Vitamins & Nutrition
Do I Need a Multivitamin?
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed August 20265 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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Most people eating a varied diet do not need one. The NHS says a balanced diet covers it, with vitamin D through autumn and winter the main exception. A multivitamin hands you a small dose of twenty-odd nutrients at once. A blood test shows which one or two you are actually short of.
Not sure which markers you need? Build your test →You are stood in Boots looking at a Wellman or a Wellwoman box, wondering whether it is worth thirteen quid a month. Or a thread on Reddit has just told you your brand is rubbish and you should buy a different one.
Both questions skip the useful one. Short of what, exactly?
1. What does a multivitamin actually do?
It sprays a modest dose of many nutrients at a body that is usually short of one or two. That is the whole design. It is insurance, not a fix.
Most UK multivitamins sit at or near the Nutrient Reference Value, the label figure that covers the needs of most healthy adults. That is a sensible amount if you are fine. It is often too little to shift a genuine shortfall.
“Most people should get all the nutrients they need by having a varied and balanced diet, although some people may need to take extra supplements.”
— NHS, Vitamins and minerals
Note the second half of that sentence. Some people do need extra. The question is whether you are one of them.
2. Who genuinely needs a supplement?
UK advice names specific groups and specific nutrients. Not a twenty-nutrient pill.
Vitamin D, for nearly everyone in winter. The NHS advises that everyone should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter. British sunlight is too weak from October to March for your skin to make its own. Some groups are advised to take it all year, including people who are rarely outdoors and people with dark skin.
Vitamin B12, if you eat plant-based. B12 comes almost entirely from animal foods. It is the one nutrient a vegan diet reliably misses.
Folic acid, if you might become pregnant. UK advice is 400 micrograms daily before conception and through the first twelve weeks.
Iron, if a test says so. Heavy periods, a vegetarian diet and endurance training all pull on iron stores. Iron is the one to test rather than guess. Too much is a problem in its own right, and iron supplements can upset your stomach for no benefit if your stores are already fine.
3. What does the evidence say about multivitamins?
The largest recent review is not encouraging. In 2022 the US Preventive Services Task Force pooled 84 studies. It concluded that the evidence is insufficient to weigh the benefits and harms of multivitamins for cardiovascular disease or cancer.
Insufficient is not the same as useless. It means eighty-four studies could not settle it either way.
The same review was firmer on two ingredients. It recommended against beta-carotene and vitamin E supplements for that purpose. Worth knowing if your box contains large doses of either.
4. Which nutrients can a blood test actually show?
This is the honest limit of the whole category. A blood test reads some nutrients well, some poorly, and some not at all.
Helvy's Vitamins & Minerals panel (£159) reports nine markers from a finger-prick sample at home:
- Vitamin D, the winter one almost everyone is advised to supplement.
- Vitamin B12 and folate, the two that work together to build red blood cells.
- Magnesium, involved in muscle and nerve function.
- Iron and ferritin. Ferritin is the protein that holds iron in reserve, so it shows how much iron you have banked.
- Transferrin, transferrin saturation and total iron binding capacity. These three describe how iron is carried around, which a single iron reading cannot.
Now the part a supplement brand will not tell you. Helvy does not measure zinc, selenium, vitamin C, vitamin K2 or omega-3, even though all five are sold in our supplement range. Routine blood levels for several of those are poor guides to what is stored in your tissues anyway.
This panel is also not an anaemia screen. That needs a full blood count and a clinical judgement alongside it. Your report shows how your iron and vitamin markers sit, rather than reaching a diagnosis.
5. What if you already take one?
Keep taking it and test anyway. A result on a supplement still tells you something useful. It tells you whether the thing you are paying for has moved the number.
Two practical points. Iron jumps after an iron supplement, so take a morning sample and skip that day's dose. And high-dose biotin, the ingredient in most hair, skin and nail products, can distort thyroid and hormone assays. Ordinary multivitamin doses rarely cause trouble, but our guide to supplements that affect blood tests covers which ones to pause and for how long.
One more thing. Stopping a supplement a clinician prescribed is their call, not a website's.
READY TO TEST?
Test first, then take the one you need
Helvy's home blood tests report vitamin D, B12, folate, magnesium and a full iron picture, with a written read of what they show. Samples are processed by UKAS-accredited UK labs. Panels start at £99.
Frequently asked questions
Do I need a multivitamin?
The NHS says most people get all the nutrients they need from a varied and balanced diet, though some people need extra. The main UK exception is vitamin D, which everyone is advised to consider through autumn and winter. A blood test is how you find out whether you are one of the exceptions.
Are Vitabiotics products any good?
Reputable UK multivitamins are made to the same food supplement rules and mostly sit near the Nutrient Reference Value, so brand choice matters less than people think. The bigger question is whether a broad low dose is what you need, or whether you are short of one thing and need a proper amount of that.
Can a blood test tell me which vitamins I am low in?
For some of them, yes. Vitamin D, B12, folate, magnesium and the iron markers are all measured on Helvy's Vitamins and Minerals panel. Zinc, selenium, vitamin C and vitamin K are not, and routine blood levels are a poor guide for several of those anyway.
Should I stop my multivitamin before a blood test?
Not usually. Skip the morning dose if iron is being measured, because iron rises sharply after a supplement. High-dose biotin is the one worth pausing, since it can skew thyroid and hormone assays. Never stop something a clinician prescribed without asking them.
Is it better to take one nutrient or a multivitamin?
It depends on what you are short of. A multivitamin gives a small dose of many things. If a test shows a real shortfall, a single nutrient at a proper dose is the usual route, and you can retest in three months to see whether it moved.
How much vitamin D should I take in the UK?
The NHS advises considering a daily supplement containing 10 micrograms through autumn and winter. Some groups are advised to take it all year, including people who are rarely outdoors and people with dark skin. Testing shows where your own level sits before you go higher than that.
Related guides
Vitamin Deficiency Blood Test UK
Which deficiencies show up in blood, and which do not.
Vitamin D Blood Test UK
The one nutrient nearly everyone here is advised to top up.
Vitamin B12 Blood Test UK
What the result means, and who runs short.
Normal Folate Levels UK
The grey zone the guideline names, and what sits in it.
Magnesium Blood Test UK
Why serum magnesium only tells you part of the story.
Iron Deficiency Blood Test UK
Ferritin, iron studies and how to read them together.