Ultraviolet (UV) light has been an important source in human health throughout human evolution. However, modern lifestyles, indoor jobs, cultural myths, religious beliefs and the increase of globalization has drastically reduced UV light exposure in humans, amounting to growing cancer rates, diseases and worldwide health deterioration. This commentary details various human activities, lifestyles and their effects on health worldwide. It also examines misinterpreted findings pertaining to the lack of UV light exposure that could further undermine existing health issues. UV light producing technologies to reduce adverse effects on human health are currently being used and are very effective. They are safer than sunlight, available at any time, inexpensive and could reduce healthcare costs by decreasing drug use and extensive cancer therapies. Public health agencies and healthcare providers throughout the world should make individuals aware of UV light exposure benefits.

Keywords: Disease, Health, Immune system, Ultraviolet light

Globalization, a phenomenon of recent and constant human migration around the world due to employment and business opportunities is also a great recent contributor to adverse effects on health, in addition to increased environmental pollutions and stressful life styles. As previously mentioned, dark skinned individuals living or migrating in places with less available sunlight than their once native places are usually at risk, it takes up to 6 times more UV light exposure in dark-skin individuals to obtain the same vitamin D levels and other necessary health benefits than light-skin individuals [16]. Additionally, concerns for rapidly spreading epidemics now and in the future [17] reveal that human immunity may be declining worldwide. One important function of UV light is the killing of many bacterial and viral pathogens [6] as well as cancer cells [18]. With antibiotic resistance constantly, increasing because of overuse and abuse [19] the mounting evidence for increases in diseases and epidemics worldwide should consider what some of their main causes are. The increasing lack of UV light exposure in humans worldwide is likely one of them [1,4,6,20].

HEALTHCARE SYSTEMS - THE CHALLENGES

The International Agency for Research on Cancer (IARC) is predicting the global burden of cancer will grow 70% over the next two decades, with an estimated 22 million new cases per year. Here we emphasize that indoor lifestyles, aging and globalization will be significant contributors to cancers in the near future. Therefore, people, healthcare systems and governments worldwide should make greater efforts in overcoming this growing challenge by supporting research and educating their citizens on the above issues.

LIFESTYLES, CULTURES AND BELIEFS

Increasing indoor lifestyles due to jobs and hobbies, such as computer and video games [21] and the lack of UV light exposure caused by cultural myths, religious beliefs and globalization are matters of great concern. Excessive sunscreen usage, sun-umbrellas and sun-blocking clothes to maintain white skin is extremely common in Asian populations (Figure 1) [1]. Permanent covering of the entire body due to cultural and religious beliefs in most of Middle East, Africa and parts of Asia likewise contribute to many health challenges [2,22].

As people travel and migrate around the world, they bring their lifestyles, traditions and beliefs with them, often adding to the local healthcare challenges. Studies reveal that dark-skin individuals are affected by the most by globalization, as many of them relocate to places with significantly less available sunlight than in their homeland [12]. Various studies support this assumption due to higher cancer rates and other diseases in African-Americans [6,12] although it might be confounded by some other environmental or economic factors such as cloudier and polluted places, low income and education.

NUTRITIONAL SUPPLEMENTS

A worldwide vitamin D deficiency epidemic points to an association among vitamin D and many diseases, particularly cancer. Vitamin D involvement in many important bodily functions is confirmed by 2,776 genomic positions the vitamin D receptor (VDR) occupies [23]; this makes a strong case for its role in cancers, other diseases and overall health. It also implies that UVB light, the main producer of vitamin D in humans could be a significant contributor to other health benefits, some of which can both, prevent and treat various diseases [5,24,25]. Notably, UV light enhances skin barrier functions, endorphins production, cardiovascular protection, lowering of cholesterol, melatonin production, wound healing, antimicrobial effects, currying of depression [6], protection against and treatment for multiple sclerosis (MS) [24] and treatment of T-cell lymphoma [18]. A low vitamin D status is a good indicator of poor health and high risk for diseases. Direct sunlight exposure to 80% of the total body skin for 30 min can generate 50,000 IU (1.25 mg) vitamin D in light skin individuals within 24 h of exposure and a series of additional health factors [26]. The body has evolved superb UV light protection and the melanin pathway is immediately activated if overexposure occurs (Figure 2) [27].

Vitamin D deficiency and related diseases especially in dark skin individuals is becoming a worldwide concern. Promoting lifestyle changes and the use of inexpensive technology (e.g. LEDs) for prevention and treatment could play a significant role in worldwide health [28]. An estimated one billion people of all races worldwide experience significant vitamin D deficiency. These individuals likely experience deficiencies of other important health factors produced by UV light mentioned previously and are at increased risks for cancers and other diseases [4,6].

SIGNIFICANT FINDINGS MISINTERPRETED

A study by Powe et al. [7] on the 25(OH)D (circulating vitamin D) level among African-Americans and Caucasians is of particular significance. It found mean levels of 25(OH)D and vitamin D-binding protein were lower in African-Americans as expected, but revealed what is a great example of recent human adaptation [8]. African-American’s BMD and calcium levels were higher than in Caucasians despite lower circulating vitamin D levels. The researchers overlooked the incidence of higher cancer rates and other diseases in blacks as compared to whites [4] and stated African-Americans are inappropriately labeled vitamin D-deficient [7]. The researchers failed to acknowledge that a low vitamin D status generally means a deficiency in all health factors produced by UV light and its associated benefits and an increased risk for diseases [5,6]. Higher level of BMD and calcium coming from lower than normal 25(OH)D levels could be attributed to phenomenal adaptation to decreased sunlight exposure over time in African-Americans as most of them have been in North America over 200 years [8]. Lower 25(OH)D levels caused by darker skin pigmentation in African-Americans require up to 6 times the sunlight exposure of light-skin individuals [16]. Socioeconomic status, stress, diet, and lifestyle all influence onset and progression of diseases, however, low 25(OH)D levels caused by lack of UV light exposure are associated with all cancers and diseases (Figure 2) [4].

INDOOR HOBBIES AND CULTURAL MYTHS

Alarming rates of vitamin D deficiencies in children and teenagers globally are evidence for that they no longer spend adequate time outdoors. Online game technologies for entertainment such as computers, I Pads, smart phones and various other indoor games keep many children and adults indoors. Additionally, both adults and children use too much sunscreen when being outdoors from either scares of skin cancer or “white skin” preferences [1].

Recently, fast developing nations like China experience a significant growing number of cancers [1,17]. Pollution, among many other harmful effects on human health blocks UV light penetration. China experienced a tremendous economic boom over the past decade that brought significant lifestyle changes: the indoor industrial jobs are replacing the outdoor agrarian lifestyles for many individuals. Additionally, cultural myths for “white skin” as a beauty symbol in most of Asia persuade women to often use sun umbrellas just to walk from home to their cars, excluding any possibility for direct UV light exposure (Figure 1).

THE SKIN CANCER MYTH

A study in 1999 erroneously published results that linked UV light exposure to very high risk of melanoma [29]. However, the risk was discovered to be much lower a few years after and other studies concluded that genetics and lack of sunlight exposure are the factors that initially make individuals more susceptible to skin cancers [30]. Moreover, 75% of melanomas appear on parts of the body that are not exposed to sunlight [31]. This maybe also an indirect support to one of our recent findings, i.e., cancer cells were more sensitive to UV exposure than other cell types. Although the melanoma scare happened more than a decade ago, the effects of a powerful sunscreen industry still persist.

UV LIGHT USES, BENEFITS AND ARTIFICIAL SOURCES

Direct exposure to artificial UV light (UV light diodes) has been known to treat and cure a variety of diseases. After being first used in the classic treatment of rickets, it is now used in treating many health problems like psoriasis and treatment of multiple sclerosis and even T-cell lymphoma [18,24,25]. In other studies, UV light was shown to decrease the frequency of headaches in men, subside pediatric and adult infections, aid with prevention/reduction of myopia and other health benefits [32,33]. For instances, phototherapy of broadband (BB) UVB (290-320 nm), narrow band (NB) UVB (310-315 nm), monochromatic UVB (308 nm from an excimer laser), broadband UVA (320-400 nm) and UVA-1 (340-400 nm) has been used successfully in treatment of both animal disorders and human clinical subjects. Recent studies reveal NB UVB (290-315 nm) is most effective and the least to cause erythema in both animals and humans [18,24,28].

CONCLUDING REMARKS

1.       Chen W, Clements M, Rahman B, Zhang S, Qiao Y, et al. (2010) Relationship between cancer mortality/incidence and ambient ultraviolet B irradiance in China. Cancer Causes Control 21: 1701-1709.

2.       Sherazee M (2011) Vitamin D and sunlight: Are you in the dark about this deficiency. The Express Tribune, August 7, 2011.

3.       Barton MK (2014) Affordable oncologic care: A challenging goal. CA Cancer J Clin 64: 75-78.

4.       Grant WB, Peiris AN (2012) Differences in vitamin D status may account for unexplained disparities in cancer survival rates between African and white Americans. Dermatoendocrinology 4: 85-94.

5.       Van der Rhee H, Coebergh JW, de Vries E (2013) Is prevention of cancer by sun exposure more than just the effect of vitamin D? A systematic review of epidemiological studies. Eur J Cancer 49: 1422-1436.

6.       Holick MF (2016) Biological effects of sunlight, ultraviolet radiation, visible light, infrared radiation and vitamin D for health. Anticancer Res 36: 1345-1356.

7.       Powe CE, Evans MK, Wenger J, Zonderman AB, Berg AH, et al. (2013) Vitamin D-binding protein and vitamin D status of black Americans and white Americans. N Engl J Med 369: 1991-2000.

8.       Marciniak S, Perry GH (2017) Harnessing ancient genomes to study the history of human adaptation. Nat Rev Genet 18: 659-674.

9.       Polimanti R, Piacentini S, Iorio A, De Angelis F, Kozlov A, et al. (2015) Haplotype differences for copy number variants in the 22q11.23 region among human populations: A pigmentation-based model for selective pressure. Eur J Hum Genet 23: 116-123.

10.    Qin B, Moorman PG, Alberg AJ, Barnholtz-Sloan JS, Bondy M, et al. (2016) Dairy, calcium, vitamin D and ovarian cancer risk in African-American women. Br J Cancer 115: 1122-1130.

11.    Breuer J, Schwab N, Schneider-Hohendorf T, Marziniak M, Mohan H, et al. (2014) Ultraviolet B light attenuates the systemic immune response in central nervous system autoimmunity. Ann Neurol 75: 739-758.

12.    Gelfand JM, Cree BA, McElroy J, Oksenberg J, Green R, et al. (2011) Vitamin D in African Americans with multiple sclerosis. Neurology 76: 1824-18230.

13.    Chakraborty D, Benham V, Bullard B, Kearney T, Hsia HC, et al. (2017) Fibroblast growth factor receptor is a mechanistic link between visceral adiposity and cancer. Oncogene 36: 6668-6679.

14.    Anastasiou A, Karras SN, Bais A, Grant WB, Kotsa K, et al. (2017) Ultraviolet radiation and effects on humans: The paradigm of maternal vitamin D production during pregnancy. Eur J Clin Nutr 71: 1268-1272.

15.    Castano AP, Mroz P, Hamblin MR (2006) Photodynamic therapy and anti-tumour immunity. Nat Rev Cancer 6: 535-545.

16.    Forrest KY, Stuhldreher WL (2011) Prevalence and correlates of vitamin D deficiency in US adults. Nutr Res 31: 48-54.

17.    WHO (2017) Ebola outbreak Democratic Republic of the Congo 2017. World Health Organization.

18.    Abdallat SA, Alqaqaa AS, Obaidat NA, Alnueimi RF (2014) Efficacy and side effects of narrowband-UVB in early stage cutaneous T-cell lymphoma in Jordanian patients. ISRN Dermatol 2014: 951821.

19.    Kennedy DA, Read AF (2017) Why does drug resistance readily evolve but vaccine resistance does not? Proc Biol Sci 284: pii: 20162562,

20.    Hart PH, Gorman S, Finlay-Jones JJ (2011) Modulation of the immune system by UV radiation: More than just the effects of vitamin D?. Nat Rev Immunol 11: 584-596.

21.    Misra M, Pacaud D, Petryk A, Collett-Solberg PF, Kappy M, et al. (2008) Vitamin D deficiency in children and its management: Review of current knowledge and recommendations. Pediatrics 122: 398-417.

22.    Arabi A, El Rassi R, El-Hajj Fuleihan G (2010) Hypovitaminosis D in developing countries - Prevalence, risk factors and outcomes. Nat Rev Endocrinol 6: 550-561.

23.    Ramagopalan SV, Heger A, Berlanga AJ, Maugeri NJ, Lincoln MR, et al. (2010) A ChIP-seq defined genome-wide map of vitamin D receptor binding: associations with disease and evolution. Genome Res 20: 1352-1360.

24.    Wang Y, Marling SJ, McKnight SM, Danielson AL, Severson KS, et al. (2013) Suppression of experimental autoimmune encephalomyelitis by 300-315 nm ultraviolet light. Arch Biochem Biophys 536: 81-86.

25.    Nakamura M, Farahnik B, Bhutani T (2016) Recent advances in phototherapy for psoriasis. F1000Res F1000 Faculty Rev-1684.

26.    Mead MN (2008) Benefits of sunlight: A bright spot for human health. Environ Health Perspect 116: A160-A167.

27.    D’Orazio J, Jarrett S, Amaro-Ortiz A, Scott T (2013) UV radiation and the skin. Int J Mol Sci 14: 12222-12248.

28.    Kalajian TA, Aldoukhi A, Veronikis AJ, Persons K, Holick MF (2017) Ultraviolet B light emitting diodes (LEDs) are more efficient and effective in producing vitamin D3 in human skin compared to natural sunlight. Sci Rep 7: 11489.

29.    Moan J, Dahlback A, Setlow RB (1999) Epidemiological support for a hypothesis for melanoma induction indicating a role for UVA radiation. Photochem Photobiol 70: 243-247.

30.    Han J, Hankinson SE, Colditz GA, Hunter DJ (2004) Genetic variation in XRCC1, sun exposure and risk of skin cancer. Br J Cancer 91: 1604-1609.

31.    Augustine CK, Freedman JA, Beasley GM, Tyler DS (2013) Ch. 66 - Melanoma. Genomic and Personalized Medicine (2^nd Edn) 1-2: 765-775.

32.    Walker VP, Modlin RL (2009) The vitamin D connection to pediatric infections and immune function. Pediatr Res 65: 106R-113R.

33.    Zasloff M (2006) Fighting infections with vitamin D. Nat Med 12: 388-390.

34.    Becklund BR, Severson KS, Vang SV, DeLuca HF (2010) UV radiation suppresses experimental autoimmune encephalomyelitis independent of vitamin D production. Proc Natl Acad Sci U S A 107: 6418-6423.