Could Sunlight Lower Leukaemia Risk?
Sunshine ~ we all love it; it brightens our mood, warms us, makes us feel alive, and smacks of summer, vacations, beach, braais, hikes, and all of those great outdoor past-times that we love.
We have also been warned that sunshine is bad for us… In recent years we have been taught to fear the sun because of the threat of skin cancer. Now there is a growing belief that exposure to the sun may not actually cause skin cancer. As a study published in the prestigious Cancer journal indicates, exposure to sun actually decreases cancer rates.”
The ideal way to get vitamin D is by exposing your skin to appropriate sunlight, but unfortunately many of us spend most of our day indoors and do not generally get sufficient sunlight.
Sun exposure (without sunscreen) of about 15 minutes a day will help your body produce sufficient natural VitaminD ~ when you put on your bathing suit and sunbathe for 30 minutes, your body produces about 20,000 IUs of vitamin D ~ as much as what can be found in about 200 glasses of milk, or the equivalent of about 50 typical multivitamins!
According to the National Cancer Institute, lifetime exposure to sunlight may reduce your risk of some of the most common types of cancer. In an analysis of death certificates from 24 states over an 11-year period, the NCI researchers found that people who lived in the sunniest parts of the country, and those exposed to the most sunlight through their jobs, had significantly lower rates of breast and colon cancer than matched controls.
The International Agency for Research on Cancer (the IARC) have a working group report on vitamin D and cancer risk.
Epidemiologists at University of California, San Diego School of Medicine report that persons residing at higher latitudes, with lower sunlight/ultraviolet B (UVB) exposure and greater prevalence of vitamin D deficiency, are at least twice as likely to develop leukaemia than those living in equatorial populations.
The findings are published in the Dec. 4, 2015 online issue of PLOS One.
“These results suggest that much of the burden of leukemia worldwide is due to the epidemic of vitamin D deficiency we are experiencing in winter in populations distant from the equator,” said Cedric Garland, DrPH, adjunct professor in the Department of Family Medicine and Public Health and member of Moores Cancer Center at UC San Diego Health.
Benefits of Sunlight
The sun, perfectly near and perfectly distant, sustains the delicate balance of life on Earth. The sun gives our planet warmth, heat and the energy needed for photosynthesis. It drives our day-night cycle and promotes feelings of well-being.
Sunlight is also essential for vitamin D synthesis in the skin — that’s why vitamin D is sometimes called the sunshine vitamin.
You can also get vitamin D from your diet, but very few of the most commonly consumed foods in Western diets are naturally good sources of vitamin D.
Natural foods high in vitamin D include oily fish such as salmon, tuna and mackerel, fish oils, mushrooms, beef liver, cheese, and egg yolks. In addition, vitamin D is widely added to many foods such as milk, orange juice, and cereals, and can also simply be consumed as a supplement.
Risks of UV Exposure
Risks from ultraviolet (UV) exposure have been recognized and discussed for years. UV radiation causes basal cell carcinoma, squamous cell carcinoma and malignant melanoma.
The risk of skin cancer increases when people overexpose themselves to sun or intentionally expose themselves to artificial sources of UV radiation such as tanning beds. For those concerned about cosmetic effects, the sun is the source of what’s known as photo-aging ~ the premature aging of the skin due to chronic UV exposure. Effects of photo-aging range from wrinkled, discoloured skin to pre-cancerous, scaly-crusty growths, or actinic keratoses.
Melanoma Skin Cancer
Though non-melanoma skin cancers are quite common, they are rarely fatal. In contrast, melanoma represents less than 5 % of all skin cancers but causes the most skin cancer deaths. It is the 2nd most common cancer of women in their 20s and the 3rd most common cancer of men in their 20s.
A heightened risk of melanoma has been found for those with increased childhood sun-exposure history.
Sunscreen protects against sunburns, and continues to be recommended by the American Academy of Dermatology. Protection against severe burns is a good thing, and it seems to stand that this might also translate to some protection when it comes to malignancy.
That said, sunscreen is just one part of the whole picture when it comes to protection from the sun, and no studies have ever demonstrated that sunscreen use alone, prevents melanomas or basal cell carcinomas, according to an article published March 20011 in the journal, “Paediatrics.” The amount of time spent in the sun and your complexion are also key factors.
Can vitamin D help prevent certain cancers and other diseases such as type 1 diabetes, cardiovascular disease, and certain autoimmune and chronic diseases? To answer these questions and more, UCSD School of Medicine and GrassrootsHealth bring you this innovative series on vitamin D deficiency. Join nationally recognized experts as they discuss the latest research and its implications. In this program, Donald Trump, MD, discusses what has been learned about vitamin D deficiency from studying cancer patients. Series: Vitamin D Deficiency – Treatment and Diagnosis [2/2009] [Health and Medicine] [Professional Medical Education] [Show ID: 15769]
Does The Sunshine Vitamin Prevent Cancer?
There’s reason to be hopeful, but there are also many questions that remain unanswered. According to laboratory studies, vitamin D deficiency does seem to help certain malignancies to develop, but experts say more research is needed before routine vitamin D supplementation for cancer prevention could be recommended.
The “Low Cloud Cover” Study and Leukaemia
Animal and laboratory studies support the idea that having adequate levels of vitamin D might help prevent leukaemia, but no such evidence exists in humans. Recently, however, a group of scientists wondered whether they could see evidence of a protective effect from sunlight (and higher levels of vitamin D) based the geography of different nations.
They proposed that people who live in countries further away from the equator, with low UVB exposure, who tend to have lower levels of vitamin D, might show a higher risk of certain cancers, including leukaemia.
In contrast to past studies, this group adjusted for the cloud cover in various countries and its effect on UVB exposure of the people living below. They made these adjustments using satellite data from NASA.
Leukaemia rates were highest in countries relatively closer to the poles, such as Australia, New Zealand, Chile, Ireland, Canada and the United States. They were lowest in countries closer to the equator, such as Bolivia, Samoa, Madagascar and Nigeria.
This kind of study cannot prove vitamin D deficiency leads to leukaemia or that spending more time outside in the sunshine could heal or prevent it, but it does show an association that can be further dissected and analysed by scientists.
Vitamin D and Leukaemia Treatment
In the case of blood cancers like leukaemia and lymphoma, evidence supports the idea that vitamin D seems to help certain cancer therapies do their job.
Studies have shown a link between vitamin D deficiency and a worse prognosis in various types of blood cancer, including chronic lymphocytic leukaemia (CLL), and diffuse large B cell lymphoma (DLBCL), the most common type of non-Hodgkin lymphoma.
But these studies look backwards, so it can be hard to tell cause from effect. Whether vitamin D will be used to increase the power of certain cancer therapies remains an open question, but data is very encouraging.
The traditional role of vitamin D for strong bones is also relevant. Many cancer therapies ~ and often the cancers themselves -~ have the tendency to deplete bone mass, increasing the risk of osteoporosis. This means that maintaining adequate levels of calcium and vitamin D may also be important from the perspective of bone health.
Vitamin D Consensus Statement
Cancer Research UK teamed up with other health organisations to bring together evidence on vitamin D.
It is endorsed by the British Association of Dermatologists, Cancer Research UK, Diabetes UK, the Multiple Sclerosis Society, the National Heart Forum, the National Osteoporosis Society and the Primary Care Dermatology Society.
Cancer Research UK: Vitamin D, Sunlight and Cancer
Balk SJ: Ultraviolet radiation: Hazard to Children and Adolescents. Paediatrics. 2011;127(3):588-97.
The American Academy of Dermatology: Sunscreen remains a safe, effective form of sun protection. Accessed January 2016.
Cuomo RE, Garland CF, Gorham ED, Mohr SB: Low Cloud Cover-Adjusted Ultraviolet B Irradiance Is Associated with High Incidence Rates of Leukemia: Study of 172 Countries. PLoS ONE. 2015;10(12):e0144308
Posted on 9 February, 2016, in Blog, Research and tagged basal cell carcinoma, leukaemia, leukemia, malignant melanoma, squamous cell carcinoma, sunburns, sunscreen, ultraviolet (UV), vitamin D. Bookmark the permalink. Leave a comment.