They're among the most taken supplements in the world, but many people have misconceptions about what a multivitamin is - and how to use them. 

A study published earlier this month found that taking a daily multivitamin may actually help us live healthier lives for longer.

Experts calculated that two years on the supplements cut biological ageing - how old the body is in terms of health - by about four months on average.

So should we all be taking one? One of the biggest myths, warn experts, is that multivitamins are a replacement for a healthy, varied diet - and another is that they're all the same. 

In fact, multivitamins are not all created equal, and with thousands on the market, it can be hard to know which is the best choice for you. 

Dietitian Dr Carrie Ruxton from the Health & Food Supplements Information Service (HSIS) tells the Daily Mail that most people could benefit from taking a multivitamin - as long as it complements their current life stage. 

'We should be able to get all the macro and micro nutrients we need from what we eat - with an additional Vitamin D tablet as we don't get enough year-round sunshine for our bodies to make it naturally,' she says. 'But the reality is that more people than I would like probably need to top up with a multivitamin.'

With this in mind, we asked Dr Ruxton to explain how to harness their potential, and how to pick the right packet for you and your loved ones.

Do you really need a multivitamin? Who should consider taking one 

An analysis of the last National Diet And Nutrition Survey found that less than one in 1000 people meet the NHS ' dietary recommendations for vitamins, minerals and healthy 'omega' fats, meaning that millions of Britons will unknowingly be at the risk of 'actual nutritional deficiencies'. 

Dr Ruxton says: 'I've been a dietician for 30 years and I've been saying the same things over and over again, "this is what we should be eating, five portions of fruit and veg a day, oily fish once a week, choose whole grains, cut down on your sweets and biscuits and confectionery and sugary drinks and things".

'It's frustrating but people just don't do it. I've reluctantly reached the stage where I think, "well, at least take a multivit, because if you're going to have a terrible diet, then at least don't be deficient in certain things".'

But it's not just steering you away from crippling deficiency-related illnesses - like anaemia, scurvy, rickets and osteoporosis - that a daily multivitamin can help with...

Who benefits most from taking a daily multivitamin? 

With such a huge proportion of people in the UK hovering dangerously close to nutritional deficiency disaster, Dr Ruxton says that it won't do anyone any harm to add a multivit to their daily routine - and it doesn't need to be pricey. 

'If you are on a very restricted budget, I would just say, just buy an own brand 100 per cent supermarket A to Z multivit, because it will provide the minimum daily amount of all the vitamins and minerals,' she says. 

However, because the NHS suggests that we have 10micrograms of vitamin D per day, double the EU's guidelines and the 'maximum' amount included in a standard multivitamin, Dr Ruxton advises adding an additional vitamin D tablet. 

She also urges people to take omega-3, a fatty acid vital for brain and heart health which is not commonly added to multivits.  

There are specific age ranges that can benefit from taking tailored multivitamins that have been especially developed to meet the biological needs associated with different points in our lives.

What vitamins and minerals are in a multivitamin? 

If you pick up a combined A-Z multivitamin and multimineral supplement, it will contain all the nutrients you should be able to get from a healthy, balanced diet - and the recommended maximum daily amount.  

The body needs vitamins for basic functions but is unable to produce them - apart from vitamin D, which can be produced when the skin is exposed to direct sunlight. 

While the NHS states that most people should be able to get all the nutrients they need from eating a varied and balanced diet, it's not always possible - or easy. 

Vitamins can be broadly categorised as either water-soluble or fat-soluble, which refers to how they are stored by the body - if at all.   

Water-soluble vitamins - vitamin C and the "B vitamins" - aren’t able to be stored in the body and any excess is passed out of the body as urine. 

They are found in fruit, vegetables, grains and pulses, so these foods need to be eaten regularly so that the body can absorb enough vitamins for its needs.

However, fat-soluble vitamins - A, D, E and K - can be stored in the liver and fatty tissues until they’re needed - but if there's an excess of them, they can be harmful. 

This sort of vitamin is found mainly in foods that are high in natural fat, such as oily fish and eggs. 

Minerals are micronutrients that the body needs in varying amounts in order to carry out basic - and essential - functions. 

There are two types of minerals, major and trace., 

Major minerals are needed in substantial amounts by the body, and are used to balance water levels, regulate metabolism and maintain healthy skin, hair, and nails. 

Trace minerals are required in smaller amounts and are used in blood for clotting and to distribute oxygen. 

Both types of minerals are required for healthy bones. 

What multivitamins should pregnant or breastfeeding women take? 

Dr Ruxton advises that all women who are hoping to start a family begin taking folic acid before conception, adding that 90 per cent of women of childbearing age are deficient in the vital vitamin. 

'What we found in studies is only about 20 to 25 per cent of women take a folic acid supplement at the right stage of their pregnancy,' she says.

'You really, really need it in the first three months, it is vital for the foetus' healthy brain development.' 

Pregnancy multivitamins will also include vitamin D, which is also vital to take while breastfeeding, along with calcium. 

'You're losing a lot of these nutrients in your breast milk, and then that's your baby's only source of nutrition,' she explains, adding that she also recommends taking an omega-3 because 'it reduces children's risk of allergies and intolerances, and helps regulate the immune response.' 

Do women in perimenopause need different vitamins? 

Dr Ruxton advises that women approaching menopause take a general women's wellness tablet, or at the very least, make sure they are supplementing both calcium and vitamin D. 

'If you're coming into menopause, you definitely want a vitamin D and calcium supplement for bone health,' she says. 

'This is the time when your bone density drops off dramatically, when you have a fall in oestrogen levels, and you will be at risk from osteoporosis over the next 10 years.

'You really want to get calcium and vitamin D in sort of in your 40s, so that you don't break bones in your 60s.' 

Do older adults need multivitamins as they age? 

As we get older, our appetite gets smaller - and that can be catastrophic for the elderly, especially as their ailing digestive systems struggle to assimilate food like they once did. 

'Because their bodies are slowing down, they aren't able to absorb nutrients such as vitamin B 12 as well as before,' says Dr Ruxton. 

'Also, they're less effective at making vitamin D from sunlight, because it's a biological process in the body that just slows down. They need to get a top up.' 

Should vegetarians, vegans or people on glp-1 weight loss drugs take multivitamins? 

Dr Ruxton says anyone with any sort of dietary restrictions - be that animal products or through eating smaller, fat jab friendly portions, should take a tablet top-up. 

'If you have any dietary restrictions you will be missing out on key nutrients,' she says. 

WHAT SHOULD A BALANCED DIET LOOK LIKE? 

Eat at least 5 portions of a variety of fruit and vegetables every day. All fresh, frozen, dried and canned fruit and vegetables count

Base meals on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain

30 grams of fibre a day: This is the same as eating all of the following: 5 portions of fruit and vegetables, 2 whole-wheat cereal biscuits, 2 thick slices of wholemeal bread and large baked potato with the skin on

Have some dairy or dairy alternatives (such as soya drinks) choosing lower fat and lower sugar options

Eat some beans, pulses, fish, eggs, meat and other proteins (including 2 portions of fish every week, one of which should be oily)

Choose unsaturated oils and spreads and consuming in small amounts

Drink 6-8 cups/glasses of water a day

Adults should have less than 6g of salt and 20g of saturated fat for women or 30g for men a day

Source: NHS Eatwell Guide  

'I saw some concerning statistics which said that people who were taking GLP-1 medications reduce their food intake by about 20 per cent - but they don't necessarily eat healthier diets, they just eat less pizza and less snacks. 

'They would definitely need a top up of a multivit, because they're missing out on a lot of nutrients.' 

Do teenagers need multivitamins for growth and energy? 

Dr Ruxton explains that bones are still developing until young adulthood for both boys and girls, making a teenager-specific multivitamin a good shout. 

'Until you get to late teens for girls and early 20s for boys, you are still putting down bone mineral density, so you need to have enough calcium and vitamin D, to be able to do that, and magnesium and phosphorus as well.' 

Again citing the National Diet And Nutrition Survey,  Dr Ruxton adds that the research found that when looking at children aged between 11 and 18, there were a series of worryingly low figures. 

In this group, 50 per cent registered as below the minimum level for iron - a key component in blood and vital for carrying oxygen through the body. 

Magnesium - vital for muscle and nerve function, blood glucose control, and blood pressure regulation - was lacking in 48 per cent of girls and 30 per cent of boys. 

Both genders were also dangerously low on selenium which is vital for thyroid function. 

This nutritional dip, says Dr Ruxton is because teenagers typically tend to be fussy eaters, opting for 'burgers and chips' as opposed to eating a varied diet.  

Should children take multivitamins? A guide for parents

The Government advises that all children aged between six months and five-years-old should take daily vitamin A, C and D supplements, usually in the form of drops. 

Babies being fed more than 500ml of infant formula per day don't need any supplements as the formula will already be fortified with the vitamins and other nutrients. 

These three vitamins are vital for a child's healthy development; vitamin A supports eyesight and skin, C strengthens the immune system, and D is vital for healthy bones and teeth. 

While they could get all of these nutrients from the food they eat, children are notoriously fussy eaters - supplementation removes a lot of stress, worry and pressure from parents. 

Breastfed babies should be given a daily vitamin D supplement from birth, regardless of if their mother is taking a supplement containing vitamin D.

How to choose a good multivitamin: what to look for and where to buy 

Sadly, the supplements world is overrun with bad actors selling products that don't meet the UK's high standards for supplements - which are classed as a food product rather than a medicine. 

'They come under food because they are a dietary supplement - they're not a medicine to treat or prevent a disease - but foods in our country are actually very strictly regulated for safety, ingredients and accuracy,' she says. 

'We've got very strict rules in this country, and if you buy from a company that's based in the UK or the rest of Europe, then they will have to follow these rules.'

For this reason, Dr Ruxton urges people to shop only recognisable brands, and to choose British or EU suppliers over ones from abroad, such as China or the USA. 

'I would not buy anything from Instagram or TikTok or anything like that. The way that you can be absolutely certain you are getting safe, legitimate products is to have a chat with a pharmacist. 

'And if that's not possible, then I would just go into one of the big high street stores or a supermarket and buy from there because you can be confident that these will be regulated.' 

What is the best time of day to take a multivitamin — and how long until it works? 

To ensure that your body can metabolise the fat-soluble vitamins in your multivit tablet, it's best to take it with a meal that contains fat, says Dr Ruxton. 

'I always advise taking it with lunch or the evening meal, because so many people skip breakfast or they just eat cereal or something quite low fat,' she says. 

'It definitely improves the absorption of the fat soluble vitamins if you can have some fat in your meal, but if people forget, it's fine to take it at breakfast. 

'Remembering to take it every day is the most important thing.' 

However, Dr Ruxton adds that you won't suddenly feel like a superhero come the seventh or tenth day of taking a multivitamin. 

'I don't think people will feel a difference, because you're just going from being suboptimal to optimal,' she explains. 

'If you were iron deficient and feeling tired, and you were taking a higher dose iron supplement, you'd probably start to feel better after maybe about two to three weeks, because you actually then have a deficiency that's making you feel tired and out of breath and things like that. 

'But for most other nutrients, like vitamin C or vitamin D, because that's an immunity and bone health vitamin you're probably not going to feel any differently.' 

Who shouldn’t take a multivitamin? When supplements may do more harm than good

Most of the ingredients in a multivitamin will not build up in your body - apart from vitamin A, which is stored in our liver. 

Dr Ruxton says: 'You're very unlikely to be overdosing vitamin A, unless you are eating incredibly rich sources, like a lot of oily fish or liver, and then taking a supplement,' says Dr Ruxton. 

'But if you're pregnant, do not take a vitamin A supplement, and that is why it's a good idea to always choose a pregnancy specific supplement, because they will have lower levels of vitamin A in it. 

'Vitamin A is teratogenic, which means it can affect the foetus if you are having a huge amount of it.'