Feeling tired does not automatically mean that you need a vitamin supplement. Poor sleep, stress, an irregular routine, medicines and several medical conditions can all contribute, so the most appropriate nutrient depends on why you feel tired.
Vitamin B2, B3, B5, B6, B12, folate and vitamin C all have recognised nutritional roles relating to the reduction of tiredness and fatigue. Iron and magnesium are minerals rather than vitamins, but they also have relevant authorised functions.
These nutrients are most likely to be relevant when they address a genuine dietary gap or deficiency. Taking more than you need will not necessarily make you feel more energetic, and supplements should not be expected to work like caffeine.
Which vitamins are associated with tiredness?
The Great Britain Nutrition and Health Claims Register permits specific tiredness and energy-related claims for qualifying amounts of certain nutrients:
| Nutrient | Recognised nutritional function |
|---|---|
| Vitamin B2 | Contributes to the reduction of tiredness and fatigue and normal energy-yielding metabolism |
| Vitamin B3 | Contributes to the reduction of tiredness and fatigue and normal energy-yielding metabolism |
| Vitamin B5 | Contributes to the reduction of tiredness and fatigue and normal energy-yielding metabolism |
| Vitamin B6 | Contributes to the reduction of tiredness and fatigue and normal energy-yielding metabolism |
| Folate | Contributes to the reduction of tiredness and fatigue |
| Vitamin B12 | Contributes to the reduction of tiredness and fatigue and normal energy-yielding metabolism |
| Vitamin C | Contributes to the reduction of tiredness and fatigue and normal energy-yielding metabolism |
| Iron | Contributes to the reduction of tiredness and fatigue, normal energy metabolism and normal oxygen transport |
| Magnesium | Contributes to the reduction of tiredness and fatigue and normal energy-yielding metabolism |
These claims may only be used when a food or supplement provides enough of the nutrient to meet the applicable conditions. They describe normal nutritional functions and do not mean that a supplement treats every possible cause of tiredness.
What can cause tiredness?
Occasional tiredness is common and may follow a period of poor sleep, increased activity, stress or disruption to your normal routine.
Other possible factors include:
- Irregular meals or limited overall food intake
- Not drinking enough fluid
- Low physical activity
- Excessive caffeine or alcohol
- Stress, anxiety or low mood
- Hormonal changes, including pregnancy or menopause
- Some medicines and medical treatments
- Iron deficiency anaemia
- Vitamin B12 or folate deficiency
- Thyroid conditions or diabetes
- Sleep apnoea or another sleep problem
The NHS guidance on tiredness and fatigue recommends speaking to a GP if tiredness has continued for a few weeks without an obvious reason, affects everyday life or occurs with other symptoms.
Vitamin B12 and tiredness
Vitamin B12 contributes to normal energy-yielding metabolism, normal red blood cell formation, normal functioning of the nervous system and the reduction of tiredness and fatigue.
Natural food sources include:
- Meat
- Fish and shellfish
- Milk and dairy products
- Eggs
- Fortified breakfast cereals
- Fortified plant-based foods and drinks
- Nutritional yeast with added vitamin B12
People following a vegan diet need a reliable B12 source because unfortified plant foods do not normally provide it. However, feeling tired does not prove that you have a B12 deficiency.
Vitamin B12 or folate deficiency may also cause symptoms such as pins and needles, muscle weakness, a sore tongue, problems with balance or changes in memory and concentration. These require appropriate medical assessment.
Our guide explaining what vitamin B12 is good for covers its recognised functions, food sources and dietary considerations in more detail.
Folate and tiredness
Folate, also known as vitamin B9, contributes to the reduction of tiredness and fatigue, normal blood formation and normal psychological function.
Food sources of folate include:
- Broccoli
- Brussels sprouts
- Spinach and other leafy green vegetables
- Peas
- Chickpeas and kidney beans
- Fortified breakfast cereals
Folic acid is the manufactured form used in many supplements and fortified foods. It is particularly important during pregnancy, but pregnancy recommendations should be followed separately rather than relying on a general energy supplement.
The NHS guide to B vitamins warns that taking more than 1mg of folic acid can mask signs of vitamin B12 deficiency. This may allow untreated B12-related nervous-system problems to continue unnoticed.
Do not use high-strength folic acid to self-treat unexplained tiredness without professional advice.
Vitamin B6 and other B vitamins
Vitamin B6 contributes to normal energy-yielding metabolism, normal red blood cell formation, normal functioning of the nervous system and the reduction of tiredness and fatigue.
Food sources include poultry, pork, fish, peanuts, soya beans, oats, bananas, milk and fortified cereals.
Vitamin B2, also called riboflavin, is found in milk, eggs, yoghurt, mushrooms and fortified breakfast cereals. Vitamin B3, or niacin, occurs in foods including meat, fish, eggs and wheat flour. Vitamin B5, or pantothenic acid, is found widely in meat, eggs, mushrooms, avocado and wholegrain foods.
These vitamins are often combined in a vitamin B complex. This can be convenient, but the complete amount of each nutrient should still be checked.
Be careful with vitamin B6
Vitamin B6 may appear in several products, including:
- Vitamin B-complex supplements
- Multivitamins
- Magnesium formulas
- Sleep supplements
- Energy products
- Sports-nutrition supplements
The NHS advises adults not to take more than 10mg of vitamin B6 a day from supplements unless instructed by a doctor. Check the combined amount from every supplement you use.
Vitamin C and tiredness
Vitamin C contributes to normal energy-yielding metabolism and the reduction of tiredness and fatigue. It also contributes to normal immune-system function and increases iron absorption.
Good food sources include:
- Peppers
- Oranges and other citrus fruit
- Strawberries
- Blackcurrants
- Broccoli
- Brussels sprouts
- Potatoes
The NHS vitamin C guidance states that adults need approximately 40mg each day and should normally be able to obtain this through a varied diet.
More is not automatically better. The NHS advises that taking more than 1,000mg of vitamin C a day can cause stomach pain, diarrhoea and flatulence.
Is vitamin D a vitamin for tiredness?
Vitamin D is frequently included in discussions about tiredness, but it does not have the same authorised reduction-of-tiredness claim as vitamin B12, vitamin B6 or vitamin C.
Vitamin D instead contributes to normal muscle function, normal immune-system function, the maintenance of normal bones and normal calcium absorption.
The NHS vitamin D guidance recommends that people in the UK consider taking 10 micrograms of vitamin D each day during autumn and winter. Some people are advised to consider supplementation throughout the year.
This seasonal guidance is important, but vitamin D should not be presented as an instant energy supplement or a guaranteed answer to unexplained tiredness.
Iron and tiredness
Iron is a mineral rather than a vitamin, but it deserves particular attention when discussing persistent tiredness. It contributes to normal formation of red blood cells and haemoglobin, normal oxygen transport, normal energy metabolism and the reduction of tiredness and fatigue.
Food sources include:
- Liver and red meat
- Beans and chickpeas
- Nuts
- Fortified breakfast cereals
- Dried fruit
- Some leafy green vegetables
Iron deficiency anaemia can cause tiredness alongside breathlessness, noticeable heartbeats, headaches or pale skin. According to the NHS iron deficiency anaemia guidance, a GP may arrange a blood test when the condition is suspected.
Do not automatically take a high-strength iron supplement because you feel tired. Too much iron can be harmful, and blood loss or another underlying cause may need investigation.
Magnesium and tiredness
Magnesium is another mineral with recognised functions relating to normal energy metabolism and the reduction of tiredness and fatigue. It also contributes to normal muscle function and normal functioning of the nervous system.
Dietary sources include nuts, seeds, spinach, beans, pulses and wholemeal bread.
The NHS states that taking more than 400mg of magnesium from supplements for a short period can cause diarrhoea. This figure is not a target intake or a reason to automatically take 400mg.
Is a vitamin B complex good for tiredness?
A vitamin B complex provides several B vitamins in one product. It may be convenient when you want a broader formula, but it is not automatically better than standalone B12 or a varied diet.
Before choosing one, check:
- Whether all eight B vitamins are included
- The amount of each vitamin in the complete daily serving
- The vitamin B6 amount
- Whether folate is supplied as folic acid
- The form and amount of vitamin B12
- Whether other ingredients or stimulants have been added
- Whether the complete formula meets your dietary requirements
For a current label example, Vitarosa Vitamin B Complex with B12 and Vitamin C lists all eight B vitamins, including 15mcg of vitamin B12 and 2mg of vitamin B6, alongside 150mg of vitamin C. Its stated serving is one capsule.
These label details can be compared with your diet and other supplements. They should not be treated as a promise that everyone will feel less tired after taking the product.
If you are deciding between a broad B complex and a targeted B12 product, read our vitamin B complex versus B12 guide.
How long do vitamins for tiredness take to work?
There is no universal timeline. It depends on the nutrient, your previous intake, whether a deficiency is present, the cause and severity of that deficiency and whether your tiredness has another explanation.
Someone whose nutrient intake is already adequate may notice no difference. When low intake is relevant, any noticeable change may take days or weeks rather than appearing immediately.
Our guide to how long vitamin B complex takes to work explains why first-day energy claims should be treated cautiously.
What should you check before buying a supplement?
- The individual nutrients: do not rely only on terms such as “energy blend” or “high strength”.
- The complete daily serving: establish whether the amounts apply to one capsule or several.
- Duplicated ingredients: check multivitamins, magnesium products and fortified drinks for repeated B vitamins.
- Vitamin B6: calculate the total supplied by all your supplements.
- Iron: avoid routine high-strength use without a suitable reason.
- Caffeine and stimulants: check for caffeine, guarana or other ingredients that could affect sleep.
- Dietary suitability: review the capsule shell and complete ingredients rather than assuming suitability from the nutrient name.
- Warnings and medicines: speak to a pharmacist if you take regular medicines or have a medical condition.
A varied and balanced diet should remain the main source of nutrients. Supplements are intended to complement the diet and should not replace sufficient food, sleep or appropriate medical care.
When should tiredness be discussed with a GP?
Arrange a GP appointment if:
- You have felt tired for several weeks without knowing why
- Tiredness affects your everyday life
- Your symptoms are getting worse
- You experience unexplained weight loss or mood changes
- You wake up gasping, snorting or choking
- You have shortness of breath, heart palpitations or pale skin
- You experience pins and needles, numbness or muscle weakness
- You develop balance, vision, memory or concentration problems
Symptoms alone cannot identify which nutrient may be low. Blood tests or other assessments may be required to find the cause.
Frequently asked questions
What is the best vitamin for tiredness?
There is no single best vitamin for everyone. Vitamins B2, B3, B5, B6, B12, folate and vitamin C have authorised claims relating to the reduction of tiredness and fatigue, but the most relevant nutrient depends on your individual circumstances.
Does vitamin B12 reduce tiredness?
Vitamin B12 contributes to the reduction of tiredness and fatigue when a qualifying amount is supplied. This does not mean it will resolve tiredness caused by poor sleep, stress or another health problem.
Does vitamin C give you energy?
Vitamin C contributes to normal energy-yielding metabolism, but it does not contain calories and should not be expected to work like caffeine.
Should I take iron when I feel tired?
Not automatically. Iron deficiency anaemia can cause tiredness, but taking iron unnecessarily may be harmful. Speak to a GP when iron deficiency is suspected.
Is magnesium a vitamin for tiredness?
No. Magnesium is a mineral, although it contributes to normal energy-yielding metabolism and the reduction of tiredness and fatigue.
Are high-strength energy vitamins better?
Not necessarily. Larger amounts do not guarantee faster or greater results and may increase the likelihood of unwanted effects. Compare individual nutrients rather than choosing the biggest numbers.
Which nutrients should you look for?
The vitamins most directly associated with the reduction of tiredness and fatigue are vitamins B2, B3, B5, B6, B12, folate and vitamin C. Iron and magnesium are relevant minerals, while vitamin D should be considered according to UK seasonal guidance rather than treated as an instant energy product.
The most appropriate choice depends on your diet, existing intake and the cause of your tiredness. Supplements are unlikely to make a noticeable difference when your intake is already adequate or when tiredness has another explanation.
For a broader comparison of nutrients, formats and buying considerations, read our UK guide to supplements for energy and tiredness. You can also compare current labels in the Energy & Performance collection.