What vitamin deficiency causes fatigue?

From the Guidelines

Vitamin B12 deficiency is a common cause of fatigue and should be treated immediately with hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement, then administer hydroxocobalamin 1 mg intramuscularly every 2 months, as recommended by NICE 1. To address fatigue related to vitamin deficiencies, it is essential to start with a blood test to identify specific deficiencies before beginning supplementation.

Key Considerations

• Vitamin B12 deficiency can cause fatigue, and treatment should be initiated promptly to prevent long-term neurological damage 1.
• Iron deficiency may also contribute to fatigue, and supplementation with 65-325 mg of elemental iron daily may be necessary, preferably taken with vitamin C to enhance absorption but separate from calcium-containing foods 2.
• Vitamin D deficiency is common in patients with inflammatory bowel disease (IBD) and may contribute to fatigue, but the optimal vitamin D level as a goal of treatment is poorly understood 2.
• Folate supplementation usually involves 400-1,000 mcg daily, but it is essential to address underlying causes of deficiencies alongside supplementation.

Treatment Approaches

• For vitamin B12 deficiency, treatment with hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks is recommended for people with no neurological involvement, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months lifelong 1.
• For iron deficiency, oral supplementation with 65-325 mg of elemental iron daily may be sufficient, but intravenous iron should be used first line in patients intolerant of oral iron who have active IBD and moderate to severe anaemia (Hb <100 g/L) 2.
• Vitamin D supplementation typically requires 1,000-4,000 IU daily, with higher doses sometimes needed for severe deficiency, but the impact of vitamin D on inflammation in IBD and its impact on disease course is poorly understood 2.

Important Considerations

• Improvement in energy levels may take several weeks to months of consistent supplementation.
• It is crucial to address underlying causes of deficiencies alongside supplementation to ensure optimal treatment outcomes.
• Fatigue in IBD can be multifactorial, including poor oral intake, malabsorption, chronic blood loss, or due to chronic inflammation, and treatment should be tailored to the individual patient's needs 3.

From the FDA Drug Label

Vitamin B12 is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. The average diet supplies about 5 to 15 mcg/day of vitamin B12 in a protein-bound form that is available for absorption after normal digestion. Vitamin B12 is not present in foods of plant origin, but is abundant in foods of animal origin In people with normal absorption, deficiencies have been reported only in strict vegetarians who consume no products of animal origin (including no milk products or eggs). The answer is: Vitamin B12 deficiency can cause fatigue.

• Key factors that contribute to vitamin B12 deficiency include: + Strict vegetarian diet + Lack of animal products in the diet + Inadequate absorption of vitamin B12 + Increased requirements during pregnancy and lactation 4 + Certain medical conditions, such as pernicious anemia 5

From the Research

Vitamin Deficiency and Fatigue

• Vitamin B12 deficiency is a common cause of megaloblastic anemia, various neuropsychiatric symptoms, and other clinical manifestations, including fatigue 6.
• Deficiency of iron, vitamin B12, or folate can result in anemia, characterized by low hemoglobin concentration, leading to symptoms such as weakness, lethargy, and shortness of breath 7.
• Vitamin B12 plays a crucial role in cellular metabolism, especially in DNA synthesis, methylation, and mitochondrial metabolism, and its deficiency can affect individuals at all ages, but particularly elderly individuals 8.

Relationship between Vitamin Deficiency and Fatigue

• Vitamin D deficiency has been associated with anemia in healthy and patient populations, and studies have suggested that vitamin D deficiency is associated with iron deficiency and anemia 9.
• Treatment of iron deficiency anemia with pharmacological iron has been shown to increase serum folate and vitamin B12 levels, suggesting that iron deficiency can affect many metabolic pathways, including vitamin B12 and folate 10.
• Screening for vitamin B12 deficiency may be warranted in patients with one or more risk factors, such as gastric or small intestine resections, inflammatory bowel disease, or use of certain medications, and initial laboratory assessment should include a complete blood count and serum vitamin B12 level 6.

Diagnostic and Management Approaches

• Diagnostic biomarkers for vitamin B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid 8.
• Management of vitamin B12 deficiency depends on supplementation, either via high-dose oral routes or via parenteral administration, and patients older than 50 years and vegans or strict vegetarians should consume foods fortified with vitamin B12 or take vitamin B12 supplements 6.