Why sunny Hua Hin still leaves people low
Your skin makes vitamin D from strong midday sun on bare skin. The catch is that almost everything we sensibly do to cope with the heat here works against that: staying indoors in air-conditioning through the hottest hours, walking early or late when the sun is weak, wearing a hat and long sleeves, and using sunscreen — which is exactly what you should do to protect your skin, but it also blocks vitamin D production.
Older skin also makes less vitamin D than young skin from the same sun, and many people over 60 spend more time indoors. Add darker skin tones, which need more sun for the same result, and it's easy to see why blood tests in tropical countries so often come back low. It is one of the genuine surprises of expat health here.
Why it matters
Vitamin D helps your body absorb calcium and keep bones strong — a real concern as we age, when a fall and a fracture can change everything. It also plays a role in muscle strength and immune function. Very low levels can cause vague, easily-missed symptoms: aches, tiredness, low mood, muscle weakness.
None of that means vitamin D is a cure-all — the supplement industry has oversold it. But keeping a genuinely low level topped up to a normal one is one of the simplest, best-evidenced things you can do, especially for bone health after 50.
Get tested, don't guess
Ask for a 25-hydroxy vitamin D (25(OH)D) blood test. Any of the Hua Hin hospitals on our Medical page can do it, usually as part of a cheap health-screen package, and you'll often get the result the same day. Testing first means you take the right amount rather than guessing — and you can re-test after a few months to check it worked.
If you can't test right away, a modest daily dose is low-risk for most adults. It's the big, untested doses that are worth avoiding.
What to take
Look for vitamin D3 (cholecalciferol) rather than D2 — it raises blood levels more effectively. It's fat-soluble, so take it with a meal that contains some fat for better absorption. Many people find a daily 1,000–2,000 IU capsule is a sensible maintenance amount; if a test shows you're genuinely deficient, a doctor may prescribe a short course of something stronger to top you up, then drop you back to a maintenance dose.
Some products pair vitamin D3 with vitamin K2, on the theory it helps direct calcium to bone — reasonable, though the evidence is still developing. Keep it simple unless your doctor suggests otherwise.