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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
INTRODUCTION
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 (2nd 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.
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