Plenty of sun, still low on vitamin D

Your skin makes vitamin D when sunlight lands on it. In theory the UAE should be the easiest place in the world to have enough. In practice, low vitamin D is one of the most common results on a blood test here, in adults and children, men and women. The reason is how we live, not how much sun there is.

Vitamin D helps your body absorb calcium and keep bones strong. It also plays a part in muscle function, the immune system and mood. Low levels are commonly linked with:

• Tiredness that does not lift with sleep
• Aching muscles and bones, or slow recovery from training
• Low mood, especially through long stretches indoors
• Picking up colds and infections more often
• Hair shedding
• Lower bone density over the long term

None of these is specific to vitamin D. Plenty of people with low levels feel fine, and plenty of tired people have normal levels. That is the reason to test rather than guess.

The test you want is 25-OH vitamin D, sometimes written 25-hydroxyvitamin D. It shows how much vitamin D is stored in your body over the past few weeks.

Labs report it in one of two units. To convert ng/mL into nmol/L, multiply by 2.5. The lines most guidelines use are:

• Under 20 ng/mL (50 nmol/L): usually treated as deficient.
• 20-29 ng/mL (50-74 nmol/L): often called insufficient.
• 30 ng/mL (75 nmol/L) and above: the usual line for sufficiency.

Reference ranges vary by lab, and some print anything over 20 as normal. So check the units, then check the number against the 30 ng/mL line, not just the word next to it.

A single result tells you where you are today. It does not tell you whether what you change is working. Vitamin D levels move slowly, over weeks to months, so a retest after around three months is what shows whether the level is actually rising.

The second test also catches the opposite problem. Vitamin D is stored in the body, and very high levels are possible if someone takes too much for too long. Any plan to raise your level is best agreed with your own doctor or a consultant who can see your result, and checked with a retest.

Season matters too. Levels are often lowest at the end of summer here, when people spend the most time indoors. If you retest, try to keep the timing similar.

If you are booking a test through your own doctor or a lab, ask for:

• 25-OH vitamin D, with the units printed on the report
• Magnesium, which your body needs to use vitamin D
• The rest of the vitamins and minerals, such as B12 and folate, since low levels often come in groups

Or do it at home. Baseline’s blood screen includes all of these, among 122 parameters across ten systems, from one draw at home with results in 48 hours. A consultant then goes through every result with you on video, and you can retest later to see what has changed.

See everything the screen covers

This page is general information, not a diagnosis. If you have bone pain, muscle weakness or symptoms that are new or getting worse, speak to a doctor.