From the Guidelines
B vitamins deficiency syndrome is primarily caused by inadequate intake, poor absorption, or increased requirements, with common risk factors including a diet low in vitamin B12, certain health conditions, and use of specific medications, as outlined in the 2024 NICE guideline summary 1. The causes of B vitamins deficiency syndrome can be multifaceted, involving various factors such as dietary habits, health conditions, and medication use.
- Key factors contributing to vitamin B12 deficiency, as highlighted in the guideline, include:
- A diet that excludes or is low in animal source foods, such as a vegan diet
- Not consuming food or drinks fortified with vitamin B12
- Having an allergy to foods like eggs, milk, or fish
- Difficulty in buying, preparing, or affording foods rich in vitamin B12
- Restricted diets due to conditions like dementia, frailty, mental health issues, or eating disorders
- Health conditions that increase the risk of vitamin B12 deficiency include:
- Atrophic gastritis affecting the gastric body
- Coeliac disease or other autoimmune conditions like thyroid disease, Sjögren syndrome, or type 1 diabetes
- Certain medications can also contribute to vitamin B12 deficiency, such as:
- Colchicine
- H2 receptor antagonists
- Metformin, with specific safety advice from the MHRA 1
- Phenobarbital
- Pregabalin
- Primidone Given the complexity and the potential for significant morbidity and mortality associated with untreated B vitamin deficiencies, it is crucial to address these underlying causes and improve diet quality to prevent long-term deficiencies, as supported by the most recent guideline evidence 1.
From the Research
Causes of B Vitamins Deficiency Syndrome
- Malabsorption and defects in cellular delivery and uptake of vitamin B12 2
- Limited dietary intake of vitamin B12, particularly in populations where food insecurity occurs 2
- Disruption of vitamin B12 transport in the blood, or impaired cellular uptake or metabolism 3
- Inadequate intake, inadequate bioavailability, or malabsorption of vitamin B12 3
- Increased risk of deficiency in certain populations, such as:
- Elderly individuals 2, 3
- Infants, children, adolescents, and women of reproductive age in populations with restricted dietary intake of B12-containing animal-derived foods 3
- People with alcoholism, patients with heart failure, patients with recent obesity surgery, and vegetarians/vegans 4
- Patients with gastric or small intestine resections, inflammatory bowel disease, or those taking certain medications such as metformin, proton pump inhibitors, or histamine H2 blockers 5
Risk Factors for B Vitamins Deficiency Syndrome
- Gastric or small intestine resections 5
- Inflammatory bowel disease 5
- Use of metformin for more than four months 5
- Use of proton pump inhibitors or histamine H2 blockers for more than 12 months 5
- Vegan or strict vegetarian diet 5
- Age older than 75 years 5
- Bariatric surgery 5