Micronutrients that matter

No single diet nails every micronutrient. A practical rundown of the four worth minding — calcium, magnesium, zinc and iron — with doses, the absorption rules, and when to just supplement.

No single diet reliably delivers every micronutrient in the dose you’d want. The body is resilient enough to make do without the optimal amount of each — but as lifespans stretch and you want your bones and muscle to last, a few are worth paying attention to and, where whole food can’t get you there, topping up. Food first, always. Supplement the gaps, don’t mega-dose them, and run anything you’re unsure about past a doctor — especially iron, for reasons below.

Before the individual nutrients, one rule that governs several of them.

The absorption rule

Calcium, magnesium and zinc compete for the same spots in the gut. Take big doses of all three at once and they get in each other’s way. So if you’re on a multivitamin that packs all three, split it into two servings across the day rather than one big hit. And where you can, buy the citrate form — it absorbs better than the oxides and carbonates most cheap Indian multivitamins use (Supradyn and its cousins mostly use magnesium oxide, which the body barely absorbs).

Calcium

Calcium is the one your bones live and die by, and it’s also used by muscles and cells to signal. You need 1 to 1.5 grams a day. There’s about 1.25 grams in a litre of milk, which tells you the problem: unless you’re drinking a litre of dairy daily, you’re probably short. Seafood eaten with the bone, tofu, almonds, and greens like broccoli and cauliflower help, but plants carry compounds that block calcium absorption, so you’d need to eat a lot. If you don’t do dairy, or you’re osteoporotic, a supplement is often the sensible route.

Citrate absorbs with or without food; carbonate needs to be taken with a meal. Either way, calcium goes down better alongside vitamin D. Don’t push past 2 to 2.5 grams a day — more just buys you discomfort, not stronger bones.

Magnesium

Magnesium is the under-appreciated one — commonly under-supplied, and a lot of people feel the difference when they fix it. You need 200 to 400 mg a day. It’s in plant and animal foods, but only in small amounts, and processing strips most of it out, which is why whole food alone often falls short. It helps sleep (a big one), bone health, hormone markers, and handling stress.

Go for magnesium citrate — harder to find locally, so read the label, because most multivitamins use the poorly-absorbed oxide. You sweat and pee it out easily, so overdosing is rare. A dose closer to bedtime tends to help sleep.

Zinc

Zinc is arguably the most important trace mineral — it touches immunity, healing, skin, appetite, mood and testosterone production. You need 10 to 15 mg a day, and your body doesn’t store it, so it has to come in daily. It lives mainly in animal foods — shellfish, red meat, fattier cuts of chicken — and if you’re not eating 250-odd grams of red meat or seafood a day, you’re likely short. Vegetarians should supplement it as a matter of course; plant sources exist but don’t get you to the number.

Zinc citrate (around 50 mg) does the job; gluconate absorbs better but is harder to find. Take it after a meal, ideally with some protein. And a note for diabetics: you tend to pass more zinc in urine, so you may need a bit more — ask your doctor.

Iron — the one to be careful with

Iron makes haemoglobin, which ferries oxygen around your body, and it plays structural roles in connective tissue too. Animal sources (red meat, seafood, and especially organ meat) carry heme iron, which absorbs easily; plant sources (spinach, pulses, greens, beans) carry non-heme iron, which absorbs poorly, so vegetarians have to make it up on volume. Even an old, poorly-seasoned cast-iron tava leaches usable iron into your food.

The daily numbers: about 8 mg for men and non-menstruating women, up to 15 mg for menstruating women, 27 mg in pregnancy, 8 to 11 mg for kids, and more for some athletes. Women between roughly 15 and 50 are the group most at risk of deficiency, because menstruation is one of the few ways the body loses iron at all.

And that’s exactly why iron is different from the others:

Don’t self-supplement iron

Iron isn’t excreted through sweat, urine or stool — you can only lose it by bleeding. So it accumulates, and the risk of over-consuming is as real as the risk of running low. Chronic iron overload is linked to organ and possibly brain damage and some cancers. Deficiency takes a long time to show as anaemia because the body stores iron well (men hold up to two years’ worth, women six to eighteen months), which means a blood test can catch a shortfall long before you feel it. So: get tested rather than guessing, and never start an iron supplement — or a multivitamin that contains iron — without a doctor’s say-so.

The short version

Eat well first — dairy or its stand-ins for calcium, animal foods for zinc and iron, whole foods across the board. Where your diet has a standing gap (calcium if you skip dairy, magnesium for most people, zinc for vegetarians), a sensible supplement in the right form closes it. Split calcium, magnesium and zinc across the day so they don’t fight for absorption. Leave iron to a blood test and a doctor. And treat none of this as a substitute for the training that actually puts the calcium to work — a supplement builds nothing on its own.

These are general starting points. Doses and needs vary with age, sex, diet and health, so use a doctor and, where it helps, a blood test to tune them to you.