Who Is at Risk of Vitamin Deficiency? Diet, Age, Medicines, Surgery and Medical Conditions
Which groups are more likely to run low on vitamins, from vegan diets and older age to metformin, stomach acid medicines, bowel disease and weight-loss surgery, and what risk does and does not mean.
Content last updated . This page has not been medically reviewed.
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Being "at risk" is not the same as being deficient. Many people in the groups below have normal vitamin levels, and symptoms such as tiredness overlap with many other conditions. The NHS says to see a GP if you think you may have a vitamin B12 or folate deficiency, because some problems it causes can be irreversible if treatment is late. [1] This page is information only. It does not diagnose anything, and it does not tell anyone to start, stop or change a medicine or supplement.Evidence labels used here: established nutritional role / deficiency treatment, mixed, insufficient evidence and Proper evidence not found.
How a shortfall usually happens
Sources describe four routes: not eating enough of the foods that supply a vitamin, not absorbing it well, needing more than usual, or losing more than usual. The groups in the table fit one or more of these. Absorption is explained in how the body absorbs and stores vitamins.Groups and why they are listed
| Group | Why the sources list it | Source and country |
|---|---|---|
| People on vegan diets without fortified foods or a B12 supplement | B12 is the vitamin most often named. Body stores can last around 2 to 5 years, so problems may take a long time to appear after a dietary change. [2] | NHS, UK |
| Older adults | Deficiency of B12 or folate affects around 1 in 10 people aged 75 or over and 1 in 20 aged 65 to 74. [1] A 2026 review calls B12 deficiency common but often missed in older adults. [3] | NHS, UK; review, 2026 |
| People taking certain medicines | NHS lists proton pump inhibitors (acid reducers), metformin and nitrous oxide for B12, and some anticonvulsants, colestyramine, sulfasalazine and methotrexate for folate. [2] | NHS, UK |
| After stomach or bowel surgery, including weight-loss surgery | Removal of part of the stomach raises B12 risk. [2] Guidelines say all weight-loss procedures can cause meaningful micronutrient deficiencies. [4] | NHS, UK; BOMSS guideline, 2020 |
| Digestive conditions (coeliac or celiac disease, Crohn's disease, ulcerative colitis, pancreatic problems) | Malabsorption can lead to vitamin and mineral deficiency. [5] See malabsorption, celiac disease, IBD and vitamin deficiency. | NHS, UK |
| Heavy alcohol use | NHS lists regular alcohol misuse among causes of folate deficiency from diet. [2] It also names long-term dependency on drugs or alcohol that affects diet as a scurvy risk. [6] Thiamin is covered in vitamins and alcohol. | NHS, UK |
| Very restricted diets, eating disorders or illness that stops eating | Folate deficiency from diet is more common with an unbalanced diet or a restrictive diet. [2] | NHS, UK |
| People who smoke (vitamin C) | Smoking reduces how much vitamin C the body gets from food. [6] | NHS, UK |
| Pregnancy, breastfeeding and premature babies | The body may need more folate in pregnancy, and premature babies are more likely to develop folate deficiency. [2] | NHS, UK |
| Little sun on the skin (vitamin D) | NHS says people do not make enough vitamin D from sunlight between October and early March in the UK. [7] People who are frail or housebound, or who cover most of their skin outdoors, may also not make enough. [7] See vitamin D deficiency and testing. | NHS, UK |
| Long-term dialysis, heart failure or liver damage | Folate can be lost through frequent urination in these conditions, including long-term dialysis. [2] | NHS, UK |
| Very low-fat diets (vitamin E) | MedlinePlus says an extremely low-fat diet can lead to vitamin E deficiency, which is very uncommon in healthy people. [8] | MedlinePlus, US |
What the numbers show
In the United States, a 2025 family-physician review puts B12 deficiency at about 2% to 3% of adults. [9] A broader 2017 review says mild "subclinical" deficiency affects between 2.5% and 26% of the general population depending on the definition, and that its clinical relevance is unclear. [10] Part of that range comes from where the cut-off is drawn, which is why the figures differ.One long-term trial follow-up of metformin users found that years of metformin use were associated with increased risk of B12 deficiency. [11] That does not mean anyone should stop a prescribed medicine. The point is that a clinician can check B12 over time.
What risk does and does not tell you
- Risk is not a diagnosis. NHS notes that some people have symptoms and seem to have normal levels, and others have low levels without symptoms. [12]
- Blood tests have limits. Inflammation can lower blood levels of several vitamins, and the authors of one review call these tests prone to misuse and misinterpretation. [13] See deficiency testing and its limits.
- Proper evidence not found that a general multivitamin prevents deficiency in each group above. We looked at the NHS and MedlinePlus pages and the PubMed reviews cited here and found treatment advice, not prevention trials for each group. Ask about your own situation.
Who should talk to a clinician or pharmacist
Anyone who falls into a group above and has symptoms, is pregnant or planning pregnancy, has kidney or liver disease, is preparing for surgery, or takes regular medicines. Do not stop a prescribed medicine on your own. Interactions are explained in medication interactions, and product quality in quality testing and certifications. Official intake levels for each vitamin are explained in RDA, AI, DV and UL.Frequently asked questions
Does being in a risk group mean I am deficient?
No. Risk means a higher chance. NHS says some people with symptoms have normal levels and some with low levels have no symptoms. [12]
Which vitamin is most often linked with vegan diets?
B12. NHS says people on a vegan diet who do not take B12 supplements or eat B12-fortified foods are at risk. [2]
Can common medicines lower vitamin levels?
Some can. NHS names acid-reducing proton pump inhibitors, metformin and nitrous oxide for B12. [2] Talk to your clinician or pharmacist before changing anything.
Are older adults more at risk?
NHS reports B12 or folate deficiency in around 1 in 10 people aged 75 or over. [1]
Should everyone with a risk factor be tested?
Not necessarily. A 2025 review says universal screening is not recommended but testing should be considered with at least one risk factor and one clinical feature of B12 deficiency. [9]
References
- NHS (UK). Vitamin B12 or folate deficiency anaemia. Page last reviewed 20 February 2023. Read 2026-10-23.
- NHS (UK). Vitamin B12 or folate deficiency anaemia: Causes. Page last reviewed 20 February 2023. Read 2026-10-23.
- Vitamin B12 deficiency among older adults and its associations with geriatric syndromes. PubMed record. Curr Opin Clin Nutr Metab Care. 2026 (abstract read). Read 2026-10-23.
- O'Kane M, Parretti HM, Pinkney J, et al.; BOMSS. Guidelines on perioperative and postoperative biochemical monitoring and micronutrient replacement for patients undergoing bariatric surgery, 2020 update. Obes Rev. 2020 (abstract read). Read 2026-10-23.
- NHS (UK). Coeliac disease: Complications. Page last reviewed 31 March 2023. Read 2026-10-23.
- NHS (UK). Scurvy. Page last reviewed 27 September 2023. Read 2026-10-23.
- NHS (UK). Vitamins and minerals: Vitamin D. Page last reviewed 3 August 2020. Read 2026-10-23.
- MedlinePlus Medical Tests (US National Library of Medicine). Vitamin E (Tocopherol) Test. Read 2026-10-23.
- Vitamin B12 Deficiency: Common Questions and Answers. PubMed record. Am Fam Physician. 2025 (abstract read). Read 2026-10-23.
- Green R, Allen LH, Bjørke-Monsen AL, et al. Vitamin B12 deficiency. Nat Rev Dis Primers. 2017 (abstract read). Read 2026-10-23.
- Aroda VR, Edelstein SL, Goldberg RB, et al. Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study. J Clin Endocrinol Metab. 2016 (abstract read). Read 2026-10-23.
- NHS (UK). Vitamin B12 or folate deficiency anaemia: Diagnosis. Page last reviewed 20 February 2023. Read 2026-10-23.
- Pitfalls in the interpretation of blood tests used to assess and monitor micronutrient nutrition status. PubMed record. Nutr Clin Pract. 2023 (abstract read). Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.