Health Column
About Vitamins
Due to the important role of vitamins in human life activities, humans have been aware of their existence since ancient times. As early as ancient Egypt, people discovered that eating certain foods could prevent night blindness, though they did not understand the specific mechanism at the time. During China's Tang Dynasty, the physician Sun Simiao pointed out that animal liver could prevent night blindness, and rice bran soup could prevent beriberi. In 1747, British naval surgeon James Lind summarized previous experience and proposed using lemons to prevent scurvy, though he still did not know exactly what substance resisted scurvy. In 1912, Polish chemist Casimir Funk extracted a white substance (thiamine) from rice bran that could treat beriberi, which he called "Vitamin" — the first time vitamins were named, described as "essential nutrients for life."
With the advancement of analytical science and medical technology, more and more vitamins were discovered, and people began to use letters to distinguish different vitamins, giving rise to names such as Vitamin A, Vitamin B1, and so on.
Vitamins are a large and diverse family, which can be divided into two major categories: fat-soluble vitamins and water-soluble vitamins. Vitamins A, D, K, and E are fat-soluble. Vitamin C, B-complex, P, and folic acid are water-soluble. Most vitamins cannot be synthesized in the body and must be regularly obtained from food.
Vitamins neither provide heat nor form tissues in the body. Their functions primarily involve regulating physiological functions, enhancing the body's immune system, and synthesizing coenzymes. Vitamins are required in extremely small amounts, measured in milligrams (mg) or micrograms (μg), but they play a critical role in growth, development, normal metabolism, and physiological functions of the body. Deficiency of one or several vitamins can result in vitamin deficiency disorders and a series of related diseases.
Common Vitamins
Vitamin A
There are two types of Vitamin A. One is retinol, the original form of Vitamin A (found only in animal foods); the other is carotene, a precursor substance that converts to Vitamin A in the body and can be obtained from both plant and animal foods. Vitamin A is a fat-soluble substance. The recommended daily intake of Vitamin A is 5,000 IU for the average adult male and 4,000 IU for females.
Vitamin B12
Vitamin B12, also known as the red vitamin, is a water-soluble vitamin. It is the only vitamin containing major minerals and is difficult for the body to absorb. It must bind with calcium for absorption to facilitate the body's functional activities. In the human diet, the main source of Vitamin B12 is animal foods; plant foods (with very few exceptions) do not contain Vitamin B12. The recommended daily intake for adults is 2 mcg.
Vitamin C
Vitamin C is a water-soluble vitamin. Most animals can synthesize Vitamin C in their bodies, but humans must obtain it from food. Vitamin C helps with iron absorption in the body and plays a very important role in collagen formation. Collagen is an essential substance for the development and repair of body tissues, gums, blood vessels, bones, and teeth. Unprocessed fruits and vegetables are rich in Vitamin C. Under stress, the body accelerates Vitamin C consumption. The recommended daily intake for adults is 60 mg (pregnant and lactating women need more — 70-95 mg). Smokers and the elderly need more Vitamin C (one cigarette can destroy 25-100 mg of Vitamin C).
Vitamin D
Vitamin D is a fat-soluble vitamin. It comes from food and sunlight (ultraviolet rays act on oils in the skin to produce Vitamin D, which is then absorbed into the body). After intense sunburn, the skin will stop producing Vitamin D. In food, it is found in commonly eaten fish such as salmon, mackerel, sardines, and tuna. The recommended daily intake for adults is 200-400 IU or 5-10 mcg.
Vitamin K
Vitamin K is a fat-soluble vitamin. There are three types of Vitamin K. K1 and K2 can be produced by intestinal bacteria, while K3 is a synthetic substance. Vitamin K is one of the chemicals that promote blood coagulation and is essential for the formation of prothrombin. Vitamin K is found in green leafy vegetables, eggs, meat, dairy products, and natto. Since Vitamin K is present in a wide range of foods, healthy people rarely experience delayed blood coagulation, i.e., Vitamin K deficiency. However, Vitamin K deficiency is more likely to occur in newborns and infants. The recommended daily intake for adults is 65-80 mcg.
Vitamin E
Vitamin E is a fat-soluble vitamin. It is primarily stored in the liver, adipose tissue, heart, muscles, testes, uterus, blood, adrenal glands, pituitary gland, etc. Vitamin E has strong antioxidant effects, preventing the oxidation of fatty compounds, Vitamin A, selenium, sulfur amino acids, and Vitamin C. Foods rich in Vitamin E include seeds and vegetable oils. The recommended daily intake for adults is 8-10 IU.
Vitamin B6
Vitamin B6 is a water-soluble vitamin. It is excreted from the body within 8 hours after digestion. Like other B-complex vitamins, it needs to be replenished through food or nutritional supplements. The daily intake is 1.6-2.0 mg.
Folic Acid
Folic acid is a member of the Vitamin B family, also known as Vitamin Bc or Vitamin M. It is also a water-soluble vitamin. Folic acid is an essential substance for the production of red blood cells and helps with protein metabolism. The recommended daily intake for adults is 180-200 mcg, with double the amount for pregnant women.
Vitamin B1
Vitamin B1, like all B-complex vitamins, does not store excess in the body but is completely excreted. Therefore, it must be replenished daily. The B-complex vitamins have a synergistic effect — that is, taking all B vitamins at once is more effective than taking them separately. Also, if the intake ratio of B1, B2, and B6 is unbalanced, there will be no effect. Vitamin B1 is abundant in pork, whole grains, fish roe, and eel. The recommended daily intake for adults is 1.0-1.5 mg. During pregnancy and lactation, 1.5-1.6 mg per day is recommended. Increased intake is needed during illness, stressful periods, and after surgery.
Author: Dr. Li Xuetuo, Health Medicine Expert