Some of the most common nutritional deficiencies can be the hardest to spot, particularly in milder stages. Subtle and vague symptoms such as tiredness, brain fog, low energy and hair shedding are all things that can contribute to making you feel a bit “off,” but the root cause can be hard to put your finger on.
However, deficiencies are worth getting to the bottom of, because over time they can contribute to poorer long-term health.
“There’s a difference between not consuming enough of a nutrient, having low levels in the body and developing a clinically diagnosed deficiency,” explains Nichola Ludlam-Raine, specialist registered dietitian and author of How Not to Eat Ultra-Processed. “Deficiencies can develop gradually, and the symptoms are often surprisingly non-specific, and can have many other causes.”
While nutrient deficiencies are common, symptoms can be easily mistaken, adds Dr Alka Gupta, GP at Bupa Health Clinics. “If you’re concerned you might have a deficiency, it’s important to speak to a doctor. A simple blood test can often help identify any underlying issues and ensure you receive the right advice and treatment.”
Iron – fatigue, pale skin, restless legs, hair loss
Iron deficiency is common and is often one of the easiest to spot, according to Gupta. “Iron plays a vital role in helping your body produce haemoglobin, a protein in red blood cells that carries oxygen around the body. When iron levels are low, your body may struggle to deliver enough oxygen to your tissues,” she says.
“Iron deficiency is something I’m particularly mindful of in women of reproductive age, especially those experiencing heavy periods or during pregnancy,” adds Ludlam-Raine. “People who eat little or no meat may need to pay closer attention to their intake, but conditions affecting nutrient absorption can also contribute, too.”
Symptoms of anaemia include persistent tiredness and low energy, dizziness, pale skin, shortness of breath, headaches and brittle nails. “Interestingly, you can have low iron stores (ferritin) without being anaemic, which is why a normal haemoglobin result doesn’t necessarily rule out iron deficiency,” Ludlam-Raine says. Lesser-known symptoms include increased hair shedding, restless legs and a sore tongue. “One particularly unusual symptom is pica, where someone develops cravings for non-food substances, such as ice, paper or soil.”
What to eat more of
Lean red meat, beans, lentils, chickpeas, tofu, breakfast cereals and dark green leafy vegetables.
“Combine plant-based iron sources with vitamin C to help improve the absorption of non-haem iron,” Ludlam-Raine suggests. “Add red peppers to a lentil salad, enjoy kiwi fruit alongside fortified cereal or squeeze lemon juice over chickpeas.
“If someone has confirmed iron deficiency, dietary changes alone may not be enough, and iron supplementation may be recommended.”
Vitamin D – tiredness, weak muscles, low mood
It is estimated nearly one in five adults in the UK have a vitamin D deficiency, and this rises to about a third in the winter months, when many are unable to produce enough vitamin D from sunlight alone.
Vitamin D helps maintain healthy bones and muscles and supports a well-functioning immune system. “Low vitamin D levels can cause symptoms such as fatigue, muscle weakness, general aches and pains, and low mood,” Gupta says.
“Some people notice these symptoms more during the darker months of the year when daylight hours are shorter.”
Mild deficiency can cause vague or few obvious symptoms, meaning people may not realise their levels are low unless they have a blood test. But prolonged deficiency over time can lead to osteomalacia in severe cases, where bones become softer and weak, Ludlam-Raine adds.
What to eat more of
Oily fish like salmon, mackerel and sardines, egg yolks, UV-exposed mushrooms and some fortified breakfast cereals and spreads. “Vitamin D is naturally present in relatively few foods, making it difficult to obtain enough through diet alone,” Ludlam-Raine says.
“It is recommended everyone aged four and over consider taking 10 micrograms (400 IU) of vitamin D daily between October and March, while certain groups are advised to take it throughout the year.”
Vitamin B12 – tiredness, brain fog, memory problems, pins and needles
Vitamin B12 is an essential nutrient that helps keep your blood cells and nervous system healthy. “It is particularly important for nerve function, memory and concentration,” says Ludlam-Raine.
Deficiency can cause symptoms of anaemia, including tiredness, weakness, breathlessness and a sore, red tongue.
“However, some of the most important warning signs are neurological, including pins and needles, numbness in the hands or feet, balance problems, memory difficulties and brain fog,” she continues.
“Prolonged B12 deficiency can cause nerve damage that may become irreversible if left untreated, so anyone experiencing these symptoms should seek medical advice promptly.”
What to eat more of
Meat, fish, eggs, milk and dairy products. “For those following a vegan diet, I’d recommend regularly including foods fortified with B12, such as certain plant-based milks, breakfast cereals and nutritional yeast, alongside a reliable B12 supplement.”
“However, it’s a misconception that B12 deficiency only affects vegans. Older adults may struggle to absorb B12 efficiently, while conditions such as pernicious anaemia can prevent the body absorbing it properly.”
Certain medications and heavy alcohol consumption can also increase the risk of low B12 levels. “If someone has a diagnosed absorption problem, they may need high-dose oral supplements or B12 injections.”
Folate (vitamin B9) – fatigue, recurrent mouth ulcers and difficulty concentrating
Folate is essential for healthy red blood cell formation and DNA synthesis. It is particularly important during pregnancy, helping to support the healthy development of a baby’s brain and spinal cord.
“Deficiency can result in a type of anaemia, with symptoms including extreme tiredness, weakness, shortness of breath and difficulty concentrating,” Ludlam-Raine says.
“Some people may also experience a sore, red tongue or mouth ulcers. Folate and vitamin B12 deficiencies can produce similar symptoms, so identifying which nutrient is lacking (rather than guessing) is key.
What to eat more of
Dark leafy greens, broccoli, Brussels sprouts, asparagus, chickpeas, lentils and fortified breakfast cereals.
“Women who are planning a pregnancy, or who could become pregnant, are advised to take a 400 microgram folic acid supplement daily, ideally before conception and continuing until the end of the first 12 weeks of pregnancy.”
Calcium – muscle cramps, tingling sensations, brittle nails
Calcium keeps our bones and teeth strong, but it is also essential for many other functions throughout the body, explains Gupta.
“In early stages, calcium deficiency may not cause obvious symptoms. Some people experience muscle cramps, muscle aches, tingling sensations, brittle nails or fatigue.
“Over time, low calcium levels or inadequate calcium intake can contribute to poor bone health and increase the risk of osteoporosis and fractures.”
What to eat more of
Milk, yoghurt and cheese, sardines and tinned salmon with edible bones and green vegetables such as kale and broccoli.
“Maintaining adequate vitamin D levels helps your body make the most of the calcium you consume,” she adds.
Iodine – tiredness, thyroid problems, difficulties with concentration
Research suggests iodine deficiency is on the rise in the UK. It is most common among children, pregnant women and people who don’t eat dairy and fish.
“Iodine is essential for producing thyroid hormones, which help regulate metabolism, growth and development,” Ludlam-Raine says.
“Mild iodine insufficiency may not cause any noticeable symptoms. However, prolonged or severe deficiency may contribute to an underactive thyroid, potentially resulting in tiredness, feeling unusually cold, constipation, dry skin and difficulties with concentration.”
What to eat more of
Milk, yoghurt, cheese, fish and eggs. “If drinking plant-based milk alternatives, check to see whether iodine has been added (not all contain iodine, even if they’re fortified with calcium and vitamin B12),” Ludlam-Raine advises.
“For those avoiding animal products altogether, an iodine-containing supplement may be worth considering. “But avoid high-doses of kelp or seaweed supplements, in which iodine levels can be extremely variable, and excessive iodine can also interfere with thyroid function.”