Millions of us suffer at least one nutrient deficiency thanks to modern diets and sedentary lifestyles.Yet most of us are entirely unaware, even though our bodies are screaming out for more iron, zinc, vitamin b12 and other essential vitamins and minerals.

Doctors say it is because the symptoms can be easily overlooked or linked to other, more innocuous, health problems. Constant fatigue may easily be dismissed as having poor sleep or a busy schedule, but in many cases it results from insufficient iron.

The metal is key to ensuring oxygen-rich blood flows around the body; without it, a person could find themselves out of breath.

And if your gums bleed often, it might be a lack of vitamin C rather than a dental issue. A poor diet could even cause brittle or damaged fingernails.

Fatigue

Fatigue is a symptom of many common ailments, described by doctors as one of, if not the, most frequent complaints across all fields of medicine. It is so common because of how prevalent iron deficiency is in the population, a Japanese research team speculated in 2017.

Iron is a crucial mineral for the body's creation of hemoglobin - a substance in the blood that carries oxygen. An iron-deficient person may feel tired because their body is not circulating enough oxygen through the blood.

In severe cases, iron deficiency can lead to a diagnosis of anemia - where the body's tissue lacks oxygen because of a shortage of healthy red blood cells.

The American Red Cross recommends iron-rich foods such as beef, lamb, chicken, spinach, broccoli, strawberries and watermelon - among many others - as additions to a diet that boosts iron intake.

Dandruff

Shedding white flakes from your hair can not only be embarrassing - but also ruin your black outfit. Dandruff is a condition where the skin on the top of a person's scalp becomes dry and scaly - causing it to flake.

Causes of dandruff are similar to those of dry hair. Niacin's boost to blood circulation to the scalp can prevent dryness, along with vitamin b6, pyridoxine, which supports the breakdown of protein and boosts brain health.

Zinc can keep skin cells on the scalp fresh and healthy, preventing shedding. Pyridoxine is in fish, poultry and chickpeas. Zinc is common in meats, nuts, seeds and many vegetables.

Hair loss

Dry hair can often lead to temporary hair loss, which can devastate self-esteem and other health issues. But, iron and protein are not the only critical components to maintaining a healthy hair due.

Vitamin b3, known as niacin, facilitates blood circulation to the scalp - which keeps hair strong and healthy. Vitamin b7, called biotin, has also been linked to hair health - as it supports keratin production in the body.

People hoping to boost their intake of both vitamins and stop hair loss should eat nuts, seeds and fish - excellent sources of niacin and biotin.

Irregular heartbeat

A variety of issues in the circulatory system can cause an irregular heartbeat. But dietary causes are often overlooked. Calcium is crucial to the circulation of blood in the body, and helps regulate electrical signals that cause the heart to beat.

Deficiencies in calcium can harm the body's ability to pump blood, leading to an occasional irregular heartbeat.

Weak bones

Not getting enough sun can leave your body brittle. Vitamin D, which is absorbed through the skin from the sun, deficiency is linked to osteomalacia - a condition where the body's bones weaken.

This is because vitamin D is crucial to the body's process for absorbing calcium - the building block of the body's skeleton.

Italian researchers in 2021 wrote that links between poor sun exposure and brittle bones had gone back as far as the 17th century. People who suffer from weak bones will often experience weakness, and pain in the bones and joints and are more likely to suffer fractures.

Dry hair

A few chicken breasts could be the answer for pesky dry hair. A few different factors can cause fuzzy, straw-like and brittle hair, but doctors warn poor iron and protein levels are one of them.

Like the causes of fatigue, dry hair can result from insufficient oxygen making its way around the body because of a shortage of iron. Protein is a crucial part of hair health too. Hair is made of a protein called keratin, and a person who lacks it in their diet will have trouble maintaining a healthy head of hair.

Meats like chicken, beef and lamb are excellent sources of both protein and iron.

Bleeding gums

Too much pink in the sink is often associated with dental diseases - but nutritionists also warn it can signal a problem in your diet.

Vitamin C, most associated with oranges and citrus fruits but also found in broccoli, peppers and tomatoes, is an integral part of the body's healing process and supports the growth of blood vessels, muscles and other tissue.

When a person lacks vitamin C, their body has trouble repairing damage caused by toxins in the air like cigarette smoke. When the body cannon repair this damage quickly, it could lead to bleeding.

In the most serious cases, a person suffering from a severe vitamin C deficiency can experience tooth loss or scurvy - an ancient disease most notably suffered by 18th-century pirates.

Night blindness

While humans do not quite have the eye-sight of cats - not being able to see at all in the dark could be a sign of a nutrient deficiency.

Night blindness is a condition where a person has trouble seeing in rooms that are not well-lit. This can include not being able to properly watch a movie in a theatre.

The condition occurs when a person's eyes do not properly adjust to changes in environmental light.

It can be caused by a shortage of rhodopsin being manufactured by the eye - a process in which vitamin A is crucial too.

The protein is vital to controlling the eye's sensitivity in light and allows it to adjust itself in low-light environments. Without it, a person's eyes can lose some function when the lights are dimmed.

Vitamin A is prevalent in leafy green vegetables, peppers, fish and dairy products.

Numb fingers

Hypocalcemia, also known as a severe calcium deficiency, can cause a person to feel a numb, tingling sensation in their fingers.

This is because calcium in the blood is crucial to nerve health. When a person suffers from dangerously low calcium levels, their periphery nerves may start to lose some function.

While it is often caused by just a lack of calcium in the diet, which can be fixed by adding more dairy, not getting enough vitamin D can lead to hypocalcemia too.

This is because the vitamin is essential for the body's metabolizing calcium into the blood.

Cold hands and feet

Anemia caused by iron deficiencies can be responsible for yet another symptom - cold hands and feet.

The lack of healthy red blood cells circulating in the body can leave it lacking it the body's extremities.

While using gloves and socks can help keep a person warm in the shorter, more iron-rich fruits and vegetables can solve the problem over time.

Swollen tongue

What does YOUR tongue say about your health?

White patches are a sign you're fighting an infection. Smoothness indicates you need vitamins.

Another sign of an iron deficiency is 'anemia tongue', when a person's tongue becomes swollen and inflamed.

Like other anemia-related symptoms, the swollen tongue is caused by the body's failure to circulate enough oxygen around the body.

Vitamin b12, called cobalamin, is also crucial to mouth health - and a deficiency of the B vitamin can be responsible for a swollen tongue.

The substance forms red blood cells, the nervous system, and cell metabolism. A shortage can lead to issues circulating blood - and tongue inflammation.

Burning mouth

Burning mouth syndrome is a condition where the tongue and roof of a person's mouth begin to feel a burning sensation. This feeling can spring out of nowhere before quickly disappearing again in sufferers.

Among the different causes of the condition are deficiencies in vitamin b12 and iron.

Similar to a swollen tongue, both substances are essential for mouth health - and the flow of blood-rich oxygen into the mouth.

It can also be caused by a shortage in zinc, which is responsible for helping cells in the body replicate and repair themselves.

Canker sores

No, the sore that opened inside your bottom lip is not caused by herpes but because you are not getting enough nutrients in your diet.

Like other issues in the mouth, they could be a sign of iron and b12 deficiencies. But, these sores opening inside the mouth could also be a sign that a person's diet lacks other B vitamins.

Vitamin b1, called thiamin, is a substance stored in the liver that is important to the growth of cells.

Ribofalvin, vitamin b2, is essential for skin and body tissue health. Pyridoxine, breaks down vital proteins for the nervous system.

Shortages of all three B vitamins have been linked to the development of canker sores. Fish, pork and dairy products are good sources of all three vitamins.

Smooth tongues

An exceptionally smooth tongue, known medically as glossitis, can be relatively harmless and overlooked. But it can also signal a dangerous lack of nutrients. Vitamin b9, known as folic acid, is crucial to the development of DNA and RNA in the body.

While researchers are not sure why, people who eat diets lacking in the vitamin will often suffer a glossy, smooth tongue. Glossitis has also been linked to deficiencies in iron and b12, like other issues in the mouth.

Folic acid is found in dark green vegetables, nuts, beans and fish.

Spoon nails

Some may realize that, over time, their nails have developed a dipping, spoon-shaped dent. Called koilonychia, the condition occurs when a person suffers from a severe iron deficiency.

The decreased flow of oxygen around the body caused by an iron deficiency can cause fingernails to soften and, eventually, lose their shape and begin to dip inwards.

Lines across the fingernails

'Beau's lines' are another fingernail issue that serves as an early sign a person is facing a nutrient deficiency.

Small indented lines across the fingernails are often associated with diabetes, vascular disease and other health issues. But, in some cases, it could also be a sign a person needs more of the nutrient zinc in their diet.

Zinc helps fuel the growth of cells in the body, and fingernail cells very quickly replicate and grow to maintain health. Foods rich in zinc include oysters, red meat, chicken and avocadoes.

Brittle nails

Brittle nails may be a sign of poor diet. Ridges indicate you're over-washing. Blotches could be much more sinister.

Italian researchers found in 2020 that one-in-five people suffer from nail brittleness, which they describe as 'nails that split, flake and crumble, become soft and lose elasticity.'

Brittle nails are a sign of poor overall health, but scientists note that it is a sign a person lacks two nutrients in particular: iron and biotin.

Biotin boosts levels of amino acids that create keratin in the body - which also contributes to the strength and growth of nails.

The flow of blood to the nails is also crucial to their health, making iron necessary too.

Restless legs

Restless leg syndrome is a condition that is not often taken very seriously but can be debilitating.

The condition occurs when uncomfortable tingling and itching sensations on the legs cause them to shake uncontrollably. It is most common in elderly people.

The tremors can disrupt a person's sleep and even to relax during waking hours. It can also be a cause for anxiety.

It has been linked to low iron levels in the brain. Scientists believe this is because iron plays a role in the brain's production of dopamine - a hormone linked to happiness - but have not determined precisely how low iron causes restless leg syndrome.

Irritability

Not getting enough essential vitamins and minerals can harm your mental health and put you in a bad mood.

Vitamin b1, thiamin, b6 and vitamin D are all known to have positive effects on a person's mental health - and shortages in a person's diet can cause issues.

While scientists have not firmly established why, absorbing vitamin D from the sun has long been linked to better mental health.

More recent studies have linked the pair of B vitamins to depression and even found that they work in tandem with antidepressants to help mental health.

Muscle twitching

Hypokalemia is a condition that occurs when the body does not have enough potassium, an electrolyte that helps a person's nerves and muscles function.

When a person does not have enough potassium, the electrical signals that keep muscles functioning are disrupted.

As a result, muscles may start to twitch uncontrollably. Bananas are the most famous fix for potassium deficiency, but other foods such as beans, potatoes and green vegetables are also excellent sources.

Nausea

Regularly suffering nausea in the morning - even during dry January - can be a sign you need more greens in your diet.

Magnesium is an essential mineral and electrolyte linked to the body's energy levels and muscle and nerve function.

Long-term deficiencies can cause issues in a person's digestive system, causing symptoms such as nausea, vomiting and a loss of appetite.

Getting more spinach, broccoli and beans into your diet can be an easy way to fix this issue.

Slow healing wounds

Have you ever had a cut that wouldn't scab over? It may mean you need to eat more oranges.

Like with bleeding gums, a lack of vitamin C in the diet harms the body's ability to replace and repair damaged tissue.

This means that when suffering a small cut, it could take people with a deficiency in the nutrient longer to have it recover.

While seemingly inconsequential, this could increase a person's risk of suffering infection after a wound.

When a person suffers a severe injury, their body may take significantly longer to recover if they do not have enough vitamin C.