B vitamins and tiredness, one by one.

Quick answer. In Great Britain, riboflavin (B2), niacin (B3), pantothenic acid (B5), vitamin B6 and folate (B9) each hold the authorised claim that they contribute to the reduction of tiredness and fatigue. Thiamin (B1) and biotin (B7) do not hold that claim: theirs is that they contribute to normal energy-yielding metabolism. Most people get enough B vitamins from a varied, balanced diet, and tiredness that lasts for weeks is a reason to see a GP.

Which B vitamin helps with tiredness?

In Great Britain, a food or a food supplement may only describe what a nutrient does in wording taken from an official list, the GB nutrition and health claims register. As GOV.UK puts it: "Only authorised claims in the Great Britain NHC register may be used in Great Britain."

For tiredness the wording is fixed. The register entry for riboflavin, for example, reads "Riboflavin contributes to the reduction of tiredness and fatigue". Among the B vitamins in Immufix, five hold that claim:

• Riboflavin (vitamin B2)
• Niacin (vitamin B3)
• Pantothenic acid (vitamin B5)
• Vitamin B6
• Folic acid, the form of folate (vitamin B9) used in supplements and fortified foods

This page covers the B vitamins that are in Immufix at 15% of their nutrient reference value (NRV) or more, the level at which we make a claim. Vitamin B12 is in Immufix at 0.25µg, which is 10% of its NRV. That is below the level, so we make no claim for it.

Do all B vitamins help with tiredness?

No. Thiamin and biotin are B vitamins, but neither holds the tiredness claim. Both hold the claim that they contribute to normal energy-yielding metabolism, which is a related but different statement. A label that says "B vitamins help with tiredness" without naming them is blurring the two.

Here is every B vitamin in a 25g scoop of Immufix, with the authorised claims it can carry about tiredness and energy.

The NRV is the daily reference amount used on food labels. The figures are set in Annex XIII of the food information regulation: 1.4mg for vitamin B6, for example, and 200µg for folic acid.

What does "reduction of tiredness and fatigue" actually mean?

It describes a contribution to the body's normal processes, not a feeling you notice after a dose. The NHS describes thiamin as helping "the body break down and release energy from food", and vitamin B6 as helping "the body to use and store energy from protein and carbohydrates in food" (NHS: B vitamins and folic acid).

Three things follow from that.

• B vitamins are not stimulants. The NHS says that "caffeine is a stimulant which means it makes you feel more awake". None of the B vitamin claims says anything like that, and you should not expect a lift within the hour.
• The word "normal" matters. The claims describe normal function. They do not promise more energy than a well-fed body already has.
• You need them most days. For thiamin, riboflavin, niacin and pantothenic acid, the NHS notes that each "cannot be stored in the body, so you need it in your diet every day."

Which foods are high in B vitamins?

B vitamins are spread across ordinary foods, which is why a varied diet covers most people. The NHS lists these good sources:

• Thiamin: peas, bananas and oranges, nuts, wholegrain breads and some fortified breakfast cereals.
• Riboflavin: milk, eggs, fortified breakfast cereals, mushrooms and plain yoghurt. The NHS adds that UV light can destroy riboflavin, so these foods are best kept out of direct sunlight.
• Niacin: meat, fish, wheat flour and eggs.
• Pantothenic acid: chicken, beef, eggs, mushrooms and avocado.
• Vitamin B6: pork, poultry, some fish, peanuts, soya beans, wheatgerm, oats, bananas and milk.
• Folate: broccoli, brussels sprouts, leafy greens such as cabbage, kale and spinach, peas, chickpeas and kidney beans.
• Biotin: found in a wide range of foods, but only at very low levels.

A bowl of porridge made with milk and topped with a banana touches thiamin, riboflavin and vitamin B6 before the day has started.

Do I need a B vitamin supplement for tiredness?

For most people, no. The NHS says that "most people should get all the nutrients they need by having a varied and balanced diet, although some people may need to take extra supplements." There are two well-known exceptions in NHS advice:

• Pregnancy. Anyone who is pregnant, trying for a baby or could get pregnant is advised to take a 400 microgram folic acid supplement daily until 12 weeks of pregnancy.
• Vegan diets. The NHS notes that vitamin B12 "is not found naturally in foods such as fruit, vegetables and grains", so vegans may not get enough from food alone.

More is not better. The NHS advises: "Do not take more than 10mg of vitamin B6 a day in supplements unless advised to by a doctor." Check the total if you take more than one product.

Tiredness also has plenty of causes that have nothing to do with vitamins. The NHS lists not enough sleep, diet, little exercise and stress among the common ones, and says to see a GP if "you've been feeling tired for a few weeks and you're not sure why" (NHS: tiredness and fatigue). If your tiredness is seasonal, our piece on why winter makes you so tired covers the routine side.

Where Immufix fits.

Immufix is one 25g scoop in around 200ml of water, once a day. It contains riboflavin, niacin, pantothenic acid, vitamin B6 and folic acid at 25% to 36% of their NRVs, and thiamin at 23% and biotin at 74%. Riboflavin, niacin, pantothenic acid, vitamin B6 and folic acid contribute to the reduction of tiredness and fatigue. Thiamin and biotin contribute to normal energy-yielding metabolism. Vitamin C and magnesium hold the tiredness claim too, and our guide to vitamins and minerals for energy covers them. Every amount is listed on the science page.

The short version.

• Riboflavin, niacin, pantothenic acid, vitamin B6 and folate hold the authorised claim for the reduction of tiredness and fatigue.
• Thiamin and biotin do not. Their claim is for normal energy-yielding metabolism.
• None of them is a stimulant. They contribute to normal processes that release energy from food.
• Milk, eggs, oats, bananas, meat, fish, mushrooms and green vegetables supply most of them.
• Tiredness that lasts a few weeks without a clear reason is a question for a GP.

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.