Vegetarian and vegan diets
What the NHS and the British Dietetic Association advise about vitamin B12, vitamin D, iodine and omega-3 on a plant-based diet, with prices per dose.
The NHS says some nutrients are harder to get without animal foods: vitamin D, vitamin B12, iodine, selenium and calcium. For these it suggests fortified foods, or supplements. Vitamin B12 is the one UK bodies single out most, because it is not found naturally in plant foods, and the NHS says vegetarians who eat few eggs or dairy foods also need a reliable source of it.
NHS: Read the label to check the vitamin D in a product is not of animal origin.
Each line below is a short summary of what the named source says, with a link to read it in full. None of it is medical advice.
Advised
Vitamin B12
A vitamin found almost only in animal foods, and added to some plant drinks and breakfast cereals.
- NHS: Vegan sources are limited, so a B12 supplement may be needed.
- British Dietetic Association: Lists 10 micrograms a day for people on a vegan diet.
Also covered by NHS, NHS inform and British Dietetic Association.
Cheapest per 1 mg · Methylcobalamin2pCompare 27 productsVitamin D
A vitamin the body makes when skin is in sunlight. D2 is plant-based; some D3 is made using lamb's wool.
- NHS: Everyone, vegans included, should consider a daily supplement in autumn and winter.
- British Dietetic Association: Vitamin D2 is a plant-based alternative to D3.
Also covered by NHS inform.
Iodine
A mineral found in cows' milk and dairy foods, eggs, sea fish and shellfish.
- NHS: Strict vegans may want to consider iodine-fortified foods or an iodine supplement.
- British Dietetic Association: Choose potassium iodide or iodate, 150 micrograms at most; never kelp or seaweed.
Also covered by British Dietetic Association.
Cheapest per 150 µg iodine · Potassium iodideunder 1pCompare 8 products
Limited evidence
Omega-3
Fats found in oily fish, and in some plant oils, nuts and seeds; supplements come from fish, krill or algae.
- British Dietetic Association: Evidence for the general population is inconclusive; algae-only products suit vegans who want one.
Things to check
- NHS: Seek advice from a healthcare professional before taking an iodine supplement.
- British Dietetic Association: With thyroid disease, check with a GP before taking any extra iodine.
- British Dietetic Association: Eat seaweed no more than once a week.
- NHS: Do not take more than 100 micrograms (4,000 IU) of vitamin D a day.
- NHS: 2mg or less a day of vitamin B12 from supplements is unlikely to cause any harm.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
Sources
- The vegan dietPlanning a vegan diet, and vegan sources of calcium, vitamin D, iron, B12 and omega-3.
- The vegetarian dietEating well as a vegetarian, and sources of iron, B12 and omega-3.
- B vitamins and folic acidEach B vitamin, including B12: where it comes from, how much people need, and how much is safe.
- IodineWhere iodine comes from, how much adults need, vegan diets and too much.
- Vitamin DWho should consider a vitamin D supplement, how much, and the most to take in a day.
- Vegetarian and vegan dietsEating well on a vegetarian or vegan diet, as advised in Scotland, including B12 and vitamin D.
- Vegetarian, vegan and plant-based dietTypes of plant-based diet and the nutrients to watch, from protein to iodine.
- SupplementsWhether you need supplements, who may need which, how to choose one, and the risks.
- IodineHow much iodine people need, where it comes from and choosing a supplement.
- Vitamin DWhere vitamin D comes from, who is at risk of low levels, and the D2 and D3 forms.
- Omega-3Omega-3 fats, where they come from, including for people who eat no fish, and supplements.
Sources checked 28 September 2026. Prices checked 20 October 2026, ranked purely by price per dose. Which sources these pages use.