It is an essential nutrient that helps the brain, nerves and blood work properly and which is found in meat, fish, eggs, dairy products and Marmite.
But it turns out that vitamin B12 could be causing acne, the skin disorder that results in spots, pimples and blackheads, scientists have found.
A new study has found that the vitamin changes the way bacteria behave on the skin of susceptible people.
Vegan diets could be the key to getting rid of spots, because B12 is mostly found in animal products. But be warned: not getting enough of the vitamin can lead to fatigue and a lack of energy.
The discovery could lead to new treatments for the distressing skin disorder, and shed light on why some people who take vitamin B12 supplements come out in spots.
While it was already known that taking the vitamin pills can result in acne flare-ups, no-one knew exactly why.
The new study solved the mystery by showing that the vitamin alters the metabolic activity of the skin bug responsible for acne, Propionibacterium acnes.
This causes the bacteria to secrete an inflammatory compound that in turn triggers pimples.
But the effect is not the same for everyone - some people are more vulnerable than others due to the complex interaction of bacteria and host.
Researchers led by Dr Huiyang Li, from the University of California, Los Angeles, write in the journal Science Translational Medicine: "Our findings suggest a new bacterial pathogenesis pathway in acne and provide one molecular explanation for the long-standing clinical observation that vitamin B12 supplementation leads to acne development in a subset of individuals.
10 best skincare products
10 best skincare products
1/10 Clean & Clear Blackhead Clearing 2-in-1 Wash and Mask
A new offering from the best-selling range that offers two for the price of one. Use this fuss-free product for your daily wash or, if you feel your T-zone needs a bit more pore cleaning attention, then apply and leave to get to work for five minutes before rinsing. £4.49 for 150ml, tesco.com
2/10 Burt’s Bees Anti-Blemish Pore Refining Scrub
Many scrubs can be harsh, especially on younger, sensitive skin. The Jojoba beads and a natural fruit acid complex in this one provide gentler exfoliation – and it’s 100 per cent natural. £9.99 for 110g, burtsbees.co.uk
3/10 Witch Mattifying Moisturiser
Extract of witch hazel plus tapioca starch and shea butter are in this light and easily absorbed moisturiser for oily/combination skin. It leaves faces shine-free, and has the added benefits of SPF 15 UVA and UVB protection. £4.99 for 50ml, boots.com
4/10 Mario Badescu Drying Lotion
This product from the luxury skin-care brand has reached something of a cult status in the US. Why? Because it’s a super-efficient spot treatment which works overnight to help clear and soothe whiteheads and other blemishes. Not cheap, but the teen in your life will thank you for investing. £14.50 for 29ml, beautybay.com
5/10 DHC Deep Cleansing Oil
Olive oil-based cleanser may sound counter-intuitive for spot-prone skin, but a bottle of this cleanser from the Japanese beauty brand is sold globally every 10 seconds. If you have a teen who goes a bit TOWIE-esque on the make-up front, one pump’s worth massaged on to dry skin gets rid of it all. £21.50 for 200ml, dhcuk.co.uk
6/10 Australian Bodycare Spot Stick
A targeted rollerball treatment that contains the classic blemish-fighting combo of tea tree oil and witch hazel. One to have with you at all times, ready for when a breakout threatens. £5.99 for 10ml, johnlewis.com
7/10 Dermalogica Clear Start Breakout Clearing Daytime Treatment
This respected brand has developed this range to prevent and treat mild to moderate acne in teens and young adults. The simple application techniques will appeal to those reluctant to adopt good skincare practice. The daytime treatment acts on congested pores and soothes inflamed skin. £16 for 60ml, dermalogica.com
8/10 Amie Morning Clear Purifying Facial Wash
This has a fresh and fruity fragrance thanks to the inclusion of natural fruit and botanical extracts and no chemical additives. An excellent starter range. £4.95 for 150ml, tesco.com
9/10 AvÈne Cleanance Cleansing Water
Based on the soothing qualities of spring water sourced from the Avène thermal spa, this cleansing water can remove water-proof make–up and regulate sebum production leaving skin soft and cleansed without too much hassle. £16 for 400ml, boots.com
10/10 Elemis Freshskin Face Mask Duo
The purifying face mask with goji berry extract and natural clays draws out impurities, while the accompanying magical moisture quenching face mask with apple extract and aloe vera is perfect for when skin needs some TLC. £15 for 6 x 7ml sachets, timetospa.co.uk
The paper adds that “interactions between the host and the skin … play essential roles in disease development”.
The research involved testing 10 volunteers who were all given vitamin B12 supplements. Within a week, just one of them broke out in spots.
To investigate what had happened the researchers collected bacterial samples from the participants' noses using deep-cleansing pore strips.
They discovered that excess B12 quenched the bacteria's own production of the vitamin, which had the effect of boosting levels of an inflammatory compound, porphyrin, released by the bugs. Porphyrin is known to drive the inflammatory skin response linked to acne.
The researchers added: "Future follow-up studies may potentially lead to the development of new therapeutics for this medically important disease."
The study proves the link between B12 and skin bacteria - but that doesn't mean people should stop taking B12, the researchers stress.
Vitamin B12 plays key roles in the normal functioning of the brain and nervous system, and red blood cell formation. Deficiency of the vitamin can lead to fatigue and lack of energy.
Perhaps the solution is to adopt a strict vegan diet – just make sure you avoid a certain divisive spread made out of yeast extract.
Additional reporting by Press AssociationReuse content