Functions of Vitamins: Do You Need to Take Them?

According to National Institute of Health: Office of Dietary Supplements (NIH ODS), Multivitamins-minerals (MVMs) first became available back in the 1940s and has been a popular dietary supplement ever since with more than one-third  of all Americans taking them.[1] Almost 17% of all dietary supplement purchases are multivitamin products and around 40% of all vitamin and mineral supplement sales are multivitamin products.[1] In 2014, multivitamin products accounted for $5.7 billion out of the total sales of $36.7 billion for all dietary supplements.[1] Based on vitamin sales statistics, vitamin sale has increased by 40% in 2018 and reached almost $31 billion in revenue.[2] With the estimated continued growth of 6.4% CAGR, based on analysis reports and data, the expected market will be around $210.3 billion by 2026.[2]

            Almost everyone has heard of or knows someone who takes multivitamins. You have probably seen the ads on TV or websites when you are browsing the internet. However, do you really know what each of the vitamins in the product does for the body? Out of all the dietary supplement products, there is no doubt that the most prominent one is the multivitamin. It is very convenient with just one pill per day and according to the bottle, provides nutritional support for “healthy energy metabolism, heart health, immune health, healthy muscle function, cell health, and healthy blood pressure.” If you look to the back of the supplement label you will notice that the multivitamin contains Vitamin A, Vitamin C, Vitamin D, Vitamin E, Vitamin K, Vitamin B1, Vitamin B2, Niacin, Pantothenic Acid, Vitamin B6, Biotin, Folate, Vitamin B12 as well as the minerals such as Calcium, Iron, Iodine, Magnesium, Zinc, etc. In this article, we will briefly go over the functions of each of the vitamins as well as the pros and cons of taking them.

            Before going over the functions of each vitamin, we need to first talk about the two types of vitamins: fat-soluble and water-soluble. Fat-soluble vitamins include vitamins A, D, E, and K and have properties similar to that of fat which requires bile and lipids for absorption. Taking too much of the fat-soluble vitamins can be dangerous because they are not as easily excreted. Everything that is not vitamin A, D, E, or K is considered to be a water-soluble vitamin. They can freely circulate through the body and excessive amounts are excreted by the kidneys through urine.

            Vitamin A is usually known to promote vision health. In addition, it plays a role in lowering prostate cancer risk, helping with tissue and skin health, and supporting bone growth and the immune system.[3,4,5] Vitamin D is generally known to promote bone health. It helps with the absorption of calcium to strengthen teeth and bone. Most people nowadays do not get enough sunlight and are prone to vitamin D deficiency.[3,4,5] According to reports, about 50% of the United States population may be deficient in Vitamin D.[2] Vitamin E is known to act as an antioxidant, neutralizing free radicals in the body to prevent cell damage.[3,4,5] Vitamin K is known to help the body with blood clotting, and one common suggestion is to keep the vitamin K levels consistent when taking anticoagulants/blood thinners such as Warfarin.[3,4,5]

Now onto the water-soluble vitamins. Vitamin C is generally known to act as an antioxidant and to help boost the immune system.[3,4,5] Scurvy is a disease that occurs from a lack of vitamin C. Vitamin B1 (Thiamin), Vitamin B2 (Riboflavin), Vitamin B3 (Niacin), and  Vitamin B5 (Pantothenic Acid) help the body to convert food into energy and is known to promote the growth and development of cells.[3,4,5] Vitamin B6 (Pyridoxine) may help with reducing the risk of heart disease, regulating sleep, appetite, and mood as well as being involved in immune function and brain development.[3,4,5] Vitamin B7 (Biotin) is known to help turn carbohydrates, proteins, and fats from food into energy such as glucose.[3,4,5] It is also prominent for being a component of many hair, skin, and nail products. Vitamin B9 (Folate) is known to help the body make DNA and other genetic materials as well as helping with cell division.[5] It is known to be part of prenatal vitamins as folic acid, which is a form of folate.[3,4,5] Vitamin B12 (Cobalamin) is known to support the health of nerve and blood cells as well as helping to make DNA and other genetic materials.[3,4,5]

Now that we have gone over a brief description of what each vitamin helps with, the question that comes to mind is “Should we be taking multivitamins?” Many of these vitamins and minerals are already part of a regular and healthy diet. So, the real question that should be asked is “Do you eat a healthy and well-balanced diet?” If you are someone who regularly eats fast food, generally stays indoors, and dislikes eating fresh fruits/vegetables, then considering to take a multivitamin daily may not be such a bad idea. However, if you are someone who regularly exercises outdoors and eats a well-balanced diet of fruits, vegetables, and red meat then taking the multivitamins will not benefit you as much. For most people, it is probably best to `pick the specific vitamin or mineral that you are deficient in recommended by your physician.

Lastly, this article is not meant to treat, diagnose, or prevent any disease; it is for informational purposes only so make sure to consult with your physician and pharmacist before starting any new medications, medical food, or supplements.


[1] “Office of Dietary Supplements – Multivitamin/Mineral Supplements.” NIH Office of Dietary Supplements, U.S. Department of Health and Human Services,

[2] Dobric, Mirjana. “31 Vitamin Statistics to Replenish Your Nutritional Gaps.” Supplements101, 26 May 2020,

[3] Publishing, Harvard Health. “Listing of Vitamins.” Harvard Health, June 2009,

[4] Ryan-Harshman, Milly, and Walid Aldoori. “Health Benefits of Selected Vitamins.” Canadian Family Physician Medecin De Famille Canadien, College of Family Physicians of Canada, 10 July 2005,

[5] “Dietary Supplement Fact Sheets.” NIH Office of Dietary Supplements, U.S. Department of Health and Human Services,

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