Reviewed and updated: 9 November 2026
The 5 best vitamins for consistent energy are vitamin B12, iron, magnesium, vitamin C and vitamin D. Four of them have authorised wording for contributing to the reduction of tiredness and fatigue or to normal energy-yielding metabolism, and vitamin D rounds out the list as the one most of us in the UK need to think about in the darker months.
5 best vitamins for consistent energy: the short list
Energy is rarely about one nutrient. When I talk to customers about afternoon slumps, I always start with food, sleep and daylight, then look at the nutrients that play a part in how the body turns food into usable energy. Here is each one in plain language, with the form to look for and when I would take it.
Quick answer
- Vitamin B12: contributes to normal energy-yielding metabolism and to the reduction of tiredness and fatigue.
- Iron: contributes to normal energy-yielding metabolism, normal red blood cell formation and the reduction of tiredness and fatigue.
- Magnesium: contributes to normal energy-yielding metabolism and the reduction of tiredness and fatigue.
- Vitamin C: contributes to the reduction of tiredness and fatigue, and helps the body absorb iron.
- Vitamin D: contributes to normal muscle function and the normal function of the immune system.
Our pick for this guide
Which B12 form suits a daily routine?
Vitamin B12 in two forms, methylcobalamin and adenosylcobalamin, at 1000µg per serving of two tablets. B12 contributes to the reduction of tiredness and fatigue. A food supplement, not a replacement for medical advice.
From £8.50 · 60 tablets
Shop Vitamin B12 →1. Vitamin B12
B12 is water-soluble and found mainly in animal foods, so people following a plant-based diet often look at a supplement. It contributes to normal energy-yielding metabolism, normal red blood cell formation and the normal function of the nervous system. Supplements come as cyanocobalamin or as methylcobalamin and adenosylcobalamin, and the second pair is the form our B12 uses. The NHS page on vitamin B12 and folate explains why absorption matters, and our complete vitamin B12 guide goes deeper.
I take B12 with breakfast. It is water-soluble, so it does not need fat, and a regular time is simply easier to remember.
2. Iron
Iron contributes to normal energy-yielding metabolism, to normal red blood cell formation and to the reduction of tiredness and fatigue. It is also the nutrient where more is definitely not better. The NHS says taking 17mg or less of iron a day in supplements is unlikely to cause harm (NHS: Iron), and iron can be dangerous for children if taken by accident, so keep it well out of reach. If you think your iron may be low, speak to your GP before starting, because a blood test is the only reliable way to know.
Form and timing matter. Ferrous fumarate is a commonly used form, and taking it with food can help if iron upsets your stomach. Vitamin C alongside iron helps absorption, while tea, coffee and calcium can get in the way, so keep them apart where you can. Our guide to choosing iron tablets covers the detail.
3. Magnesium
Magnesium contributes to normal energy-yielding metabolism, to the reduction of tiredness and fatigue, and to normal muscle and nervous system function. Chelated forms such as glycinate are usually gentler on the stomach than oxide. Our Magnesium Glycinate 3-in-1 combines magnesium glycinate, malate and citrate. Many people take magnesium in the evening, and that is a matter of routine, not a rule. See what to look for in magnesium supplements for more.
4. Vitamin C
Vitamin C contributes to the reduction of tiredness and fatigue and to the normal function of the immune system, and it increases iron absorption. Most of us can get plenty from fruit and vegetables, such as citrus fruit, peppers and berries, and a supplement is a convenience rather than a necessity. Taking a vitamin C food with an iron supplement is a simple way to use it well.
5. Vitamin D
From October to March there is not enough UV in the UK for the skin to make vitamin D, so the NHS advises considering a daily 10 microgram (400 IU) supplement over autumn and winter (NHS: Vitamin D). It contributes to normal muscle function and to the normal function of the immune system. Vitamin D is fat-soluble, so take it with a meal that contains a little fat. See our buyer's guide to vitamin D3 and K2 for forms and doses.
When to take them
- With breakfast: B12, and iron if you take it, with a vitamin C food and away from tea and coffee.
- With a meal containing fat: vitamin D.
- Whenever suits you: magnesium. The best time is the one you will keep to.
Consistency matters more than the hour. Our guides on what vitamins help with tiredness and natural energy without the caffeine crash look at the wider picture, and our guide for busy professionals shows how to put a short routine together.
What to realistically expect
Supplements are not a quick fix and they are not a stimulant. They sit alongside good food, sleep and daylight. If you feel unusually tired for a long time, see your GP, because persistent tiredness can have many causes that a supplement will not address.
A few cautions worth knowing
Do not exceed the recommended daily intake. Speak to your GP or pharmacist before starting a supplement if you are pregnant, breastfeeding, take regular medication, have a medical condition, or take blood thinners. Keep iron products out of reach of children. Food supplements are not a substitute for a varied diet.
Frequently asked questions
Which vitamins should I look at if I often feel tired?
B12, iron, magnesium and vitamin C each contribute to the reduction of tiredness and fatigue. If tiredness is persistent, speak to your GP, who can check whether anything needs attention.
What is the best time of day to take energy vitamins?
B12 and iron are often taken with breakfast, vitamin D with a meal containing fat, and magnesium whenever suits you. Keep iron away from tea, coffee and calcium where you can.
How do I know if a supplement is well absorbed?
Check the named form on the label. For example, magnesium glycinate is usually gentler than oxide, B12 comes as methylcobalamin and adenosylcobalamin or cyanocobalamin, and vitamin D3 is generally preferred to D2.
Our pick for this guide
Ready to start with B12?
Vitamin B12 in two forms, methylcobalamin and adenosylcobalamin, at 1000µg per serving of two tablets. B12 contributes to the reduction of tiredness and fatigue. A food supplement, not a replacement for medical advice.
From £8.50 · 60 tablets
Shop Vitamin B12 →Sources
- NHS: Vitamin B12 or folate deficiency anaemia
- NHS: Iron
- NHS: Vitamin D
- GB nutrition and health claims register (GOV.UK)
Browse more in our supplement guides hub or start from the home page.
Dr. Miron, Founder of Pure Vitamins UK.
Food supplements should not replace a varied, balanced diet and a healthy lifestyle. Do not exceed the recommended daily intake. Keep out of reach of children.
