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Sunshine for Vitamin D?

Article written by Daniel Healy.

Experts are talking the world over about a new epidemic that may be dramatically increasing our risk of the flu, osteoporosis and even cancer.3 It’s a lack of Vitamin D and the solution may be as simple as spending 15 minutes in the sun each day.

But what exactly is vitamin D?

Vitamin D is a fat soluble vitamin that is metabolised by the body from either dietary intake or the sun.4 It is made up from two molecules – ergocalciferol (D2) and cholecalciferol (D3).4 When UV radiation, via sunlight is absorbed into our skin it reacts with a cholesterol like substance to form Vitamin D (the D3 form).4 Vitamin D (D2 and D3) is also available from dietary sources such as milk, sardines, salmon, eggs and meat however it’s estimated that the average food intake of vitamin D contributes to about one fifth of our recommended requirements.5 Translation - we need to get some sunlight to get adequate vitamin D intake. Vitamin D from the sun or dietary sources will eventually end up in the liver where it is converted to the major circulating form of vitamin D, it then travels to the kidneys to become the active form of vitamin D (calcitriol).4 Once it has been activated it can then be used for a variety of functions in the body including maintenance of adequate levels of calcium and phosphorus in the blood.4

What’s so good about vitamin D?

Well a number of studies on this vitamin seem to indicate that adequate intake either through diet, the sun or both may be essential to good health. In fact a deficiency may even play a role in the development of a number of health conditions. What are some of these?

Could vitamin D be the new vitamin C when it comes to cold and flu protection?

A recent study indicated that adequate levels of vitamin D may have a significant impact on reducing the occurrence of the cold and flu (respiratory tract infection) on adult and adolescent population.1 The experiment looked at 19,000 people and found that those with the lowest Vitamin D levels were 40% more likely to develop a cold compared to those with higher vitamin D levels.1

Vitamin D and Osteoporosis

Vitamin D deficiency may be strongly correlated with osteoporosis.3 If you don’t get enough vitamin D your body may not absorb as much calcium as it needs to maintain bone density.2 This is something worth listening to if you work for the health department as according to Professor Rebecca Mason from the University of Sydney , in Australia osteoporosis costs the tax payer around 7 billion dollars a year.3 Not surprisingly, one of the most at risk population to osteoporosis, the elderly, particularly those in nursing homes, are predominantly vitamin D deficient.3 Osteoporosis is a major risk factor for hip fractures which are one of the major causes of death and disability in the elderly.5

It should be noted that the elderly are not the only high risk group when it comes to vitamin D deficiency. Other groups include people with dark skin, those who where veils or dress very conservatively, pregnant women and hostel residents.5

Vitamin D and Breast Cancer

A link has also been found between vitamin D deficiency and breast cancer.1 Professor Michael Holick from Boston University Medical Centre states that “In Europe it’s estimated that 25% of women that die from breast cancer may not have died of breast cancer if they would have maintained adequate vitamin D levels throughout their lives.”3

The Solution?

So, do we slip slop slap or do we liberate our skin and bear all?  Professor Holick estimates that a minimum of 25% of American adults are deficient in vitamin D.3 So it appears that yes, sun exposure is something we may need to consider.  Interestingly sunscreen greater than SPF8 will block the absorption of UV rays preventing vitamin D absorption.4 So while sunscreen is important to help prevent skin cancer, a short period of time in the sun without sunscreen may be beneficial to boost your vitamin D intake. But before you pull out your beach towel and head to your favourite beach for a day of sun tanning, it needs to be pointed out that too much sun is not so good either. How much sunlight you need is a matter of balance.  Professor Holick states, “You really don’t need more than 20 – 25% of the amount of sunlight that would cause a mild sunburn.”3 The peak UV exposure time is generally between 10am and 3pm.2 During the summer months it’s especially best to stay out of the sun or wear protective clothing, hat and sunscreen between the peak hours.2 If you have fair skin, you will burn a lot faster than someone who has dark skin, in fact people with dark skin may need three to four times more sun exposure to achieve sufficient levels of vitamin D.2 During summer those with fair skin should get a few minutes of sun exposure before or after the peak UV exposure time. During winter aim to get 2-3 hours of sun exposure each week.2

So it appears that a small amount of sun may actually be good for us. But like everything, moderation is the key, too much sun exposure can lead to skin cancer. So what is the take home message? Get your few minutes of sun each day, then slip slop and slap for any additional time in the sun!

References

  1. Daniells, Stephen, February 2009. Forget C, D may be the vitamin for cold and flu protection: Study [Online]. Available at http://www.nutraingredients.com/Research/Forget-C-D-may-be-the-vitamin-for-cold-and-flu-protection-Study  [Accessed 21st March 2009].
  2. Deakin University - Better Health Channel, December 2008.  Vitamin D [Online]. Available at http://www.betterhealth.vic.gov.au/BHCV2/BHCARTICLES.NSF/pages/Vitamin_D?OpenDocument [Accessed 21st March 2009].
  3. Kelly, Karina, March 23rd 2003. Vitamin D and Cancer [Online]. Available at http://www.abc.net.au/catalyst/stories/s805444.htm [Accessed 21st March 2009].
  4. Malone, Rebecca W. And Kessenich, Cathy, 2008. Vitamin D Deficiency: Implications Across the Lifespan [Online].  Available at www.medscape.com/viewarticle/578508 [Accessed 26th March 2009].
  5. Nowson, Caryl A. and Margersion, Claire, August 2002.  Vitamin D Intake and Vitamin D Status of Australians. MJA [Online] 177 p.149-152. Available at http://www.mja.com.au/public/issues/177_03_050802/now10763_fm.html [Accessed 23rd March 2009].


Last updated 17 June 2009