Nutrition

Vitamin B Complex | What Is It? Benefits? Deficiency Symptoms?

The group of vitamins known as the vitamin B complex plays many roles in keeping us healthy and active. You may hear about B vitamins being included in supplements that promise higher energy, and that is because many B vitamin functions relate to food metabolism.

Optimal levels of B vitamins can help our body to best absorb and use nutrients from food, which can impact workout performance. This article will help you learn the benefits of the B vitamin complex, as well as food sources and potential signs of deficiencies, when supplements can be especially helpful.

In this article, you’ll find:

variety of fruit and healthy food

What is the Vitamin B Complex?

Vitamin B complex is the term for a group of B vitamins that our body needs for optimal health. Because they are water soluble (dissolve in water) instead of fat soluble, they are not stored in our bodies and need to be obtained daily from our diet or supplements, although in small amounts.1 B vitamins impact appetite, vision, skin, nerves, and red blood cell formation.1 The vitamin B complex includes:

  • B1 (Thiamin) — essential for the growth, development, and function of our body’s cells2
  • B2 (Riboflavin) — plays a key role in harnessing the food we eat for energy and for cellular growth and function3
  • B3 (Niacin) — plays a role in converting foods to energy, as well as helping digestion, skin, and nerve cell function4
  • B5 (Pantothenic Acid) — helping convert our food to energy; crucial for making and breaking down fats5
  • B6 (Pyridoxine) — used for many metabolic functions, immunity, and plays a role in brain development6
  • B7 (Biotin) — plays a role in the metabolism of all three macronutrients (protein, carbohydrates, and fat)7
  • B9 (Folate) — crucial for cell division and DNA formation, making it especially important in the diets of pregnant women8
  • B12 (Cobalamin) — similar in function to other B vitamins (red blood cell development, neurological function, DNA formation) but is only found naturally in animal-based sources9

Some B complex vitamin supplements also contain vitamin C, since it is also water soluble. B vitamins are present in many animal based protein sources, like meat, fish, eggs, milk, and pork. Plant based food sources include leafy greens, beans, whole grains, and nuts.10

Because B vitamins are so crucial for health, many foods have them added during processing, called fortification. Foods like breakfast cereals and breads, since they are so widely consumed, are commonly fortified with B vitamins.10

vitamin b complex

Vitamin B Complex Deficiency Symptoms

When you don’t get enough of the vitamin B complex in your diet, deficiencies can show up in several different ways. The most common is anemia, when you are low in B12 and/or B6, and your blood can’t carry enough oxygen through your body.11 This may be of concern to those following a vegan diet, since animal products are common sources of these B vitamins.

Symptoms of anaemia include headaches, and being tired, weak, cold, or dizzy.11 Although there are many causes of anaemia, low levels of B6 and B12 can contribute to chronic anaemia.11

Other common symptoms of vitamin B deficiencies show up in the skin, nails, and hair – like rashes or cracks in the skin.1 Long term deficiency of thiamin causes beriberi (tingling/numbness, loss of muscle).2 Chronically low vitamin B3, or Niacin, results in a condition known as pellagra, which causes digestive and cognitive problems.10 Folate impacts cell and protein production, so a deficiency can impact growth in adults and developing babies.1

Who Should Take Vitamin B Complex?

Although B vitamins are commonly found in food, there are several groups of individuals in particular who can benefit from taking vitamin B complex supplements:

  • Those with a poor, low calorie diet
  • Vegans (typically low in B12)
  • Alcoholics – often times alcohol replaces calories from food
  • Pregnancy
  • Aging and other conditions that impact food intake
  • Those with digestive disorders who might have malabsorption of food1

Your doctor can order a simple blood test to diagnose a deficiency. As you can see from these groups, anyone who is not eating a well balanced, adequate calorie diet may benefit from a vitamin B complex supplement.

Pregnant and breastfeeding women require adequate B complex vitamins due to their crucial roles in healthy fetal and infant development.11 Adequate folate is recommended for women who are trying to conceive, because this vitamin is crucial in very early pregnancy.8

Many of the other B complex vitamins, like Thiamin, B6, and B12 are also crucial for developing babies due to their roles in cell development and DNA formation.2,6,9 Most pre-natal vitamins contain the vitamin B complex.

Vitamin B Complex Benefits

The benefits of taking vitamin B complex are related to its many roles in how our body functions. In addition to preventing the conditions associated with B Vitamin deficiencies, it can help boost energy and maximize your workout performance.1

Having the right levels of B vitamins improves digestion and absorption of nutrients, and keeps your hair, skin, and nails healthy.10 Ensuring adequate levels of B vitamins can improve mood and cognition, and some research shows benefits in other health conditions, like migraines.5,10

oranges

Vitamin B Complex Dosage & Side Effects

Because vitamin B complex vitamins are water soluble, they are not stored in our body and typically an overdose is not a concern.1 However, you may experience side effects of very large doses of any particular vitamin or supplement.

For example, starting a Niacin (B3) supplement can cause flushing of the skin, and pantothenic acid (B5) can cause an upset stomach.6,7

The following list shows the amounts of each B vitamin needed daily for adults – keep in mind that we obtain a lot of this amount from food, so a supplement need not contain more than these amounts:

  • B1 – Thiamin: 1.1-1.2 mg per day2
  • B2 – Riboflavin: 1.1-1.3mg per day (those who avoid dairy products or are vegan or vegetarian may need more)3
  • B3 – Niacin: 14-16mg per day4
  • B5 – Pantothenic acid: 5mg per day5
  • B6 – Pyridoxine: 1.2 – 1.3 mg per day (if over 50 increases to 1.5-1.7mg)6
  • B7 – Biotin: 30 mcg per day of biotin7
  • B9 – Folate: adults 400mg daily and pregnant women 600mg, but not more than 1000mg8
  • B12 – Cobalamin: 2.4mg per day9

Two items to note: there is an established upper limit for folic acid (B9), meaning more than this amount can be detrimental to health.8 B12 is one vitamin that is commonly supplemented alone because it is not always well absorbed from its food sources.

For this reason, it’s available in several different oral supplement forms, as well as a prescription strength injection.11

 

Take Home Message

Many of the B complex vitamins are found in every-day foods, but it is possible to become deficient with inadequate dietary intake or problems with absorption. For this reason, a B Complex Vitamin (on its own or as part of a multivitamin) can help to cover your daily needs. Because B Complex Vitamins are water soluble, they do not stay stored in our bodies and need to be taken in daily.1

Because all over the counter supplements may interact with other medications you are taking, speak with your doctor if you are concerned about your possible need for a supplement.

Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you’re concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.


  1. Bellows, L., Moore, R., Anderson, J., & Young, L. (2012). Water-soluble vitamins: B-complex and vitamin C. Food and nutrition series. Health; no. 9.312.
  2. Office of Dietary Supplements. (2016, April 13). National Institutes of Health Office of Dietary SupplementsThiamin.
  3. Office of Dietary Supplements. (2016, February 17). National Institutes of Health Office of Dietary Supplements – Riboflavin.
  4. US National Library of Medicine. (2018, June 20). MedlinePlus Medical Encyclopedia – Niacin.
  5. Office of Dietary Supplements. (2018, June 12). National Institutes of Health Office of Dietary Supplements – Pantothenic Acid.
  6. Office of Dietary Supplements. (2016, February 17). National Institutes of Health Office of Dietary Supplements – Vitamin B6.
  7. Office of Dietary Supplementes. (2017, December 8). National Institutes of Health Office of Dietary Supplements – Biotin.
  8. Office of Dietary Supplements. (2018, December 7). National Institutes of Health Office of Dietary Supplements – Folate.
  9. Office of Dietary Supplements. (2011, June 24). National Institutes of Health Office of Dietary Supplements – Vitamin B12.
  10. US National Library of Medicine. (2015, April 2). Health Topics: B Vitamins.
  11. US National Library of Medicine. (2016, July 29). Health Topics: Anemia.

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Claire Muszalski

Claire Muszalski

Registered Dietitian

Claire is a Registered Dietitian through the Academy of Nutrition and Dietetics and a board-certified Health and Wellness Coach through the International Consortium for Health and Wellness Coaching. She has a Bachelor of Science in Biology and a Master’s degree in Clinical Dietetics and Nutrition from the University of Pittsburgh.

Talking and writing about food and fitness is at the heart of Claire’s ethos as she loves to use her experience to help others meet their health and wellness goals.

Claire is also a certified indoor cycling instructor and loves the mental and physical boost she gets from regular runs and yoga classes. When she’s not keeping fit herself, she’s cheering on her hometown’s sports teams in Pittsburgh, or cooking for her family in the kitchen.

Find out more about Claire’s experience here.


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