A quiet word on vitamin B12 - and why so many people are short of it

Vitamin B12 - sometimes listed as cobalamin - is one of those quiet, behind-the-scenes vitamins. It's water-soluble, it isn't produced by the body, and it has to come in through what you eat. Most of it sits in animal-based foods: red meat, poultry, fish, eggs and dairy. If you've moved to a stricter plant-based diet without thinking about it, you're already on the back foot.

It helps the body build red blood cells, keeps the nervous system insulated, and is involved in the synthesis of DNA. It also plays a role in mood, memory, balance and the way you metabolise food into energy. When levels drop, the symptoms creep in slowly enough that people often blame everything else first.

• An exhaustion that doesn't shift after a good night's sleep
• A red, sore or oddly smooth tongue
• Pale or slightly yellow-tinged skin
• Pins and needles in hands or feet
• Patchy memory, low mood, a foggy head
• Changes in balance or the way you move

Two reasons, broadly. The first is dietary - you're not eating enough B12-rich food. The second is absorption: conditions like Crohn's, pernicious anaemia, certain digestive surgeries, and long-term use of acid-reducing medication (PPIs) all stop the body from pulling B12 out of food properly.

We run the service in partnership with Treatlocal. You start with a short online questionnaire, a UK prescriber reviews it, and once approved you book a slot at the pharmacy. The injection itself is a hydroxocobalamin 1000mcg/ml dose, given intramuscularly into the upper arm. £29 per injection, in and out in minutes.

Vitamins shouldn't replace a balanced diet - but for people who can't absorb enough, or who've been advised by their GP to top up, an injection is a reliable, properly dosed option.