It’s essential for a healthy immune system and regulates mood. A growing number of UK clinics market vitamin injections to healthy people but do you really need them?

Why do I need vitamin B12?

B12 is involved in producing red blood cells, maintaining a healthy nervous system, and converting food to energy. It also helps to regulate the immune system and mood, and control levels of the amino acid homocysteine, elevated levels of which are associated with heart disease. Most people who eat meat, fish, eggs and dairy products get enough B12. Vegans are advised to eat fortified food and take supplements.

How much do I need?

The UK government says adults need 1.5 micrograms (mcg) a day, the US National Institutes of Health advises 2.4mcg, and the European Food Safety Authority says 4mcg a day is adequate. The US and Europe, but not the UK, recommend higher levels for pregnant and breastfeeding women. A study published last year found one in 12 women aged between 19 and 39 were B12 deficient, despite consuming at least the UK recommended minimum intake.

What are the symptoms and causes of B12 deficiency?

Symptoms include fatigue, faintness, headaches, pale skin, loss of appetite, weight loss, pins and needles and a sore, red tongue. One of the main causes is the autoimmune condition pernicious anaemia. Other causes are conditions affecting the stomach or small intestine, such as Crohn’s disease, operations such as gastrectomies (which involve removal of part of the stomach), and certain medications. Researchers have also identified a gene variation linked to B12 deficiency. Long-term deficiency can lead to serious heart and neurological problems.

Am I likely to have B12 deficiency?

Studies suggest the prevalence of deficiency in the UK is one in 10 people aged 75 and over, one in 20 aged 65-74, and lower in younger age groups – except for vegans, where prevalence is around 11%. However, some say these rates are based on deficiency thresholds that are set too low. The main test measures B12 circulating in blood serum. Doctors can also look for enlarged red blood cells. Newer tests are more precise but are not widely available.

Experts disagree about how sensitive these tests are. “The blood tests are largely reliable,” says Catherine Collins, spokeswoman for the British Dietetic Association. “There may be some people who fall within the normal range but need a little more B12, but I reject the idea that they need a lot more.”

Dr Ayan Panja, a GP in St Albans with an interest in preventive medicine, disagrees. “There is much disagreement around the validity of the tests among professionals. My view is that B12 deficiency is underdiagnosed, and can sometimes explain clusters of symptoms such as migraines, cramps, food digestion and sleep problems, dementia and depression.”

Who needs B12 injections?

Dietary deficiency can be treated with tablets. Those with problems absorbing B12 from the stomach are often given hydroxocobalamin, an injectable form of B12. This is given six times over two weeks, followed by once every three months. NHS guidelines say those with neurological symptoms should receive more frequent treatment, but some patients complain this is often ignored.

Campaigners are calling for more frequent testing and treatment. “Dogs diagnosed [with a deficiency] can have B12 injections weekly, so why can’t humans?” asks Tracey Witty, who launched a petition for injectable B12 to be made available over the counter, as it is in France and Germany. “Most of the dose is excreted within 24 hours, so many patients are on their knees for probably 10 of the 12 weeks between injections, or they feel forced to buy B12 online from abroad,” she says.

Why are B12 injections available on the high street?

Intravenous vitamin treatment was popularised in the US in the 1980s by Dr John Myers of Baltimore who offered his “Myers cocktails” for various medical conditions. Alternative health practitioners opened IV lounges that spread across North America. Celebrity devotees are reported to include Madonna, Justin Bieber and Rita Ora. The past three years have seen a growing number of spas, IV lounges and clinics in the UK offering intravenous and intramuscular injections of vitamins. These make a variety of claims. The website of one London clinic, for example, states that its injections including B12 can treat anaemia, help with weight loss, boost energy, strengthen the immune system and prevent illness.

B12 jabs can only be used as a medical treatment under prescription in the UK. Otherwise it is unlawful for companies to claim it can relieve symptoms, provide cures or remedies. “MHRA is aware of clinics offering intravenous nutritional therapy products,” says a spokesperson for the Medicines and Healthcare products Regulatory Agency. “We are in active discussions with the sector to ensure regulatory compliance.”

Do B12 injections sold for non-medical purposes work?

There is no evidence that jabs can help those who are not deficient in B12. The doses involved are usually many times the levels the body can absorb, so most of the B12 is rapidly excreted in urine. It could be that apparently healthy people who report benefits may have undiagnosed B12 deficiency.

Geeta Sidhu-Robb, founder of Nosh Detox, which sells B12 injections and infusions at Harvey Nichols in Knightsbridge, London, believes her customers do benefit. “To feel OK and to feel great are two different states,” she says. “If you look at somebody and think will they get an awful lot more energy, yes, I do think that it does make a big difference.”

Collins believes any perceived benefits in healthy people are down to a placebo effect. “B12 injections and infusions for healthy people create an aura of fabricated need. It’s like having a plaster put on your knee and getting a cuddle when you fall over.”