The body never breaks down suddenly. Before any system ‘burns out’, the body sends out dozens of signals that we’ve grown accustomed to ignoring, attributing them to poor sleep, the change of season or stress at work. But what appears to be temporary fatigue is often the result of cellular ‘starvation’. Vitamins are not just supplements, but cofactors – a sort of ‘ignition key’ for biochemical reactions. If the key is missing, the metabolic process grinds to a halt. Given the pace of modern life and depleted soils, deficiencies have become the norm rather than the exception, and it is important to learn to interpret your body’s signals before they turn into a diagnosis.

How to recognise a vitamin deficiency through how you feel

The body never breaks down suddenly. Before any system ‘burns out’, the body sends out dozens of signals that we’ve grown accustomed to ignoring, attributing them to poor sleep, the change of season or stress at work. But what seems like temporary fatigue is often the result of cellular ‘starvation’. Vitamins are not just supplements, but cofactors – a sort of ‘ignition key’ for biochemical reactions. If the key is missing, the metabolic process grinds to a halt. Given the pace of modern life and depleted soils, deficiencies have become the norm rather than the exception, and it is important to learn to interpret your body’s signals before they turn into a diagnosis.

The crux of the problem in simple terms

The main pitfall of deficiencies is their stealth. The body is a brilliant strategist: when resources are scarce, it ‘shuts down’ the supply to secondary systems to maintain the functioning of the heart, brain and liver. The skin, hair, sleep quality and emotional stability are sacrificed.

The standard approach of ‘I’ll just buy any vitamins from the chemist’ often fails. Popular multivitamins contain minimal doses that are unable to plug the ‘hole’ that has already formed in your metabolism. What’s more, uncontrolled intake of random supplements can block the absorption of the nutrients you actually need, creating a dangerous imbalance.

Why vitamin deficiencies occur

Even with a ‘clean’ diet, the risk of deficiencies remains high. Here are the real reasons that often go unnoticed:

Absorption issues: Vitamins do not enter the bloodstream directly from your plate. If you have low stomach acidity or an inflamed gut, even the most expensive food simply passes through. A classic example is vitamin B12, which requires a special protein (intrinsic factor) in the stomach. No protein – no vitamin, no matter how much meat you eat.
Pharmacy depletion: Many common medicines are the enemies of nutrients. Heartburn remedies block magnesium and calcium, oral contraceptives deplete B-vitamin stores, and statins ‘steal’ energy from the heart by lowering coenzyme Q10 levels.
‘Overdrive’ mode: Chronic stress causes the adrenal glands to burn through vitamin C and B vitamins many times faster. In this state, the standard vitamin intake is like trying to put out a forest fire with a glass of water.
Empty-calorie foods: Intensive farming has made fruit and vegetables look attractive but nutrient-poor. An apple today may contain 40% fewer minerals than those harvested in the middle of the last century.

Constant tiredness and weakness

This isn’t laziness or a lack of motivation, but a physical lack of ‘fuel’ in the cells.

Reason: Vitamin B12 and iron are essential for producing red blood cells. If there isn’t enough of them, the blood struggles to carry oxygen – the tissues literally start to suffocate. Vitamin D, in turn, regulates the function of mitochondria – the ‘power stations’ of our cells.
Consequence: You feel exhausted just a couple of hours after waking up. Coffee provides a brief boost, but this is followed by an even deeper slump.
Conclusion: If sleep doesn’t leave you feeling refreshed, check your basic ‘fuel’ – iron, B12 and D3.

Problems with skin, hair and nails

When deficient, the body considers hair and nails a ‘luxury’ and stops maintaining them.

Reason: Hair loss and brittle nails are a cry for help from the thyroid gland, which is lacking in zinc, selenium or biotin (B7). Dry skin that does not respond to creams signals a deficiency in fat-soluble vitamins A and E, which build the epidermis’s protective barrier.
Mistake: Spending thousands on mesotherapy and face masks without first ensuring the follicle is properly nourished from within. Cosmetics are the tuning, but vitamins are the engine.

Cracks in the corners of the mouth and mouth ulcers

The mucous membranes renew themselves every few days. This is the most energy-intensive process, requiring a constant supply of nutrients.

Cause: Painful cracks (angular cheilitis) in the corners of the mouth are a sign of a deficiency in vitamin B2 or iron. Mouth ulcers (stomatitis) often indicate critically low levels of folic acid (B9) or B12.
Observation: These symptoms often appear after a course of antibiotics, which destroy the microflora that produces B vitamins.

Tingling and numbness in the limbs

These sensations are a direct signal from your nervous system that the ‘insulation’ is being damaged.

Cause: Vitamin B12 plays a role in the formation of the myelin sheath – the insulating layer of nerve fibres. Without it, nerve impulses begin to ‘short-circuit’.
Consequence: Initially, this manifests as a slight tingling in the fingers or ‘pins and needles’. If ignored, the process can lead to impaired coordination and cognitive lapses, which are easily mistaken for premature ageing.

Frequent infections

The immune system is an army that cannot fight without supplies.

The role of vitamins: Vitamin D activates ‘killer cells’ (T-killers); without it, they remain dormant. Vitamin C ensures the transport of immune cells to the site of infection. Vitamin A is responsible for the ‘integrity’ of the mucous membranes – preventing viruses from passing through the nasopharynx.
Fact: If you fall ill more than three times a year, your immune system is working itself to the bone without external support.

Vision problems

The eyes consume a huge amount of energy and are extremely sensitive to oxidative stress.

Reason: Vitamin A is a component of visual pigment. If there is a deficiency, you begin to see poorly in twilight (the ‘night blindness’ effect). The sensation of ‘grit’ in the eyes is often caused not by a computer screen, but by a malfunction of the lacrimal glands due to a lack of this same vitamin.
Risk: A prolonged vitamin A deficiency can lead to irreversible changes in the cornea.

When to see a doctor

Self-medicating with vitamins on the ‘more is better’ principle is dangerous. An excess of fat-soluble vitamins (A, D, E, K) is toxic, as they accumulate in the tissues and can damage the liver.

When to act immediately:

Persistent weakness that does not go away after the weekend.
Numbness or tingling in the limbs.
A sudden deterioration in the condition of the skin and mucous membranes.

Where you can save money, and where you cannot: Do not waste money on multivitamins from the supermarket. Instead, invest in high-quality laboratory testing. A basic check-up should include vitamin D (25-OH), ferritin (iron stores) and vitamin B12. These three figures will provide more answers than a dozen subjective feelings.

Your body is a perfect system capable of healing itself if given the necessary tools. A vitamin deficiency is not a death sentence, but a matter of proper nutrient management. Start with the basics: regulate your sleep, support your digestion and address any deficiencies under the supervision of a specialist. Health begins not at the chemist’s, but with an understanding of the needs of every cell in your body. Timely correction of deficiencies can restore vigour and mental clarity faster than any rest.

Sources used in preparing this material:

National Institutes of Health (NIH) Office of Dietary Supplements – global standards for intake levels.
Mayo Clinic – clinical guidelines for the diagnosis of anaemia and vitamin deficiencies.
World Health Organization (WHO) – data on global micronutrient deficiencies.
Harvard T.H. Chan School of Public Health – the impact of micronutrients on the prevention of chronic diseases.
Clinical protocols in neurology and nutrition.

FAQ: Frequently Asked Questions

Can I take ‘hair and nail’ vitamins without having tests?

It is not advisable. If your hair loss is caused by low ferritin levels and you are only taking biotin, the problem will not be resolved. Furthermore, an excess of zinc can inhibit the absorption of copper, leading to a new deficiency.

How quickly do the effects of taking them kick in?

The first changes in energy levels (B vitamins) are noticeable after 10–14 days. It takes at least 3–4 months to restore hair structure or build up vitamin D levels.

Is it true that vitamins from food are not absorbed?

They are absorbed, but their concentration is often insufficient to treat a deficiency. Food maintains normal levels, whilst supplements repair a damaged system.

When is the best time to take supplements?

Fat-soluble vitamins (A, D, E, K) should be taken strictly with meals containing healthy fats. B vitamins should be taken in the morning, as they can stimulate the nervous system and interfere with sleep.