What are vitamins?
The term vitamin is derived from the words vital and amine, because vitamins are required for life and were originally thought to be amines. Although not all vitamins are amines, they are organic compounds required by humans in small amounts from the diet.
Vitamins are a group of substances that are needed for normal cell function, growth, and development. There are 13 essential vitamins. This means that these vitamins are required for the body to work properly. They are two types of vitamins:
- Fat-soluble vitamins are stored in the body’s fatty tissue. The four fat-soluble vitamins are vitamins A, D, E, and K. These vitamins are absorbed more easily by the body in the presence of dietary fat.
- Water-soluble vitamins: Vitamin C and eight B vitamins. The body must use water-soluble vitamins right away. Any leftover water-soluble vitamins leave the body through the urine. Vitamin B12 is the only water-soluble vitamin that can be stored in the liver for many years.
Each of the 13 vitamins has an important job in the body. A vitamin deficiency occurs when you do not get enough of a certain vitamin. Vitamin deficiency can cause health problems.
Not eating enough vegetables, whole grains and fortified dairy foods may increase your risk for health problems, including heart disease, cancer, and poor bone health. In the bottom of this article, we list the function and sources of each vitamin.
What kind of multivitamin should I take?
Meeting all your nutrition needs from diet is ideal but is not possible sometimes. Vitamin deficiencies are commonly linked to chronic diseases, special life stage such as pregnancy and menopause. Even a complete diet may not be giving you the nutrients you need. That’s where multivitamins come in.
Multivitamins are supplements that contain many different vitamins and minerals, sometimes along with other ingredients. Multivitamins are the most commonly used supplements in the world. A daily multivitamin can help provide a good foundation for your health. It can also protect you when you’re experiencing stress, sleeping poorly, or not getting regular exercise. The question is: with so many choices available, how do you know exactly what to look for when shopping for a multivitamin?
Experts say there are seven ingredients your multivitamin should have, no matter what brand you choose:
- Vitamin D: it helps our bodies absorb calcium, which is important for bone health. Not getting enough of vitamin D can increase your likelihood of getting sick, bone and hair loss, and back pain.
- Magnesium: it is best known for being important to our bone health and energy production.
- Calcium: many people are not getting this mineral they need for strong bones and teeth.
- Zinc: it supports our immune system and helps our body use carbohydrates, protein, and fat for energy. It also aids in wound healing.
- Iron: certain circumstances like having your menstrual cycle, going through puberty, and being pregnant may increase the amount of iron you need.
- Folate: it is needed to make red and white blood cells in the bone marrow, convert carbohydrates into energy, and produce DNA and RNA.
- Vitamin B-12: it works to keep the body’s nerve and blood cells healthy and helps make DNA. Vegan or vegetarians are prone to vitamin B-12 deficiency.
(Source: National Institute of Health)
Did you know?
Pregnant and breastfeeding women need more vitamin B6 and B12, as well as folic acid (or folate, if possible), to prevent vitamin deficiencies that could harm a developing fetus. Folate can help reduce the risk of a number of birth defects, and can also prevent low birth weight. It’s best to take folate daily for at least a year before your planned pregnancy.
Vitamin D deficiency has been linked to a whole number of health issues from osteoporosis to heart disease and depression. Typically, the sun helps your body produce all the vitamin D you need, or at least close enough that you can get the rest through your diet. But if you live in the North, there’s a good chance you aren’t getting enough of it in the fall and winter months.
If you do decide vitamin D supplements are right for you, look for a product that contains vitamin D3, which your body can absorb better than vitamin D2. You should pair it with at least 1,000 milligrams of calcium per day, either through diet or a combination of diet and supplements.
Typical vitamin E supplements contain only alpha-tocopherol, the best known member of the eight-member vitamin E family. The less known member, tocotrienol, due to small but important structural differences, can get more involved in profound biological processes, such as modulating gene expressions and regulating vital enzyme functions.
Tocotrienols have potent antioxidant effects and may have anticancer and anti-diabetes abilities. It is now apparent that studies showing little or no effect from vitamin E supplementation failed in part because they used only alpha-tocopherol, rather than also including tocotrienols.
Fat-soluble Vitamins
Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids. Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision.
Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation.Vitamin D promotes calcium absorption in the gut and maintains adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and to prevent hypocalcemic tetany. It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts. Vitamin D has other roles in the body, including modulation of cell growth, neuromuscular and immune function, and reduction of inflammation.
Vitamin E is the collective name for a group of fat-soluble compounds with distinctive antioxidant activities. Vitamin E is a nutrient that’s important to vision, reproduction, and the health of your blood, brain and skin.Foods rich in vitamin E include canola oil, olive oil, margarine, almonds and peanuts. You can also get vitamin E from meats, dairy, leafy greens and fortified cereals. Vitamin E is also available as an oral supplement in capsules or drops.
Vitamin K, the generic name for a family of compounds with a common chemical structure of 2-methyl-1,4-naphthoquinone, is a fat-soluble vitamin that is naturally present in some foods and is available as a dietary supplement. Vitamin K is an important nutrient that plays a vital role in blood clotting and bone and heart health. Inadequate intake may cause bleeding, weaken your bones and potentially increase your risk of developing heart disease.
Water-soluble Vitamins
Thiamin (or thiamine) is one of the water-soluble B vitamins. It is also known as vitamin B1. Thiamin is naturally present in some foods, added to some food products, and available as a dietary supplement. This vitamin plays a critical role in energy metabolism and, therefore, in the growth, development,
Riboflavin (also known as vitamin B2) is one of the B vitamins and is naturally present in some foods, added to some food products, and available as a dietary supplement. This vitamin is an essential component of two major coenzymes, flavin mononucleotide (FMN; also known as riboflavin-5’-phosphate) and flavin adenine dinucleotide (FAD). These coenzymes play major roles in energy production; cellular function, growth, and development; and metabolism of fats, drugs, and steroids.
Niacin helps the digestive system, skin, and nerves to function. It is also important for converting food to energy.
Pantothenic acid, also called vitamin B5 (a B vitamin), is a water-soluble vitamin. Pantothenic acid is an essential nutrient. Animals require pantothenic acid in order to synthesize coenzyme-A (CoA), as well as to synthesize and metabolize proteins, carbohydrates, and fats.
Vitamin B6 (Pyridoxine) is a vitamin that is naturally present in many foods. The body needs vitamin B6 for more than 100 enzyme reactions involved in metabolism. Vitamin B6 is also involved in brain development during pregnancy and infancy as well as immune function.
Vitamin B7 (Biotin) is a water-soluble vitamin that’s a part of the vitamin B family. It’s also known as vitamin H. Your body needs biotin to help convert certain nutrients into energy. It also plays an important role in the health of your hair, skin, and nails.
Vitamin B9, more commonly known as folate (naturally-occurring form of B9) or folic acid (a synthetic form), is a water-soluble vitamin that is part of the B vitamin family. It is important in red blood cell formation and for healthy cell growth and function. The nutrient is crucial during early pregnancy to reduce the risk of birth defects of the brain and spine. Folate is found mainly in dark green leafy vegetables, beans, peas and nuts.
Vitamin B-12 (cobalamin) is a water-soluble vitamin that plays essential roles in red blood cell formation, cell metabolism, nerve function and the production of DNA. Vitamin B12 functions as a cofactor for methionine synthase and L-methylmalonyl-CoA mutase. Food sources of vitamin B-12 include poultry, meat, fish and dairy products.
Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenously, so it is an essential dietary component. Vitamin C is required for the biosynthesis of collagen, L-carnitine, and certain neurotransmitters; vitamin C is also involved in protein metabolism.
Fat-soluble vitamins
Fat-soluble vitamins are stored in the body’s cells and are not excreted as easily as water-soluble vitamins. They do not need to be consumed as often as water-soluble vitamins, although adequate amounts are needed. If you take too much of a fat-soluble vitamin, it could become toxic.
A balanced diet usually provides enough fat-soluble vitamins. You may find it more difficult to get enough vitamin D from food alone and may consider taking a vitamin D supplement or a multivitamin with vitamin D in it.
Nutrient | Function | Sources |
Vitamin A (and its precursor*, beta-carotene) | Needed for vision, healthy skin and mucous membranes, bone and tooth growth, immune system health | Vitamin A from animal sources (retinol): fortified milk, cheese, cream, butter, eggs, liverBeta-carotene (from plant sources): Leafy, dark green vegetables; dark orange fruits and vegetables (carrots, winter squash, sweet potatoes, pumpkin) |
Vitamin D | Needed for proper absorption of calcium; stored in bones | Egg yolks, liver, fatty fish, fortified milk. When exposed to sunlight, the skin can make vitamin D. |
Vitamin E | Antioxidant; protects cell walls | Polyunsaturated plant oils (soybean, corn, cottonseed); leafy green vegetables; wheat germ; whole-grain products; liver; egg yolks; nuts and seeds |
Vitamin K | Needed for proper blood clotting | Leafy green vegetables such as kale, and spinach; green vegetables such as broccoli, asparagus; also produced in intestinal tract by bacteria |
Water-soluble vitamins
Water-soluble vitamins travel freely through the body, and excess amounts usually are excreted by the kidneys. The body needs water-soluble vitamins in frequent, small doses. These vitamins are not as likely as fat-soluble vitamins to reach toxic levels.
A balanced diet usually provides enough of these vitamins. People older than 50 and some vegetarians may need to use supplements to get enough B12.
Nutrient | Function | Sources |
Thiamine (vitamin B1) | Part of an enzyme needed for energy metabolism; important to nerve function | Found in all nutritious foods in moderate amounts: pork, whole-grain or enriched breads and cereals, legumes, nuts and seeds |
Riboflavin(vitamin B2) | Part of an enzyme needed for energy metabolism; important for normal vision and skin health | Milk and milk products; leafy green vegetables; whole-grain, enriched breads and cereals |
Niacin (vitamin B3) | Part of an enzyme needed for energy metabolism; important for nervous system, digestive system, and skin health | Meat, poultry, fish, whole-grain or enriched breads and cereals, vegetables peanut butter |
Pantothenic acid (vitamin B5) | Part of an enzyme needed for making DNA and new cells, especially red blood cells | Leafy green vegetables and legumes, seeds, orange juice, and liver; now added to most refined grains |
Pyridoxine (vitamin B6) | Part of an enzyme needed for protein metabolism; helps make red blood cells | Meat, fish, poultry, vegetables, fruits |
Biotin (vitamin B7) | Part of an enzyme needed for energy metabolism | Widespread in foods; also produced in intestinal tract by bacteria |
Folic acid (vitamin B9) | Part of an enzyme needed for making DNA and new cells, especially red blood cells | Leafy green vegetables and legumes, seeds, orange juice, and liver |
Cobalamin (vitamin B12) | Part of an enzyme needed for making new cells; important to nerve function | Meat, poultry, fish, seafood, eggs, milk and milk products; not found in plant foods |
Ascorbic acid (vitamin C) | Antioxidant; part of an enzyme needed for protein metabolism; important for immune system health; aids in iron absorption | Found only in fruits and vegetables, especially citrus fruits, vegetables in the cabbage family, peppers, tomatoes, potatoes, lettuce, kiwifruit, etc |