Sun and vitamin D: how to get enough without harming your skin

Why vitamin D is low in the world's sunniest region

It sounds like a contradiction: the Middle East is bathed in sunshine for most of the year, yet vitamin D deficiency is widespread across the region. A 2015 review published in the South African Medical Journal found deficiency and insufficiency affecting large proportions of the population in Africa and the Middle East despite year-round sunny days. A 2016 study of Arab children and adults by Al-Daghri and colleagues found that sun exposure patterns and skin tone were key drivers of vitamin D status.

The sun is not the problem. The way people interact with it is. Modest and full-coverage clothing, air-conditioned offices and car-dependent lifestyles all mean that skin rarely encounters the specific rays that trigger vitamin D production. Going outdoors in the early morning or late afternoon, which is the natural preference when avoiding midday heat, also reduces vitamin D synthesis because the UV angle is unfavourable.

Glass blocks UVB rays almost completely. Sitting by a window, driving in a car with a glass roof, or working near a sunlit wall provides no vitamin D benefit. Only direct outdoor exposure counts.

Darker skin tones require longer exposure times to produce the same amount of vitamin D as lighter skin, because melanin acts as a natural UV filter. This means that many people in the region face a double disadvantage: cultural or climate-driven avoidance of midday sun, combined with a skin tone that needs more of it.

How sunlight makes vitamin D in your body

Vitamin D is less a vitamin and more a hormone that your body manufactures when UVB rays hit bare skin. A compound in the skin called 7-dehydrocholesterol absorbs UVB energy and converts to pre-vitamin D3. This travels to the liver where it becomes 25-hydroxyvitamin D (the form measured in blood tests), and then to the kidneys where it is converted to the active hormone. As Wacker and Holick described in a 2013 review in Dermato-endocrinology, this pathway requires adequate UVB intensity, which is only present during certain hours of the day.

UVB has a wavelength of 290 to 315 nanometres. When the sun is low in the sky, these rays travel a longer path through the atmosphere and are largely absorbed by the ozone layer before reaching skin. This is why the effective window for vitamin D production is roughly between 10 am and 3 pm across most of the Middle East. Outdoor time at dawn or dusk, while pleasant and thermally sensible, does little for vitamin D.

The implications matter for daily planning. A walk at 7 am is excellent for well-being and cardiovascular health, but it does not substitute for the midday exposure needed for vitamin D synthesis.

How much sun do you actually need?

There is no single answer because the time required varies with skin tone, body weight, latitude, season, and how much skin is exposed. In most of the Middle East during warm months, exposing the arms and legs (or arms and face) to midday sun for 10 to 20 minutes most days is adequate for lighter-skinned people. Darker skin tones typically need 20 to 30 minutes for equivalent production, because melanin filters the same UVB that drives synthesis.

In winter or at higher latitudes such as northern Syria, Lebanon, or North Africa above the 35th parallel, UVB intensity drops significantly even on a clear day, and longer outdoor exposure may produce very little vitamin D. The practical threshold is when the UV Index falls below 3, which for most of the region happens in December and January at higher latitudes.

The amount of skin exposed matters enormously. Sitting in the sun for an hour in full clothing with only your face uncovered will produce very little vitamin D. The forearms and lower legs offer the most practical and socially accessible surface area. After your brief intentional exposure, covering up or applying sunscreen for the rest of your time outdoors is the correct approach to managing both need and risk.

Body weight also plays a role. Vitamin D is fat-soluble and distributes into adipose tissue. Two people with identical sun exposure can have different blood levels if one carries significantly more body fat. People with higher body weight often need higher supplement doses to reach the same circulating level, which is another reason that testing matters more than estimating.

Does sunscreen or covered clothing cause deficiency?

Applied before sun exposure, sunscreen significantly reduces UVB penetration and therefore vitamin D synthesis. Clothing covers completely. This is the mechanism behind the high deficiency rates in covered populations. But the answer is not to abandon sun protection.

The practical solution is sequencing: allow 10 to 15 minutes of unprotected midday exposure on bare skin, then apply sunscreen if you plan to stay outdoors. That brief window is enough for your skin to initiate synthesis without accumulating meaningful UV damage on that occasion.

Women who wear full-coverage garments are likely to need a daily vitamin D supplement. A 2024 systematic review in Cureus found high rates of deficiency among children in Saudi Arabia, and covering clothing was among the identified risk factors. For adults in covered clothing, checking a blood level and discussing a supplement dose with a doctor is sensible rather than guessing.

Do not take high-dose vitamin D supplements based on a friend's recommendation or social media advice. Vitamin D is fat-soluble and accumulates. Excess causes hypercalcaemia, with symptoms including nausea, fatigue and kidney damage. Test first, then dose.

The real risks of too much sun

Sun exposure is not a free medicine without a cost. UVA and UVB rays accumulate damage in skin over years and are the primary cause of premature skin ageing and skin cancer. The World Health Organization classifies ultraviolet radiation as a Group 1 carcinogen, meaning the evidence for a causal link to cancer is strong and consistent.

Repeated sunburn, even mild reddening that fades after a day, is cumulatively harmful and raises the lifetime risk of melanoma and non-melanoma skin cancers. Darker skin offers more natural protection because melanin absorbs UV, but it does not eliminate the risk. People of all skin tones develop skin cancer, and in darker-skinned people it tends to be diagnosed at a more advanced stage because doctors and patients may not look for it as readily.

Photoageing is separate from chronological ageing. The deep facial creases, irregular pigmentation and leathery texture seen in older farmers and outdoor workers are primarily caused by decades of UV exposure rather than age itself. Consistent use of sunscreen from early adulthood significantly reduces this accumulation.

Heat exhaustion and heat stroke are dangers completely independent of UV damage. During Gulf summers, when air temperature exceeds 45 degrees Celsius and humidity is high, midday outdoor exposure risks life-threatening overheating. In those conditions, staying indoors and using supplements is not a concession but the correct clinical choice.

Regional realities: heat, clothing and habits

In Gulf summers where temperatures exceed 45 degrees Celsius and humidity is high, midday sun exposure is a heat hazard in its own right and should be avoided. For these months, a vitamin D supplement is more sensible than seeking UV exposure at personal risk. Check a blood level, get a dose recommendation from a doctor, and reserve outdoor activity for very early morning or after sunset when it is thermally safe even if UV output is low.

In the cooler months, a late-morning walk with forearms exposed is both thermally comfortable and productive for vitamin D. Some traditional habits inadvertently support vitamin D status: sitting in a walled courtyard in the morning, children playing in a garden or schoolyard, men taking tea on an outdoor step. These real-world exposures count and should not be dismissed as too informal.

Children deserve particular attention because their current lifestyle patterns work against vitamin D production at every point. School hours are spent indoors, the journey to school is usually by car or bus, afternoon leisure is increasingly indoor and screen-based. A 2024 systematic review in Cureus found deficiency affecting a significant proportion of Saudi children and adolescents. If your child's paediatrician has not mentioned vitamin D, it is a reasonable question to raise at the next visit.

Outdoor workers in construction, agriculture and delivery often have adequate vitamin D from occupational exposure, but they accumulate the highest UV dose and are at greatest risk of long-term skin damage. If you work outdoors, you likely do not need more sun for vitamin D, but you do need consistent sunscreen use, protective clothing and a hat during prolonged shifts.

Older adults are a third high-risk group. The skin's capacity to synthesise vitamin D from UV declines with age, and mobility limitations mean that many elderly people in the region rarely go outdoors. For them, a daily supplement is not optional but a genuine nutritional necessity.

Food sources and when supplements are necessary

The traditional Arab diet contains few rich vitamin D sources. Fatty fish (salmon, sardines, tuna) are the best food sources, followed by egg yolk and fortified dairy products. Even a diet that includes these regularly is unlikely to provide enough vitamin D if sun exposure is limited, because food typically contributes a small fraction of what skin can produce.

Supplements are appropriate for many people in the region: women with covered clothing, elderly people who go out rarely, children, and those with largely indoor occupations. The correct dose depends on your baseline blood level. A result below 20 ng/mL (50 nmol/L) suggests deficiency needing a therapeutic dose; a result between 20 and 30 ng/mL suggests insufficiency. Above 30 ng/mL is adequate for most people.

The standard supplement form is cholecalciferol, also written as vitamin D3. It is available over the counter across the region without a prescription, which makes unsupervised high-dose use a real risk. Taking 10,000 IU or more per day without monitoring can cause toxicity. Typical daily maintenance doses are in the range of 1,000 to 2,000 IU for adults, but the right dose for you is a number only your blood result can guide.

A practical daily plan

Balancing vitamin D production and skin protection is not complicated once you understand the mechanism. The goal is not choosing between sun and shade, but managing when and how you expose skin.

In cool or mild weather, plan a 10 to 20 minute midday walk or sit in the sun with forearms or lower legs exposed before applying sunscreen. In summer heat, use supplements and exercise outdoors only in early morning or evening. Check your blood level at least once, and ask a doctor whether you need a supplement and at what dose.

Watch your skin. In a region where sun exposure is high and dermatology access can be limited, self-examination matters. Any changing mole, non-healing sore, or new growth should be shown to a doctor.

Sources

• Green RJ, Samy G, Miqdady MS et al: Vitamin D deficiency and insufficiency in Africa and the Middle East, despite year-round sunny days, South African medical journal, 2015
• Al-Daghri NM, Al-Saleh Y, Khan N et al: Sun exposure, skin color and vitamin D status in Arab children and adults, The Journal of steroid biochemistry and molecular biology, 2016
• Al-Daghri NM: Vitamin D in Saudi Arabia: Prevalence, distribution and disease associations, The Journal of steroid biochemistry and molecular biology, 2018
• Wacker M, Holick MF: Sunlight and Vitamin D: A global perspective for health, Dermato-endocrinology, 2013
• Holick MF: Biological Effects of Sunlight, Ultraviolet Radiation, Visible Light, Infrared Radiation and Vitamin D for Health, Anticancer research, 2016
• Alhamed MS, Alharbi F, Al Joher A et al: Vitamin D Deficiency in Children and Adolescents in Saudi Arabia: A Systematic Review, Cureus, 2024
• World Health Organization: Ultraviolet radiation and health