Buying guide · Sources checked 17 October 2026 · Not clinically reviewed
Two packs can say “vitamin D” and still need a closer look. Start with the amount per tablet, then check the directions, ingredients and the exact version being sold.
A comparison of two published product labels. We have not purchased, laboratory-tested or physically tested these products. This is not a ranking or a recommendation to start a supplement.
Start with public health guidance
Public health nutrition guidance commonly advises adults to consider a supplement providing 10 micrograms of vitamin D daily during autumn and winter, and explains who may benefit from year-round supplementation. Ten micrograms is equivalent to 400 IU; these are two ways of expressing the same amount.
Some medical conditions affect how much vitamin D a person can safely take. Follow any advice given by your clinician, and use the primary vitamin D reference guidance for context. This adult-focused comparison does not cover infant or child dosing.
Two labels, side by side
We selected these examples because their published strength per tablet is the same. Matching strength alone does not establish equal quality, suitability or value.
| Label detail | Vitabiotics Ultra Vitamin D 400IU | Holland & Barrett Vitamin D 400 I.U. 10µg |
|---|---|---|
| Format | Tablet | Tablet |
| Vitamin D per tablet | 10 µg / 400 IU | 10 µg / 400 IU |
| Published ingredient information | Identifies vitamin D3 (cholecalciferol), plus coating and other ingredients. | Lists vitamin D, bulking ingredients and anti-caking ingredients. |
| Source to check | Vitabiotics product information | H&B 240-tablet product information |
Look at the actual listing
The same brand may offer several strengths, formats and pack sizes. Compare the listing with the manufacturer’s current information, and read the label on the pack you receive. Check the seller and delivery terms as well as the product name.
Official consumer guidance on food supplements advises buying from reputable businesses and taking particular care on online marketplaces. It also advises consulting a healthcare professional before taking a supplement if you have a medical condition, take prescribed medicines, are pregnant or are breastfeeding.
Browse by product name
These links open searches on Amazon.co.uk. Search results may include other strengths and sellers; availability and prices have not been verified. These are not affiliate links, and we do not earn commission from them.
Once you have checked the exact label and a current price, the cost-per-serving tool can help with the arithmetic. Read our guide to supplement labels for a broader checklist.
Sources: Public health vitamin D guidance, Vitabiotics, Holland & Barrett and consumer food supplements guidance. Checked 17 October 2026. Published product information can change. How we approach product research.