Vitamin B12

Know If You’re Low

* Please check with your medical provider before making any changes to your diet or supplements.

B12 helps red blood cells form, cells grow, and stay healthy. When B12 is low, it can affect athletic performance. You aren’t deficient, but it’s important to keep on top of it. Increase your intake of B12-rich foods if possible.

If your vitamin B12 is highlighted in yellow, it means your levels are below or above athlete optimal but are still considered to be within normal ranges.

B12 Foods

Good sources include meat, seafood, dairy, eggs, nutritional yeast, and fortified products such as cereals.

Below is a table of specific foods and how much B12 they contain per serving.


B12 Supplements

Vitamin B12 supplements to potentially including

Over supplementing with vitamin B12 is very common among athletes. Most athletes will only need to supplement for 4 to 8 weeks. Your body will store vitamin B12 for later use.

What if my levels are too high?

High vitamin B12 is very common among athletes that supplement with vitamin B12.

If your vitamin B12 is highlighted in yellow, it means your levels are getting close to being high. If you take a supplement, you can cut back your intake by 30 to 50%.

If vitamin B12 is highlighted in red, it means your levels are now outside the normal limits. You can stop your vitamin B12 for 2 to 3 months. If you want to start back on vitamin B12, consider taking a lower dose.

If you are not taking vitamin B12, then review the labels of your supplements, energy drinks, energy bars, and other sports-related nutritional products to determine if there may be a cause of high B12.


  • NIH – Vitamin B12 Fact Sheet for Health Professionals
  • Krzywański, J., Mikulski, T., Pokrywka, A., Młyńczak, M., Krysztofiak, H., Frączek, B., & Ziemba, A. (2020). Vitamin B12 Status and Optimal Range for Hemoglobin Formation in Elite Athletes. Nutrients12(4), 1038.
  • Herrmann M, Obeid R, Scharhag J, Kindermann W, Herrmann W. Altered vitamin B12 status in recreational endurance athletes. Int J Sport Nutr Exerc Metab. 2005 Aug;15(4):433-41. doi: 10.1123/ijsnem.15.4.433. PMID: 16286674.
  • E. Andrès, K. Serraj, J. Zhu, A.J.M. Vermorken, The pathophysiology of elevated vitamin B12 in clinical practice, QJM: An International Journal of Medicine, Volume 106, Issue 6, June 2013, Pages 505–515,
  • Hazra, A., Kraft, P., Selhub, J., Giovannucci, E. L., Thomas, G., Hoover, R. N., Chanock, S. J., & Hunter, D. J. (2008). Common variants of FUT2 are associated with plasma vitamin B12 levels. Nature genetics40(10), 1160–1162.