Vitamin D for women in Singapore: why many are low despite the sun

In short

• Vitamin D helps your body use calcium and phosphate, which keep bones, teeth and muscles healthy.
• Singapore is sunny, but many people here are still low in vitamin D, mostly because we spend our days indoors, in the shade or under sunscreen.
• Try these in order: a little safe sun, vitamin D-rich foods, a blood test if you are unsure, and then a supplement if your doctor or dietitian agrees.

What vitamin D does

Vitamin D helps your body absorb calcium and phosphate, which bones, teeth and muscles need. Over a long time, being low in vitamin D is linked to weaker bones and muscles in adults. Your skin makes vitamin D when sunlight reaches it, and you also get a little from food.

Why people here can be low

It surprises many people that a country on the equator has a vitamin D problem. The reasons doctors and dietitians give are everyday ones:

• We work indoors, in air-conditioning, and avoid the midday heat.
• We use umbrellas, sunscreen, hats and long sleeves, which is good for protecting skin but also blocks the sunlight that makes vitamin D.
• Darker skin makes vitamin D more slowly from the same sunlight.
• Skin makes less vitamin D as we get older.

How common is it? A 2024 study of 93 women in early pregnancy at KK Women's and Children's Hospital found only about 2% had enough vitamin D, and about half were below the level doctors use as "sufficient". That is one hospital and one group, so it does not describe every woman, but it shows low levels are not rare. A 2010 National Health Survey figure often quoted by Singapore health sites put about 40% of Singaporeans as deficient. NUHS+ also reports a 2019 study in which nearly one in three indoor workers in Singapore was deficient. Different studies use different cut-offs, so treat these as a rough picture, not an exact rate.

Step one: a little safe sun

Singapore health writers suggest roughly 10 to 30 minutes of sun on your arms and legs most days, ideally before 10am or after 3pm to limit UV. Sun protection still matters for your skin, so do not stay out longer to "make more". If you burn easily, have had skin cancer or have been told to avoid the sun, ask your doctor.

Step two: food

Few foods are rich in vitamin D, which is why food alone can be hard:

• Oily fish: salmon, tuna, mackerel and sardines are the best sources. About 85 g of salmon has roughly 11 micrograms.
• Egg yolks: about 1 microgram per egg.
• Fortified foods: some breakfast cereals, milks and plant milks, and spreads. Check the label.

Step three: a blood test

Being a little low often causes no symptoms, so the only way to know is a blood test, ordered by your doctor. The result also helps your doctor suggest how much to take, if anything.

Step four: a supplement, if you need one

A supplement can help if you cannot get enough from sun and food. Check with your doctor or dietitian first, especially if you are pregnant or breastfeeding, take regular medication, or have a kidney, liver or bowel condition.

How much? Advice differs by country and by person. The UK's NHS suggests 10 micrograms (400 IU) a day for adults. Singapore dietitians quoted by NUHS+ suggest 400 to 800 IU a day for adults under 65 who get little sun. The NHS says not to take more than 100 micrograms (4,000 IU) a day, because too much vitamin D can build up calcium in the blood and harm the kidneys and heart. If you already take a multivitamin, add its vitamin D to your total.

Who should ask a doctor first

• Anyone who is pregnant or breastfeeding
• Anyone with a kidney, liver, bowel or calcium-related condition
• Anyone who takes regular medication, including calcium or heart medicines
• Anyone who has been told to avoid the sun

Vitamin D supports bone and muscle health. It is not a treatment for any condition, and it works best alongside strength exercise and enough protein, as the guide to strength after 40 explains.