Vitamins

Definition

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:

Vitamins are grouped into two categories:

Some vitamin-like nutrients are also needed by the body such as:

Function

Each of the vitamins listed below 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 fruits, vegetables, beans, lentils, whole grains and fortified dairy foods may increase your risk for health problems, including heart disease, cancer, and poor bone health (osteoporosis).

Food Sources

FAT-SOLUBLE VITAMINS

Vitamin A:

Vitamin D:

Vitamin E:

Vitamin K:

WATER-SOLUBLE VITAMINS

Biotin:

Folate:

Niacin (vitamin B3):

Pantothenic acid:

Thiamine (vitamin B1):

Pyridoxine (vitamin B6):

Vitamin B12:

NOTE: Animal sources of vitamin B12 are absorbed much better by the body than plant sources.

Vitamin C (ascorbic acid):

Side Effects

Many people think that if some is good, a lot is better. This is not always the case. High doses of certain vitamins can be toxic. Ask your health care provider what is best for you.

Recommendations

Recommendations for vitamin A, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:

Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.

Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.

The best way to get all the daily vitamins you need is to eat a balanced diet that contains a wide variety of fruits, vegetables, fortified dairy foods, legumes (dried beans), lentils, and whole grains.

Dietary supplements are another way to get the vitamins you need if the food you eat is not supplying enough vitamins. Supplements can be helpful during pregnancy and for special medical problems.

If you take supplements, do not take more than 100% of the RDA unless you are under a provider's supervision. Be very careful about taking large amounts of fat-soluble vitamin supplements. These include vitamins A, D, E, and K. These can build up in your body and may cause harmful effects.

References

Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 205.

Markell M, Siddiqi HA. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 27.

National Institutes of Health website. Nutrient Recommendations: Dietary Reference Intakes (DRI). ods.od.nih.gov/HealthInformation/nutrientrecommendations.aspx. Accessed February 21, 2023.



Review Date: 1/19/2023
Reviewed By: Stefania Manetti, RD/N, CDCES, RYT200, My Vita Sana LLC - Nourish and heal through food, San Jose, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
© 1997- adam.comAll rights reserved.
A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.