What are vitamins and how is it that they work?

What are vitamins and how is it that they work?

Vitamins are organic compounds, which are needed to sustain life in small quantities. The bulk of the vitamins will come from food.

This is because either the human body does not contain enough of them, or it produces no at all.

Each organism has different requirements regarding vitamins. People need to eat vitamin C, or ascorbic acid, for example, but dogs don’t. Dogs can provide enough vitamin C for their own needs, or synthesize it, but humans can’t.

People tend to get most of their vitamin D from sunlight exposure, because it is not available in food in large enough quantities. Yet when exposed to sunlight, the human body will synthesize it.

Various vitamins have different roles and varying quantities are required.

This article explains what are the vitamins, what they do, and what foods each type offers. To learn more about each form of vitamin follow the links.

Fast Vitamin Facts

Here are a few key points on vitamins. The main article includes more descriptions and supporting information.

  • There are 13 vitamins that are known.
  • Vitamins are either soluble in water or soluble in fat.
  • The body can store fat-soluble vitamins better than water-soluble vitamins.
  • Vitamins always contain carbon, so they are described as “organic.”
  • Food is the best vitamin source, but a doctor may advise some people to use supplements.
Fruit and vegetables are an excellent source of a variety of vitamins.
Fruit and vegetables are an excellent source of a variety of vitamins.

A vitamin is one of a group of organic substances present in minute quantities in natural foodstuffs. Vitamins are essential for normal metabolism. If we don’t take enough of any kind of vitamin, it can result in certain medical conditions.

A vitamin is both:

  • an organic compound, which means that it contains carbon
  • an essential nutrient that is not properly produced by the body and needs to be derived from food.

There are currently 13 vitamins recognised

Fat-soluble and water-soluble vitamins

Vitamins are either fat-soluble or water-soluble.

Fat-soluble vitamins

Fat soluble vitamins are contained in both body and liver fatty tissues. The vitamins A, D, E and K are soluble in fat. These are easier to store than water-soluble vitamins and for days, and sometimes months, they will stay in the body as reserves.

Fat-soluble vitamins are absorbed by fats, or lipids, through the intestinal tract.

Water soluble vitamins

Water-soluble vitamins do not remain long in the body. These can not be processed by the body, and will soon be excreted in urine. Because of this it is necessary to replace water-soluble vitamins more often than fat-soluble ones. Vitamin C and all the vitamins B are water soluble.


Below are the different types of vitamins.

Vitamin A

Chemical terms A: Retinol, retinal and four carotenoids, including beta carotene.

  • It’s soluble in water.
  • Deficiency can cause night-blindness and keratomalacia, which leads to a dry cornea.
  • Great sources include: liver, cod liver oil, cabbage, broccoli, sweet potatoes, butter, kale, spinach, pumpkin, collard greens, some cheeses, bacon, apricot, melon cantaloupe, and milk.

Vitamin B

Chemical name: Thiamine.

  • It is soluble in water.
  • Deficiency may cause Beriberi and Wernicke-Korsakoff syndrome.
  • Great sources include: yeast, bacon, cereal grains, sunflower seeds, brown rice, wholegrain rye, asparagus, kale, cauliflower, cabbage, grapes, liver, and eggs.

Vitamin B2

Chemical name: Riboflavin

  • It is water soluble
  • Deficiency may cause ariboflavinosis
  • Good sources include: asparagus, bananas, persimmons, okra, chard, cottage cheese, milk, yogurt, meat, eggs, fish, and green beans

Vitamin B3

Chemical names: Niacin, niacinamide

  • It is water soluble.
  • Deficiency may cause pellagra, with symptoms of diarrhea, dermatitis, and mental disturbance.
  • Good sources include: liver, heart, kidney, chicken, beef, fish (tuna, salmon), milk, eggs, avocados, dates, tomatoes, leafy vegetables, broccoli, carrots, sweet potatoes, asparagus, nuts, whole-grains, legumes, mushrooms, and brewer’s yeast.

Vitamin B5

Chemical name: Pantothenic acid

  • It is water soluble.
  • Deficiency may cause paresthesia, or “pins and needles.”
  • Good sources include: meats, whole-grains (milling may remove it), broccoli, avocados, royal jelly, and fish ovaries.

Vitamin B6

Chemical names: Pyridoxine, pyridoxamine, pyridoxal

  • It is water soluble.
  • Deficiency may cause anemia, peripheral neuropathy, or damage to parts of the nervous system other than the brain and spinal cord.
  • Good sources include: meats, bananas, whole-grains, vegetables, and nuts. When milk is dried, it loses about half of its B6. Freezing and canning can also reduce content.

Vitamin B7

Chemical name: Biotin

  • it is water soluble.
  • Deficiency may cause dermatitis or enteritis, or inflammation of the intestine.
  • Good sources include: egg yolk, liver, some vegetables.

Vitamin B9

Chemical names: Folic acid, folinic acid

  • It is water soluble.
  • Deficiency during pregnancy is linked to birth defects. Pregnant women are encouraged to supplement folic acid for the entire year before becoming pregnant.
  • Good sources include: leafy vegetables, legumes, liver, baker’s yeast, some fortified grain products, and sunflower seeds. Several fruits have moderate amounts, as does beer.

Vitamin B12

Chemical names: Cyanocobalamin, hydroxocobalamin, methylcobalamin

  • It is water soluble.
  • Deficiency may cause megaloblastic anemia, a condition where bone marrow produces unusually large, abnormal, immature red blood cells.
  • Good sources include: fish, shellfish, meat, poultry, eggs, milk and dairy products, some fortified cereals and soy products, as well as fortified nutritional yeast.

Vegans are advised to take B12 supplements.

Vitamin C

Chemical name: Ascorbic acid

  • It is water soluble.
  • Deficiency may cause megaloblastic anemia.
  • Good sources include: fruit and vegetables. The Kakadu plum and the camu camu fruit have the highest vitamin C contents of all foods. Liver also has high levels. Cooking destroys vitamin C.

Vitamin D

Chemical names: Ergocalciferol, cholecalciferol.

  • It is fat soluble.
  • Deficiency may cause rickets and osteomalacia, or softening of the bones.
  • Good sources: Exposure to ultraviolet B (UVB) through sunlight or other sources causes vitamin D to be produced in the skin. Also found in fatty fish, eggs, beef liver, and mushrooms.

Vitamin E

Chemical names: Tocopherols, tocotrienols

  • It is fat soluble.
  • Deficiency is uncommon, but it may cause hemolytic anemia in newborns. This is a condition where blood cells are destroyed and removed from the blood too early.
  • Good sources include: Kiwi fruit, almonds, avocado, eggs, milk, nuts, leafy green vegetables, unheated vegetable oils, wheat germ, and whole-grains.

Vitamin K

Chemical names: Phylloquinone, menaquinones

  • It is fat soluble.
  • Deficiency may cause bleeding diathesis, an unusual susceptibility to bleeding.
  • Good sources include: leafy green vegetables, avocado, kiwi fruit. Parsley contains a lot of vitamin K.

Nutrition sources

The U.S. 2015–2020 Dietary Guidelines concentrate on overall diet as the best way to obtain adequate nutrients for wellbeing. Firstly, vitamins will come from a healthy and varied diet with lots of fruits and vegetables.

Fortified foods and supplements may however be sufficient in some cases. A health care practitioner can prescribe vitamin supplements to people with certain conditions, during pregnancy, or to those with a restricted diet.

Everyone taking supplements should be careful not to exceed the maximum dose indicated, as health problems will result. Several drugs can also interfere with vitamin supplements, so before using supplements, it is important to talk to a health care provider.

Watch The ABCs of vitamins video below


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