You're Tired, Anxious and Getting Sick Often - It Might Be a Vitamin Deficiency

You're exhausted but sleeping enough. Anxious for no clear reason. Getting every cold that goes around. Your hair is thinning. Brain fog that won't shift no matter how much coffee you drink.

You've quietly accepted this as your normal.

It's not normal. And it might have a remarkably simple explanation.

Here are the four deficiencies I see most frequently — and exactly what to do about each one.

1. Vitamin D — The Silent Epidemic

This is the most common deficiency in the world and simultaneously the most under-diagnosed.

Over one billion people worldwide are deficient in Vitamin D. But the statistics for specific countries are staggering.

Vitamin D deficiency prevails in epidemic proportions all over the Indian subcontinent, with a prevalence of 70% to 100% in the general population. PubMed Central That is not a typo. Up to 100% of some Indian population studies show deficiency — in a country with abundant sunshine year-round. The reason? Skin pigmentation, indoor lifestyles, dietary habits, and pollution blocking UV rays.

The UK tells an equally alarming story. Among UK Biobank participants of Asian ancestry — which includes a significant proportion of South Asian immigrants — vitamin D deficiency prevalence reached 57.2% in winter and spring, compared to 17.5% in White European participants during the same period. ScienceDirect

If you have South Asian heritage and live in the UK — you are at extremely high risk.

Symptoms of Vitamin D deficiency:

  • Chronic fatigue that sleep doesn't fix
  • Bone and muscle pain, especially in the legs and back
  • Depression and persistently low mood
  • Frequent infections — Vitamin D is critical for immune function
  • Brain fog and difficulty concentrating

Your body makes Vitamin D from sunlight exposure to skin. Most of us sit indoors under artificial lighting for 8 to 10 hours a day. The maths does not work in our favour.

The test: Ask for a 25-OH Vitamin D blood test. Levels below 50 nmol/L indicate deficiency in most UK guidelines.

2. Vitamin B12 — The One That Creeps Up on You

B12 deficiency is dangerous specifically because it develops slowly and silently. By the time your symptoms become obvious, neurological damage may already be in progress.

B12 is essential for the production of red blood cells, the maintenance of the myelin sheath that protects your nerve fibres, and the synthesis of DNA. Without it, your nervous system begins to deteriorate — and this process is not always reversible if caught late.

Symptoms of B12 deficiency:

  • Tingling or numbness in hands, feet or legs — early nerve damage
  • Memory problems and difficulty concentrating
  • Extreme fatigue and weakness
  • Mood changes, irritability, depression
  • Pale or slightly yellowish skin
  • A sore, inflamed tongue
  • Unsteadiness when walking in more advanced cases

Who is most at risk:

  • Vegetarians and vegans — B12 exists naturally only in animal products
  • People over 50 — stomach acid production decreases with age, reducing B12 absorption
  • People on long-term Metformin (common diabetes medication) — it significantly reduces B12 absorption
  • People with gut conditions like Crohn's disease or previous stomach surgery

The test: Ask for B12 and folate levels. Both are often tested together as they work in tandem. Levels below 200 pg/mL are generally considered deficient, though symptoms can occur even in the lower normal range.

3. Iron Deficiency — Not Just Anaemia

Most people think iron deficiency only matters when it becomes anaemia. This is one of the most common misconceptions I see clinically.

You can be significantly iron deficient — with a low ferritin level — while your haemoglobin remains completely normal. Your body will be quietly robbing iron from storage to keep your blood count looking acceptable on a basic test. Meanwhile you feel terrible and nobody can explain why.

Symptoms of iron deficiency before anaemia develops:

  • Unexplained fatigue and low energy
  • Hair thinning and increased shedding
  • Cold hands and feet — poor peripheral circulation
  • Difficulty concentrating — iron is essential for brain function
  • Restless legs syndrome at night — iron deficiency is one of the most common treatable causes
  • Pica — craving ice, chalk, or non-food substances — this is a classic but often unrecognised sign

Who is most at risk:

  • Women with heavy periods — the most common cause of iron deficiency in women worldwide
  • Pregnant women
  • Vegetarians and vegans — plant-based iron (non-haem iron) is absorbed far less efficiently than animal-based iron
  • Athletes — particularly distance runners, due to mechanical haemolysis

The critical point: Always ask for your serum ferritin specifically — not just a full blood count. Ferritin is your iron storage marker. It catches deficiency weeks to months before anaemia develops on a standard blood test. Many women walk around with ferritin levels of 8 or 10 while being told their blood test is "normal" because only haemoglobin was checked.

4. Magnesium — The Most Overlooked Mineral

Magnesium is involved in over 300 biochemical reactions in the human body. It plays a role in energy production, nerve function, muscle contraction, blood sugar regulation, blood pressure control, and the synthesis of protein and DNA.

And up to 75% of people in the developed world do not get enough of it.

Symptoms of low magnesium:

  • Anxiety and irritability — magnesium directly regulates the nervous system
  • Poor sleep quality and difficulty staying asleep
  • Muscle cramps, twitching, and spasms
  • Frequent headaches and migraines — low magnesium is one of the most well-studied migraine triggers
  • High blood pressure — magnesium relaxes blood vessel walls
  • Heart palpitations — magnesium is critical for normal cardiac rhythm
  • Constipation and gut motility issues

The reason magnesium deficiency is so widespread is that modern food processing strips magnesium from grains, our soils are increasingly magnesium-depleted, and high stress itself causes increased urinary excretion of magnesium — creating a vicious cycle where stress depletes magnesium and low magnesium worsens stress response.

The test: Serum magnesium — though it is worth noting that serum levels can appear normal even when cellular magnesium is low. Ask your doctor specifically for this test as it is not included in standard blood panels.

How to Check — Don't Guess, Test

Symptom-matching is unreliable. Many deficiencies share overlapping symptoms with each other and with dozens of other conditions. The only way to know is blood tests.

Ask your doctor for these specifically:

  • ✅ 25-OH Vitamin D — the correct test for Vitamin D status
  • ✅ B12 and folate — always test both together
  • ✅ Full blood count — screens for anaemia
  • ✅ Serum ferritin — catches iron deficiency before anaemia develops
  • ✅ Serum magnesium — less routinely tested, ask specifically

These are inexpensive, widely available tests. In the UK, your GP can request all of them. In India, any diagnostic lab can run them for a fraction of the cost of a single specialist appointment.

Food First — Always

Before you reach for supplements, build your foundation through food:

  • Vitamin D → 20 minutes of direct sunlight on skin daily + fatty fish, egg yolks, fortified foods
  • B12 → Meat, fish, dairy, eggs. If vegan - supplement is non-negotiable, not optional
  • Iron → Red meat, lentils, spinach, tofu. Always pair plant-based iron with Vitamin C to significantly improve absorption
  • Magnesium → Dark chocolate, nuts, seeds, leafy green vegetables, whole grains

Supplements fill gaps. Real food builds the foundation.

One important warning: do not self-prescribe high-dose supplements without medical supervision. Vitamin D, in particular, is fat-soluble - meaning excess amounts accumulate in the body rather than being excreted. Vitamin D toxicity is real, causes hypercalcaemia, and can be seriously harmful. More is not always better. Get your levels tested, then supplement to target — not blindly.

The Final Word

Your body is not dramatic. It does not send symptoms without reason.

Fatigue, anxiety, hair loss, brain fog, frequent illness - these are messages, not personality traits. Stop normalising them. Get your bloods done. Know your numbers.

A basic blood test panel costs very little and could explain symptoms you have been living with for years.

This blog is for educational purposes and my personal opinion only and does not constitute medical advice. Always consult a qualified healthcare professional before starting any supplementation.

Written by Dr. Hari — follow on X @Harigaran21 for daily health and wealth insights.

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