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Vitamins & Minerals

Vitamin B12Evidence & Dosage

Holo-TC vs. total B12, methylcobalamin, vegan diets.

Studies last updated

Evidence at a glance

Total studies
659
With abstract
45
Meta / Systematic / RCT
134
Highly cited
50
Publication years
1978–2026

Vitamin B12 in the context of Vitamins & Minerals

This topic is part of our "Vitamins & Minerals" world. There you'll find methodology, evidence and the highest-impact levers — plus the order in which they sensibly build on each other.

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Top studies on Vitamin B12

Ranked by influential-citation count and publication year.

  1. Metformin Use Associated with Reduced Risk of Dementia in Patients with Diabetes: A Systematic Review and Meta-Analysis.

    J Alzheimers Dis2018n=14Meta-Analysis100 influential citations

    Background: Metformin, a first line antihyperglycemic medication, is an AMPK activator and has been hypothesized to act as a geroprotective agent. Studies on its association with various classifications of age-related cognitive decline…

  2. Impact of Vegan and Vegetarian Diets on Neurological Health: A Critical Review.

    Nutrients2025n=112systematic96 influential citations

    BACKGROUND/OBJECTIVES: The global shift towards vegan and vegetarian diets has garnered attention for their ethical, environmental, and potential health benefits. These diets are often rich in phytonutrients and antioxidants, which have…

  3. Vitamin Supplementation and Dementia: A Systematic Review.

    Nutrients2022systematic85 influential citations

    BACKGROUND: Dementia is a syndrome characterized by progressive cognitive impairment that interferes with independent function in daily activities. Symptoms of dementia depend on its cause and vary greatly between individuals. There is…

  4. Homocysteine levels, genetic background, and cognitive impairment in Parkinson's disease.

    J Neurol2023n=246Meta-Analysis67 influential citations

    Background Hyperhomocysteinemia is considered an independent risk factor for cognitive impairment. Objective To study the correlation between homocysteine levels and cognitive impairment in patients with PD. Methods We conducted a…

  5. Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life.

    Cochrane Database Syst Rev2018n=28Meta-Analysis65 influential citations

    <h4>Background</h4>Vitamins and minerals play multiple functions within the central nervous system which may help to maintain brain health and optimal cognitive functioning. Supplementation of the diet with various vitamins and minerals…

  6. Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression.

    Nutrients2021n=627Meta-Analysis64 influential citations

    Vitamin B12 is often used to improve cognitive function, depressive symptoms, and fatigue. In most cases, such complaints are not associated with overt vitamin B12 deficiency or advanced neurological disorders and the effectiveness of…

    Finding: Vitamin B12 supplementation was likely ineffective for improving cognitive function in patients without advanced neurological disorders.

  7. Micronutrient's deficiency in India: a systematic review and meta-analysis.

    J Nutr Sci2021n=270Meta-Analysis61 influential citations

    India is coming to grips with a stage of nutrition transition. According to the Food Safety and Standards Authority of India (FSSAI), preventable micronutrient deficiency is arising public health precedence in India. However, the foremost…

  8. Nutrient supplementation for prevention of viral respiratory tract infections in healthy subjects: A systematic review and meta-analysis.

    Allergy2022n=7,419Meta-Analysis57 influential citations

    It remains uncertain as to whether nutrient supplementation for the general population considered healthy could be useful in the prevention of RTIs, such as COVID‐19. In this systematic review and meta‐analysis, the evidence was evaluated…

  9. Is low folate a risk factor for depression? A meta-analysis and exploration of heterogeneity.

    Journal of epidemiology and community health2007n=31555 influential citations

    Low folate has been causatively linked to depression, but research is contradictory. An association may arise due to chance, bias, confounding or reverse causality. A systematic review of observational studies which examined the…

  10. Influence of Diet in Multiple Sclerosis: A Systematic Review.

    Adv Nutr2017n=47Systematic Review55 influential citations

    Nutrition is considered to be a possible factor in the pathogenesis of the neurological disease multiple sclerosis (MS). Nutrition intervention studies suggest that diet may be considered as a complementary treatment to control the…

Frequently asked

What dosage was studied?
• plant-based diets (mainly vegetarian and vegan) • Metformin use (Not reported) • Vegan and vegetarian diets; review also discusses nutrient supplementation and food preparation strategies (Not applicable; review of diverse diets and nutrient strategies)
Are there safety considerations for Vitamin B12?
• Vitamin B12 deficiency is discussed as a potential adverse effect mechanism. • The review does not support metformin for dementia prevention in people without diabetes. • B12 deficiency in vegans is linked to neuropathy and cognitive impairment. • Low DHA/EPA intake may worsen mood and cognitive outcomes.

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