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B Vitamins
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Food Nutrition

B Vitamins

B vitamins are essential nutrients that help your body convert food into energy and support the formation of red blood cells.

The B Vitamin Complex

The B vitamins include:

  • B1 (thiamine)
  • B2 (riboflavin)
  • B3 (niacin)
  • B5 (pantothenic acid)
  • B6
  • B7 (biotin)
  • B12
  • Folic acid

Sources and Deficiency

B vitamins are found in protein-rich foods such as fish, poultry, meat, eggs, and dairy products. They are also present in leafy green vegetables, beans, and peas, and are frequently added to cereals and breads.

A deficiency in specific B vitamins can lead to health issues; for instance, a lack of B12 or B6 can result in anemia.

Frequently Asked Questions

Common symptoms of B vitamin deficiency include fatigue, weakness, and shortness of breath due to anemia. Specific signs depend on the vitamin: B12 deficiency can cause tingling in the hands and feet, memory problems, and balance issues. B1 deficiency may lead to confusion or heart problems. B3 deficiency can cause a rash, diarrhea, and dementia. Because symptoms often overlap, a blood test is the only way to confirm a specific deficiency.
Most B vitamins are water-soluble and can be taken on an empty stomach, but some people experience mild nausea or stomach upset. If you have a sensitive stomach, it is best to take them with a small meal or snack. Taking them with food may also improve the absorption of certain forms, particularly if you are taking a multivitamin that includes minerals like zinc or iron, which can compete for absorption.
For most healthy individuals who eat a varied diet including meat, eggs, dairy, whole grains, and vegetables, dietary intake is usually sufficient, and supplements are not necessary. However, certain groups are at higher risk for deficiency and may need supplements. These include older adults, who may have reduced stomach acid affecting B12 absorption, vegans and vegetarians who may lack B12, and people with gastrointestinal disorders like celiac disease or Crohn's disease that impair nutrient absorption.
The timeline varies by the specific vitamin and the severity of the deficiency. Water-soluble B vitamins like B1 and B6 are absorbed quickly, so you may notice improved energy levels within days to weeks. However, correcting a severe deficiency of B12 or folate, which can cause anemia or neurological issues, often requires several weeks to months of consistent supplementation before blood markers normalize and symptoms fully resolve. Always follow your healthcare provider's schedule for retesting.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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