Vitamin D, Iron and Vitamin B12 Deficiencies: Recognising the Signs

Feeling constantly tired, struggling to concentrate or noticing changes in your mood can have many possible causes. Sometimes, these symptoms may be linked to a vitamin or mineral deficiency.

Vitamin D, iron and vitamin B12 deficiencies are among the most common nutritional deficiencies seen in adults. While they can often be treated successfully, they should be diagnosed by a healthcare professional, as symptoms can overlap with many other health conditions.

Vitamin D deficiency

Vitamin D plays an important role in maintaining healthy bones, muscles and the immune system. It also helps the body absorb calcium.

In the UK, vitamin D is mainly produced when the skin is exposed to sunlight, which means levels often fall during the autumn and winter months.

Common symptoms may include:

• Tiredness or fatigue.
• Muscle weakness.
• Bone or joint pain.
• Frequent infections.
• Low mood.

Some people have no symptoms at all and only discover they are deficient following a blood test.

Who may be at greater risk?

Vitamin D deficiency is more common in people who:

• Spend little time outdoors.
• Cover most of their skin when outside.
• Have darker skin tones.
• Are older adults.
• Are pregnant or breastfeeding.
• Have certain medical conditions affecting nutrient absorption.

The UK Government recommends that many people consider taking a daily vitamin D supplement during the autumn and winter months, with some groups advised to take supplements all year round.

Iron deficiency

Iron is essential for making haemoglobin, the protein in red blood cells that carries oxygen around the body.

Without enough iron, the body may develop iron deficiency, which can progress to iron deficiency anaemia if left untreated.

Symptoms may include:

• Persistent tiredness.
• Weakness.
• Shortness of breath.
• Pale skin.
• Dizziness.
• Headaches.
• Cold hands and feet.
• Brittle nails.

Women who have heavy menstrual periods are at increased risk of iron deficiency because of ongoing blood loss.

Possible causes include:

• Heavy menstrual bleeding.
• Pregnancy.
• Poor dietary intake.
• Certain digestive conditions.
• Blood loss from other causes.

Treatment depends on identifying and addressing the underlying cause.

Vitamin B12 deficiency

Vitamin B12 is needed for healthy nerve function, red blood cell production and DNA synthesis.

Because the body stores vitamin B12, deficiency may develop slowly over several months or even years.

Symptoms may include:

• Fatigue.
• Memory problems or “brain fog.”
• Difficulty concentrating.
• Tingling or numbness in the hands and feet.
• Balance problems.
• Mood changes.
• A sore tongue.

If left untreated, vitamin B12 deficiency can sometimes cause permanent nerve damage, making early diagnosis particularly important.

Who is at greater risk?

Vitamin B12 deficiency may be more common in people who:

• Follow a strict vegan diet without supplementation.
• Have certain stomach or bowel conditions.
• Have had stomach surgery.
• Take some long-term medications that affect vitamin B12 absorption.
• Are older adults.

Many symptoms overlap

One of the challenges with vitamin and mineral deficiencies is that symptoms are often non-specific.

Fatigue, poor concentration and low mood may be caused by:

• Nutritional deficiencies.
• Thyroid disorders.
• Sleep problems.
• Stress.
• Menopause.
• Mental health conditions.
• Other medical conditions.

This is why it is important not to self-diagnose.

When should you seek medical advice?

Speak to your GP or another healthcare professional if you experience:

• Persistent or unexplained tiredness.
• Ongoing fatigue despite adequate rest.
• Breathlessness.
• Dizziness.
• Tingling or numbness.
• Memory problems.
• Symptoms that interfere with your daily life.

Your healthcare professional may recommend blood tests to identify whether a deficiency is present and determine the most appropriate treatment.

Should you take supplements?

Although supplements are widely available, they are not always necessary.

Taking high doses of certain vitamins or minerals without medical advice can sometimes be harmful or delay the diagnosis of an underlying condition.

It is generally best to seek professional advice before starting supplements, particularly if symptoms are persistent or severe.

Looking after your health

Eating a varied, balanced diet, spending time outdoors safely and attending routine health checks can all help support your overall wellbeing.

If you have ongoing symptoms such as fatigue, brain fog or weakness, don’t assume they are simply part of a busy lifestyle or getting older. Identifying and treating an underlying deficiency can make a significant difference to your health and quality of life.

Medical Disclaimer

This article is intended for general information only and should not be considered medical advice. It should not be used to diagnose or treat any medical condition. If you think you may have a vitamin or mineral deficiency, speak to your GP or another qualified healthcare professional. Do not start high-dose supplements without appropriate medical advice, particularly if you have ongoing symptoms or underlying health conditions. If you experience severe symptoms such as chest pain, difficulty breathing, collapse or significant neurological changes, seek immediate medical attention.

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