Vitamins and minerals are needed in small amounts, but they play an important role in keeping the body working properly. They support energy release, red blood cell production, immune function, bones, muscles, nerves, skin, wound healing and many other normal body processes.
Most people can get the nutrients they need from a varied and balanced diet. However, some people may be at higher risk of deficiency because of diet, medical conditions, pregnancy, breastfeeding, age, restricted eating patterns, certain medicines, reduced sunlight exposure or absorption problems.
This guide from I-Prescribe explains common vitamin and mineral deficiencies, the symptoms that may occur, when to seek medical advice and how to approach supplements safely. It is written for general patient information and does not replace medical advice, diagnosis or treatment.
I-Prescribe is based at Unit 10F, Lister Hills Science Park, Bradford, BD7 1HR. We support patients in Bradford, West Yorkshire and across the UK with online pharmacy services, private treatment information and access to medicines where clinically appropriate.
What is a vitamin deficiency?
A vitamin deficiency happens when the body does not have enough of a particular vitamin to function properly. This can happen because a person is not getting enough from food, cannot absorb it properly, has increased requirements, or is losing nutrients because of illness or another health factor.
Deficiencies can develop slowly, and early symptoms may be vague. Tiredness, weakness, low mood, mouth ulcers, pins and needles, hair changes, muscle aches or frequent infections can have many possible causes. A vitamin deficiency is one possibility, but it should not be assumed without proper assessment.
In some cases, a blood test may be needed to confirm deficiency and guide treatment. Taking high-dose supplements without knowing whether you need them can be unsafe, especially with certain vitamins and minerals.
Common signs of vitamin or mineral deficiency
Symptoms depend on which nutrient is low, how severe the deficiency is and whether there are other health conditions. Possible symptoms may include:
- Feeling tired, weak or low in energy
- Shortness of breath or palpitations
- Pale skin
- Mouth ulcers or a sore tongue
- Hair shedding or brittle nails
- Muscle aches, cramps or bone pain
- Pins and needles or numbness
- Low mood, brain fog or poor concentration
- Frequent infections or slow wound healing
- Bleeding gums or easy bruising
These symptoms can also be caused by thyroid disease, diabetes, anaemia, infection, stress, poor sleep, menopause, depression, inflammatory conditions or other medical issues. If symptoms are persistent, worsening or unexplained, speak to a healthcare professional rather than self-diagnosing.
Vitamin D deficiency
Vitamin D helps regulate calcium and phosphate in the body, which supports healthy bones, teeth and muscles. In the UK, vitamin D deficiency is more common during autumn and winter because sunlight is weaker and people spend more time indoors.
Low vitamin D can contribute to bone pain, muscle weakness and, in severe cases, bone problems such as osteomalacia in adults or rickets in children. Some people are at higher risk, including those with limited sun exposure, people who cover most of their skin outdoors, people with darker skin, older adults, care home residents and people with certain medical conditions.
UK guidance advises that everyone should consider taking a daily vitamin D supplement during autumn and winter. Some higher-risk groups may be advised to take vitamin D throughout the year. However, more is not always better. Taking too much vitamin D over time can be harmful because it may cause too much calcium to build up in the body.
Vitamin B12 deficiency
Vitamin B12 is important for red blood cell production, nerve function and normal DNA formation. B12 deficiency can cause tiredness, weakness, mouth ulcers, a sore tongue, pins and needles, balance problems, memory issues and mood changes.
B12 is mainly found in animal-derived foods such as meat, fish, eggs and dairy. People following a vegan or very restricted diet may be at higher risk unless they use fortified foods or appropriate supplementation. Other causes include pernicious anaemia, stomach or bowel surgery, inflammatory bowel disease, some medicines and absorption problems.
B12 deficiency should be taken seriously because nerve-related symptoms can sometimes become long-lasting if not treated appropriately. If symptoms suggest B12 deficiency, medical assessment and blood tests may be needed.
Folate deficiency
Folate, also known as vitamin B9, helps the body make healthy red blood cells. Folate deficiency can cause anaemia and symptoms such as tiredness, weakness, mouth ulcers, reduced appetite and problems with concentration.
Good dietary sources include green leafy vegetables, beans, peas, chickpeas and fortified foods. Folate deficiency may occur due to low intake, alcohol use, pregnancy, certain medicines, coeliac disease or other absorption problems.
Folic acid is particularly important before and during early pregnancy. People trying to become pregnant, or who could become pregnant, are generally advised to take folic acid before pregnancy and during the first 12 weeks. Some patients need a higher dose, but this should be advised by a healthcare professional.
Iron deficiency
Iron is a mineral rather than a vitamin, but it is one of the most common nutritional deficiencies. Iron helps make red blood cells, which carry oxygen around the body. Low iron can lead to iron deficiency anaemia.
Symptoms may include tiredness, weakness, shortness of breath, dizziness, palpitations, pale skin, headaches, brittle nails or restless legs. Causes can include heavy periods, pregnancy, low dietary intake, gastrointestinal bleeding, inflammatory bowel disease, poor absorption or recent blood loss.
Iron deficiency should not be ignored. In adults, especially men and post-menopausal women, unexplained iron deficiency may need further medical investigation to rule out bleeding or other underlying causes.
Iron supplements can be helpful when needed, but they are not suitable for everyone and can cause side effects such as constipation, nausea or dark stools. Taking iron unnecessarily can be harmful. If iron deficiency is suspected, a blood test and clinical review are usually appropriate.
Vitamin C deficiency
Vitamin C supports healthy skin, blood vessels, bones, cartilage and wound healing. It also helps the body absorb iron from plant-based foods.
Severe vitamin C deficiency can lead to scurvy, although this is uncommon. Symptoms may include tiredness, weakness, swollen or bleeding gums, easy bruising, joint or muscle pain, dry skin, poor wound healing and small red or blue spots on the skin.
Fruit and vegetables are the main dietary sources of vitamin C. A varied diet containing foods such as citrus fruits, berries, peppers, broccoli, potatoes and leafy greens can help maintain intake. If your diet is very limited or you have symptoms of deficiency, seek advice before relying on supplements alone.
Vitamin A: why balance matters
Vitamin A supports vision, immune function and skin health. It is found in foods such as dairy products, eggs, oily fish and liver, and the body can also make vitamin A from beta-carotene in foods such as carrots, sweet potatoes and leafy greens.
Vitamin A deficiency is uncommon in the UK, but taking too much vitamin A can be harmful. This is particularly important during pregnancy because high vitamin A intake can harm an unborn baby. Pregnant patients should avoid supplements containing vitamin A unless advised by a healthcare professional, and should follow NHS pregnancy supplement advice.
Who is more at risk of deficiencies?
Some people have a higher risk of vitamin or mineral deficiency. This does not mean they definitely have a deficiency, but it may mean they should be more aware of symptoms and seek advice when needed.
- People with very restricted diets
- People following vegan or vegetarian diets without appropriate planning
- People with heavy periods
- Pregnant or breastfeeding patients
- Older adults
- People with darker skin or limited sun exposure
- People with coeliac disease, Crohn’s disease or ulcerative colitis
- People who have had bariatric surgery or bowel surgery
- People taking medicines that affect absorption or nutrient levels
- People with alcohol dependence
- People with long-term poor appetite or unintentional weight loss
Can medicines affect vitamin and mineral levels?
Some medicines may affect appetite, absorption or nutrient levels. For example, long-term use of some acid-reducing medicines may be associated with lower levels of certain nutrients in some patients. Metformin can be associated with vitamin B12 deficiency in some people. Some anti-epileptic medicines, weight loss medicines, laxatives or long-term restrictive diets may also affect nutritional status.
Do not stop prescribed medicine without speaking to a healthcare professional. If you are concerned about a medicine and possible deficiency symptoms, ask a pharmacist, GP or prescriber for advice.
Should you take a multivitamin?
A multivitamin may be useful for some people, but it is not a substitute for a balanced diet and it may not correct a confirmed deficiency. Some deficiencies require a specific dose, formulation or treatment plan. Others may need investigation to find the cause.
For many people, improving diet and taking only appropriate supplements is safer than taking multiple overlapping products. It is easy to accidentally double up on ingredients when using multivitamins, vitamin D products, hair supplements, pregnancy supplements, energy supplements and fortified drinks together.
Before taking supplements, check the label carefully and consider whether you actually need the product. Speak to a healthcare professional if you are pregnant, breastfeeding, taking regular medicines, have kidney disease, liver disease, cancer, diabetes, a history of kidney stones or a long-term medical condition.
Can you take too many vitamins?
Yes. More does not always mean better. Some vitamins are water-soluble and excess amounts may be passed in urine, but high doses can still cause side effects. Other vitamins, such as vitamins A, D, E and K, are fat-soluble and can build up in the body.
Taking too much vitamin D can cause excessive calcium levels, which may damage the kidneys, bones and heart. Too much vitamin A can be harmful, particularly during pregnancy. Excess iron can be dangerous and should not be taken unless needed. High-dose supplements should be used only when clinically appropriate.
If you feel unwell after starting a supplement, stop and seek advice, especially if you develop nausea, vomiting, abdominal pain, constipation, confusion, severe thirst, weakness or symptoms that are unusual for you.
Food first: building a nutrient-supportive diet
A food-first approach is usually the best starting point for long-term health. A balanced diet can provide vitamins, minerals, fibre, protein and other nutrients that supplements cannot fully replace.
Helpful dietary principles include:
- Eat a variety of fruit and vegetables each day
- Include protein sources such as fish, eggs, lean meat, beans, lentils, tofu or dairy
- Choose wholegrains where suitable
- Include calcium-rich foods such as dairy or fortified alternatives
- Consider oily fish where appropriate
- Use fortified foods if following a plant-based diet
- Avoid relying heavily on ultra-processed foods
- Limit alcohol intake
People with allergies, intolerances, religious dietary requirements, eating disorders, gastrointestinal conditions or diabetes may need more tailored nutrition advice.
When should you ask for a blood test?
You may need medical advice or blood tests if you have persistent symptoms that could suggest deficiency, especially if symptoms are affecting daily life or are getting worse.
Speak to a GP or healthcare professional if you have:
- Ongoing tiredness or weakness
- Shortness of breath or palpitations
- Pins and needles, numbness or balance problems
- Unexplained weight loss
- Persistent mouth ulcers or a sore tongue
- Heavy periods or suspected blood loss
- Bone pain or muscle weakness
- Recurrent infections or poor wound healing
- Symptoms after bariatric surgery or bowel surgery
- A restricted diet with symptoms of deficiency
Blood tests may check levels such as full blood count, ferritin, B12, folate, vitamin D, thyroid function, kidney function, liver function or inflammation markers, depending on symptoms and clinical judgement.
Red flags: when to seek urgent medical help
Some symptoms should be assessed urgently and should not be managed with supplements alone. Seek urgent medical advice if you have chest pain, severe shortness of breath, fainting, confusion, sudden weakness, black stools, vomiting blood, severe abdominal pain, severe allergic symptoms, or symptoms that feel serious or rapidly worsening.
If you have neurological symptoms such as new weakness, difficulty speaking, facial drooping or sudden severe headache, call 999 immediately.
Vitamin deficiencies and tiredness
Many people search online for “why am I tired all the time?” Vitamin deficiencies can contribute to tiredness, but they are only one possible cause. Poor sleep, stress, anxiety, depression, thyroid disease, diabetes, anaemia, infection, menopause, medication side effects and long-term health conditions can also cause fatigue.
If tiredness is persistent, severe or unexplained, it is better to seek assessment rather than guessing. Taking supplements without identifying the cause may delay appropriate diagnosis and treatment.
Vitamin deficiencies and hair, skin and nails
Hair shedding, brittle nails and skin changes are commonly blamed on vitamin deficiency, but the cause is not always nutritional. Stress, thyroid disease, iron deficiency, recent illness, hormone changes, scalp conditions, medicines and genetics can all contribute.
Supplements marketed for hair, skin and nails are not always necessary and may contain high doses or multiple ingredients. If symptoms are new, severe, patchy, associated with scalp inflammation or linked with other symptoms, seek clinical advice.
Vitamin deficiencies in pregnancy and breastfeeding
Pregnancy and breastfeeding change nutritional requirements. NHS guidance recommends folic acid before and during early pregnancy, and vitamin D is also important. However, some supplements are not suitable during pregnancy, particularly those containing vitamin A unless specifically advised.
If you are pregnant, trying to become pregnant or breastfeeding, speak to a midwife, GP or pharmacist before starting supplements. Some people need higher-dose folic acid or additional support based on medical history, BMI, medicines or previous pregnancy history.
How I-Prescribe can support patients
I-Prescribe provides online pharmacy support and patient information for people who want clear, responsible healthcare guidance. Based in Bradford, BD7 1HR, we support patients across West Yorkshire and the UK.
If you are concerned about symptoms that could be linked to vitamin or mineral deficiency, our team can help with general pharmacy advice and signposting. Depending on your symptoms, you may be advised to speak to your GP, arrange blood tests, contact NHS 111 or seek urgent care.
Online advice is not suitable for all symptoms. Persistent, severe, unexplained or worsening symptoms should be assessed by an appropriate healthcare professional.
Final advice: do not guess, check properly
Vitamin deficiencies can affect health in many ways, but symptoms are often non-specific. The safest approach is to consider diet, lifestyle, risk factors and symptoms together, and to seek medical advice when symptoms persist or suggest something more serious.
Supplements can be useful when they are appropriate, but they should be used carefully. Avoid high-dose products unless advised, do not combine multiple supplements without checking ingredients, and do not use supplements as a substitute for medical assessment.
If you are unsure, speak to a pharmacist, GP or another appropriate healthcare professional.
Contact I-Prescribe or browse our A-Z online treatments for more information.
Frequently asked questions
What are common vitamin deficiency symptoms?
Possible symptoms include tiredness, weakness, mouth ulcers, pins and needles, muscle aches, bone pain, hair changes, brittle nails, poor wound healing and low mood. These symptoms can have many causes, so assessment may be needed.
Can vitamin D deficiency make you tired?
Low vitamin D may contribute to muscle aches, weakness or general symptoms in some people, but tiredness can have many causes. If fatigue is persistent or severe, seek medical advice.
Who is at risk of vitamin B12 deficiency?
People following vegan or very restricted diets, older adults, people with pernicious anaemia, absorption problems, bowel conditions or certain medicine use may be at higher risk.
Should I take iron if I feel tired?
Not without checking whether iron deficiency is likely or confirmed. Iron can be harmful if taken unnecessarily. Persistent tiredness, heavy periods or symptoms of anaemia should be discussed with a healthcare professional.
Can I take several supplements together?
You should check labels carefully because products can contain overlapping ingredients. Taking multiple supplements may increase the risk of excessive intake, especially with vitamin D, vitamin A, iron or other high-dose ingredients.
Do I need a blood test for vitamin deficiency?
A blood test may be needed if symptoms are persistent, unexplained, severe or linked with risk factors. A healthcare professional can advise which tests are appropriate.
Is I-Prescribe based in Bradford?
Yes. I-Prescribe is based at Unit 10F, Lister Hills Science Park, Bradford, BD7 1HR, and supports patients across the UK through online pharmacy services.
Compliance note: This article is for general information only and does not replace medical advice. Do not use supplements to self-treat persistent, severe or unexplained symptoms without appropriate clinical assessment. For urgent or severe symptoms, seek medical help immediately.