Five signs you’re lacking in vital nutrients and what to do about it

Even if you think your diet is healthy, these are the consequences of missing out on essential vitamins and minerals

If you’ve ever wondered why you’re always getting ill, it might be time to take a long, hard look at your diet. Because however much we religiously stick to our five a day, we can still end up nutrient deficient. Dr Sarah Brewer, who is a GP, nutritionist and nutritional therapist, says: “If you’re lacking in essential nutrients, you may get recurring colds due to reduced immune function, or may struggle with tiredness and fatigue, muscle weakness and low energy.
“A lack of essential nutrients also shows in brittle nails and hair, skin complaints and adult acne – these are all indicators that what you’re eating is not a good nutritional balance,” says Melissa Snover, a nutritionist and the founder of Nourished. Studies in the UK have shown that a high percentage of chronically ill people have calcium deficiency, and up to 60 per cent of the UK population are considered as having insufficient levels of vitamin D. 
There can be a multitude of reasons for this deficiency in essential vitamins and minerals. For one thing, the nutritional value of many of our foods has dropped significantly, with a US study finding some garden crops are up to 38 per cent lower in important nutrients than they were in mid-20th century, with intensive farming techniques often to blame. 
But our eating habits can also be at fault. An over-reliance on processed foods is leaving our diet devoid of the vitamins, minerals and other compounds that we need to maintain our health and vitality. Organic foods may not have the shelf life of standard produce, but they do, in some cases, contain higher levels of certain nutrients, yet with many of us tightening our belts, going organic can be beyond the household budget. 
And even if we do our best to cook at home, busy lives can leave little time for planning meals with optimal nutrition in mind. “Many of us tend to eat a restricted diet, have too many poor-quality foods and not enough fruit and vegetables or fish. And cutting back on our food intake to lose weight can often mean less nutrients, especially if we’re getting in a rut of sticking to the same foods every day and not getting the variety required,” says Dr Brewer. 
Snover adds: “When people make food choices on the go, they are often prioritising things like calories, protein, sugar and salt, but very few are checking food packaging for micronutrient density.”
“Following a restrictive diet for any reason, whether that’s religion, because of an allergy or condition or by choice, you need to look at which nutrients you could be missing. For example, if you’re vegan, you are going to really struggle to get B vitamins and iron from your diet.”
While the safety net of a multivitamin seems like a good back-up plan, it’s important to be realistic about their value. Dr Helen Wall, a GP in Greater Manchester, says: “For the majority of us, no supplement can beat a well-balanced varied diet. There are various essential nutrients in food that even the most comprehensive supplement is unlikely to compensate for, such as phytochemicals (plant chemicals) and fibre”.  
We certainly do like popping a pill to keep ourselves in peak condition. The UK revenue generated in the vitamins and minerals market reached £600 million in 2024. But dietary supplements don’t come cheap. In Mintel’s Vitamins and Supplements Market Report 2023, 40 per cent of us stopped using or cut back on vitamins and minerals last year due to financial concerns. 
And how do you know which ones you need? Vitamins are involved in every metabolic reaction within the body, from digestion, energy production and immunity to cell division, hormone secretion and mental alertness. Knowing what you are lacking is not always straightforward.
“Deficiency symptoms include constant tiredness, weakness, poor wound healing, impaired immunity and reduced fertility – but to avoid deficiency, good diet should always come first,” says Dr Brewer, recommending a whole food diet, ideally a Mediterranean one (ie, vegetables, nuts, pulses, poultry, oily fish, extra virgin olive oil, whole grains and a little cheese or yogurt). 
The Association of UK Dietitians recommends that we should all consider a vitamin D supplement, especially during winter months, and that vegans may need supplementation with vitamin B12 and iodine. “Up to 25 per cent of UK women are low in vitamin D, which can cause problems with your immune system, tiredness and poor bone health,” says Dr Wall. “It is recommended that everyone over the age of 12 take 600IU of vitamin D a day, at least in the darker autumn and winter months”.
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Taking too much of a vitamin or mineral can be dangerous, so if you take more than one supplement, make sure that you are not doubling up on any nutrients. “Some vitamins such as A, D and E can be toxic in higher than recommended doses. It is possible to overdose and incredibly easy to under-dose in essential nutrients by relying solely on a supplement,” says Dr Wall. “So, while good vitamin supplements do have their place, you really can’t beat a good, varied diet.”
“If you decide to take a multivitamin, choose one according to your stage of life. After middle age, your needs for many vitamins and minerals increases, partly because your metabolism becomes less efficient, and partly because you are less able to absorb certain key nutrients from your diet – it’s a double whammy,” says Dr Brewer.
If you tend to get mouth ulcers and cracks in the corners of the mouth, these can be a sign of deficiencies in iron, zinc or B vitamins. One study found that patients with recurring mouth ulcers had deficiencies in thiamine (vitamin B1), riboflavin (vitamin B2), pyridoxine (vitamin B6) or a combination of the three. 
A recurrent mouth ulcer might also be due to viral infection, genetics or certain medications, and a long-lasting mouth ulcer is sometimes a sign of mouth cancer, so do seek advice from your GP.
Foods rich in iron include poultry, meat, fish, legumes, dark leafy greens, nuts, seeds, and whole grains. Good sources of thiamine, riboflavin, and pyridoxine include whole grains, poultry, meat, fish, eggs, dairy, organ meats, legumes, green vegetables, starchy vegetables, nuts, and seeds. 
A good-quality multivitamin and mineral supplement should provide all the vitamins and minerals you are lacking, or take a B vitamin supplement that contains B1, B2 and B6. 
From bald patches to thinning, brittle hair can be distressing. Hair loss typically affects the scalp but can also occur anywhere on the body, such as eyelashes or eyebrows. If your nails become brittle, this may make them cracked, pitted, soft and discoloured. Brittle hair and nails can be a sign of biotin deficiency – B7 – which works to metabolise the amino acids in your body, producing strong and healthy hair and nails. “Hair and nails becoming brittle are signs of low iron and B vitamins but can also be due to thyroid disorder,” says Dr Wall.
You need foods packed with iron and B vitamins, omega-3 fatty acids, and vitamins A, C, and E. Go for foods like salmon, nuts, avocados, fruits and vegetables. If you’re in a rush, try a health shot to boost the health of your hair and nails. “A small, concentrated juice made from ingredients known to have beneficial nutrients and properties such as turmeric and ginger, these are a quick way of giving yourself a nutrient boost,” says Snover.
There are many supplements on the market targeted specifically at improving brittle hair and nails. One study found that taking biotin (B7) can help. “But it’s such a complex mix of vitamins and minerals that you need for hair and nails that the best solution of all is a varied diet,” says Dr Wall.
Your skin reflects your overall health, so if you’re getting dry, scaly skin, keratosis pilaris (‘chicken skin’), dandruff or seborrheic dermatitis, nutrient deficiencies may be the cause. If you’re not getting enough vitamin D, niacin, zinc, or iron, you can develop excessively dry skin.
“Lack of vitamin A can cause scaly skin, and you can also get little pimples around your hair follicles. Lack of Vitamin C reduces skin quality as does lack of essential fatty acids, causing scaly skin,” says Dr Brewer. With dandruff and seborrheic dermatitis, low levels of riboflavin (vitamin B2) and pyridoxine, (vitamin B6), may be at fault.
Foods rich in riboflavin and pyridoxine include poultry, meat, fish, eggs, dairy, oats and nuts. Eat butter, liver and eggs for vitamin A, citrus fruits for vitamin C and olive oil and avocados for vitamin E. Omega-3 fatty acids have been shown to decrease the production of inflammatory compounds that cause seborrheic dermatitis, so eat fatty fish (salmon, mackerel, and sardines), flaxseeds and walnuts.
Vitamin C, vitamin D, folic acid and fish oil, as well as collagen can really help improve your skin’s health.
Unexplained fatigue and that constant feeling like you’re running on empty can leave you struggling to meet the demands of your life. You may also get muscle weakness and achy joints. And unless you’re recovering from illness or struggling to get enough sleep, you may need to ask your doctor for a blood test to check the cause.
You need an iron-rich diet, including red meat, eggs and beans, dairy products for vitamin B12 and oily fish for vitamin D. Snover says: “Eating a wide variety of rainbow-coloured fruits and vegetables will ensure you get a wide variety of balanced micronutrients crucial for so many of the body’s energy and day to day processes and functions. The colour of a plant indicates the types of nutrients inside – if it’s green, it’s probably got iron and B vitamins,” both of which are essential for energy.
Vitamins B, E and C, calcium, iron, magnesium, zinc, folate, selenium and potassium are all essential for beating fatigue. “I would also recommend coenzyme Q10 for anyone over 50 to help improve energy levels,” says Dr Brewer. 
While the main cause of bleeding gums is a build-up of plaque at the gum line, vitamin C and vitamin K deficiencies can also cause gums to bleed easily, due to weakened collagen. 
Eating foods rich in vitamin C can strengthen your immune system and help fight off the gum infections that cause bleeding gums. For vitamin C eat plenty of citrus fruits, tomatoes and peppers. Vitamin K can be found in watercress, spinach and olive oil. 
This is another reason for taking a vitamin D supplement, as maintaining optimal levels supports your gum health and reduces the risk of gum-related problems, and it also has anti-inflammatory properties that can help heal gum inflammation.
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