What Are Vitamins?

There are 13 essential vitamins that your body needs to function properly.

Vitamins are nutrients that your body needs for normal cell function, growth, and development.

They can be grouped into two main categories based on how they act in your body.

Fat-soluble vitamins, such as vitamins A, D, E, and K, are stored in your body's fatty tissue, where they are absorbed easily.

Water-soluble vitamins, such as vitamins B and C, are used immediately after entering the body.

Unneeded water-soluble vitamins are excreted from the body in your urine. The only exception is vitamin B12, which can be stored in your liver for years, per StatPearls.

Essential Vitamins

The following vitamins are considered essential, meaning your body can't produce them but needs them to function properly. Here are some of their key functions, per MedlinePlus:

Vitamin A, which helps form and maintain teeth, bones, soft tissue, mucous membranes, and skin
Vitamin C (ascorbic acid), which promotes healthy teeth and gums, healing of wounds, and absorption of iron by the body
Vitamin D, which helps absorb and maintain proper blood levels of phosphorus and calcium, minerals needed for development and healthy teeth and bones
Vitamin E, which helps red blood cells form and use vitamin K
Vitamin B1 (thiamine), which helps convert carbohydrates into energy and is important for the heart and nerve cells
Vitamin B2 (riboflavin), which promotes body growth and the production of red blood cells
Vitamin B3 (niacin), which helps maintain healthy skin and nerves and can lower blood cholesterol levels
Vitamin B 5 (pantothenic acid), which is needed to metabolize food and helps produce hormones and cholesterol
Biotin (B7), which is needed to metabolize proteins and carbohydrates, and to produce hormones and cholesterol
Vitamin B6, which helps red blood cells form, helps maintain brain function, and supports protein synthesis
Vitamin B12 (cyanocobalamin), which helps with metabolism, red blood production, and maintaining the central nervous system
Folate (folic acid and B9), which helps red blood cells form and is needed to produce DNA, which controls tissue growth and cell function
Vitamin K, which is necessary for blood clotting

Getting the Right Amount of Vitamins

Eating a balanced diet that includes a variety of fruits, vegetables, fortified dairy foods, legumes (beans, lentils, and peas), and whole grains is the best way to get adequate vitamins, per the Centers for Disease Control and Prevention (CDC).

In some cases, though, you may need to take supplements if your diet isn't providing enough vitamins or if you have a medical condition that affects the way your body absorbs nutrients.

Talk with your doctor about what's best for you. Keep in mind that taking too much of certain vitamins, without medical supervision, can cause serious health problems.

The recommended dietary allowance (RDA), set by the Institute of Medicine, is a guideline for how much of each vitamin most people should get daily.

Vitamin Deficiencies and Malnutrition

Despite being a well-nourished population, nearly one-third of the U.S. population (31 percent, to be exact) over age 9 is at risk of having at least one vitamin deficiency or has anemia, according to research that pulled data from the 2003–2006 National Health and Nutrition Examination Survey (NHANES) analyzing vitamins A, B6, B12, C, D, E, folate, and anemia status.

In this study, females, people who are pregnant or breastfeeding, non-Hispanic Black people, those with low socioeconomic status, and people who have overweight or obesity were the groups at highest risk for a vitamin deficiency, the researchers found. The largest number of people had a vitamin B6 deficiency, while adult males (ages 19 to 50) had elevated rates of vitamin C deficiency, theorized to be due to not consuming enough fruits and vegetables. Those taking a multivitamin or eating an adequate diet (based on the "estimated average requirements") had a decreased risk of a deficiency, though it did not eliminate it completely. (Though it’s still important to consume a well-balanced diet despite taking a multivitamin.)

Another population study looking at the 2005–2016 NHANES data of nutrients key for immune health found that a “substantial” number of people were inadequate in 4 out of the 5 nutrients looked at. The researchers found that an estimated 45 percent of the U.S. population was inadequate in vitamin A, 46 percent inadequate in vitamin C, 95 percent inadequate for vitamin D, and 84 percent were inadequate in vitamin E. (Just 15 percent were inadequate in zinc.)

The World Health Organization (WHO) reports that iron deficiency is the most common micronutrient malnutrition globally.

Summary

There are 13 essential vitamins that your body needs to function properly. One-third of the U.S. population is at risk for a vitamin deficiency, though eating a well-balanced diet and taking a multivitamin decreased that risk. If you’re in a group who is especially vulnerable to a deficiency — for example, you’re female, currently pregnant or breastfeeding, or are a non-Hispanic Black person — talk to your doctor about your risk.

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