On the panel
Vitamin B12 — 6 mcg
Nothing in the plant kingdom makes it, and no cell divides properly without it.
What It Is
Vitamin B12 is the largest and most structurally elaborate vitamin there is, built around a cobalt atom held inside a corrin ring. Nothing in the plant kingdom manufactures it. Bacteria make it, and it reaches us through animal foods where those bacteria did the work upstream.
Our panel uses methylcobalamin, the form that takes part directly in the methylation reaction described below rather than requiring conversion first.
What It Actually Does
Three jobs, described without the marketing vocabulary.
It keeps folate usable
B12 donates a methyl group to the enzyme that regenerates folate. Without working B12, folate becomes trapped in a form the cell cannot spend — the methyl folate trap — which is why the two deficiencies produce the same picture in a blood count.
No copied genome without it
Because folate carries the carbon atoms DNA is written with, and because B12 keeps folate circulating, a B12 shortfall stops cells finishing a division. Bone marrow and the basal layer of skin are the two tissues that notice first.
It shows on skin and hair
B12 deficiency is associated with hyperpigmentation, most often over the knuckles and in the palmar creases, and with premature greying. Each is well recorded and each fades once B12 is back, which is a helpful reminder that this vitamin shows up on the outside.
6 mcg In Every Serving
Our serving carries 6 mcg against an adult requirement of roughly 2.4 mcg a day. That is a deliberate multiple, because B12 absorption is inefficient at the best of times and becomes less efficient with age.
B12 donates a methyl group to the enzyme that regenerates folate into a usable form. Take B12 away and folate becomes trapped in a shape the cell cannot spend, which halts the carbon chemistry that writes DNA. Skin feels that before slower tissues do, because it rebuilds its own surface roughly every month.
Who Tends To Fall Short
Deficiency is common and under-diagnosed, and it has two quite different causes. The first is dietary: vegans and strict vegetarians take in almost none without fortified food or a supplement. The other is uptake, and it is the version that dominates in later life.
Getting B12 out of food takes stomach acid, and getting it through the gut wall takes intrinsic factor. Age reduces stomach acid, so do proton pump inhibitors taken long term, metformin interferes further down the chain, and autoimmune loss of intrinsic factor causes pernicious anaemia.
Nerve symptoms — tingling in hands and feet, unsteadiness, memory changes — can appear before any change in the blood count and can become permanent if left. This is a nutrient to test for rather than guess about.
Where It Turns Up In Food
| Source | Roughly | Notes |
|---|---|---|
| Clams | Over 80 mcg per 100 g | Extraordinarily rich |
| Liver | ~70 mcg per 75 g | One serving covers weeks |
| Salmon | ~4.9 mcg per 100 g | Ordinary and reliable |
| Beef | ~2.5 mcg per 100 g | Everyday coverage |
| Dairy and eggs | 0.5–1.4 mcg a serving | The vegetarian mainstay |
| Fortified plant milks | Varies by brand | The only reliable vegan route besides supplements |
The Ceiling, And The Cautions
No upper intake limit has been established. B12 is water soluble, absorption through the intrinsic factor route is self-limiting, and the excess is excreted.
The real risk with B12 runs the other way. High folate intake can correct the blood picture of a B12 deficiency while nerve damage continues underneath, unnoticed. That is one specific reason this panel carries both, and the reason anyone with tingling, numbness or unsteadiness should have B12 measured rather than supplemented on spec.
Where This Comes From
- Methionine synthase requires B12 to regenerate tetrahydrofolate from 5-methyltetrahydrofolate.
- Neurological presentation can precede haematological change, which is why testing matters.
- Absorption depends on gastric acid and intrinsic factor, both of which decline with age and with certain medications.
General nutritional science rather than claims about this product. Nothing on this page is medical advice; see our disclaimer.
Vitamin B12 Questions
What we get asked about this line of the label specifically.
Methylcobalamin or cyanocobalamin?
Methylcobalamin is used directly in the methylation reaction and needs no conversion. The cyano form holds up better on a shelf and has far more research behind it. Either will lift a blood level, and the gap between them is narrower than the packaging implies.
I am vegan. Is 6 mcg enough?
It is a sensible daily contribution, but if you eat no animal products you should be managing B12 deliberately and testing occasionally rather than relying on a skin supplement to cover it.
Will it reverse grey hair?
Where grey hair traces back to a confirmed B12 shortfall, fixing the shortfall can turn it around. Grey that simply arrives with age is written into your genes and no jar undoes it.
Will it give me energy?
For somebody genuinely short of it, putting that right can change a great deal. If you are not, it does nothing and the excess is excreted. Fatigue has many causes and most are not this one.