Vitamins and Minerals: A Quick Guide
- , by SANUSq Research team
- 10 min reading time
Vitamins and minerals are the tiny helpers behind almost everything your body does — here's a clear, practical guide to the essentials.
Two families of micronutrients
We need vitamins and minerals in only small amounts, which is why they're called micronutrients — but "small" doesn't mean minor. They drive the chemical reactions that turn food into energy, build and repair tissues, and keep every system running. They fall into two broad groups: vitamins (organic compounds, from plants and animals) and minerals (inorganic elements, from soil and water that enter the food chain).
The key vitamins
The fat-soluble vitamins (A, D, E, K) are stored in the body. Vitamin A supports vision and immunity; vitamin D, bones and immunity; vitamin E is an antioxidant; and vitamin K supports blood clotting and, as K2, directs calcium to bone. The water-soluble vitamins (the B group and vitamin C) aren't stored much, so they're needed regularly. The B vitamins power energy metabolism and the nervous system, while vitamin C supports collagen, immunity and antioxidant defence.
Vitamin D illustrates how a single micronutrient reaches beyond one role: a meta-analysis of randomised trials found vitamin D supplementation reduced the risk of acute respiratory infections, especially in those who were deficient (Martineau et al., 2017).
Why fat-soluble and water-soluble matters
That split is not a piece of trivia; it changes how you should think about each group. Fat-soluble vitamins need fat present for the gut to absorb them properly, which is a good argument for eating your vegetables with some olive oil, and for taking any fat-soluble supplement with a meal rather than on an empty stomach. Because the body can store them, a day or two of low intake is easily absorbed — but for the same reason a persistently high intake accumulates, which is why excess is a real consideration with this group and rarely with the other.
The water-soluble vitamins behave almost in reverse. The body holds only modest reserves and passes surplus out in the urine, so intake needs to be regular rather than occasional. They are also the fragile ones in the kitchen: vitamin C and several B vitamins leach into cooking water and degrade with prolonged heat, so steaming, roasting or brief cooking preserves more than a long boil, and reusing the cooking water in a soup or sauce keeps what would otherwise be poured away. Vitamin B12 is the exception that proves the rule — water-soluble, but stored in the liver, which is why a shortfall can take a long time to show itself.
The essential minerals
Minerals split into major minerals (needed in larger amounts) and trace minerals (needed in tiny amounts). The major ones include calcium and magnesium (bones, muscle and nerve function), potassium and sodium (fluid balance and nerve signals). Trace minerals include iron (oxygen transport), zinc (immunity and healing), selenium (antioxidant defence and thyroid), and iodine (thyroid hormones).
Zinc shows why trace minerals matter: even mild-to-moderate zinc deficiency impairs immunity and wound healing, because zinc is essential for immune-cell function (Maywald et al., 2017).
You can read more on individual nutrients in zinc, magnesium and vitamin D.
Where these nutrients actually come from
Names on a label are easier to remember once you know which foods carry them. Oily fish, eggs and fortified foods are the main dietary sources of vitamin D; liver, dairy and orange or dark green vegetables supply vitamin A or the carotenoids the body converts into it. Nuts, seeds and vegetable oils provide vitamin E, while vitamin K comes largely from leafy greens. For the water-soluble group, wholegrains, meat, eggs, dairy and pulses cover most of the B vitamins, with B12 found almost entirely in animal foods and fortified products, and vitamin C concentrated in fruit and vegetables — peppers, berries, citrus, tomatoes and brassicas among the richer ones.
On the mineral side, dairy, tinned fish with bones, and fortified plant drinks are familiar calcium sources; magnesium comes from nuts, seeds, wholegrains and leafy greens; potassium from vegetables, fruit and pulses. Iron appears in two forms, the readily absorbed kind in meat and the less readily absorbed kind in pulses, wholegrains and greens — which is where vitamin C earns its keep, since eating it alongside a plant source of iron improves absorption. Shellfish, meat, pulses and seeds supply zinc; brazil nuts, fish and eggs supply selenium; and iodine comes chiefly from dairy, fish and iodised salt.
Who is more likely to fall short
Shortfalls are not distributed evenly, and knowing whether you sit in a higher-risk group is more useful than worrying in general. Vitamin B12 is the classic gap on a strict plant-based diet without fortified foods or a supplement, and absorption of it also declines with age. Iron needs are higher in pregnancy and in people with heavy periods. Folate matters especially before and in early pregnancy. Vitamin D depends on sunlight rather than food, so almost everyone at northern latitudes runs lower through the winter, and more so with darker skin, older age or little time outdoors. Conditions that impair absorption — coeliac disease, inflammatory bowel disease, or surgery affecting the gut — can cause several shortfalls at once, and some long-term medicines affect specific nutrients.
A vitamin deficiency chart matching symptoms to nutrients is how many people try to settle this for themselves, and it is not a reliable method. The early signs of most shortfalls are vague and overlapping — tiredness, poor concentration, low mood, brittle nails — and they are equally at home in ordinary stress, poor sleep or an underlying condition that has nothing to do with nutrition. What such a chart can reasonably do is prompt a question for your doctor; what it cannot do is answer it.
Why more is not better
It is easy to assume that if a little is essential, more must be better. Micronutrients do not work that way. Above the amount your body can use, benefit levels off, and for several nutrients the risks then start to climb. The fat-soluble vitamins accumulate rather than being flushed out, so sustained high intakes are the ones to be careful with, and vitamin A in particular has clear cautions in pregnancy. Minerals compete with one another for absorption: a large ongoing zinc intake can interfere with copper, for instance, and iron taken without a demonstrated need is not benign. Supplements can also interact with prescription medicines, which is a good reason for your doctor to know what you take.
Food first, then fill the gaps
The best way to get this whole cast of nutrients is a varied, colourful, whole-food diet — different foods supply different micronutrients, which is why variety beats any single "superfood". Supplements have their place for genuine gaps (for example, vitamin D in winter, B12 for vegans, iron for those who are low), but they work best filling specific shortfalls rather than replacing good food. If you suspect a deficiency, a blood test and a chat with your doctor beat guesswork.
Frequently asked questions
What are essential vitamins and minerals?
Essential micronutrients include the vitamins (A, D, E, K, the B group and C) and minerals (such as calcium, magnesium, potassium, iron, zinc, selenium and iodine). The body needs them in small amounts for countless functions.
What's the difference between vitamins and minerals?
Vitamins are organic compounds from plants and animals; minerals are inorganic elements from soil and water. Both are needed in small amounts, but they come from different sources and play different roles.
Which vitamins are fat-soluble and which are water-soluble?
Fat-soluble vitamins (A, D, E, K) are stored in the body; water-soluble vitamins (the B group and vitamin C) are not stored much and are needed regularly through the diet.
Do I need to take a multivitamin?
Most people who eat a varied, whole-food diet get what they need from food. Supplements are most useful for specific gaps, such as vitamin D in winter or B12 on a vegan diet.
How do I know if I'm deficient?
Deficiency symptoms are often vague, so guessing is unreliable. A blood test arranged by your doctor is the way to confirm a specific deficiency and target it.
What do the percentages on a supplement label mean?
They are usually reference intakes — a single figure set for a general adult population, not a personal requirement worked out for you. Reaching 100 per cent means the amount is considered adequate for most people; it is not a score to beat, and a figure several times higher is not several times better. The more useful things to read on a label are which nutrients are actually in it, in what chemical form, and whether they duplicate what you already get from fortified foods or another product, since intakes from several sources stack up without anyone noticing.
Can I get everything I need from a plant-based diet?
Largely, with attention to a few nutrients. Vitamin B12 needs fortified foods or a supplement, and iron, zinc, iodine and omega-3 sources are worth planning for, since the plant forms of some of these are absorbed less readily. Pairing plant iron with a source of vitamin C helps.
References
- Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017;356:i6583. PMID 28202713
- Maywald M, Wessels I, Rink L. Zinc Signals and Immunity. Int J Mol Sci. 2017;18(10):2222. PMC5666901
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The team at SANUSq.
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The health information in this article is provided for educational purposes only. Consult your healthcare professional before making any medical decisions.
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