Vitamins: What are they and why do we need them?
Vitamins are organic substances that are present in small amounts in natural foodstuffs. They are essential nutrients that the body cannot synthesize in sufficient quantities and therefore must obtain from the diet. Vitamins have various roles in the body, such as regulating metabolism, supporting growth and development, protecting cells from damage, and maintaining normal function of organs and systems.
Types of vitamins
Vitamins can be classified into two groups based on their solubility in water: water-soluble vitamins and fat-soluble vitamins.
• Water-soluble vitamins are vitamins that dissolve in water and are easily absorbed and excreted by the body. They include vitamin C and the B-complex vitamins (thiamin, riboflavin, niacin, pantothenic acid, biotin, folate, vitamin B6, and vitamin B12). Water-soluble vitamins are involved in various processes such as energy production, antioxidant defense, nerve function, blood formation, and gene expression. Because water-soluble vitamins are not stored in the body, they need to be consumed regularly to avoid deficiency. Excess intake of water-soluble vitamins is usually harmless, as they are eliminated in the urine, but may cause some side effects such as nausea, diarrhea, or flushing at high doses.
• Fat-soluble vitamins are vitamins that dissolve in fat and are stored in the liver and fatty tissues. They include vitamin A, vitamin D, vitamin E, and vitamin K. Fat-soluble vitamins are important for vision, bone health, skin health, blood clotting, and immune function. Because fat-soluble vitamins are stored in the body, they do not need to be consumed as frequently as water-soluble vitamins, but they can also accumulate to toxic levels if consumed in excess. Excess intake of fat-soluble vitamins can cause symptoms such as headache, nausea, vomiting, liver damage, or bleeding disorders.
Why do we need vitamins?
Vitamins are essential for life because they participate in various biochemical reactions that are necessary for normal health and growth. Vitamins have several functions in the body:
- Vitamin A helps maintain healthy vision , skin , mucous membranes , and immune system . It also supports growth and development of bones , teeth , and cells .
- Vitamin C helps synthesize collagen , which is a structural protein found in connective tissue , skin , bones , cartilage , and blood vessels . It also acts as an antioxidant , which protects cells from free radical damage . It also enhances iron absorption , wound healing , and immune function .
- Vitamin D helps regulate calcium and phosphorus metabolism , which are essential for bone health . It also modulates immune function , cell growth , and inflammation .
- Vitamin E helps protect cell membranes from oxidative damage caused by free radicals . It also supports immune function , blood circulation , and nerve function .
- Vitamin K helps activate proteins involved in blood clotting , bone metabolism , and vascular health . It also regulates gene expression and cell signaling .
- Thiamin helps convert carbohydrates into energy . It also supports nerve function , muscle contraction , and heart function .
- Riboflavin helps produce energy from carbohydrates , fats , and proteins . It also supports antioxidant defense , red blood cell production , and skin health .
- Niacin helps produce energy from carbohydrates , fats , and proteins . It also supports DNA repair , cholesterol metabolism , and skin health .
- Pantothenic acid helps produce energy from carbohydrates , fats , and proteins . It also supports hormone synthesis , fatty acid synthesis , and wound healing .
- Biotin helps produce energy from carbohydrates , fats , and proteins . It also supports fatty acid synthesis , amino acid metabolism , and hair and nail growth .
- Folate helps synthesize DNA and RNA , which are the genetic material of cells . It also supports red blood cell production , cell division , and neural tube development in embryos .
- Vitamin B6 helps metabolize amino acids , which are the building blocks of proteins . It also supports hemoglobin synthesis , neurotransmitter synthesis , hormone regulation , and immune function .
- Vitamin B12 helps synthesize DNA and RNA . It also supports red blood cell production , nerve function , homocysteine metabolism , and brain health .
How much vitamins do we need?
The amount of vitamins that we need depends on various factors such as age, gender, activity level, health status, and dietary intake. The recommended dietary allowances (RDAs) or adequate intakes (AIs) for some essential vitamins for adults are:
- Vitamin A: 700 to 900 mcg per day
- Vitamin C: 75 to 90 mg per day
- Vitamin D: 15 to 20 mcg per day
- Vitamin E: 15 mg per day
- Vitamin K: 90 to 120 mcg per day
- Thiamin: 1.1 to 1.2 mg per day
- Riboflavin: 1.1 to 1.3 mg per day
- Niacin: 14 to 16 mg per day
- Pantothenic acid: 5 mg per day
- Biotin: 30 mcg per day
- Folate: 400 mcg per day
- Vitamin B6: 1.3 to 1.7 mg per day
- Vitamin B12: 2.4 mcg per day
However, not all vitamins are beneficial in excess. Some vitamins can cause adverse effects or interfere with the absorption or metabolism of other nutrients if consumed in high amounts. The tolerable upper intake levels (ULs) for some potentially harmful vitamins for adults are:
- Vitamin A: 3,000 mcg per day
- Vitamin C: 2,000 mg per day
- Vitamin D: 100 mcg per day
- Vitamin E: 1,000 mg per day
- Niacin: 35 mg per day
- Folate: 1,000 mcg per day
- Vitamin B6: 100 mg per day
Vitamins are organic substances that are present in small amounts in natural foodstuffs. They are essential nutrients that the body cannot synthesize in sufficient quantities and therefore must obtain from the diet. Vitamins have various roles in the body, such as regulating metabolism, supporting growth and development, protecting cells from damage, and maintaining normal function of organs and systems. Vitamins should be obtained from a balanced diet that includes a variety of foods from different sources. Vitamins should be consumed in adequate amounts to meet the body’s needs, but not in excess to avoid adverse effects.