A customer put two B12 tubs on my counter last month, one from a supermarket and one of ours, and asked why mine cost more when the supermarket one had the same big "B12" on the front. Fair question. The answer is one word on the back label: the supermarket tub said cyanocobalamin, ours says methylcobalamin. Same vitamin, different form, and the difference is worth understanding before you spend a penny. Here's the whole story, the way I explain it across the counter.
- Vitamin B12 pulls a lot of weight for such a tiny nutrient.
- B12 is found almost entirely in animal foods: meat, fish, eggs, dairy.
What B12 actually does
Vitamin B12 pulls a lot of weight for such a tiny nutrient. The EFSA-authorised claims: B12 contributes to normal energy-yielding metabolism, the reduction of tiredness and fatigue, normal functioning of the nervous system, normal red blood cell formation, normal psychological function and normal function of the immune system. That's regulator-approved language, and it's why tiredness is the reason most people come looking for B12 in the first place.
Methylcobalamin vs cyanocobalamin: the two forms explained
Cyanocobalamin is the synthetic form. It's stable, it's cheap to manufacture, and it's what you'll find in most supermarket B12 capsules UK shelves carry. Your body can't use it as-is: it has to strip off the cyanide group (a tiny, harmless amount, before anyone panics) and convert it into an active form.
Methylcobalamin is one of the two forms your body actually uses, the other being adenosylcobalamin. It's the form found naturally in food, and supplementing it means you're taking the finished article rather than asking your body to do the conversion. It costs more to make, which is why the cheap end of the market avoids it.
Will you feel a dramatic difference between the two? I won't pretend the gap is night and day, because both forms can raise B12 levels. But given the price difference is modest at our end of the market, my view after 30 years is simple: if you're taking B12 anyway, take the form your body recognises. It's the same logic as buying magnesium citrate instead of oxide.
Who tends to run low on B12
B12 is found almost entirely in animal foods: meat, fish, eggs, dairy. That geography explains most of who runs short. Stating the facts plainly:
- Vegans and vegetarians. With few or no animal foods in the diet, a B12 supplement isn't optional, it's essential. Even the Vegan Society says so.
- Over-60s. Absorbing B12 from food requires stomach acid and a protein called intrinsic factor, and both tend to decline with age. You can eat plenty of B12 and still absorb it poorly.
- People on certain long-term medications. Metformin and acid-reducing medicines such as proton pump inhibitors are both associated with lower B12 levels over time. That is a fact worth knowing, not a reason to stop any medication.
If any of that is you, or you're dealing with ongoing unexplained tiredness, ask your GP for a B12 blood test before assuming. It's a standard, cheap test, and knowing your starting point beats guessing. Genuine deficiency is a medical matter for your GP to manage, sometimes with injections, and a shop supplement is not a substitute for that.
How much B12 do you need?
The NHS reference intake is tiny, around 1.5 micrograms a day. So why do supplements like our LSC B12 Methylcobalamin 1000mcg contain hundreds of times that? Absorption. The intrinsic factor system that actively absorbs B12 saturates at a few micrograms per meal, and beyond that only around one percent of a dose passively diffuses through. One percent of 1000mcg is roughly 10mcg absorbed, which comfortably covers your needs even if your active absorption is poor. That's the logic behind B12 methylcobalamin 1000mcg as a standard daily dose, and it's why high-dose B12 has a long track record of safe use. B12 is water-soluble and your body simply passes what it doesn't use.
Sublingual vs capsules
You'll see sublingual B12 marketed hard, tablets or sprays held under the tongue, on the theory that it absorbs through the mouth and bypasses the gut. Honest answer: the studies comparing sublingual against ordinary swallowed B12 at matched doses show they raise levels about equally well. The dose matters far more than the delivery route. So pick on preference. Capsules are cheap and simple. A liquid like Viridian's B12 Liquid, which combines methylcobalamin with adenosylcobalamin, suits anyone who hates swallowing capsules. And if you like your nutrients with botanicals alongside, Terranova's B12 500ug Complex is the thoughtful middle ground.
View in the shop
Quick questions from the shop floor
Is methylcobalamin better than cyanocobalamin?
Both raise B12 levels. Methylcobalamin is the naturally occurring, bioactive form your body uses directly, cyanocobalamin needs converting first. At similar prices I'd choose methylcobalamin every time, and that's what our own-label B12 uses.
Is 1000mcg of B12 too much to take daily?
For most healthy adults, no. Because only a small fraction of a large oral dose is absorbed, 1000mcg daily is a standard, well-tolerated amount with a long history of use. If you have a diagnosed condition or take regular medication, check with your GP or pharmacist first.
How long does B12 take to work?
If you were genuinely low, energy typically improves over weeks, not days. Your body also stores B12 in the liver, so both running low and topping up are slow processes. Consistency wins.
Should I get tested before supplementing?
Ideally, yes, especially if you have real symptoms. A GP blood test tells you where you stand, and ongoing fatigue has plenty of other possible causes that deserve a proper look.