Why Sunny Mediterranean Countries Still Face Vitamin D Deficiency

Why Mediterranean Populations Have Vitamin D Deficiency Despite Sunny Weather

1. Melanin and Skin Pigmentation in Mediterranean Populations
Despite the abundant sun exposure in the Mediterranean basin, a surprising number of individuals suffer from vitamin D deficiency. One contributing factor is skin pigmentation. Many Mediterranean populations, particularly in southern Europe, the Middle East, and North Africa, have moderate to high melanin levels. Melanin acts as a natural sunscreen by absorbing UVB radiation, the specific wavelength responsible for vitamin D synthesis in the skin. While protective against UV damage, higher melanin levels reduce the skin's ability to produce vitamin D efficiently. This means that individuals with darker skin require more prolonged sun exposure to generate adequate amounts of vitamin D compared to those with lighter skin.

2. Cultural Practices and Clothing Habits
In several Mediterranean societies, especially those with Islamic cultural influences, traditional clothing such as long dresses, headscarves, and garments that cover most of the body are common. These cultural and religious garments significantly limit direct sunlight exposure to the skin, even during the sunniest months. Women, in particular, are more affected due to social norms that emphasize modesty. Even when individuals spend time outdoors, if only the face and hands are exposed, vitamin D production is minimal. Additionally, in conservative settings, outdoor activity may be limited altogether, reducing the opportunity for sun-induced vitamin D synthesis.

3. Urbanization and Indoor Lifestyles
Modernization across Mediterranean countries has led to increasingly indoor lifestyles. Sedentary occupations, education systems, and urban living environments encourage people to spend long hours indoors under artificial lighting, minimizing natural sun exposure. Children and adolescents, who once played in open fields, now spend more time in classrooms or on electronic devices. Adults commute in cars, work in offices, and return to indoor environments. Even elderly populations, who are at the highest risk of vitamin D deficiency due to decreased skin capacity for synthesis, often remain indoors due to mobility issues or heat intolerance during summer.

4. Air Pollution and Environmental Factors
Major Mediterranean cities—like Athens, Rome, Istanbul, and Cairo—face serious air pollution challenges. Smog and particulate matter in the atmosphere can scatter and absorb UVB radiation, preventing it from reaching the Earth's surface. This is particularly problematic in densely populated and industrialized regions, where the “sunshine” does not translate into effective UVB exposure for the skin. The invisible layer of pollution acts as an additional barrier, compounding the already limited cutaneous synthesis of vitamin D.

5. Seasonal Behavior Patterns and Heat Avoidance
While the Mediterranean enjoys abundant sunlight for most of the year, the hottest months—particularly July and August—can be excessively hot and uncomfortable. As a result, locals often avoid outdoor activity during peak sunlight hours (10 AM to 4 PM), which is ironically the best time for vitamin D synthesis. Instead, people choose early morning or late evening hours for outdoor exposure, when UVB radiation is insufficient. Tourists may sunbathe, but locals, especially older adults and women, often actively avoid the sun to protect their skin or prevent heat-related illnesses.

6. Use of Sunscreens and Sun Avoidance for Cosmetic Reasons
Another underestimated factor is the widespread use of sunscreens. Mediterranean populations are increasingly aware of the dangers of photoaging and skin cancer, leading to frequent use of SPF creams and lotions. While this is commendable from a dermatological standpoint, it significantly impairs vitamin D production. SPF 15 can reduce vitamin D synthesis by about 93%, and higher SPFs can block up to 99%. Furthermore, there is a growing cultural preference for lighter, un-tanned skin in some Mediterranean societies, which encourages sun avoidance altogether.

7. Diet Is Not Always Vitamin D Rich
Contrary to the perception that Mediterranean diets are always healthy, the reality is more complex. While traditional Mediterranean diets include fish, olive oil, fruits, and vegetables, not all regions follow this model strictly. Economic disparities and urban fast food trends have led to less consumption of fatty fish like sardines and mackerel—important dietary sources of vitamin D. Vitamin D-fortified foods are not widely consumed or promoted in several Mediterranean countries, unlike in the USA or Northern Europe. Additionally, many people are lactose intolerant or avoid dairy, further reducing intake of fortified milk or yogurt.

8. Genetic Polymorphisms and Vitamin D Receptor Sensitivity
Emerging research has suggested that certain genetic variants common in Mediterranean populations might influence vitamin D metabolism and vitamin D receptor (VDR) function. Polymorphisms in genes such as GC (which encodes vitamin D binding protein), CYP2R1, and VDR itself can reduce the efficiency of vitamin D transport, activation, or cellular response. This means even when adequate vitamin D is produced in the skin, its biological effects might be reduced. These genetic predispositions may explain why some people exhibit deficiency symptoms despite relatively normal serum levels.

9. Limited Public Health Focus on Vitamin D
Many Mediterranean countries do not prioritize vitamin D deficiency as a public health crisis, despite high prevalence rates. National healthcare strategies in countries like Greece, Italy, and Egypt may focus more on communicable diseases, cardiovascular health, or obesity, leaving micronutrient deficiencies under-addressed. Public awareness campaigns are limited, and routine vitamin D screening is rarely conducted unless patients present with bone-related complaints. Unlike countries such as Finland or Canada, where fortification policies are robust and deficiency awareness is widespread, Mediterranean countries have lagged behind.

10. Pediatric and Geriatric Risk Groups
Children and the elderly are particularly vulnerable to deficiency in the Mediterranean region. In infants, especially those who are exclusively breastfed without supplementation, vitamin D levels can drop dangerously low. Breast milk is not a rich source of vitamin D unless the mother herself is supplemented. Yet many mothers are unaware of this fact or are not guided to supplement their newborns. In the elderly, reduced skin capacity to synthesize vitamin D, combined with reduced mobility and outdoor exposure, results in widespread suboptimal levels. This becomes a key driver of osteoporosis, fractures, and muscle weakness in aging populations.

11. Pregnancy and Maternal Health
Pregnant women in the Mediterranean region often show alarming rates of vitamin D deficiency, which can adversely affect fetal development and maternal health. The physiological demand for vitamin D increases during pregnancy, yet due to conservative dress, sun avoidance, and lack of supplementation, many women remain deficient. Studies have linked maternal vitamin D deficiency with complications like gestational diabetes, preeclampsia, and low birth weight. Unfortunately, routine antenatal care in some countries does not include vitamin D screening or supplementation guidelines.

12. Misconceptions About Sunlight and Health
A recurring issue is the belief that simply "living in a sunny country" guarantees sufficient vitamin D. This misconception is widespread among both the general population and even some healthcare providers. People may assume that brief daily exposure or incidental sun (while walking or commuting) is enough to meet vitamin D needs, without realizing that time of day, skin surface area exposed, skin tone, and duration are all critical factors. Without targeted education, people may continue to unknowingly live with chronic insufficiency.

13. Lack of Fortified Food Policies
Unlike Northern Europe or North America, Mediterranean countries have not implemented widespread vitamin D fortification programs. Products like cereals, juices, or bread are rarely fortified. Where fortification exists (like in some dairy products), it is voluntary and not consistently consumed by all population groups. Additionally, because supplementation is not embedded in routine care or covered by all healthcare systems, people must rely on over-the-counter options, which are often neglected unless there is an existing medical condition.

14. Vitamin D Deficiency in Refugee and Immigrant Populations
Mediterranean countries like Italy, Greece, and Turkey have become major hubs for refugee populations from Africa, the Middle East, and South Asia. Many refugees live in overcrowded shelters, with limited access to healthcare, poor nutrition, and virtually no sun exposure due to social and living constraints. These communities are at very high risk for hypovitaminosis D and its complications, including rickets in children and osteomalacia in adults. The healthcare systems in host countries are often overburdened and do not consistently address this silent epidemic.

15. Misdiagnosis and Underreporting of Symptoms
Vitamin D deficiency is often underdiagnosed because its symptoms are vague and overlap with other conditions. Chronic fatigue, muscle pain, depression, or frequent infections may not immediately prompt a doctor to order vitamin D levels. In Mediterranean healthcare settings, where time with patients is often limited and lab resources may be scarce or expensive, these symptoms are sometimes brushed off or treated symptomatically. As a result, true prevalence may be higher than reported.

16. Paradox of High Obesity and Low Vitamin D
The obesity epidemic has not spared the Mediterranean. Obesity is a well-known risk factor for vitamin D deficiency because vitamin D is a fat-soluble vitamin and gets sequestered in adipose tissue, making it less bioavailable. Countries like Egypt, Turkey, and southern Italy have rising rates of adult and childhood obesity, which further exacerbate the issue. Obese individuals may also engage in less physical activity, stay indoors more, and suffer from metabolic syndrome—all contributing to low circulating vitamin D.

17. Lack of National Screening Guidelines
There is currently no unified guideline across Mediterranean countries recommending regular vitamin D screening. While some local societies do advocate testing in specific risk groups—such as the elderly or pregnant women—these are not enforced systematically. Without screening programs or physician alerts in electronic health records, the deficiency remains undetected until advanced symptoms or complications emerge. This contrasts with countries like the UK, which has national guidance from NICE (National Institute for Health and Care Excellence) advocating for supplementation in at-risk groups.

18. Misleading Laboratory Reference Ranges
Another problem lies in the interpretation of vitamin D lab results. Different laboratories use different cut-off levels to define deficiency, insufficiency, and sufficiency. In some countries, serum levels above 20 ng/mL are considered “adequate,” whereas in others, the threshold is set at 30 ng/mL. This inconsistency leads to confusion among physicians and patients alike. Moreover, patients with borderline levels may be dismissed as normal when, in fact, they could benefit from supplementation.