Vitamin C is a water-soluble vitamin, also called ascorbic acid, that is mainly found in fruits, and vegetables. It is a thermolabile vitamin that is destroyed by heat, so the regular consumption of fresh and raw vegetables contributes to a greater conservation of this vitamin. By heating food by different cooking methods, we will destroy part of this vitamin, especially if we heat too high temperatures, a long time, or reheat the food several times. L-ascorbic acid is an electron donor that contributes to the prevention of oxidative damage. This mechanism is beneficial in human diseases such as atherosclerosis (through the oxidation of low-density lipoproteins), type 2 diabetes (through oxidative stress in the beta cell), and cancer (through the repair mechanism of DNA and damage related to DNA oxidation). Besides, L-ascorbic acid is essential for collagen and L-carnitine biosynthesis (important for membrane integrity during pregnancy and for the conversion of dopamine to norepinephrine).
The Immune System
Vitamin C does not actually cure the flu, as some may believe, but it can and does help strengthen the immune system against infectious diseases. Also, it stimulates the proper functioning of the bacterial flora, a determining factor in intestinal and digestive health. The immune system is a complicated network of cells (macrophages, lymphocytes, etc.) distributed throughout the body and a set of molecules (cytokines, antibodies, etc.) that work together to defend it from pathogenic microorganisms and foreign substances.
The functions of vitamin C on the immune system are the following:
- Improves the integrity of the epithelial barrier, promoting collagen synthesis.
- Maintains the oxidative state of cells and protects against reactive oxygen species generated during the respiratory burst and the inflammatory response.
- Stimulates the correct function of leukocytes
- Regulates the immune response through its antiviral and antioxidant properties.
- Reduces the incidence of the common cold and pneumonia in individuals who engage in vigorous physical exercise or who live in crowded environments.
Vitamin C and Colds
One of the most used home remedies for colds is taking lots of citrus fruits, rich in vitamin C, or even supplements of this vitamin, as popular belief ensures that it is capable of preventing or even curing colds. The first is to ensure that vitamin C was useful to prevent catarrhal processes or other viral processes was Linus Pauling, a prestigious chemist who won the Nobel Prize twice. In his book ‘Vitamin C and the Common Cold,’ published in the 70s of the last century, he argued that high doses of vitamin C, about 3,000 milligrams a day – almost 40 times the RDA that is recommended today, which is 80 milligrams – prevented bronchitis, allergies, fever, pneumonia, and colds. His theory was based on the fact that the vitamin is essential for the formation of leukocytes, the most important cells in charge of defending ourselves against external pathogens.
Since then, dozens of studies have been carried out looking for the relationship between vitamin C – or ascorbic acid – and the cold, and, although the conclusions are disparate, in most, a direct relationship has not been found between the intake of large amounts of this vitamin and prevention. In other words, there is no solid evidence that supplements of this vitamin reduce the chances of catching a cold or the flu. However, there is a population group that can slightly reduce the incidence of colds if they take high doses of vitamin C (1,000 mg), those subjected to high physical stress, that is, professional athletes. The reduction is slight in any case, 10%.
Vitamin C in The Diet
Despite the evidence that vitamin C prevents common colds, it is still an important vitamin for our body and that we must ingest through the diet. Always referring to the healthy adult population, it is established that the average consumption is between 70 and 110 mg per day, respectively. Pregnant women would need, in any case, a somewhat higher consumption, just like smokers. Without vitamin C, the body cannot make collagen, a protein necessary to build and maintain healthy bones, joints, skin, and digestive tract tissues. Also, some studies suggest that vitamin C may help lower the risk of heart disease. However, the human body does not store vitamin C. So people need to obtain this nutrient through their daily diet with foods such as oranges, strawberries, broccoli, potatoes, kiwi, mango, lemon, and grapefruit.