Vitamins & Supplements
Vitamins and supplements correct the nutritional gaps behind everyday complaints like tiredness, low energy, poor concentration and low immunity. Shortfalls are common in the UK, with around 18% of adults low in vitamin D, often due to limited sunlight, restricted diets or poor absorption. Options range from daily multivitamins, vitamin D, iron and omega-3 to advanced injectables like NAD+ injections by Vivere, plus vitamin B12 injections available after an online consultation.
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An Overview From Our Superintendent Pharmacist
At a glance
- Vitamins and supplements help correct nutrient shortfalls and support everyday goals like steady energy, immune function, healthy bones and concentration.
- The most-used options are vitamin D, iron, vitamin B12, magnesium, zinc, omega-3 and daily multivitamins, alongside advanced choices such as NAD+ injections by Vivere.
- Most are food supplements you can buy directly. Vitamin B12 injections need a short online consultation, while NAD+ injections need no prescription in the UK.
- Deficiencies are common. Around 18% of UK adults are low in vitamin D,13 so it is worth confirming a genuine need, ideally with a blood test, before starting long-term use.
- Buying from a UK registered online pharmacy means pharmaceutical-grade products, safe dosage guidance and a registered pharmacist to check suitability.
"Most people reach for vitamins and supplements to correct a nutritional shortfall or to support a specific goal, whether that is steadier energy, a stronger immune system, healthy bones or clearer concentration. The essentials, like vitamin D, iron, vitamin B12, magnesium, zinc and omega-3, are food supplements you can buy and use safely at home, while newer options such as NAD+ injections are used to support cellular energy and general wellbeing.
A daily multivitamin suits many people, but targeted supplementation works best when it matches a genuine need. If you are dealing with persistent tiredness, low mood, hair thinning or frequent infections, it is worth confirming the cause first, because the right treatment depends on the reason behind your symptoms. If you think a prescription option such as a vitamin B12 injection may help, start an online consultation and one of our clinicians will review whether it is suitable for you."
Where can you buy vitamins and supplements online?
You can buy vitamins and supplements from Mail My Meds, a UK registered online pharmacy, with everyday products added straight to your basket and prescription options supplied after a short online consultation. Ordering is simple, your items are dispensed by a registered pharmacist, and treatments are delivered discreetly to your door.
How you order depends on how the product is classified:
- Food supplements such as vitamin D3, vitamin C, iron, magnesium, zinc, calcium, omega-3, daily multivitamins and probiotics can be bought directly, with no consultation needed.
- NAD+ injections by Vivere are available to buy without a prescription in the UK, so there is no consultation to complete. Each kit arrives with clear instructions for at-home subcutaneous use.
- Prescription treatments such as vitamin B12 injections (hydroxocobalamin) need a quick online consultation, which is reviewed by a regulated prescriber before any medicine is supplied.
For prescription options, the online consultation takes just a few minutes:
- Choose the treatment you are interested in and select "Start your online consultation".
- Answer a short set of confidential medical questions about your health and symptoms.
- A regulated prescriber reviews your answers to check the treatment is safe and suitable for you.
- If approved, your medicine is dispensed by our pharmacy and posted to you in discreet packaging.
What are vitamin and mineral deficiencies?
A vitamin or mineral deficiency happens when your body does not get enough of a particular micronutrient to work at its best. Vitamins and minerals support processes such as energy release, immune defence, bone strength, red blood cell production and healthy nerves. A shortfall in one or more of them can gradually affect how you feel day to day.
Micronutrients fall into a few groups. Water-soluble vitamins, including vitamin C and the B-complex vitamins (such as vitamin B12 and vitamin B6), are not stored in large amounts, so they need topping up regularly. Fat-soluble vitamins (A, D, E and K) are stored in the body's tissues. Minerals include macrominerals like calcium and magnesium and trace minerals like iron and zinc. How well your body takes up each nutrient is known as its bioavailability, and the absorption rate can vary depending on the form you take, your diet and your gut health.
How common are nutrient deficiencies in the UK?
Nutrient shortfalls are surprisingly common across the UK, even though food is widely available. National surveillance data show that low vitamin D, iron and vitamin B12 levels affect millions of people. Some groups are at higher risk, including women of childbearing age, older adults, and people who eat little or no animal produce.
- Vitamin D: the National Diet and Nutrition Survey (2019 to 2023) found around 18% of adults aged 19 to 64 were deficient overall, rising to about 31% in winter. Among older teenagers the winter figure reached roughly 36%.13
- Iron: iron deficiency is the most common nutritional deficiency worldwide, according to the World Health Organization.15 Iron deficiency anaemia affects an estimated 2% to 5% of adult men and postmenopausal women in developed countries, and iron depletion without anaemia is around three times more common again.
- Vitamin B12: the NHS reports that B12 or folate deficiency anaemia affects around 1 in 10 people aged 75 or over and about 1 in 20 people aged 65 to 74.12
- Folate: the same national survey found 83% of women aged 16 to 49 had red blood cell folate levels below the point linked to a higher risk of neural tube defects in pregnancy.13,10
What causes low vitamin and mineral levels?
Low vitamin and mineral levels are usually caused by not taking in enough of a nutrient, not absorbing it properly, or needing more than usual at a particular time of life. Often it is a combination of factors rather than a single cause, which is why the same symptom can point to different underlying reasons.
- Limited sunlight: the skin makes vitamin D from sunlight, so levels fall between October and March when there is less UVB in the UK.2
- Diet: vitamin B12 and haem iron come mainly from animal foods, so vegan and vegetarian diets can run low without fortified foods or supplements.
- Blood loss and pregnancy: heavy periods, pregnancy and breastfeeding raise iron demand considerably.
- Absorption problems: conditions such as coeliac disease, Crohn's disease and pernicious anaemia, and some medicines like proton pump inhibitors, reduce how much you absorb.8
- Ageing: the body absorbs some nutrients less efficiently over time, and NAD+, a natural cellular coenzyme, also declines with age.9
What vitamin and supplement treatments are available, and how do they compare?
Vitamin and supplement treatments range from everyday oral products to injectable options, and the best choice depends on which nutrient you need and how well your body absorbs it. Oral tablets and capsules suit most people, while injections and intravenous (IV) routes are used when higher doses or better absorption are needed, because they bypass the digestive system.
| Treatment type | How it works | Typically used for | Prescription needed? |
|---|---|---|---|
| Daily multivitamins | A blend of vitamins and minerals at everyday doses to cover general dietary gaps | Broad, convenient nutritional support | No, food supplement |
| Single vitamins and minerals (vitamin D3, iron, magnesium, zinc, calcium) | Targets one nutrient at a chosen strength for a specific need | Correcting or preventing a known shortfall | No, food supplement |
| Omega-3 fish oils | Provides the EPA and DHA fatty acids that diets low in oily fish often lack | Normal heart, brain and vision function | No, food supplement |
| Probiotics | Live bacteria and yeasts that add to the gut microbiome | Digestive wellbeing | No, food supplement |
| Vitamin B12 injections (hydroxocobalamin) | Delivers B12 into the muscle, bypassing gut absorption entirely | Diagnosed B12 deficiency and pernicious anaemia | Yes, prescription after consultation |
| NAD+ injections (Vivere) | Subcutaneous NAD+ to raise levels of this cellular coenzyme, absorbed without passing through the gut | Cellular energy and general wellbeing support | No, available without prescription |
| IV nutrient therapy | Vitamins and minerals infused into a vein under clinical supervision | High-dose, rapid delivery in a clinic setting | Clinic-administered |
The key difference is absorption. Oral supplements have to be broken down and absorbed through the digestive system, so their bioavailability varies. Injectable and IV routes deliver nutrients more directly, which is why prescribers use vitamin B12 injections when the problem is poor absorption rather than diet.8 NAD+ injections are given under the skin for the same reason, and more specialised approaches such as peptide therapy and amino acid formulations are sometimes used in wellness and recovery settings.
"When someone cannot absorb a nutrient properly, such as vitamin B12 in pernicious anaemia, tablets alone may not be enough. That is exactly the situation where an injection, which bypasses the gut, makes a real difference."
Rachael Clarke MRCPharm, Superintendent Pharmacist at Mail My Meds.What are the most popular vitamins and supplements?
The most popular vitamins and supplements in the UK are those that address the nutrients people most often fall short of, led by vitamin D, iron, vitamin B12, magnesium and omega-3. Below is a quick guide to what each one is recognised to do, based on authorised UK health claims.
- Vitamin D3 (cholecalciferol): contributes to normal immune function, bones, teeth and muscle function. The NHS advises adults to consider a 10 microgram daily supplement in autumn and winter. Clinical research, including a widely cited 2017 BMJ meta-analysis, links vitamin D supplementation to a lower risk of acute respiratory infections, especially in people who are deficient.1,2
- Vitamin C: contributes to normal immune function, the reduction of tiredness and fatigue and normal collagen formation, and it also helps the body absorb iron. It is an antioxidant that helps protect cells from oxidative stress. A Cochrane review of vitamin C and the common cold found that regular supplementation can modestly shorten how long colds last, although it does not stop most people catching one.3
- B-complex (vitamin B12 and B6): contribute to normal energy-yielding metabolism and the reduction of tiredness and fatigue, with B12 supporting normal red blood cell formation and both supporting normal psychological function.8
- Magnesium: contributes to the reduction of tiredness and fatigue, normal muscle function, normal function of the nervous system and electrolyte balance.
- Zinc: contributes to normal immune function, normal cognitive function and the protection of cells from oxidative stress, working as one of the body's antioxidant coenzymes.
- Iron: contributes to normal formation of red blood cells and haemoglobin, normal oxygen transport and the reduction of tiredness and fatigue.4
- Calcium: contributes to normal bones and teeth and normal muscle function, and it is often paired with vitamin D to support bone density. Evidence including the Women's Health Initiative shows calcium with vitamin D supports bone health, with the clearest benefit in older adults and people who are deficient.6
- Omega-3 (EPA and DHA): contribute to normal heart function, with DHA also supporting normal brain function and vision. A large Cochrane review of omega-3 and cardiovascular disease found only a small effect for most people, so omega-3 is best seen as one part of a heart-healthy diet.5
- Daily multivitamins and probiotics: multivitamins give convenient all-round cover, while probiotics are live cultures that add to the gut microbiome. In the COSMOS trial, a daily multivitamin was associated with better memory and slower cognitive decline in older adults.7
- NAD+ injections (Vivere): deliver nicotinamide adenine dinucleotide, a coenzyme found in every living cell that is central to converting food into cellular energy (ATP) inside the mitochondria. It is used to support energy and general wellbeing. Early human research, including a 2018 Nature Communications study, shows NAD+ precursors can raise NAD+ levels, though evidence specifically on NAD+ injections is still developing.9
What are the common side effects of vitamins and supplements?
Most vitamins and supplements are well tolerated when taken at the recommended dose, and side effects are usually mild. They are more likely if you take high doses, take several products together, or take a supplement your body does not actually need, so sticking to a safe dosage matters.
"With supplements, more is not better. Match the dose to a genuine need and stay within the recommended upper limits, especially for fat-soluble vitamins like A and D that can build up in the body over time."
Rachael- Iron: can cause constipation, nausea, stomach discomfort and darker stools.
- Vitamin C in high doses: may cause stomach upset or loose stools.
- Fat-soluble vitamins (A, D, E, K): can build up in the body if you take too much over time, so upper limits should be respected.
- NAD+ injections (Vivere): the manufacturer lists possible mild nausea, headache, dizziness, tiredness, flushing and discomfort at the injection site, which are usually temporary.
- Vitamin B12 injections: mild injection-site pain is the most common effect, with allergic reactions being rare.
Always read the product leaflet or patient information supplied with your treatment, and check with a pharmacist if you are unsure.
What do people say about taking vitamins and supplements?
People's experiences with vitamins and supplements vary, and that is normal, because the benefit you notice depends on whether you were low in that nutrient to begin with. Those who correct a genuine deficiency, for example iron, vitamin B12 or vitamin D, often report that persistent tiredness, low energy or poor concentration gradually ease over several weeks.
Many people take a daily multivitamin or vitamin D through the darker months as a simple insurance policy and say it gives them peace of mind. Others use targeted supplements around specific goals, such as magnesium in the evening, omega-3 for a diet low in oily fish, or NAD+ injections as part of an energy and wellbeing routine. It is worth remembering that supplements work best alongside a balanced diet rather than as a replacement for one, and that results build over time rather than overnight.
Who should take vitamins and supplements?
Vitamins and supplements are suitable for most adults who want to top up a specific nutrient or who have higher needs than diet alone can meet. Some groups are more likely to benefit, and national guidance already recommends supplements for several of them.
- Everyone in autumn and winter: the NHS advises considering a daily 10 microgram vitamin D supplement from October to March.11
- People who are pregnant or planning a pregnancy: following the landmark MRC Vitamin Study, folic acid is recommended before conception and in early pregnancy to reduce the risk of neural tube defects.10
- Vegans and vegetarians: may need vitamin B12, iron and an algal omega-3.
- Menstruating women: higher iron needs due to monthly blood loss.4
- Older adults: absorption of some nutrients, including vitamin B12, tends to fall with age.
- People with limited sun exposure or covered skin: may need year-round vitamin D.
Warnings and precautions
Before you start
- Do not exceed the recommended dose or the stated upper limit. For adults, the NHS sets the upper level for vitamin D at 100 micrograms (4,000 IU) a day.11
- Tell your prescriber or pharmacist about every supplement you take, as some interact with medicines. For example, vitamin K can affect warfarin, and calcium or iron can reduce the absorption of certain medicines.
- If you are pregnant or breastfeeding, avoid high-dose vitamin A (retinol) and check any supplement is suitable first.
- NAD+ injections by Vivere should not be used in pregnancy or breastfeeding, or by people with active cancer or certain liver or kidney conditions, according to the manufacturer. Follow the supplied instructions for safe subcutaneous use.
- Keep iron and other supplements out of the reach of children, as iron overdose is dangerous for young children.
When should you see a doctor?
You should see a doctor rather than self-treat if your symptoms are persistent, severe or getting worse, because ongoing tiredness or other signs can point to an underlying condition that needs proper diagnosis. A simple blood test can confirm whether you are genuinely low in a nutrient before you commit to long-term supplements.
"If tiredness has lasted more than a few weeks, it is worth a simple blood test before reaching for supplements. Persistent fatigue occasionally points to something that needs proper investigation, so it is best not to self-treat indefinitely."
Rachael- Ongoing fatigue, breathlessness, a pale complexion or a fast or pounding heartbeat, which can suggest anaemia.
- Pins and needles, numbness, memory problems or a sore, red tongue, which can point to vitamin B12 deficiency.8
- Bone pain or frequent muscle aches and cramps.
- Symptoms that do not improve after a reasonable period of sensible supplementation.
Which lifestyle and dietary factors affect your nutrient levels?
Your day-to-day diet and lifestyle have the biggest influence on your vitamin and mineral levels, often more than supplements do. A varied diet, sensible sun exposure and good gut health help your body take in and use nutrients efficiently, while some habits work against them.
- Diet quality: oily fish provides omega-3 and vitamin D, red meat and pulses provide iron, dairy and fortified alternatives provide calcium and B12, and nuts, seeds and wholegrains provide magnesium and zinc.
- Sunlight: short spells of sun on bare skin in summer help maintain vitamin D.
- Alcohol and smoking: heavy drinking and smoking can deplete several nutrients and increase oxidative stress.
- Gut health: a healthy gut microbiome supports digestion and the absorption of some nutrients.
- Life stage and activity: pregnancy, older age and intense training all raise demand for certain nutrients.
How do you start supplement treatment?
Starting is straightforward once you know what you need. As Rachael puts it, the best supplement is the one that fills a genuine gap, so match it to a real requirement, follow the dosing instructions, and review how you feel after a few weeks.
- Identify the need: consider your diet, symptoms and life stage, and arrange a blood test if you are unsure which nutrient is low.
- Choose your option: add a food supplement or NAD+ injection kit to your basket, or select "Start your online consultation" for a prescription treatment such as a B12 injection.
- Follow the dosing: take it as directed and at a consistent time so it becomes a habit.
- Review: reassess after a few weeks and speak to a pharmacist or prescriber if anything is unclear or your symptoms persist.
Are there non-medical ways to improve your nutrient levels?
Yes, for most people a food-first approach is the best foundation, and supplements simply fill the gaps a normal diet leaves behind. Building meals around nutrient-dense foods covers the majority of your needs without any tablets at all.
- Iron: lean red meat, beans, lentils, tofu and dark leafy greens, paired with vitamin C to boost absorption.
- Vitamin D: oily fish, eggs, and safe summer sunlight.
- Calcium and B12: dairy, or fortified plant-based milks and cereals.
- Magnesium and zinc: nuts, seeds, wholegrains and shellfish.
- Gut microbiome: fibre-rich foods and fermented foods such as yoghurt and kefir.
Good sleep, regular activity, moderating alcohol and stopping smoking all help your body make the most of the nutrients you take in.
Frequently asked questions
Do I really need to take vitamin supplements?
Not everyone does. A varied, balanced diet supplies most of the vitamins and minerals a healthy adult needs. That said, the NHS recommends a daily 10 microgram vitamin D supplement for everyone in autumn and winter, and supplements are useful if your diet, life stage or a health condition leaves you short of a specific nutrient.
Are injections better absorbed than tablets?
Injections bypass the digestive system, so they can be more reliably absorbed than tablets when the gut is the problem. This is why vitamin B12 injections are used for pernicious anaemia, where B12 cannot be absorbed from food. For people with normal absorption, a good-quality oral supplement is often enough.
Do I need a prescription for NAD+ injections in the UK?
No. NAD+ injections by Vivere are available to buy without a prescription in the UK, so there is no online consultation to complete. Each kit is supplied with clear instructions for at-home subcutaneous use, and you should follow the dosing and safety guidance provided.
Do I need a prescription for vitamin B12 injections?
Yes. Prescription vitamin B12 injections (hydroxocobalamin) require a short online consultation that is reviewed by a regulated prescriber before the medicine is supplied. This makes sure the treatment is appropriate for your symptoms and medical history.
What is NAD+ and what does it do?
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every living cell. It plays a central role in converting food into cellular energy (ATP) inside the mitochondria, and it is involved in processes linked to DNA repair and cellular ageing. NAD+ levels naturally decline with age, which is part of the interest in supplementing it.
Can I take more than one supplement at the same time?
Often yes, but it depends on the combination and the doses. Some nutrients compete for absorption or interact with medicines, so it is best to keep to recommended amounts and avoid doubling up on the same vitamin across several products. A pharmacist can check your combination is safe.
Are your vitamins and supplements safe and good quality?
Our vitamins and supplements are pharmaceutical-grade and dispensed through a UK registered online pharmacy, with prescription treatments overseen by a regulated prescriber and a registered pharmacist. Choosing high-purity products from a regulated pharmacy gives you reassurance on quality, dosing and safety.
When is the best time to take vitamins?
It depends on the nutrient. Fat-soluble vitamins such as vitamin D are absorbed better with a meal that contains some fat, iron is often taken with vitamin C and away from tea or coffee, and magnesium suits many people in the evening. Consistency matters more than the exact time, so pick a routine you can stick to.
Medical disclaimer
The information on this page is provided for general informational purposes only and does not replace individual advice from a qualified healthcare professional. It should not be used to diagnose or treat a health condition. Always speak to your GP, pharmacist or prescriber for personalised advice, and read the patient information leaflet supplied with any product before use.
Our commitment to content accuracy
Our health content is written and checked by qualified professionals and is regularly reviewed by our team of medical experts to make sure it stays accurate, evidence-based and up to date. Where we cite statistics, we draw on trusted sources such as the NHS, NICE, the National Diet and Nutrition Survey, the BNF and the World Health Organization, together with the peer-reviewed studies, clinical trials and systematic reviews listed in the Key studies section below.
Medically reviewed by Rachael Clarke MRCPharm, Superintendent Pharmacist.
Last reviewed: 10 August 2026. Next review due: 10 August 2027.
Sources and references
The information on this page is evidence-based. The clinical studies, trials and systematic reviews below support the claims made above, alongside guidance from the NHS, NICE, the BNF and other authorities.
Key studies, trials and reviews
- Martineau AR, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ, 2017.
- Scientific Advisory Committee on Nutrition (SACN). Vitamin D and Health. 2016.
- Hemila H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews, 2013.
- Low MSY, et al. Daily iron supplementation for improving anaemia, iron status and health in menstruating women. Cochrane Database of Systematic Reviews, 2016.
- Abdelhamid AS, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews, 2020.
- Jackson RD, et al. Calcium plus vitamin D supplementation and the risk of fractures (Women's Health Initiative). New England Journal of Medicine, 2006.
- COSMOS trial. Baker LD, et al. Effects of cocoa extract and a multivitamin on cognitive function, Alzheimer's & Dementia, 2023; and the COSMOS-Web memory sub-study, American Journal of Clinical Nutrition, 2023.
- Devalia V, Hamilton MS, Molloy AM. Guidelines for the diagnosis and treatment of cobalamin and folate disorders. British Journal of Haematology, 2014.
- Martens CR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nature Communications, 2018.
- MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. The Lancet, 1991.
Further reading
- NHS. Vitamin D.
- NHS. Vitamin B12 or folate deficiency anaemia.
- Office for Health Improvement and Disparities. National Diet and Nutrition Survey (2019 to 2023).
- NICE Clinical Knowledge Summaries. Anaemia, iron deficiency.
- World Health Organization. Anaemia.
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