Feeling constantly drained is a common complaint, often blamed on late nights, poor weather, or simply not drinking enough water. However, for many, this persistent exhaustion is a red flag for an underlying health issue: a deficiency in vitamin B12 or folate.
The hidden culprit behind chronic fatigue
Millie Bull, Deputy Editor at Spare Time, discovered her own unrelenting tiredness was due to a B12 deficiency, likely linked to her ulcerative colitis, which limited her diet and nutrient absorption. Her experience is far from unique. Extreme fatigue is a hallmark symptom of a B12 deficiency, but it often comes with other tell-tale signs.
Dr Jeff Foster, medical director at the British online health platform Voy, explains that B12 is vital for the nervous system. "Common signs include persistent tiredness, weakness, breathlessness, headaches, pale or slightly yellow skin, a sore or smooth tongue, mouth ulcers, and pins and needles in the hands or feet," he states. The latter, known as a "glove and stocking neuropathy," is a classic indicator of seriously low levels.
Memory lapses, concentration problems, low mood, and in severe cases, issues with balance, can also occur. Women's health specialist Dr Shirin Lakhani notes the condition is particularly prevalent among women.
Who is most at risk of a B12 deficiency?
A deficiency can arise from several factors, not just diet. Clinically trained pharmacist Nasir Ali outlines the main causes:
- Dietary insufficiency: Common in vegan or plant-based diets without fortified foods or supplements.
- Absorption problems: Conditions like pernicious anaemia, coeliac disease, Crohn's disease, or previous stomach surgery.
- Medications: Long-term use of metformin, proton pump inhibitors (PPIs), or H2 blockers can reduce B12 levels.
- Age and lifestyle: Absorption declines with age, and heavy alcohol or nitrous oxide misuse can deplete or inactivate B12.
Dr Tina Ghela, a Medichecks digital clinician, identifies pernicious anaemia as a leading cause. She also highlights that recent Government guidelines recommend screening for B12 deficiency in long-term metformin users. Dr Angela Rai, a GP, adds that elderly people are especially vulnerable, with up to one in five over 60 potentially affected.
Diagnosis, treatment, and prevention
If you suspect a deficiency, medical experts strongly advise consulting your GP, especially if you have symptoms or are in a high-risk group. Diagnosis requires a blood test. Dr Ghela recommends asking for an active B12 test for greater accuracy, as total B12 measurements can sometimes be misleading.
Treatment depends on severity. For mild cases, oral B12 supplements and dietary changes may suffice. For those with absorption issues like pernicious anaemia, B12 injections or high-dose sublingual (under the tongue) supplements, which bypass the gut, are often necessary.
To prevent deficiency, focus on B12-rich foods: meat, fish, shellfish, dairy, and eggs. For plant-based diets, consistently consume fortified cereals, plant milks, and nutritional yeast. Supplements are a reliable option for vegans, older adults, and those with absorption difficulties. Biochemist Dr Max Gowland notes that around five million B12 prescriptions were issued in the UK in 2024, underscoring how common supplementation is.
Dr Tamsin Lewis, a psychiatrist, recalls cases where patients presented with seeming psychiatric disorders, only to find a reversible B12 deficiency was the cause. Her takeaway is clear: "If symptoms don't quite add up, think B12. It's an easy thing to test, but missing it can have life-changing consequences."
