• Vitamins & Supplements
  • Food & Drink
  • Sports Nutrition
  • Free From
  • Natural Beauty
  • Weight Management
  • Offers
  • Summer Shop
  • The Health Hub
  • Learn more Healthbox
  • Account
Track your order Delivery & Returns Help Centre My subscriptions

Customer Service

  • Contact us
  • Site map
  • Site map
  • Store locator

About us

  • Who are we
  • Working at Holland & Barrett
  • Press releases
  • Privacy & cookie policy
  • Terms & conditions
  • Holland & Barrett More
  • Holland & Barrett International
  • Corporate Social Responsibility
  • Modern Slavery Statement

Connect with us

Store
0370 606 6606
My account
Rewards
  • Sign in
  • How do I join?
  • What are the benefits?
  • FAQs
Holland & Barrett :: the good life
  • Menu
  • Account
  • Store
  • Basket
    Search for
    • Vitamins & Supplements
    • Food & Drink
    • Sports Nutrition
    • Free From
    • Natural Beauty
    • Weight Management
    • Offers
    • The Health Hub
    • Healthbox

    Home / Vitamins & Supplements / Vitamins / Vitamin B / Vitamin B complex: functions, foods, deficiency and supplements

    Vitamin B complex: functions, foods, deficiency and supplements

    Find out all about vitamin B, including what it does, how much you need, where to find it, and who might need to supplement their diet

    Overview of vitamin B

    What is vitamin B complex and what does it do?

    Vitamin B is the name for a group of eight B vitamins that are essential for the healthy functioning of the body, while vitamin B complex is a supplement containing all the B vitamins you need each day.1

    Vitamin B complex usually contains these nutrients:2

    • thiamin (vitamin B1)
    • riboflavin (vitamin B2)
    • niacin (vitamin B3)
    • pantothenic acid (vitamin B5)
    • pyridoxine (vitamin B6)
    • biotin (vitamin B7)
    • folic acid (vitamin B9) – this is the synthetic version of folate
    • cyanocobalamin (vitamin B12)

    Each B vitamin has a different function and is needed in different amounts. In general, B vitamins help to release energy from food while keeping your blood, skin and nervous system healthy.3

    The B vitamins are water soluble, which means that – with the exception of vitamin B12 – they can’t be stored in the body, so you need to replace them every day.4 Most people get all the B vits they need from their diet, with good sources including seeds, fish, eggs, meat, poultry, and leafy greens.5

    If you’re vegan, you could be at risk of B12 deficiency because this nutrient is only found in animal sources such as meat, fish and dairy. Symptoms include muscle weakness and extreme tiredness.6

    Functions of vitamin B

    What do the B vitamins do in the body?

    thiamin – helps turn carbohydrates and sugar into energy, plays a key role in nerve, muscle and heart function, and is essential for a healthy brain

    riboflavin – important for energy release, helps the body to absorb nutrients, including iron, and is crucial for healthy eyes, skin and nervous system8

    niacin – helps release energy from food, keeps the nervous and digestive systems healthy, and is essential for normal growth and healthy skin9

    pantothenic acid – helps the body turn protein and fat into energy, and is needed for healthy growth10

    pyridoxine – helps break down protein from food, reduces tiredness and fatigue, and is essential for healthy red blood cells and nervous system11

    biotin – helps the body break down nutrients from food and process glucose, maintain mucous membranes, and keeps skin and nails healthy12

    folate/folic acid – essential during pregnancy to help prevent neural tube defects (spina bifida) in babies, helps maintain healthy red blood cells, and contributes to reduction of fatigue13

    vitamin B12  – vital for the nervous and immune systems, helps fight tiredness and fatigue, and needed for healthy DNA14

    How much of each B vitamin do I need?

    The amount of vitamin B you need depends on your age, sex and other factors, like whether you’re pregnant. Below are the reference nutrient intakes (RNIs) for women and men:15

    • thiamin (B1) – women 0.8mg, men 1mg
    • riboflavin (B2) – women 1.1g, men 1.3mg
    • niacin (B3) – women 13.2mg, men 16.5mg
    • pantothenic acid (B5) – women and men up to 200mg
    • pyridoxine (B6) – women 1.2mg, men 1.5mg
    • biotin (B7) – up to 0.9mg a day for both women and men
    • folate (B9) – women and men 200mcg. However, women who are trying to conceive or pregnant should take 400mcg until 12 weeks pregnant
    • vitamin B12 – women and men 1.5mcg

    Vitamin B foods

    Which foods are the best sources of vitamin B?

    It’s easy to eat a diet packed with B vitamins. Here’s where to find your eight essential B vitamins:

    • thiamin – wholemeal bread, peas, eggs, beans, brown rice16
    • riboflavin – milk, eggs, fortified breakfast cereals, cheese, certain green veg17
    • niacin – bread, potatoes, peas, peanuts, brown rice, salmon18
    • pantothenic acid – wholegrains, eggs, green leafy veg, avocado, potatoes19
    • pyridoxine – wholegrains, eggs, soya beans, fish, vegetables, peanuts, milk, potatoes20
    • biotin – egg yolk, legumes, yeast, nuts, milk21
    • folate  – Brussels sprouts, dark green leafy vegetables, peas, chickpeas, fortified breakfast cereals22
    • vitamin B12 – milk, cheese, eggs, salmon, meat, fortified breakfast cereals, plant milks23

    Vitamin B deficiency

    What are the symptoms of a vitamin B deficiency?

    Vitamin B deficiency is rare in the UK, but two of the more common ones are a lack of vitamin B12 and folate.

    Older people and vegans are most at risk of low vitamin B12 levels: older people because they produce too little ‘intrinsic factor’ in the stomach – a natural chemical that boosts B12 absorption – and vegans because they eat mainly plant foods.

    Folic acid insufficiency now affects 75% of women of childbearing age in the UK, which could have a negative impact on foetal health.

    A vitamin B12 or folate deficiency can lead to a type of anaemia called megaloblastic anaemia, where you produce red blood cells that are larger than normal. Symptoms include fatigue, feeling short of breath, racing heart, diarrhoea and nausea.24,25

    What happens if I consume too much vitamin B?

    As B vitamins are water soluble, it’s tricky to get too much from your diet or from taking a vitamin B complex.26 However, taking large amounts of single B nutrients as supplements may cause side effects such as vomiting, liver damage or nerve damage.27,28,29

    Shop Vitamins

    Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies.

    Written by Carole Beck on October 24, 2018
    Reviewed by Dr Carrie Ruxton PhD on November 3, 2018

    Sources
    1. NHS. B vitamins and folic acid. Available from: www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b/
    2. As above
    3. Jillian Kubala. B-Complex Vitamins: Benefits, Side Effects and Dosage. Available from: www.healthline.com/nutrition/vitamin-b-complex
    4. Mayo Clinic. Vitamin B12. Available from: www.mayoclinic.org/drugs-supplements-vitamin-b12/art-20363663
    5. As Source 3
    6. NHS. Vitamin B12 or folate deficiency anaemia. Available from: www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/
    7. HSIS. Vitamin B1 (Thiamin or Thiamin). Available from: www.hsis.org/a-z-food-supplements/vitamin-b1-thiamin-or-thiamin/
    8. Christian Nordqvist. Benefits and sources of vitamin B2. Available from: www.medicalnewstoday.com/articles/219561.php
    9. HSIS. Vitamin B3 (Niacin). Available from: www.hsis.org/a-z-food-supplements/vitamin-b3-niacin/
    10. HSIS. Pantothenic acid. Available from: www.hsis.org/a-z-food-supplements/pantothenic-acid/
    11. MedlinePlus. Vitamin B6. Available from: www.medlineplus.gov/ency/article/002402.htm
    12. Medical News Today. Why do we need biotin, or Vitamin B7? Available from: www.medicalnewstoday.com/articles/219718.php
    13. HSIS. Folic acid. Available from: www.hsis.org/a-z-food-supplements/folic-acid/
    14. HSIS. Vitamin B12 (Cyanocobalamin). Available from: www.hsis.org/a-z-food-supplements/vitamin-b12-cyanocobalamin/
    15. As Source 1
    16. As Source 7
    17. HSIS. Vitamin B2 (Riboflavin). Available from: www.hsis.org/a-z-food-supplements/vitamin-b2-riboflavin/
    18. Erica Julson. 16 Foods That Are High in Niacin (Vitamin B3). Available from: www.healthline.com/nutrition/foods-high-in-niacin#section3
    19. MedlinePlus. Pantothenic acid and biotin. Available from: www.medlineplus.gov/ency/article/002410.htm
    20. As Source 1
    21. As Source 19
    22. As Source 1
    23. As Source 1
    24. Steven Kim. Megaloblastic Anemia. Available from: www.healthline.com/health/megaloblastic-anemia
    25. As Source 1
    26. Ellsworth MA, et al. Acute Liver Failure Secondary to Niacin Toxicity. Available from: www.ncbi.nlm.nih.gov/pmc/articles/PMC3965920/
    27. Mayo Clinic. Niacin. Available from: www.mayoclinic.org/drugs-supplements-niacin/art-20364984?pg=2
    28. Jacquelyn Cafasso. Can You Overdose on Niacin? Available from: www.healthline.com/health/food-nutrition/niacin-overdose
    29. As Source 1
    30. ScienceDirect. B vitamins. Available from: www.sciencedirect.com/topics/neuroscience/b-vitamins
    31. Kennedy DO, et al. Effects of high-dose B vitamin complex with vitamin C and minerals on subjective mood and performance in healthy males. Available from: www.ncbi.nlm.nih.gov/pmc/articles/PMC2885294/
    32. Lewis JE, et al. The effect of methylated vitamin B complex on depressive and anxiety symptoms and quality of life in adults with depression. Available from: www.ncbi.nlm.nih.gov/pubmed/23738221

    Tweet
    Follow on Instagram
    Vitamin B

    You may also like

    What’s the best Vitamin B to take?

    Article

    What’s the best Vitamin B to take?

    Thinking about taking a Vitamin B supplement, but aren’t too sure what the options are..

    READ MORE...
    Folic acid for pregnancy

    Article

    Folic acid for pregnancy

    Are you pregnant? Or is there a chance you might get pregnant? If so, it’s..

    READ MORE...
    Should men take folic acid?

    Article

    Should men take folic acid?

    It’s common to hear folic acid supplements recommended for women, but can boosting this vitamin..

    READ MORE...

    Connect with us

    • Log in Register
    • rewards for life

    Customer service

    • Store locator
    • Contact us
    • Site feedback
    • Frequently asked questions
    • Delivery & returns
    • Site map
    • My account

    About us

    • Who we are
    • Working at Holland & Barrett
    • Press room
    • Privacy & cookie policy
    • Terms & conditions
    • Holland & Barrett More
    • Holland & Barrett International

    Brands

    • Holland & Barrett
    • Bootea
    • Dr Organic
    • Precision Engineered
    • Manuka Doctor
    • Good n Natural
    • Miaroma
    Register
    Click to verify if this website is operating legally

    Copyright © Holland & Barrett Retail Limited, 2017. All rights reserved. hollandandbarrett.com is a trading name of Holland & Barrett Retail Limited,. Registered office: Samuel Ryder House, Barling Way, Nuneaton, Warwickshire CV10 7RH. Registered in England: company no. 2758955. Registered VAT no. 211727395.