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Dr. Andrea Pinto Lopez

Dr. Andrea Pinto Lopez

Dec 11, 20227 min read

What are Vitamins and How Do They Work?

The information provided herein does not constitute an expert or medical advice, nor intended to replace such advice.


No matter who you are, it’s very likely that you’ve heard someone discussing the benefits of vitamins and how to get enough vitamins in your diet or through supplements. But what exactly are vitamins, how many types of vitamins are there, and what functions do they have inside the human body?

Read this article to learn more about how vitamins help to keep the body healthy at STDWatch.com

What are vitamins?

Vitamins are organic substances that your body needs to function properly, which means they work as micronutrients inside the human body. According to the Harvard T.H. Chan School of Public Health, these micronutrients aren’t produced by the body itself, so we need to get them from the foods we eat every day.

All vitamins and what they do is necessary to maintain human health, since they’re involved in a large number of metabolic processes. However, we don’t need to consume the same amount of each vitamin, and the risks of excessive consumption also vary from one vitamin to the next.

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How many different types of vitamins are there?

Vitamins are typically classified as fat-soluble and water-soluble. These kinds of vitamin groups share some similarities that can affect how the body absorbs and uses them, and how often you need to consume them to stay healthy.

Fat-soluble vitamins can be absorbed into different fatty tissues throughout your body after you consume them. According to StatPearls, fat-soluble vitamins can be retained by your body for a longer time than water-soluble vitamins. However, fat-soluble vitamins are also more likely to produce toxicity if you take them in excessive amounts. Fat-soluble vitamins include:

  • Vitamin A
  • Vitamin D
  • Vitamin E
  • Vitamin K

Water-soluble vitamins, on the other hand, dissolve in water. As a result, excess vitamin levels are excreted through the urine and your body is unable to store large amounts of these nutrients. According to StatPearls, water-soluble vitamins can be easily “washed out” from your body, and as a result, regular intake of water-soluble vitamins is necessary to avoid deficiencies. Water-soluble vitamins include:

  • Vitamin B1 or thiamine
  • Vitamin B2 or riboflavin
  • Vitamin B3 or niacin
  • Vitamin B5 or pantothenic acid
  • Vitamin B6 or pyridoxine
  • Vitamin B7 or biotin
  • Vitamin B9 or folic acid
  • Vitamin B12 or cobalamin
  • Vitamin C or ascorbic acid

The effects of vitamins on the body

The purpose of vitamins can be very different depending on the type of vitamin. However, they’re all necessary to maintain optimal human health, and they’re all involved in regulating numerous processes throughout the body. According to MedlinePlus, vitamins and their benefits include:

  • Vitamin A: this vitamin is involved in maintaining healthy teeth, bones, skin, tissues, mucous membranes, and eyes.
  • Vitamin B1 or thiamine: this helps cells transform carbohydrates into energy. It also aids in normal heart function and nerve cell function.
  • Vitamin B2 or riboflavin: this vitamin is important for growth and the production of red blood cells.
  • Vitamin B3 or niacin: the benefit of this vitamin is in maintaining healthy skin and nerves. It also helps regulate your cholesterol levels.
  • Vitamin B5 or pantothenic acid: this plays an essential role in food metabolism, along with hormone and cholesterol production.
  • Vitamin B6 or pyridoxine: this vitamin helps form red blood cells and protect your brain function. It’s also heavily involved in protein metabolism.
  • Vitamin B7 or biotin: this vitamin is essential for protein, fats, and carbohydrate metabolism, and it also helps produce cholesterol and hormones.
  • Vitamin B9 or folic acid: this micronutrient works with other vitamins to form red blood cells. It’s also needed for DNA production, which is especially important during pregnancy in order to control tissue and cell growth.
  • Vitamin B12 or cobalamin: it helps form red blood cells and plays an important role in nutrient metabolism. It also helps protect the nervous system and its functions.
  • Vitamin C or ascorbic acid: the benefit of this vitamin is that it acts as an antioxidant, and it also helps maintain oral health. Vitamin C also helps you absorb iron correctly, and it’s involved in wound healing.
  • Vitamin D: this vitamin helps the body absorb calcium and phosphorus, which are needed to keep healthy bones and teeth.
  • Vitamin E: this vitamin helps the body use vitamin K correctly, and it’s also involved in red blood cell formation.
  • Vitamin K: this vitamin is essential for normal blood clotting, and it also plays a role in bone health.

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What are the sources of vitamins?

According to the National Institute on Aging, dietary sources of vitamins include:

  • Eggs
  • Dairy products
  • Vegetables
  • Fruits
  • Meat
  • Poultry
  • Fatty fish
  • Organ meats
  • Whole grains
  • Fortified cereals
  • Leafy greens
  • Nuts
  • Seeds
  • Legumes
  • Vegetable oils

How much of each vitamin do we need daily?

There is a recommended dietary allowance (RDA) determined for most vitamins, which tells you how much of each vitamin you need to consume every day in order to stay healthy. However, it’s also important to highlight that some vitamins can produce toxicity if you take them in excessive amounts, and a safe upper limit or tolerable upper intake level has also been determined for these vitamins. This is the highest amount of a vitamin that you can take each day without harming yourself.

The RDA and upper limit for each vitamin as:

  • Vitamin A: RDA is 700-900 micrograms (2,300-3,000 IU). Upper limit is 3,000 micrograms or 10,000 IU.
  • Vitamin B1: RDA is 1.1-1.2 milligrams, while its upper limit is unknown.
  • Vitamin B2: RDA is 1.1-1.3 milligrams, and its upper limit is unknown.
  • Vitamin B3: RDA is 14-16 milligrams. Upper limit is 35 milligrams.
  • Vitamin B5: RDA is 5 milligrams, while its upper limit is unknown.
  • Vitamin B6: RDA is 1.3-1.7 milligrams, depending on your age. Upper limit is 100 milligrams.
  • Vitamin B7: RDA is 30 micrograms, and its upper limit is unknown.
  • Vitamin B9: RDA is 400 micrograms, while its upper limit is 1,000 micrograms.
  • Vitamin B12: RDA is 2.4 micrograms, while the upper limit is unknown.
  • Vitamin C: RDA is 75-90 milligrams, while the upper limit is 2,000 milligrams.
  • Vitamin D: RDA is 600-800 IU, depending on your age and gender. Upper limit is 4,000 micrograms.
  • Vitamin E: RDA is 15 milligrams, while its upper limit is 1,000 milligrams.
  • Vitamin K: RDA is 90-120 micrograms, and its upper limit is unknown.

Vitamins: FAQ

Do vitamins contain carbon?

Vitamins do contain carbon, which is why they’re considered to be an organic compound.

Who discovered vitamins?

Casimir Funk was the first person to use the term “vitamin” in 1912. 

Can I take 5 different vitamins at once?

Yes, as long as you’re following the RDA for each vitamin. In fact, there are many multivitamin preparations available that contain most of the vitamins and minerals you need in your everyday life.

Which vitamins should not be taken together?

  • Multivitamin + magnesium/calcium supplement: magnesium and calcium can compete for absorption with your multivitamin.
  • Vitamins D, E, and K: vitamins D and E could lower your absorption of vitamin K.
  • Vitamins C and B12: vitamin C could damage vitamin B12 in your digestive tract.

Head over to STDWatch.com now to learn more about many topics on general wellness and sexual and reproductive health.

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Vitamins and Minerals - hsph.harvard.edu

Biochemistry, Water Soluble Vitamins - ncbi.nlm.nih.gov

Biochemistry, Fat Soluble Vitamins - ncbi.nlm.nih.gov

Vitamins - medlineplus.gov

Vitamins and Minerals for Older Adults - nia.nih.gov

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