Health Saver Deals · Buying guide
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Vitamin D supplements UK: strengths, vegan sources and cost
Start a vitamin D comparison with the amount in micrograms, then check the source, dosage form and pack cost. The NHS advises adults to consider 10 micrograms daily in autumn and winter; a higher-strength product is not automatically a closer match to that advice.
Use UK guidance before shopping by strength
The NHS vitamin D guidance explains seasonal advice and the groups who should consider supplementation throughout the year. Children and babies have separate guidance. If you have been prescribed a dose or told to follow a particular regimen, a general buying comparison should not replace it.
Our examples below are higher than the general 10-microgram adult seasonal amount. They are included to explain the labels, not to recommend taking more. Do not combine several products without checking their total vitamin D content.
Micrograms and IU: translating the label
For vitamin D, one microgram equals 40 international units (IU). Therefore 10 micrograms equals 400 IU, 25 micrograms equals 1000 IU and 50 micrograms equals 2000 IU. Compare equivalent units before comparing prices. A larger number printed in IU is not necessarily a larger amount than a figure given in micrograms.
| Product example | Amount / form | Pack and one-off price | Item cost per labelled serving |
|---|---|---|---|
| Together Health vegan D3 | 25µg / 1000 IU; lichen-sourced D3 | 30 capsules; £7.49 | 25.0p at one capsule |
| Simply Supplements D3 2000 IU | 50µg / 2000 IU; vegetarian-labelled tablet | 180 tablets; £6.69 | 3.7p at one tablet |
Sources: Together Health vegan D3 and Simply Supplements D3 2000 IU. Checked 3 October 2026; confirm the selected pack and live price before purchase. Shipping is extra where applicable. The cheaper serving supplies a different amount and has different source information.
Vegan D3: check more than the capsule shell
A vegetable capsule does not establish the source of the vitamin inside it. D3 may come from different sources, including animal-derived sources and lichen. Together identifies lichen for the product above. Simply’s example is labelled vegetarian; we have not verified it as vegan and do not present it as a vegan alternative.
The NHS Specialist Pharmacy Service guide discusses source and formulation checks. Look for a clear vegan statement for the exact product, then read all ingredients and any relevant certification details. See our vegan supplement buying guide for a broader checklist.
Tablets, capsules and combinations
Choose a format you can use according to its directions. Do not assume a tablet can be split accurately or a capsule opened unless the manufacturer confirms it. Combination products may add nutrients you already get from another supplement, making an apparently simple comparison less useful.
Pack size affects the initial outlay and storage period. A 180-tablet pack can look inexpensive per tablet, but check the expiry date and whether you intend to use it for that long. A subscription interval should match use rather than simply the default shown on a product page.
Buying checklist
- Confirm the amount appropriate to your circumstances.
- Convert micrograms and IU to the same unit.
- Check source, dietary suitability and other ingredients.
- Calculate pack price divided by labelled servings.
- Include postage and identify recurring orders.
If neither example fits the amount or formulation you need, look for a suitable alternative. There is no need to choose between these two solely because they are featured here.