How much of each nutrient does an adult need per day?

These are the UK reference nutrient intakes for adults aged 19 to 64. They cover the needs of nearly everyone, so they are a benchmark, not a target to beat. Nutrient Men Women Vitamin C 40 mg 40 mg Vitamin A 700 µg 600 µg Iron 8.7 mg 14.8 mg Calcium 700 mg 700 mg Magnesium 300 mg 270 mg Zinc 9.5 mg 7 mg The higher iron figure applies to women aged 19 to 49. Source: NHS

Which form should I choose?

The form changes how much of a dose you actually take up, and how well you tolerate it. These are the forms we prefer and why. Nutrient Form we prefer Why Magnesium Bisglycinate or citrate Absorbed better than oxide Vitamin B12 Methylcobalamin Ready to use, no conversion Vitamin D3 Softgel in oil Needs fat for uptake Folate Methylfolate Works with poor conversion Omega-3 Triglyceride or algae oil Absorbed better than ethyl ester

Supplements for adults: vitamins, minerals and forms

Where adults actually run short

Between 19 and 64 your nutrient needs stay fairly stable. What changes is your week: shift work, an indoor job, hard training, a plant-based diet, or planning a pregnancy. Those things decide your gaps, far more than your age does. An adult collection is not a different set of nutrients, it is a different set of reasons to take them.

In the UK the clearest gap is vitamin D. Between October and March the sunlight is too weak for your skin to make it, whatever you eat. Vitamin D contributes to the maintenance of normal bones and to the normal function of the immune system. Ten micrograms (400 IU) a day is the standard adult amount here. You can take that on its own from our daily vitamin D3 options, or get it built into a multi.

Two groups have a second clear reason to look further. Women who menstruate need almost twice as much iron as men, and iron contributes to the reduction of tiredness and fatigue. People who eat no animal products need a reliable source of vitamin B12, because plants do not provide it. They also tend to sit low on the omega-3 fats EPA and DHA, where algae oil is the direct plant source.

The form on the label decides how much reaches you

Two products can list the same number of milligrams and behave very differently. That is why we read the form first:

Magnesium: bisglycinate or citrate are absorbed better than oxide, which largely passes through.
Vitamin B12: methylcobalamin and adenosylcobalamin are the ready-to-use forms.
Folate: methylfolate suits people who convert folic acid poorly.
Vitamin D3: in oil or a softgel, because it needs fat to be taken up.

A broad Multivitamins product covers small gaps across the board. A single nutrient makes sense once you know your gap and want a meaningful amount of it, not a token 10 percent.

How we choose what sits in this collection

We look at three things: the form, the dose, and whether a combination makes sense. We prefer magnesium bisglycinate over oxide because more of it is absorbed, and methylcobalamin over cheaper B12. We are brand-neutral, so we carry what delivers results, not what pays best, and we buy directly from the brands, with no middlemen. Every product passes our compliance team before it goes live, we test products ourselves, and independent labs spot-check batches. We only use claims the European food safety authority (EFSA) has approved, and we say so when a dose is simply too low to do anything. You can read how we select.

What to expect, honestly

Supplements fill gaps in a diet. They do not replace vegetables, sleep or training, and most people feel nothing on day three. Judge a routine after six to eight weeks of consistent use, taken at a moment you will remember, usually with a meal. Two products taken now and then rarely beat one taken every day. If you are pregnant or could become pregnant, UK advice is 400 micrograms of folic acid daily and no vitamin A supplements or liver. If your needs are shifting with age, our pages for other life stages are a better starting point.

For most adults in the UK the short list is short. Vitamin D is the one with a national recommendation, because between October and March sunlight is too weak for your skin to make it. Beyond that it depends on your plate: iron matters more for women who menstruate, vitamin B12 and omega-3 for people who eat no animal products, and calcium for anyone avoiding dairy. Everything else is worth adding only when you have a reason.

It depends what you want from it. A multivitamin spreads a modest amount over twenty or more nutrients, which suits an irregular diet and small gaps. It is rarely enough when you have one clear, larger need, because the dose per nutrient stays low by design. In that case a single nutrient at a proper amount works better. Many adults combine the two: a multi as a base, plus one targeted product.

These are the UK reference nutrient intakes for adults aged 19 to 64. They cover the needs of nearly everyone, so they are a benchmark, not a target to beat.

Nutrient	Men	Women
Vitamin C	40 mg	40 mg
Vitamin A	700 µg	600 µg
Iron	8.7 mg	14.8 mg
Calcium	700 mg	700 mg
Magnesium	300 mg	270 mg
Zinc	9.5 mg	7 mg

The higher iron figure applies to women aged 19 to 49.

Source: NHS

The form changes how much of a dose you actually take up, and how well you tolerate it. These are the forms we prefer and why.

Nutrient	Form we prefer	Why
Magnesium	Bisglycinate or citrate	Absorbed better than oxide
Vitamin B12	Methylcobalamin	Ready to use, no conversion
Vitamin D3	Softgel in oil	Needs fat for uptake
Folate	Methylfolate	Works with poor conversion
Omega-3	Triglyceride or algae oil	Absorbed better than ethyl ester

The time that you will not forget is the best time. Beyond that, two rules help. Fat-soluble nutrients, vitamins A, D, E and K plus omega-3, are taken up better with a meal that contains some fat. Magnesium is often taken in the evening because people find it easier on the stomach then. Iron is absorbed better away from tea, coffee and dairy, so between meals with a little vitamin C.

Longer than most packaging suggests. If you were genuinely low in something, blood levels usually need weeks to move, and only then can you notice a change in how you feel. We suggest judging a supplement after six to eight weeks of daily use, not after a fortnight. Some things you will never feel directly, such as vitamin D in winter, and that is normal: they work quietly rather than noticeably.

Yes, but for different reasons. If you eat no animal products, vitamin B12 has no plant source, so a supplement is not optional, and EPA and DHA come from algae oil rather than fish. If you train hard, your losses are mostly fluid, salts and protein, so electrolytes and protein matter more than extra vitamins. Iron is worth checking for endurance athletes and for women who menstruate.

Gradually. Absorption of vitamin B12 from food tends to drop with age because stomach acid falls, and calcium and vitamin D matter more for maintaining bones. Appetite often shrinks too, so the same diet delivers less. The change is slow rather than sudden, which is why we treat it as a separate stage: our supplements for over 55s follow that logic instead of simply adding more of everything.

More is not better, and some minerals have a fairly narrow window. The amounts below are the levels the NHS describes as unlikely to cause harm for adults. Higher intakes over a long period can cause problems, so check the total across all your products, since a multi and a single nutrient can stack.

Nutrient	Unlikely to cause harm
Magnesium (supplements)	400 mg a day
Zinc	25 mg a day
Selenium	350 µg a day
Potassium (supplements)	3700 mg a day

Source: NHS

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