A new wave of research is shedding light on the extensive—and sometimes unexpected—health implications of vitamin D deficiency, with experts warning that failing to get enough of the so-called “sunshine vitamin” could have far-reaching effects beyond what most people realize. These findings are particularly relevant for Thai readers, given shifting lifestyles, urbanization, and the rising prevalence of indoor work and study patterns, all of which can contribute to vitamin D insufficiency.
Vitamin D is vital for maintaining strong bones, reducing inflammation, and supporting immune function, with a growing body of evidence suggesting its influence extends to mood regulation, cardiovascular health, and even the risk of chronic diseases. According to the National Institutes of Health (NIH), approximately 35% of Americans have insufficient vitamin D levels, and global estimates suggest that up to half of the world’s population may not be getting enough of the nutrient, emphasizing the universality of this concern (NIH). While there is less robust epidemiological data focused specifically on Thailand, a 2019 cross-sectional study from Mahidol University estimated that almost 45% of Thai adults have below optimal serum vitamin D levels, especially those living in urban environments where sun exposure is limited (PubMed – Vitamin D Status of Thai Adults).
The latest findings, highlighted in a July 2025 Prevention magazine review, reveal not only the familiar bone-related symptoms like fatigue, muscle aches, and an increased risk of osteoporosis and fractures but also a spectrum of lesser-known side effects. Notably, individuals with vitamin D deficiency are 54% more likely to develop multiple sclerosis (MS), a serious autoimmune condition, compared to those maintaining adequate levels (Prevention). These numbers are supported by a 2024 meta-analysis demonstrating a statistically significant association between low vitamin D and increased MS risk (Prevention).
What makes vitamin D deficiency especially concerning is its subtlety—many people may not exhibit overt symptoms until the problem is well advanced. Early signs often include vague complaints: persistent tiredness, general aches and pains, muscle weakness, and mild depressive symptoms. Medical experts explain that these conditions are sometimes dismissed as ordinary stress or aging, leading to delayed diagnosis and missed opportunities for early intervention (NIH Fact Sheet).
Serious chronic outcomes linked to a lack of vitamin D have come under increasing scrutiny. Recent research detailed in PubMed-indexed reviews underscores the connection between low vitamin D and a higher risk of cancers, including colorectal, breast, and prostate cancer. There is also emerging evidence linking deficiency to elevated risks of heart disease, diabetes, immune dysfunction, and complications during pregnancy (StatPearls Vitamin D Deficiency – NCBI Bookshelf). For example, a 2025 systematic review emphasized a strong association between vitamin D deficiency and chronic liver disease, recommending supplementation as a preventive measure (Role of Vitamin D Supplementation in Chronic Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials, 2025). Likewise, researchers examining maternal and neonatal health have linked low vitamin D levels to higher rates of neonatal hyperbilirubinemia and adverse outcomes in both mothers and infants (Maternal and neonatal vitamin D levels and hyperbilirubinemia: A systematic review and meta-analysis, 2025).
Expert insight into these revelations is unequivocal. One academic endocrinologist at a leading university hospital in Thailand notes, “Vitamin D’s role is much broader than previously understood; we are now recognizing its profound impact on immune modulation and chronic disease prevention. Given how prevalent indoor lifestyles have become across urban Thailand, this issue is especially pressing for the younger generation and office-based workers.” This perspective is echoed internationally, with the Cleveland Clinic emphasizing that vitamin D deficiency is “a big deal,” given how many functions depend on adequate levels (Prevention).
For Thai society, the implications are significant. Many people—especially in Bangkok and other cities—spend much of their days indoors, whether in offices, schools, or at home. Cultural preferences for lighter skin can also lead to limited sun exposure, as the use of umbrellas, hats, and sunscreen to avoid tanning is widespread. Traditional Thai diets, though rich in vegetables, generally contain low amounts of vitamin D, unless fortified foods or certain types of fish are regularly consumed. It is also important to consider religious or modest dress traditions, which may further reduce skin exposure to sunlight among certain groups (Vitamin D deficiency in Thai children and adolescents).
Looking back, vitamin D-related bone diseases like rickets were historically rare in Thailand, but recent urbanization and changing lifestyles have shifted the epidemiological landscape. While nutritional improvements have combated many classical deficiencies, modern living has introduced new vulnerabilities. In rural communities, children and workers are more likely to be exposed to sunshine, thus naturally synthesizing adequate vitamin D. However, as cities expand and digital work becomes ubiquitous, the risk of deficiency increases.
Future trends suggest further challenges. Studies project that unless preventive steps are taken, vitamin D deficiency rates will climb in tandem with urbanization and aging demographics—both correlating with reduced time outdoors and changes in metabolism (Vitamin D - Health Professional Fact Sheet, NIH). Thailand’s Ministry of Public Health has already flagged this issue as an emerging public health concern. Policy responses may include public awareness campaigns, increased screening among high-risk groups, and even potential food fortification programs. Recent efforts in several countries to mandate vitamin D enrichment in staple foods—such as milk, rice, and oil—demonstrate promising results in improving population health. Thai policymakers and public health experts may look to these models for inspiration, adapting interventions to suit local dietary customs and climate.
For ordinary Thai readers, the critical takeaway is that vitamin D deficiency can be both silent and serious. Simple steps to maintain optimal vitamin D status include spending 10–30 minutes in the midday sun several times per week, consuming vitamin D-rich foods (such as mackerel, salmon, sardines, liver, egg yolks, and vitamin D-fortified products), and considering supplements when at risk or as recommended by health professionals (MD Anderson Cancer Center, Vitamin D Deficiencies: What to Know). Those with chronic illnesses, pregnant women, infants, older adults, and people with limited sun exposure should be particularly vigilant.
In summary, vitamin D deficiency remains an underrecognized threat to public health in Thailand, one that transcends simple bone health and touches nearly every aspect of well-being. Thai readers are encouraged to discuss vitamin D screening with their healthcare providers, particularly if they experience persistent fatigue, muscle aches, or frequent illness. As research continues to evolve, staying informed and proactive is the best defense—enabling not just stronger bones, but a healthier, more resilient Thailand for years to come.
For more information on vitamin D, consult resources from the Thai Ministry of Public Health, major university medical centers, or the U.S. NIH’s comprehensive fact sheets (NIH Vitamin D Fact Sheet).