2) Transporting methyl groups. Participating in the synthesis of important substances such as methionine and choline. Giving vitamin B12 to patients with liver disease can prevent fatty liver. (3) Maintaining the metabolism and function of nerve myelin sheath. Vitamin B12 deficiency can cause neurological disorders, spinal cord degeneration, demyelination, and severe mental symptoms. Vitamin B12 can be synthesized by intestinal bacteria, and its food sources are mainly animal foods, such as liver, kidney, and heart, which contain more vitamin B12.

Vitamin C, also known as ascorbic acid, has the following physiological functions: (1) Participation in hydroxylation reactions. Proline and lysine on the α-peptide chain of procollagen must be hydroxylated to form hydroxyproline and hydroxyline residues before collagen can be synthesized. Secondly, the synthesis of 5-hydroxytryptophan from tryptophan also requires the participation of vitamin C. In addition, the hydroxylation of steroid compounds, such as the conversion of cholesterol into bile acids, also requires the participation of vitamin C. (2) Reduction. Vitamin C is an antioxidant that can reduce ferric iron to ferrous iron, which is easily absorbed by the intestines, thereby improving the body's utilization of iron. Therefore, it has a certain auxiliary effect in the treatment of iron deficiency anemia and megaloblastic anemia. (3) Detoxification. Chemical substances such as alcohol, carbon tetrachloride, ozone, and nitrogen dioxide can produce free radicals that damage the heart during metabolism in the body. Vitamin C can destroy these free radicals. (4) Prevention of arteriosclerosis. Vitamin C can lower blood cholesterol and β-lipoprotein while increasing high-density lipoprotein, thereby preventing cholesterol from depositing on the arterial wall. (5) Histamine-dissolving effect. Vitamin C can break down histamine, causing vasoconstriction and reduced permeability, thus preventing skin bleeding. (6) Anti-carcinogenic effect. Vitamin C can block the formation of carcinogenic nitrosamines from nitrites in the body. In populations with low vitamin C intake, the incidence of esophageal and gastric cancer is significantly increased. Vitamin C deficiency has many adverse effects on health, but more is not necessarily better. Long-term high-dose vitamin C intake can lead to a significant increase in oxalate crystals in urine, resulting in urinary tract stones; induce diabetes; cause a relative deficiency of vitamin B1 in the body; and cause abdominal pain and diarrhea.

Vitamin C tablets cannot replace vegetables and fruits. Vegetables, in addition to being rich in vitamin C, also contain inorganic salts, carotene, and other essential vitamins and fiber. Vitamin C tablets are pure pharmaceutical preparations and do not contain the various nutrients found in vegetables. Overdosing on vitamin C tablets not only provides no benefit but can even lead to poisoning. Vegetables high in vitamin C include: mustard greens, shepherd's purse, green garlic, cauliflower, red bell peppers, chili peppers, garlic sprouts, radishes, lettuce, and cabbage. Fruits rich in vitamin C include: citrus fruits, fresh dates, hawthorn berries, strawberries, pineapples, persimmons, and pears. Vitamin C tablets should not be stored at home for extended periods. Prolonged exposure to air or damp conditions can cause the tablets to turn yellow, affecting their efficacy and potentially even decomposing into harmful substances. Vitamin C tablets that have turned yellow should not be taken and should be stored in a brown glass bottle in a cool, dry, and dark place. Recent clinical trials have shown that excessive vitamin C intake not only fails to aid recovery but also produces negative effects, causing a reaction similar to "iron rusting" in the body. Medical experts point out that taking more than 100 mg of vitamin C tablets daily poses a threat to human health. This is because the body releases a large amount of free iron under these conditions, and vitamin C reacts with this free iron in a chemical reaction similar to that between iron and a water-oxygen mixture. Under normal circumstances, the iron in the body is bound to proteins and enzymes and cannot react with vitamin C. However, when the body's tissues are inflamed, a large amount of free iron is released, causing "rusting" within the body. Furthermore, consuming vitamin C with pork liver significantly reduces its efficacy. Vitamin C is an enol-structured substance, easily oxidized and destroyed. Its oxidation is even faster when it encounters metal ions (such as copper and iron). Pork liver is the richest source of the trace element copper. The copper and iron ions in pork liver will oxidize vitamin C into dehydroascorbic acid, thus losing its original pharmacological effects.