The vitamins and minerals behind a normal immune system.

Quick answer. In Great Britain, vitamin A, vitamin C, vitamin D, vitamin B6, folate, zinc and selenium each hold the authorised claim that they contribute to the normal function of the immune system. Copper, iron and vitamin B12 hold the same claim. The NHS says most people can get enough of these nutrients from a varied, balanced diet, with sources such as oranges, peppers, eggs, oily fish, leafy greens, meat, shellfish and brazil nuts.

Which vitamins support the normal function of the immune system?

Many labels mention the immune system. In Great Britain only a fixed list of nutrients may lawfully be described as contributing to its normal function, and only in one form of words. The GB nutrition and health claims register sets that wording, and GOV.UK is plain about it: "Only authorised claims in the Great Britain NHC register may be used in Great Britain."

The register entry for vitamin C reads "Vitamin C contributes to the normal function of the immune system". The same sentence, with the nutrient's name swapped in, is authorised for:

• Vitamins: vitamin A, vitamin C, vitamin D, vitamin B6, folate and vitamin B12
• Minerals: zinc, selenium, copper and iron

That is the whole list for vitamins and minerals. Our guide to authorised health claims explains how the register works.

What does "normal function of the immune system" mean?

It means the nutrient is one of those the body needs for the immune system to function normally. Three points follow from the wording.

• The word "normal" is the claim. It describes ordinary function in a body that is getting enough of the nutrient. It does not describe more than normal.
• The claim belongs to the nutrient. It is vitamin C, or zinc, that contributes to normal function. A food or supplement can only repeat the claim for a nutrient it contains in a significant amount.
• More is not better. Once you are getting enough, extra adds nothing to the claim, and several of these nutrients have NHS upper limits for supplements.

Which vitamins for the immune system are in Immufix, and where are they in food?

A product may only use the claim when the nutrient is present at 15% or more of its nutrient reference value (NRV) per daily serving. All of them except copper, iron and vitamin B12 are in a 25g scoop of Immufix at that level. The table sets out the amount in a scoop, the NHS daily amount for adults aged 19 to 64, and the NHS food sources.

Sources: NHS pages on vitamin A, vitamin C, vitamin D, B vitamins and folic acid and zinc and selenium. NRVs are from Annex XIII of the food information regulation.

Copper, iron and vitamin B12 are also in Immufix, but each is below 15% of its NRV, so we make no claim for them.

Two figures need a note. The NRV for vitamin D is 5µg, so 1.25µg is 25% of it, but the NHS daily amount for adults is 10µg: a scoop gives an eighth of that. And vitamin A is a stored vitamin. The NHS says "any vitamin A your body does not need immediately is stored for future use. This means you do not need it every day."

Can I get these vitamins from food alone?

For most people, yes. For every nutrient in the table except vitamin D, the NHS page says you should be able to get what you need from a varied and balanced diet. A few foods do a lot of the work:

• Fruit and vegetables cover vitamin C, folate and beta-carotene. The NHS notes that vitamin C "cannot be stored in the body, so you need it in your diet every day."
• Eggs, dairy and oily fish cover vitamin A, and oily fish and eggs are two of the few food sources of vitamin D.
• Meat, fish and shellfish cover zinc, selenium and vitamin B6.
• Brazil nuts are the standout for selenium. The NHS says "if you eat meat, fish or nuts, you should be able to get all the selenium you need from your daily diet."

Vitamin D is the odd one out because so few foods contain it. The body makes it from direct sunlight on the skin, and the NHS sets out when a supplement is advised on its vitamin D page. For per-portion figures on two of the others, see our guides to vitamin C foods and zinc-rich foods.

How much is too much?

If you take more than one supplement, add the totals up. The NHS gives these upper guides for adults:

• Vitamin A: no more than 1.5mg (1,500µg) a day from food and supplements combined. The NHS also advises against supplements containing vitamin A if you eat liver every week.
• Vitamin C: less than 1,000mg a day from supplements is unlikely to cause any harm.
• Vitamin D: do not take more than 100 micrograms a day.
• Vitamin B6: do not take more than 10mg a day in supplements unless advised to by a doctor.
• Folic acid: 1mg or less a day from supplements is unlikely to cause any harm.
• Zinc: do not take more than 25mg a day in supplements unless advised to by a doctor.
• Selenium: 350µg or less a day from supplements is unlikely to cause any harm.

A scoop of Immufix is well inside each of these, but the totals matter if you also take a multivitamin or a single-nutrient supplement.

Where Immufix fits.

Immufix is one 25g scoop in around 200ml of water, once a day. It contains vitamin A, vitamin C, vitamin D3, vitamin B6, folic acid, zinc and selenium at 25% to 136% of their NRVs. Vitamin A, vitamin C, vitamin D, vitamin B6, folate, zinc and selenium contribute to the normal function of the immune system. It is a food supplement, taken alongside a varied diet. Every amount is listed on the science page.

The short version.

• Vitamin A, vitamin C, vitamin D, vitamin B6, folate, zinc and selenium contribute to the normal function of the immune system. Copper, iron and vitamin B12 hold the same claim.
• The word "normal" is the claim. It describes ordinary function, not more than ordinary.
• Fruit, vegetables, eggs, dairy, fish, meat and brazil nuts supply most of them. Vitamin D is the hardest to get from food.
• In Immufix, copper, iron and vitamin B12 are below 15% of the NRV, so no claim is made for them. The other seven are at qualifying levels.
• Check the NHS upper limits if you take more than one supplement.

Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. If you have a medical condition, are pregnant, breastfeeding or taking medication, speak to your GP or pharmacist before taking any food supplement.