Vitamins are not the raw materials that make up the human body, nor do they supply energy, but they are essential nutrients for maintaining normal life activities. A deficiency can disrupt the body's metabolism and even lead to diseases, known as "avitaminosis." The human body requires only small amounts of vitamins, but most cannot be synthesized within the body and must be supplied by food. There are many types of vitamins, which are divided into two main categories: fat-soluble and water-soluble.
In terms of solubility, vitamins are divided into two main categories: fat-soluble and water-soluble. Specifically, they include the following:
1. Vitamin A: Also known as retinol or carotene. It is often found in food along with fats and is mainly sourced from animal liver, egg yolks, dairy products, as well as carrots, green leafy vegetables, red peppers, apricots, and persimmons. Carotene can be converted into vitamin A in the body. Vitamin A is essential for maintaining normal vision, protecting epithelial tissues, increasing resistance to infectious diseases, and promoting growth and development. A deficiency can lead to symptoms such as night blindness, dry skin, follicular keratosis, and slowed growth and development. Excessive intake can result in vitamin A poisoning.
2. Vitamin D: It is also fat-soluble and has many types. It is found in higher concentrations in animal liver, cod liver oil, and eggs. Its main function is to regulate calcium and phosphorus metabolism and promote their absorption. Under normal dietary conditions, a person who is regularly exposed to sunlight is unlikely to be deficient. A deficiency can reduce the intestines' ability to absorb calcium and phosphorus, leading to softened bones, impaired tooth calcification, rickets in children, and osteomalacia in adults. Conversely, excessive intake of vitamin D can cause poisoning.
3. Vitamin B1: Also known as thiamine. Dietary sources of thiamine are relatively abundant, with higher levels found in grains, yeast, legumes, lean meat, eggs, and animal heart, liver, kidney, and brain. A deficiency can affect appetite and lead to "beriberi," characterized by polyneuritis, edema, and, in severe cases, heart failure.
4. Vitamin B2: Also known as riboflavin. It is found in higher concentrations in animal foods such as liver, kidney, and milk, and is also abundant in legumes and green leafy vegetables. A deficiency can cause symptoms such as cracked and wet corners of the mouth, ulcers, cheilitis, glossitis, keratitis, seborrheic dermatitis, and scrotal dermatitis.
5. Vitamin C: Also known as ascorbic acid, it is a substance indispensable in human metabolism. It maintains the normal function of teeth, bones, blood vessels, and muscles, and has a detoxifying effect. It can enhance the body's resistance to diseases, promote wound healing, and help prevent tumors. It is abundant in fresh vegetables and fruits, especially green leafy vegetables, acidic fruits like tomatoes, and bean sprouts. A deficiency can cause scurvy, characterized by fragile bones. It should be noted that it is easily destroyed by heat, alkali, and certain metals (such as copper), and can be lost or degraded during improper cooking.