Vitamin D deficiency: signs, causes and how to check
Vitamin D is the vitamin your skin makes from sunlight, and the one modern indoor life most reliably runs short of. Low vitamin D is common worldwide โ including in sunny countries like Lebanon, where time outdoors doesn't always match the sunshine. Here's how it works, what low levels can feel like, and how to find out for sure.
What vitamin D does
Vitamin D's best-understood job is helping your gut absorb calcium, which is why it matters so much for bones and teeth. It also plays a role in muscle function and supports the normal working of the immune system.
Your body makes it when skin is exposed to direct sunlight, and you get smaller amounts from foods like oily fish and egg yolks. Because few foods carry much of it, sunlight habits largely decide your level.
Signs that can go with low vitamin D
Low vitamin D is often silent. When people do notice something, the common threads are tiredness that doesn't track with sleep, aching bones or lower back, muscle weakness or cramps, and low mood โ especially through winter.
None of these signs is specific to vitamin D โ each has many possible causes. That's exactly why guessing doesn't work and testing does: a simple 25(OH)D blood test, available at any Lebanese lab, tells you your actual level.
Who tends to run low
Levels tend to be lower in people who spend most of the day indoors, cover most of their skin outdoors, use sunscreen consistently, have darker skin (which makes vitamin D more slowly), are over 65, or carry extra body weight โ vitamin D is fat-soluble, so it gets stored where blood tests can't see it.
If several of those describe you, it's reasonable to ask your doctor about testing even without symptoms.
Food, sun and supplements
Regular short stretches of midday sun on bare arms go a long way, and oily fish (sardines, salmon, tuna) helps. When sun and food aren't enough โ which testing will show โ a vitamin D3 supplement is the standard way to bring levels up, because D3 is the same form your skin makes.
Common daily supplement doses run from 600โ2000 IU for maintenance, with higher short-term doses used under medical guidance when a deficiency is confirmed. D3 is fat-soluble, so take it with a meal. If you're correcting a confirmed deficiency, your doctor will set the dose and re-test โ more is not automatically better.
D3 with K2
Some formulas pair D3 with vitamin K2. K2 contributes to normal blood clotting and to the maintenance of normal bones, and the pairing is popular with people taking higher D3 doses. If you take blood-thinning medication, talk to your doctor before adding K2 โ vitamin K interacts with those medicines.
Food supplements are not medicines and do not treat or cure disease. Speak to your doctor or pharmacist if you are pregnant, nursing, on medication, or unsure what's right for you.
