A GP’s field guide for families who “already get plenty of sun”
When a woman in my Jeddah clinic says the line which I hear in three different countries, in three different accents:
“But Doctor, we have so much sun here ….” but her blood test says otherwise.
I hear the same disbelief from a mother in Lahore, whose son studies indoors all afternoon and plays on his phone after Evening (Maghrib).
I already hear a version of it from families preparing to move, quietly assuming that “we’re used to heat” will carry them through a Dublin January.
None of them are wrong to be surprised. They live under bright skies. Their vitamin D is still running on empty.
That gap … between the sun outside and the sun that actually reaches skin … is what this guide is about.
The paradox, in numbers …
Sunshine does not automatically mean sufficiency. It means opportunity, and modern life is very good at wasting it.
In Saudi Arabia, large hospital-based studies still find roughly half of people tested are deficient, with women affected slightly more than men … despite a climate that is sunny almost every day of the year.
Among Saudi children and teenagers, inadequate levels have been the norm rather than the exception in several studies.
Pakistan & South Asia tell a similar story with relatively less public awareness.
The National Nutrition Survey found vitamin D deficiency in roughly six in ten young children and around eight in ten women of reproductive age … and, tellingly, urban and wealthier households were not protected.
Indoor routines and covered skin cut across income and education levels.
Ireland does not hide its problem at all. From roughly Halloween to St Patrick’s Day, the sun sits too low in the sky to trigger vitamin D production in skin, no matter how clear the day looks.
Irish health authorities treat a winter supplement as ordinary life, not a special intervention … and for people with darker skin, they recommend taking it all year round.
Three very different climates. One shared cause: skin that never actually meets UVB light.
What vitamin D is actually doing for us
The internet has turned vitamin D into a cure for almost everything, and the solid evidence is narrower than that.
Vitamin D helps our gut absorb calcium, which our bones and muscles then use to grow and repair.
Severe, long-standing deficiency in children can cause rickets … soft, bowed bones and delayed walking.
In adults it can cause osteomalacia: bone pain, weak thighs and shoulders, and a higher risk of falls and fractures later in life.
It is also relevant in pregnancy, where low levels are common in South Asian and Arab women and worth correcting properly rather than guessing.
What it is not: a guaranteed fix for every infection, every low mood, or every flat Sunday.
Treat it as bone-and-muscle insurance with a few possible extras … that is the honest picture.
Why the AC, the abaya and the office all work against us …
Our skin needs direct ultraviolet B (UVB) light to make vitamin D.
Ordinary window glass blocks almost all of it … so a sunlit office, a car ride, or a seat by a bright window feels warm but makes essentially no vitamin D at all.
Layer modern routines on top of that:
- Heat-driven indoor living. In Jeddah’s peak summer, people move from air-conditioned home to air-conditioned car to air-conditioned mall, sprinting through the few minutes of actual outdoor exposure.
- Modest dress. Hijab and abaya are not an illness. The medical fact is only this: less skin in the light means less vitamin D from the sky. Face and hands alone are usually not enough.
- Darker skin. More melanin means more time is needed in the same sunlight to make the same amount of vitamin D.
- Sunscreen and shade. Both are good for skin-cancer prevention. Both further reduce UVB … a reason to supplement, not a reason to skip sun protection.
- A quiet awareness gap. In parts of Pakistan, many parents cannot name sunlight as the main source of vitamin D at all. “He drinks milk, he’s fine” is common and often false: unfortified milk is mostly a calcium source, not a vitamin D one.
Who should assume they are at risk …
Think household by household, not just by passport:
- Children and teens who rarely play outdoors, or who are fully covered at school
- Women who dress modestly outside the home, work indoors, or are pregnant or breastfeeding
- Anyone with noticeably darker skin living through a northern winter
- Adults over 65, housebound people, and anyone with coeliac disease, inflammatory bowel disease, kidney or liver disease, or a history of bariatric surgery
- Anyone on long-term steroids or certain anti-seizure medicines
- Families relocating from the Gulf or South Asia to Ireland or the UK …. you bring darker skin and covered clothing into a winter that already catches out fair-skinned locals
Do you actually need a blood test?
Usually, no. Healthy people who simply live indoors, dress modestly, or face an Irish winter can start a standard preventive dose without a lab visit first … that is official guidance in Ireland, and it matches how many of us already practise in the Gulf.
A blood test (serum 25-hydroxyvitamin D) earns its place when there is persistent bone pain, real muscle weakness, a suspected case of rickets in a child, unexplained fractures, or a medical condition that affects absorption.
If you are tested, ask which unit was used … labs report in either nmol/L or ng/mL (roughly, ng/mL × 2.5 = nmol/L).
Thresholds vary slightly between guidelines, so let your own clinician interpret the number rather than a WhatsApp group.
The actual plan ….
1. Safe sun, when the weather allows it
In Jeddah and much of Pakistan, short spells on arms and legs still help if clothing and heat allow it.
Early morning or late afternoon is kinder to skin. Midday makes vitamin D faster. It also burns faster.
In Ireland, April to September is the only reliable window for skin-made vitamin D. From October to March, a sunny lunch break will not do the job.
Never chase a burn. That is an injury, not a treatment. Never put a baby in strong direct sun to “make vitamin D.” Do not use a tanning bed.
2. Food, as backup, not the main plan
Helpful foods: oily fish (salmon, sardines, mackerel), egg yolks, and milk, yoghurt or cereal that is labelled fortified.
Read the label. Ordinary fresh milk in most Gulf and Pakistani kitchens is not fortified. It is mainly calcium, not vitamin D. Everyday mushrooms do little unless they were treated with UV light.
Food helps. For an indoor or covered week, or an Irish winter, food alone is usually not enough.
3. A daily supplement — the unglamorous fix
Vitamin D is written as micrograms (µg) or international units (IU).
1 µg = 40 IU.
So 5 µg = 200 IU, 10 µg = 400 IU, and 15 µg = 600 IU.
Read the dropper. Brands differ. Count drops, multivitamins, “bone” tablets and cod-liver oil together so you do not stack them by accident.
These are prevention doses from Irish public guidance (HSE / Department of Health / FSAI). They are not a treatment course for a very low blood test.
- Baby 0–12 months, breastfed or formula under 300 ml a day: 200 IU (5 µg), all year
- Age 1–4: 200 IU (5 µg) from Halloween to St Patrick’s Day; all year if darker skin or little sun
- Age 5–12: 400 IU (10 µg) in winter; all year if darker skin or little sun
- Age 13–64: 600 IU (15 µg) in winter; all year if darker skin, covered clothing, indoor life, or pregnancy
- Age 65+: 600 IU (15 µg), all year
If a doctor has already given a loading course for confirmed deficiency, finish that first.
UK NHS often uses 400 IU for many adults in winter. US infant drops are often 400 IU. Ireland’s baby dose is 200 IU. Do not mix three countries on one shelf. In Jeddah or Pakistan, follow local child or adult guidance.
Vitamin D3 is the usual first choice. Many capsules come from lanolin (sheep wool). If you need a plant-based option, ask a pharmacist for D2 or lichen D3.
More is not better
I still see patients who have bought … or been given … large weekly or “one-shot” high-dose vitamin D, hoping to solve the problem in a single go.
That decision belongs with a clinician who has seen the bloods, the kidneys and the calcium level, not a pharmacy shelf or a relative’s leftover box.
Too much vitamin D raises blood calcium, and can cause nausea, excessive thirst, frequent urination, kidney strain, and in severe cases real harm.
Ask before high doses if there is kidney disease or stones, high calcium, hyperparathyroidism, sarcoidosis, malabsorption, or use of thiazide water tablets.
Irish public guidance lists these safety ceilings from all supplement sources combined …. ceilings, not targets:
- Babies under 1 year: 25 µg (1,000 IU) a day
- Children aged 1–10: 50 µg (2,000 IU) a day
- Age 11 and over: 100 µg (4,000 IU) a day
Keep adult high-dose capsules away from small children. And vitamin D without calcium is a key without a lock: a normal mixed diet with dairy or fortified alternatives usually covers the calcium side without extra tablets.
Signs worth a clinic visit
Vitamin D deficiency can be silent. Tiredness alone does not prove it.
See a doctor if a child is not walking when expected, has visibly bowed legs or knock-knees, swollen wrists, unexplained bone pain, poor growth, or a soft spot that is slow to close.
Seizures, muscle spasms or breathing difficulty in a child are urgent, as severe low calcium can be dangerous.
In adults, persistent bone pain in the back, ribs, pelvis or legs, difficulty rising from a low chair without using your hands, repeated falls, or a fracture after a minor knock are all worth checking.
Confusion, vomiting or severe thirst after starting a high-dose supplement can signal high calcium and needs prompt attention.
The one sentence to remember
Sunlight is a gift, not a lab result. An abaya in Jeddah, a study timetable in Lahore, and an Irish November are three very different kinds of weather … but they can all leave skin never actually meeting UVB.
A small daily supplement, a little outdoor time when it is safe, and food that genuinely contains vitamin D is the whole plan. It is not dramatic. It works.
About the author:
Dr Mohaisin Sharif is a General Practitioner with over five years of full-time independent practice across Pakistan and Saudi Arabia. He is registered with the Irish Medical Council, SCFHS and PMDC, and is preparing to bring that experience into Irish general practice. He is a father of three. This piece is written from clinic rooms in which families kept saying, “But we have sun.”
Disclaimer:
This article is for general health education only. It is not medical advice, diagnosis or treatment, and does not replace a consultation with your own doctor, midwife, pharmacist or paediatrician. Supplement doses above standard prevention, injections, and treatment of confirmed deficiency should be decided by a clinician who knows your history and blood results. Confirm infant drops with a local pharmacist — concentrated brands differ per drop. Seek urgent medical care for seizures, muscle spasms, severe weakness, breathing difficulty, or a child who is seriously unwell.
References
- Al-Otaibi T, et al. Prevalence and trends of vitamin D deficiency among patients undergoing testing at the Maternity and Children Hospital, Dammam, Eastern Province of Saudi Arabia (2023–2025). Frontiers in Public Health.
- Al-Ghamdi S, et al. Vitamin D deficiency in children and adolescents in Saudi Arabia: a systematic review. Cureus.
- UNICEF / Government of Pakistan. National Nutrition Survey 2018 — vitamin D in children and women of reproductive age.
- Khan GN, et al. High prevalence of vitamin D deficiency among women of reproductive age and children 6–59 months in Pakistan. Current Developments in Nutrition, 2025.
- Mahar B, et al. Vitamin D deficiency prevalence in Pakistan: a comprehensive meta-analysis. Journal of Diabetology. 2024;15(4):335–348.
- Health Service Executive (Ireland). Vitamin D — who should take a supplement, how much, and upper limits. hse.ie
- Food Safety Authority of Ireland / Department of Health. Vitamin D recommendations for people living in Ireland.
- NICE Clinical Knowledge Summaries. Vitamin D deficiency in adults.
- NHS. Vitamins and minerals — Vitamin D.
- Endocrine Society. Vitamin D for the prevention of disease: clinical practice guideline, 2024.
- Royal Osteoporosis Society. Vitamin D and bone health in adults.