Vitamin B12

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Vitamin B12 is a necessary component of DNA production, the function of blood cells and nervous system processes. It is commonly found in animal products and not present in fruits or vegetables. As a result, vegans and vegetarians are at higher risk for vitamin B12 deficiency. Older adults are also found to have lower vitamin B12 levels because they have difficulty absorbing it. The FDA recommends 2.4mcg of vitamin B12 per day, but supplements often include much higher levels.

Cognitive and Nervous System

From 2006 to 2008, men and women aged 45 to 69 from Eastern Europe were studied to observe the effect of serum folate and B12 on cognitive function. Immediate and delayed recall tests, verbal fluency tests, and letter search tests were administered at the baseline and end of the study period. Participants with the highest levels of folate scored the best on verbal fluency and immediate recall test. High vitamin B12 levels were also associated with better word recall and higher verbal fluency scores.

A cross-sectional study was performed on 2,287 adults aged 72 to 83. The study found 7% of participants were deficient in B12 and an additional 10% of participants had low levels. B12 deficient status was associated with greater insensitivity to light and touch and worse nerve conduction amplitude and velocity.

  1. Serum folate, vitamin B-12 and cognitive function in middle and older age: The HAPIEE study.

    Horvat P, Gardiner J, Kubinova R, Pajak A, Tamosiunas A, Schöttker B, Pikhart H, Peasey A, Jansen E, Bobak M., Experimental gerontology, 2016

  2. Relationship between vitamin B12 and sensory and motor peripheral nerve function in older adults.

    Leishear K, Boudreau RM, Studenski SA, Ferrucci L, Rosano C, de Rekeneire N, Houston DK, Kritchevsky SB, Schwartz AV, Vinik AI, Hogervorst E, Yaffe K, Harris TB, Newman AB, Strotmeyer ES; Health, Aging and Body Composition Study., Journal of the American Geriatrics Society, 2012


Vegetarians and vegans have a higher risk of Vitamin B12 deficiency because it is a vitamin largely found in animal products, not in plant or grain-based products except those that are fortified with it.

  1. Health effects of vegan diets

    Winston J Craig, The American Journal of Clinical Nutrition, 2009

  2. Nutritional Update for Physicians: Plant-Based Diets

    Tuso PJ, Ismail MH, Ha BP, Bartolotto C., The Permanente Journal, 2013

  3. Vitamin B12 - Dietary Supplement Fact Sheet

    Office of dietary supplements, National Institutes of Health, 2016