Vitamins and Minerals: The Simple, Essential Starter Guide

Vitamins and minerals are micronutrients your body needs in small amounts to function: vitamins are organic compounds (fat-soluble A, D, E and K, and water-soluble C and the B group), while minerals are elements such as calcium, iron, magnesium and zinc that come from soil and water through food. Most healthy adults can get what they need from a varied diet, and supplements are best kept for specific gaps identified with a doctor, pharmacist or dietitian.

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This guide is the starting point for every vitamin and mineral article on this site. It explains the two groups and why the difference matters, how much adults need (and why countries publish different numbers), where each nutrient comes from in food, who is more likely to run short, the risks of taking too much, and how to decide whether a supplement is worth discussing. Each section links to a deeper guide on that nutrient or question.

At a glance

• Two groups, different behaviour: fat-soluble vitamins (A, D, E, K) can build up in the body; water-soluble ones (C and B vitamins) are mostly not stored and excess is lost in urine.
• Food first: health authorities agree that a varied diet should supply most nutrients, with supplements filling identified gaps rather than replacing meals.
• Numbers differ by country: Australia and New Zealand, the US, the UK and Europe set different reference values for the same nutrient, often because of different methods, not different bodies.
• More is not better: several nutrients have upper limits, and doubling up across products and fortified foods is common.
• Supplements are lightly regulated: in most countries they reach the shelf without proof that they work, so labels and certification seals matter.

Vitamins versus minerals: the basics

Harvard’s Nutrition Source draws the distinction simply. Vitamins are organic substances made by plants or animals, and they are classed as fat-soluble or water-soluble. Minerals are inorganic elements found in soil and water, absorbed by plants or eaten by animals, and they keep their chemical identity whatever happens to the food.

Fat-soluble vitamins

Vitamins A, D, E and K dissolve in fat, are absorbed best with some fat in the meal, and can be stored in the liver and fatty tissue. Because they accumulate, they are the vitamins most associated with problems from excess intake, especially vitamins A and D from supplements.

Water-soluble vitamins

Vitamin C and the eight B vitamins (thiamin, riboflavin, niacin, pantothenic acid, B6, biotin, folate and B12) dissolve in water. Most are not stored in large amounts, and unused amounts are mainly lost in urine, so a regular supply from food matters. Vitamin B12 is the exception: the liver can hold several years’ worth.

Major minerals and trace minerals

Minerals are often split into major minerals, needed in larger amounts (calcium, phosphorus, magnesium, sodium, potassium, chloride), and trace minerals, needed in tiny amounts (iron, zinc, iodine, selenium, copper and others). Trace does not mean unimportant: iron and iodine shortfalls are among the most common nutrient problems worldwide.

How much do adults need?

Reference values are designed to cover the needs of nearly all healthy people in a group. They are population guides, not personal prescriptions, and pregnancy, breastfeeding, illness and some medicines change them. The table compares common adult figures from the Nutrient Reference Values for Australia and New Zealand (NHMRC) and the US figures published by the NIH Office of Dietary Supplements.

Nutrient	Australia and New Zealand (adults)	United States (adults)	Good food sources
Vitamin A	Men 900 mcg, women 700 mcg	Men 900 mcg, women 700 mcg	Dairy, eggs, liver; orange and dark green vegetables (as beta-carotene)
Vitamin C	45 mg	Men 90 mg, women 75 mg	Citrus, kiwifruit, capsicum, berries, broccoli
Vitamin D	5 mcg (19–50), 10 mcg (51–70), 15 mcg (over 70) as Adequate Intakes	15 mcg (19–70), 20 mcg (71+)	Mainly sunlight on skin; oily fish, eggs, fortified foods
Folate	400 mcg DFE	400 mcg DFE	Leafy greens, legumes, fortified bread and cereals
Vitamin B12	2.4 mcg	2.4 mcg	Meat, fish, eggs, dairy, fortified plant foods
Calcium	1,000 mg; 1,300 mg for women over 50 and men over 70	1,000 mg; 1,200 mg for women over 50 and men over 70	Dairy, calcium-set tofu, fortified plant milks, canned fish with bones
Iron	Men 8 mg; women 18 mg (19–50), 8 mg (51+)	Men 8 mg; women 18 mg (19–50), 8 mg (51+)	Red meat, poultry, fish, legumes, fortified cereals
Magnesium	Men 400–420 mg, women 310–320 mg	Men 400–420 mg, women 310–320 mg	Seeds, nuts, legumes, whole grains, leafy greens
Zinc	Men 14 mg, women 8 mg	Men 11 mg, women 8 mg	Meat, shellfish, legumes, nuts, whole grains
Iodine	150 mcg	150 mcg	Seafood, dairy, iodised salt, bread made with iodised salt

Two countries can give different numbers without either being wrong. Vitamin C is a clear example: the Australian figure is 45 mg while the US figures are 75–90 mg, because the two bodies chose different criteria for what an adequate intake should achieve. Vitamin D differs even more. The UK’s NHS gives 10 micrograms a day for adults and advises everyone to consider a 10 microgram supplement in autumn and winter, reflecting low winter sunlight at that latitude. The European Food Safety Authority uses different terms again (Average Requirement, Population Reference Intake and Adequate Intake), so a European number and an American one are not always measuring the same thing.

Labels add another layer. Many US labels show a “% Daily Value”, which uses one reference figure for all adults, while Australian labels list amounts per dose. The guide to how to read a supplement label explains these differences, and how to read a vitamin D label covers the IU-to-microgram conversion that trips many people up.

Food first, and why

Health authorities are consistent on this point. Harvard’s Nutrition Source says a diet with plenty of fruit, vegetables, whole grains, good protein sources and healthy fats should supply most of the nutrients needed for good health, while noting that multivitamins can play a role when needs are not met through diet. Whole foods also bring fibre, protein and many other compounds that a tablet cannot copy. The guide to dietary fibre is a good example of a nutrient most supplements leave out entirely.

Food fortification fills some gaps at population level. In Australia, for example, bread-making flour must have folic acid added and bread must be made with iodised salt, both since 2009; other countries fortify different foods. That is helpful, but it also means fortified foods count towards your total if you take supplements.

Nutrient-by-nutrient guides on this site

Each of these articles goes deeper on one nutrient: what it does, how much adults need, food sources, what studies have tested and what to check on a label.

Vitamin D and calcium

• Vitamin D in Australia: sunlight and testing explains how sun exposure, skin type and season affect vitamin D, and when testing is and is not recommended.
• Reading a vitamin D label covers D2 versus D3, IU versus micrograms, and how to check a dose against guidelines.
• Vitamin D3 and K2 together sets out what the trials of combined products actually measured.
• Calcium citrate versus carbonate compares the two main forms, how much elemental calcium each provides and when each is usually taken.
• Strength training and bone density covers the non-nutrient side of bone health that matters alongside calcium and vitamin D.

Magnesium

• How to get more magnesium from your diet lists the richest everyday foods, daily targets and a worked day of eating.
• Magnesium supplement forms explains citrate, glycinate, oxide and other forms, and what “elemental magnesium” means on a label.
• Magnesium glycinate and sleep looks at what the sleep trials tested and how strong the evidence is.

B12, iron, zinc and vitamin C

• Vitamin B12 supplements covers why absorption often falls with age and in people taking some medicines, and the forms you will see on labels.
• Iron supplements explains why testing comes first, what elemental iron means and how timing affects absorption.
• Zinc supplements sets out what the cold research tested and why high doses over time can cause problems.
• Vitamin C supplements looks at doses, colds research and what happens to large doses in the body.

Multivitamins and combined products

• Multivitamins after 50 explains how to compare labels against age-specific needs and avoid unnecessary extras.
• Electrolyte tablets and hydration salts covers sodium, potassium and magnesium in hydration products and who actually needs them.
• Nutritionally complete supplement drinks explains who these products are designed for and how they differ from a multivitamin.
• Spirulina looks at a “whole food” supplement often marketed for its vitamin and mineral content, and what the evidence supports.

Choosing and buying any supplement

• The supplements evidence and label guide is the site’s main supplements hub, covering how to judge evidence, read labels and compare products.
• Supplement bioavailability explains what absorption claims mean and why they are easy to overstate.
• Supplement certification seals explains what USP, NSF and Informed Sport testing does and does not check.
• Buying supplements internationally covers the different rules and risks when ordering from overseas.

Who is more likely to run short?

Some situations make it harder to get enough from food alone. These are general patterns, not a reason to self-diagnose; a doctor can check what is relevant to you.

Situation	Nutrients often discussed	Why
Older adults	Vitamin D, calcium, vitamin B12, protein	Less sun exposure and skin production of vitamin D, lower B12 absorption from food, smaller appetites
Vegan diets	Vitamin B12, iodine, iron, zinc, calcium	B12 is found naturally almost only in animal foods; plant iron and zinc are less readily absorbed
Heavy periods or pregnancy	Iron, folate, iodine	Higher losses or higher needs
Little sun exposure	Vitamin D	Covered skin, indoor life, darker skin or living far from the equator
Some medicines	B12, magnesium and others	Metformin and long-term reflux medicines can lower B12; some reflux medicines and diuretics can lower magnesium
Gut conditions or surgery	Several nutrients	Reduced absorption, for example with coeliac disease or after weight-loss surgery

In these cases a targeted supplement may be reasonable, ideally chosen with professional guidance. Talk to your doctor or pharmacist before starting one, and ask whether a blood test makes sense first. For some nutrients, such as iron, testing before supplementing is particularly important because excess iron can be harmful.

The risks of too much

More is not automatically better. High doses, combining many products, or using a supplement in place of a prescribed medicine all raise the risk of problems. Several nutrients have tolerable upper intake levels, the highest daily amount unlikely to cause harm for most people.

Nutrient	Adult upper level (example)	Possible effects of excess
Vitamin A (preformed)	3,000 mcg a day (US)	Liver problems, headaches, bone and joint pain; particular caution in pregnancy
Vitamin D	100 mcg (4,000 IU) a day (US, EFSA and NHS guidance)	High blood calcium, nausea, kidney problems
Iron	45 mg a day (US)	Stomach upset and constipation; serious poisoning in children
Zinc	40 mg a day (US); 25 mg (EFSA)	With weeks of high doses, reduced copper absorption and lower HDL cholesterol
Calcium	2,500 mg a day (EFSA; US 2,000–2,500 depending on age)	Constipation, kidney stones in some people
Magnesium (supplements only)	350 mg a day (Australia/NZ and US)	Diarrhoea and stomach cramps

Some nutrients have no upper limit set: the NIH did not set one for vitamin B12 because of its low potential for toxicity, and none is set for beta-carotene from food. Others matter because of interactions. The NIH notes that vitamin K can reduce the effect of the blood thinner warfarin, and that St John’s wort can speed the breakdown of many medicines and make them less effective. Between supplements and fortified foods and drinks, it is easy to get more of a nutrient than you think.

What the multivitamin trials found

Multivitamins are the most widely used supplements and among the most studied. The NIH reports that 31.2% of US adults had taken one in the previous 30 days, based on national survey data from 2011–2014.

Two large randomised trials dominate the evidence. The Physicians’ Health Study II followed 14,641 male doctors for a median of 11.2 years and found no reduction in heart attacks, strokes or cardiovascular deaths; it did find a modest 8% lower rate of total cancer and a 9% lower rate of cataract. The COSMOS trial followed 21,442 older adults for a median of 3.6 years and found no reduction in cardiovascular events from the multivitamin. The NIH’s own summary is that multivitamins do not appear to reliably reduce the risk of chronic diseases. It also points out that multivitamins have no standard definition, so two products with similar names can differ a great deal. The multivitamins after 50 guide shows how to compare them.

How supplements are regulated

Regulation is lighter than most people assume, and it differs by country:

• Australia: the Therapeutic Goods Administration regulates vitamins and minerals as complementary medicines. Most are “listed” medicines with an AUST L number, which are checked for quality and safety of ingredients but are not evaluated for whether they work before sale. A smaller number are “registered” (AUST R) and are assessed more fully.
• United States: under the Dietary Supplement Health and Education Act of 1994, manufacturers are responsible for the safety and labelling of their products, with no pre-market approval. The FDA can act after a product reaches the market.
• Elsewhere: the UK and EU regulate most supplements as foods, with rules on ingredients, maximum levels and the health claims that may appear on labels.

Independent testing seals can add some reassurance about what is in the bottle, though not about whether it works. The guides to certification seals and buying supplements from overseas explain what to check.

A checklist before you buy any vitamin or mineral

1. Look at your diet first. Can a food change cover the gap?
2. Ask whether you are in a higher-risk group (see the table above), and talk to your doctor or pharmacist about whether testing makes sense.
3. Check the dose against your country’s reference value and upper level, not just the number on the front of the pack.
4. Add up every product you take, including multivitamins, electrolyte drinks, fortified foods and drinks.
5. Check for interactions with any medicines, especially blood thinners, thyroid medicines, antibiotics and bone medicines.
6. Look for an AUST L or AUST R number in Australia, or an independent testing seal elsewhere.
7. Keep a written list of everything you take, with doses, and share it at every medical appointment.
8. Review it at least yearly. A supplement that made sense once may no longer be needed.

Common mistakes

• Using supplements as a safety net: a pill does not make up for a poor diet, and large trials have not shown multivitamins reliably reduce chronic disease.
• Doubling up: taking a multivitamin plus separate vitamin D, zinc or iron can push intake over upper limits without anyone noticing.
• Confusing units: IU, micrograms, milligrams and “elemental” amounts are easy to mix up. Vitamin D labels are a frequent source of error.
• Assuming natural means safe: herbal and “whole food” products can still interact with medicines.
• Comparing across countries without context: an overseas product may be dosed for a different reference value or regulatory system.
• Skipping the conversation: not telling your doctor or pharmacist what you take is one of the most common and avoidable risks.

Upper limits can differ sharply between countries, as the guide to vitamin B6 upper limits shows.

Related guide: What Is Folic Acid Used For? A Simple, Essential Guide.

Sources this guide draws on: NHMRC and New Zealand Ministry of Health, Nutrient Reference Values for Australia and New Zealand; NIH Office of Dietary Supplements, fact sheets on individual vitamins and minerals and on multivitamin/mineral supplements; NHS, Vitamins and minerals guidance; European Food Safety Authority, Dietary Reference Values and overview of tolerable upper intake levels; Harvard T.H. Chan School of Public Health, The Nutrition Source, Vitamins and Minerals; Therapeutic Goods Administration, guidance on listed and registered complementary medicines; US Food and Drug Administration, information on dietary supplements; Physicians’ Health Study II and COSMOS trial publications.

Frequently asked questions

What is the difference between vitamins and minerals?

Vitamins are organic compounds made by living things, grouped as fat-soluble (A, D, E, K) or water-soluble (C and B vitamins). Minerals are inorganic elements, such as calcium and iron, that come from soil and water through the food chain. Both are needed in small amounts for normal body function.

Which vitamins and minerals are adults most likely to be low in?

It depends on diet, age, sun exposure and health. Vitamin D, iron, calcium, B12 and iodine are commonly discussed, and older adults, vegans, pregnant women and people on certain medicines are at higher risk. A doctor can advise whether testing is worthwhile for you.

Can you get all your vitamins and minerals from food?

Most healthy adults can get most nutrients from a varied diet, which is why health authorities recommend food first. Vitamin D is a partial exception because it mainly comes from sunlight, and some groups need targeted advice.

Is it safe to take a multivitamin every day?

For most people, a standard multivitamin at label doses is unlikely to cause harm, but large trials have not shown that it reliably reduces chronic disease. Check it against your diet and other supplements to avoid doubling up, and talk to your doctor or pharmacist if you take medicines.

Which vitamins are dangerous in high doses?

Fat-soluble vitamins, especially A and D, can build up and cause harm at high doses. Among minerals, iron, zinc, calcium and selenium all have upper limits. Water-soluble vitamins are generally less risky, though high-dose B6 over time has been linked to nerve problems.

Should I take vitamins with food?

Fat-soluble vitamins are absorbed better with a meal that contains some fat, and taking supplements with food often reduces stomach upset. Some products, such as certain iron preparations, have specific timing advice, so follow the label or ask your pharmacist.

Vitamins and minerals matter, but for most people the honest starting point is a varied diet, with supplements used deliberately, for a known reason, and with advice. Use the guides above to go deeper on any nutrient, and bring your questions to your doctor or pharmacist.

This guide is general education based on published research and national reference values. It is not medical advice. Talk to your doctor or pharmacist before starting any supplement, especially if you take medicines, are pregnant or have a health condition.