Search for almost any vitamin and you will find two products that look identical on the front and are argued about fiercely on the back. One lists folic acid, the other calcium-L-methylfolate. One lists cyanocobalamin, the other methylcobalamin. One lists magnesium oxide, the other magnesium glycinate. The marketing around these differences is confident in a way the underlying science often is not.
Naming the form is genuinely useful, because it tells you precisely which compound is in the capsule rather than leaving you with a nutrient name and a number. What it does not do is settle the question of which product is better for you. This guide explains what each of the commonly debated forms is, where the differences are well established, and where the honest answer is that it depends.
Why a vitamin needs a form at all
Vitamin B12 cannot be tipped into a capsule as pure vitamin B12 in the way sugar goes into a bowl. Nutrients are added to food supplements as specific chemical compounds that are stable, that can be manufactured to a consistent purity, and that appear on the list of substances UK law permits for this use. Every supplement on the shelf therefore uses a form, whether or not the label admits it.
That is why a label saying folate, 200 µg is less informative than it looks. It has told you the nutrient and the amount but not the compound, so you cannot compare it against the product next to it, you cannot check it against a study, and you cannot raise it usefully with a pharmacist. Naming the form costs the manufacturer nothing except the willingness to be specific.
Folate: folic acid, folate salts and calcium-L-methylfolate
Folate is the umbrella term for the B vitamin. Folic acid is the synthetic form used in most supplements and in food fortification, and it is the form used in the large trials that established folate's role before and during early pregnancy. Calcium-L-methylfolate is a salt of the form that circulates in the body, and it is the form on our own panel at 200 µg, which is 100% of the NRV.
The genuine, uncontroversial part is that these are different compounds and that a label should say which one it uses. The contested part is how much practical difference it makes for most people. You will see confident claims tied to variations in the MTHFR gene; the research there is more mixed and more nuanced than supplement marketing usually allows.
One point is not contested at all. If you are pregnant, planning a pregnancy or could become pregnant, UK guidance on folic acid is specific and comes from the NHS rather than from a supplement label. Follow that advice, and take the question of which form to a midwife, GP or pharmacist.
Vitamin B12: cyanocobalamin and methylcobalamin
Cyanocobalamin is the most studied and most stable form of vitamin B12, and it is what the majority of supplements and fortified foods use. Methylcobalamin is one of the forms the body uses directly. Our multivitamin lists 100 µg as methylcobalamin, at 4000% of the NRV.
That percentage surprises people, so it is worth explaining. B12 absorption is limited by a receptor-based mechanism that saturates, and only a small fraction of a large oral dose is taken up once that route is full. Higher label amounts are common for this reason rather than because more is presumed better.
B12 status genuinely matters for people following vegan or largely plant-based diets, for many older adults, and for people taking certain long-term medicines. If any of those apply to you, the useful step is a conversation with a GP about whether testing is appropriate, not a decision between two forms on a shelf.
Minerals: elemental amount versus compound weight
This is the single most useful thing to understand about mineral supplements, and it catches out careful readers. When a label says magnesium glycinate, the compound includes both the magnesium and the glycine, and only part of that weight is the mineral itself. The figure that matters is the elemental amount — the amount of actual magnesium — and that is the figure the %NRV refers to.
So a front-of-pack claim of 1,000 mg of a magnesium compound and a panel figure of 100 mg of magnesium can both be true and describe the same capsule. Our Advanced Calm + Sleep panel states 70 mg of magnesium at 19% of the NRV, supplied as the glycinate; the 70 mg is elemental magnesium.
The rule is simple. Compare the nutrition panel against the nutrition panel. If a product's largest number appears only in marketing copy and not in the panel, it is probably the compound weight.
Magnesium: oxide, citrate and glycinate
Magnesium oxide carries a high proportion of elemental magnesium by weight and is inexpensive, which is why it appears in so many low-cost products. It is also the form most associated with a laxative effect. Magnesium citrate is widely used and generally well tolerated. Magnesium glycinate, sometimes labelled bisglycinate, is magnesium bound to the amino acid glycine, and is often chosen where tolerability matters.
Chelated is the word you will see attached to forms like glycinate. It describes a mineral bound to an organic molecule, usually an amino acid. It is a real chemical description, not a quality grade, and there is no legal definition that guarantees anything about a product carrying the word.
For an evening formula, tolerability and the elemental amount are the practical considerations. Ours supplies 70 mg of elemental magnesium as the glycinate, which is a contribution to the day's intake rather than the whole of it, and the panel says so.
Vitamin K: phylloquinone and menaquinone-7
Vitamin K comes in two families. K1, phylloquinone, is the form in leafy green vegetables. K2 covers the menaquinones, of which MK-7 is the one most often used in supplements. They behave differently in the body, and a label that groups them as vitamin K is hiding a distinction worth seeing.
Our two labels handle it differently because the formulas differ. Complete Daily Multivitamin lists 65 µg of vitamin K as phylloquinone and 10 µg of K2 as menaquinone-7 as two separate rows. Vitamin D3+K2 Advanced supplies 80 µg of K2 as MK-7 in a two-capsule serving.
There is one caution here that outranks everything else on this page. Vitamin K interacts with anticoagulant medicines such as warfarin. If you take one, do not start a vitamin K-containing supplement without speaking to whoever manages your anticoagulation first.
What bioavailability does and does not prove
Bioavailability describes how much of an ingested nutrient reaches circulation in a usable state. It is measured in controlled studies, usually in modest numbers of people, often over short periods, and frequently comparing single doses rather than months of daily use.
Those studies are informative and they are not the same as evidence that a finished product produces a particular outcome for you. A form can be better absorbed and still be supplied at an amount too low to matter, or supplied alongside ingredients that make the product unsuitable. Absorption is one variable in a chain that ends with whether the product is right for a specific person.
This is also where UK claims rules bite, and reasonably so. A supplement may only carry health claims from the authorised list, using approved wording, and those claims attach to nutrients rather than to brands or forms. No form of any nutrient earns a manufacturer the right to promise an outcome.
Reading a form-by-form panel
Put the pieces together and a panel becomes straightforward to interrogate. Four questions cover almost everything.
- Is the exact form named in brackets after each nutrient, or is the label stopping at the nutrient name?
- Is the amount per daily serving, and for minerals is it the elemental amount that the %NRV refers to?
- Is the same nutrient listed twice? Our panel lists vitamin B2 and vitamin B6 twice each because two forms of each are included, and both rows are printed rather than merged into one figure.
- Do the warnings match the formula? A product containing vitamin A, vitamin K or a botanical should say so in the cautions.
A label that answers those four is being straight with you. Whether the product suits you is a separate question, and usually a better one to ask a pharmacist than a search engine.
Frequently asked questions
Is methylfolate better than folic acid?
They are different compounds and a label should name which it uses, but better is not a question a label can settle. Folic acid is the form used in most fortification and in the large trials behind UK pregnancy guidance. Claims that everyone needs the methylated form go further than the evidence supports. If folate matters to you for a specific reason, including pregnancy or a known genetic result, discuss it with a GP or pharmacist.
What does chelated mean on a mineral supplement?
It describes a mineral bound to an organic molecule, commonly an amino acid — magnesium glycinate and zinc bisglycinate are typical examples. It is a chemical description rather than a quality standard, and no legal definition attaches a guaranteed benefit to the word. Check the elemental amount in the panel regardless of whether the word appears.
Does everyone need methylated vitamins?
No. Methylated is a description of a chemical form, not a recommendation. Most people using a well-formulated supplement will do perfectly well with conventional forms, and the strongest marketing claims in this area run ahead of the research. If you have had a specific test result or diagnosis that you think is relevant, take that to a healthcare professional rather than to a product page.
Why does one panel list the same vitamin twice?
Almost always because two different forms of that nutrient are included and the label is declaring each separately instead of pooling them. Our multivitamin does this for vitamin B2 and vitamin B6. It looks like a duplication and is actually the more transparent choice, because you can see exactly what makes up the total.
Before choosing a supplement
- Read the complete current label, including the active and the other ingredients.
- Compare the daily serving rather than the number printed on the front of the bottle.
- Add up every source of the same nutrient across your whole routine.
- Ask a pharmacist or qualified healthcare professional about medicines, pregnancy, breastfeeding, surgery or an existing condition.
- Remember that food supplements do not replace a varied, balanced diet and a healthy lifestyle.
Related guides on this formula
- How to read a multivitamin label: %NRV, servings and forms
- Building a simple supplement routine that you can keep
View the Complete Daily Multivitamin label, the full ingredient panel and current purchase options.
Also useful: RevaHealth Journal · full range · Ingredients · Contact.
References and further reading
- NHS: B vitamins and folic acid
- NHS: Other vitamins and minerals
- GOV.UK: Great Britain nutrition and health claims register
This article is general educational information, not medical advice. Food supplements are not medicines and are not intended to diagnose, treat, cure or prevent disease. Always read the complete physical label before use, and speak to your GP or pharmacist if you are unsure whether a supplement is right for you.
