Vitamin D deficiency: Symptoms to watch out for

Written and medically reviewed by Arnaud, a Doctor of Pharmacy and owner of the Soin et Nature Pharmacy.

Vitamin D deficiency refers to a lack of 25-hydroxyvitamin D in the blood, often below 30 ng/mL. Very common in France, it directly affects the immune system, vitality, hormones and metabolism. In our pharmacy, we find that many patients are living with a deficiency without realising it.

What are the symptoms of a vitamin D deficiency?

The signs of a vitamin D deficiency are often vague and difficult to identify. However, certain symptoms should raise a red flag:

Persistent chronic fatigue
Muscle pain and weakness
Frequent infections
Low mood or mood disorders

If you are experiencing unexplained fatigue, read our comprehensive analysis:
vitamin D and chronic fatigue.

Why are we all deficient today?

Modern lifestyles severely limit natural synthesis:

Indoor work
Lack of sun exposure
Use of sunscreen

To understand the role of the sun, read our article:
Vitamin D: sun or supplements.

What impact does this have on hormones and metabolism?

A vitamin D deficiency is not limited to fatigue. It can also lead to:

Thyroid dysfunction
Reduced libido
Weight gain

For more information, see our article:
vitamin D and hormones.

How can you tell if your levels are too low?

Diagnosis is based on a blood test measuring 25(OH)D. If in doubt, this test is essential.

Interpreting vitamin D levels
Level	Interpretation
< 20 ng/mL	Deficiency
20–30 ng/mL	Deficiency
30–60 ng/mL	Optimal

How can a vitamin D deficiency be corrected?

Several strategies are possible:

Regular exposure to sunlight
Appropriate diet
Targeted supplementation

In most cases, supplementation is necessary. Discover our selection of
vitamin D supplements.

To avoid common mistakes, consult our guide:
vitamin D supplementation.

Should you take supplements all year round?

Supplementation is often necessary in winter or in cases of deficiency. It must be tailored to each individual’s needs.

For a comprehensive overview, consult our complete guide:
vitamin D: complete guide.

Frequently asked questions about vitamin D deficiency

What are the first signs of a deficiency?

Fatigue, muscle pain and frequent infections.

Is vitamin D deficiency common?

Yes, it affects a large proportion of the population.

Can a deficiency be corrected quickly?

Yes, with appropriate supplementation.

Does vitamin D help with fatigue?

Yes, it plays a key role in energy levels.

Should you consult a doctor before taking supplements?

Yes, especially if you have any doubts or an underlying medical condition.