What this checker does, and what it cannot do
This checker takes a list of symptoms you select and ranks ten common vitamin and mineral deficiencies by how well each one matches. For each it shows food sources, a caution and what to raise with a clinician.
It cannot diagnose anything. Almost every symptom associated with a nutritional deficiency is also associated with several conditions that have nothing to do with nutrition, and the only way to establish a deficiency is a blood test. This page exists to help you have a better conversation with a GP or pharmacist, not to replace one.
1. Choose symptoms
2. Results
Generated from selected symptoms in the Vitamin & Mineral Symptom Checker.
How to use this responsibly
This is a screening aid, not a diagnosis. The safest next step is usually a blood test or professional advice, especially for B12, folate, vitamin D and iron. Consider food intake, medical conditions, medicines, alcohol intake, gut problems, heavy periods, pregnancy, vegan or vegetarian diet, and limited sunlight exposure.
Evidence base used: NHS pages on vitamins and minerals, vitamin D, B vitamins/folate, vitamin K and iron deficiency anaemia; NHS Inform on B12/folate deficiency; NIH Office of Dietary Supplements B12 fact sheet; Healthdirect vitamin C deficiency; UK government and Patient.info vitamin A deficiency guidance.
Before you use it
- Some symptoms need urgent medical attention rather than a checker. Chest pain, severe breathlessness, fainting, one-sided weakness, confusion, black stools, coughing blood or thoughts of suicide require immediate help — contact 999 or NHS 111.
- Do not start high-dose supplements based on a result. Several nutrients are harmful in excess, and supplementing can mask a condition that needs treating.
- Persistent tiredness has many causes. It is one of the most common reasons people see a GP and is rarely explained by a single nutrient.
- If you are pregnant, breastfeeding, taking regular medication or have a diagnosed condition, take any supplement question to a pharmacist or GP first.
Tiredness, low mood, poor concentration and brittle nails appear in the symptom lists of several different deficiencies, and also in thyroid disease, depression, sleep disorders, coeliac disease and dozens of other conditions. A ranking based on symptoms alone can point to a plausible area to investigate; it cannot exclude anything.
How this calculator works
Each nutrient carries a weighted list of associated symptoms. The checker scores and ranks them:
Score = sum of the weights of your selected symptoms for that nutrient
Percentage = score ÷ the nutrient's top symptom weights, capped at 100
Results are ranked by score, then by how many symptoms matchedWeights reflect how characteristic a symptom is of that deficiency rather than how severe it is — pins and needles score higher for B12 than tiredness does, because tiredness accompanies almost everything.
The percentage is a match strength against that nutrient's own symptom profile. It is not a probability that you have the deficiency, and comparing percentages between nutrients is more meaningful than reading any single figure.
Worked example: how a ranking forms
Selecting extreme tiredness, pins and needles and a sore red tongue produces a strong match for vitamin B12, because pins and needles and tongue changes are both weighted heavily for B12 and rarely appear together otherwise. Iron will also appear, since tiredness is weighted for it too, but lower down.
What the checker then shows matters more than the ranking. For B12 it flags that folic acid alone should not be relied on where B12 symptoms are present, because untreated B12 deficiency can cause nerve damage that folate supplementation masks. That caution is the genuinely useful output — it is the kind of thing worth knowing before you buy a supplement, and the kind of thing a ranked list alone would not tell you.
Common mistakes
- Treating a high match as a diagnosis. It reflects symptom overlap, nothing more.
- Buying supplements on the strength of a result. Excess vitamin A, vitamin D and iron are all genuinely harmful.
- Taking iron without a test. Iron overload is dangerous, and iron tablets are a common cause of serious poisoning in young children.
- Assuming a deficiency explains everything. Persistent symptoms deserve investigation regardless of what this suggests.
- Delaying seeing a GP because the checker offered an explanation.
Frequently asked questions
Which nutrients does it cover?
Vitamin B12, iron, vitamin D, vitamin C, vitamin A, vitamin K, calcium, magnesium, iodine and zinc. These are the deficiencies most commonly encountered or asked about in the UK. It does not cover folate, B vitamins other than B12, or any non-nutritional cause.
Should I just take a multivitamin to be safe?
A standard multivitamin at recommended levels is unlikely to do harm, but it is not a substitute for finding out what is actually going on, and it can complicate diagnosis by partially correcting a deficiency before it is measured. The one supplement UK guidance recommends broadly is vitamin D during autumn and winter, and for some groups year round.
Which supplements can be harmful?
Several. Vitamin A in high doses is toxic and is specifically cautioned against in pregnancy. Vitamin D in very high doses causes calcium build-up. Iron is dangerous in overdose and should not be taken without evidence of deficiency. Some supplements interact with prescribed medicines — vitamin K with warfarin being a well-known example. A pharmacist can check interactions free of charge.
How would a deficiency actually be diagnosed?
Usually a blood test requested by a GP, sometimes alongside other tests to rule out different causes. For iron this typically means a full blood count and ferritin; for B12, a serum B12 level often with folate. Testing before supplementing matters, because supplementation can normalise a result and obscure the underlying picture.
Is what I select stored?
No. Symptom selections are processed entirely in your browser and are never transmitted or retained. Even so, treat any public website as an unsecured place and use your judgement about what you enter.
Related tools
References
- NHS — vitamins and minerals, recommended intakes, and when to seek medical advice
- GOV.UK — Scientific Advisory Committee on Nutrition reports on vitamin D and other nutrients
- National Institute for Health and Care Excellence — clinical guidance on diagnosing and managing nutritional deficiencies
Sources are checked at publication and can change — how I choose and check references.