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Vitamin B (B6, B9, B12)

What is vitamin B?

B vitamins help your body perform a variety of functions, including energy metabolism, creating blood cells, and maintaining brain function. 

Vitamin B6, also called pyridoxine, helps digest nutrients, create blood cells, and produce signals to allow our brains to function properly. Low levels of vitamin B6 may lead to confusion or depression, a weakened immune system, and anemia. Taking pyridoxine supplements may help address nausea and vomiting in pregnant women¹.

Vitamin B9, also called folate and folic acid, contributes to cell growth and the production of DNA and red blood cells. Lack of folate may cause anemia and fatigue and is especially important for healthy fetal development.

Vitamin B12, also called cobalamin, helps create new red blood cells, breaks down fats and proteins to be used for energy, and maintains brain function. Vitamin B12 deficiency may cause confusion or depression. A long-term deficiency may result in permanent nerve and brain damage.

What causes vitamin B deficiency?

Those at risk for not getting enough B vitamins in their diet include the elderly who have a poor diet, alcoholics, those with digestive disorders that prevent nutrient absorption, and pregnant women. 

Your healthcare professional may recommend testing your levels of B vitamins if you experience symptoms including fatigue, weakness, constipation, loss of appetite, numbness in the hands and feet, confusion, nausea, anemia, skin rashes, heart palpitations, shortness of breath, or open sores in your mouth²,³.


What is a normal vitamin B level?

The normal ranges for B vitamins in the blood are as follows:

  • Vitamin B6: 5–50 µg/L
  • Vitamin B9: >4.0 µg/L
  • Vitamin B12: 180–914 ng/L

Those with vitamin B12 levels of 150–400 ng/L are borderline deficient and require further testing to determine the cause.


How can I improve my vitamin B levels?

To address a deficiency of any of the above B vitamins, healthcare professionals may suggest supplements, taken orally or as an injection.


  1. Sahakian V, Rouse D, Sipes S, et al. Vitamin B6 is effective therapy for nausea and vomiting of pregnancy: a randomized, double-blind placebo-controlled study. Obstet Gynecol 1991;78(1):33–36.
  2. Healthline. Symptoms of vitamin B deficiencies. Available from: https://www.healthline.com/health/symptoms-of-vitamin-b-deficiency
  3. Mayo Clinic. Vitamin deficiency anemia. Available from: https://www.mayoclinic.org/diseases-conditions/vitamin-deficiency-anemia/symptoms-causes/syc-20355025 
  4. Mayo Clinic Laboratories. Test ID: B6PRO. Vitamin B6 Profile (pyridoxal 5-phosphate and pyridoxic acid), plasma. Available from: https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/42360 
  5. de Benoist B. Conclusions of a WHO Technical Consultation on folate and vitamin B12 deficiencies. Food Nutr Bull 2008;29(2 Suppl):S238–244.
  6. Mayo Clinic Laboratories.
Last updated:
September 23, 2021

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