The short answer, for a person eating a reasonably varied diet with no particular medical condition, is no. This is one of the clearest gaps between what the evidence supports and what gets sold.
What the evidence shows
Large trials in well-nourished populations have repeatedly failed to show that routine multivitamin use reduces heart disease, cancer or death. Some studies suggest very small benefits on specific measures, others show nothing, and a few have found harm from high doses of individual nutrients. Taken together this is not a picture of a useful intervention for the general population.
That is a different statement from saying vitamins do not matter. Deficiencies are real and treating them works well. The question is whether topping up someone who is not deficient does anything, and the answer is mostly no.
Who genuinely benefits
There are real exceptions, and they are specific:
- Folic acid before and during early pregnancy. This one is Grade A and it is not optional.
- Vitamin D for people with little sun exposure, darker skin at northern latitudes, or who are housebound. Cyprus makes this less pressing than northern Europe, but it still applies to some people.
- Vitamin B12 for vegans, for people on long-term metformin, and for many people over 60 whose absorption has declined.
- Iron where a blood test has shown deficiency. Not on a hunch, and not because you feel tired.
What to do
If you fall into one of the groups above, take the specific thing you need at the dose recommended, not a broad multivitamin that contains a little of everything and enough of nothing.
If you do not, the money is better spent on food. A multivitamin is a poor substitute for a diet, and it was never designed to be one.
Cautions
More is not better and can be worse. Fat soluble vitamins, A, D, E and K, accumulate. High dose vitamin A in pregnancy causes birth defects. High dose vitamin E has been associated with harm in some trials.
Several vitamins and minerals interact with medicines. Vitamin K affects warfarin directly. Calcium, iron, magnesium and zinc all interfere with the absorption of common antibiotics and thyroid medication. If you take anything regularly, ask your pharmacist before adding a supplement.
When to see a doctor
Persistent tiredness deserves a blood test, not a supplement bought on a guess. Fatigue has many causes and most of them are not fixed by a multivitamin.