Vitamin Deficiency
Vitamin and mineral deficiencies — particularly vitamin D, B12, and iron — are extremely common among expats in southern Europe and can cause fatigue, low mood, hair loss, and impaired immunity that is often attributed to other causes. A simple blood test identifies what is low so it can be corrected, often with a rapid and dramatic improvement in how you feel.
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This page provides general health information only. Do not self-treat with high-dose supplements without blood tests — excess of some vitamins can cause harm.
Vitamin D deficiency
Paradoxically, vitamin D deficiency is extremely common among expats in Portugal and Spain — despite abundant sunshine. Many people avoid sun exposure for skin protection, work indoors, or have darker skin with reduced UV synthesis. Vitamin D is essential for bone health, immune function, mood, muscle strength, and cardiovascular health.
- Symptoms — fatigue, bone pain, muscle weakness, low mood, and frequent infections
- Diagnosis — 25-OH vitamin D blood test
- Treatment — high-dose loading supplementation (typically 50,000 IU weekly for 8–12 weeks), followed by daily maintenance supplementation
Vitamin B12 deficiency
B12 is essential for nerve function, red blood cell production, and DNA synthesis. Deficiency develops slowly — often over years — and can cause irreversible neurological damage if not treated. It is particularly common in vegetarians and vegans, older adults, and those on metformin or proton pump inhibitors.
- Symptoms — fatigue, tingling and numbness in hands and feet, cognitive difficulties, low mood, glossitis (sore red tongue), and megaloblastic anaemia
- Diagnosis — serum B12, full blood count, and sometimes methylmalonic acid or homocysteine levels
- Treatment — B12 injections (hydroxocobalamin) for deficiency with neurological features; oral high-dose B12 for dietary deficiency without neurological symptoms
Iron deficiency
Iron deficiency is the most common nutritional deficiency worldwide and a very frequent cause of fatigue and brain fog — often before anaemia develops. See the dedicated Iron Deficiency page for full details.
Other common deficiencies
- Magnesium — common in people with poor diet, alcohol excess, or diabetes; causes muscle cramps, fatigue, and sleep disturbance
- Folate (B9) — essential in pregnancy; deficiency causes megaloblastic anaemia and neural tube defects
- Zinc — supports immune function and wound healing; deficiency common in restrictive diets
- Iodine — essential for thyroid function; increasingly common deficiency in Europe
- Vitamin K2 — often overlooked; important for bone and cardiovascular health alongside vitamin D
When to get tested
If you have persistent unexplained fatigue, low mood, brain fog, or muscle weakness, a comprehensive blood panel including vitamin D, B12, iron studies, full blood count, and thyroid function is an excellent first step. Many people find answers they have been looking for for years with a single set of blood tests.
Expats who have recently moved to Portugal or Spain often benefit from a baseline health check — including vitamin levels — as part of establishing care with a new doctor. eMedClinic can coordinate all of this in a single consultation.
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How eMedClinic can help
Our doctors arrange comprehensive nutritional blood panels, interpret results in the context of your symptoms and lifestyle, prescribe appropriate supplementation (including prescription-strength vitamin D and B12 injections), and monitor levels to ensure they return to optimal range. We take unexplained fatigue and brain fog seriously and look for all treatable causes.
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