The dog days of winter have people north of the 49^thparallel feeling a little blue.  Heaps of snow, overcast skies and the prospect of a 5pm sunset do not help matters.  This is the time of year when most people dream of making an escape from their frigid environment to exotic regions closer to the equator.  Like Bora Bora…..

I recently came across an article in “The American Journal of Clinical Nutrition” which suggests that our risk of cancer, multiple sclerosis, and cardiovascular disease is influenced by the latitude in which we live.  This is a scary thought, but the idea of taking more hot vacations in the name of “healthy living” sounds good to me……..

Apperley(97) reported his remarkable observation that people in the United States who lived at higher latitudes, such as in New Hampshire, Vermont, and Massachusetts, had overall greater risks of dying as a result of cancer, compared with men and women of similar ages who lived in southern states, such as Texas, Georgia, and Alabama.

Clearly, there seems to be a correlation between latitude and incidence of cancer even many years ago.  It is interesting to note that today the same patterns exist and are not exclusive to cancer.  The incidence of other diseases are also more prevalent in higher latitudes as well.

Interestingly, there is also a latitudinal association with increased risk of developing multiple sclerosis (106 –108) and cardiovascular disease (109). Rostand (109) observed in 1979 that people who lived at higher latitudes in the United States, Europe, and Asia were more likely to have hypertension. It is well established that there is a latitudinal association with the prevalence of multiple sclerosis. People who were born below 35° N latitude and lived at or below that latitude for the first 10 years of their lives had decreased lifetime risks of developing multiple sclerosis, compared with those who were born above 35° N latitude (106, 107)

I guess this means we need to spend more time in the sun!  Think of it as research giving us the green light to take a vacation, in the middle of winter!  While we are at it, maybe we should just relocate our families closer to the equator.  I heard Costa Rica boasts some affordable real-estate at the moment.  Looks like a nice place…..

What is so special about the sun?

For starters, it’s ability to stimulate natural Vitamin D production in our bodies.

How is it possible that vitamin D can have such a wide range of therapeutic and health-related benefits? The answer lies in the fact that the VDR is present in most cells and tissues in the body. 1,25(OH)2D is one of the most potent regulators of cellular growth in both normaland cancer cells (2, 3, 22, 26, 76, 82, 83).  It has been suggested that increased vitamin D intake or increased exposure to sunlight, raising blood concentrations of 25(OH)D above 78 nmol/L (30 ng/mL), is necessary for maximal extrarenal production of 1,25(OH)2D in a wide variety of tissues and cells in the body, including colon, breast, prostate, lung, activated macrophages, and parathyroid cells.

But you are probably thinking that as northerners we get plenty of sun in the winter.  In fact the sun is even closer to the earth’s surface during the winter months, so how can we be experiencing a deficiency in Vitamin D?

The reason is that, although the sun is closest to the earth in the winter, the sun’s rays are entering at a more oblique angle (zenith angle) and more UVB photons are efficiently absorbed by the ozone layer, because the more oblique angle causes the UVB photons to pass through the ozone for a greater distance.  Therefore, very little if any vitamin D3 is produced in the skin during the winter.

Ok then…So what is the solution?  As nice as it would be, we can’t just all pack up and head south in search of quality sun exposure.

One suggestion is to go outside more often, as it has been shown to decrease the likelihood on cancer, or even extend the period of time before cancer develops.

Bodiwala et al(112) reported that men who worked outdoors and had increased sun exposure throughout their lifetimes had a 3–5-y “honeymoon” period before they developed prostate cancer, compared with age-matched control subjects who had little sun exposure and began developing prostate cancer at the age of 53 y.

Take a Vitamin D Supplement

While taking vitamin D supplements is beneficial it is important to realize the vitamin D is more potent when produced naturally in our bodies through sun exposure.

Going back to the Zenith angle stuff about the sun’s light refracting off the ozone layer.  The optimal time for sun exposure, strictly for the purpose of producing vitamin D in our body is between the hours of 11am and 3 pm.  If you are hoping that your morning walks are helping you increase blood concentrations of vitamin D, understand that the time of day you are exposing yourself to sunlight plays a crucial role in the production of Vitamin D.

What about the risk of skin cancer?

The article has some interesting points regarding this as well.  Firstly, we should note that the most serious form of skin cancer is not caused by direct sun exposure.

The most serious form of skin cancer is melanoma. It should be recognized that most melanomas occur on non—sun-exposed areas (41) and that having more sunburn experiences, having more moles, and having red hair increase the risk of the deadly disease (36).

If you are really concerned about increasing your risk of developing skin cancer then avoiding the sun may seem like a good plan.  Just remember that increased sun exposure causes Vitamin D production in the body, which is extremely beneficial.

Vitamin D Benefits

• Boosts immunity
• Aids in cell differentiation
• Improves mood (serotonin levels)
• Aids in Eczema/psoriasis treatment
• Regulate insulin secretion
• Decrease blood pressure
• Decrease incidence of multiple Sclerosis

If you are really worried about skin cancer, (and I’m not being ignorant because my mother has had skin cancer) than consider this statement from the article.

There needs to be a reexamination of the relationship between skin cancer and other cancers, noting that “the presence of skin cancer is really an occasional accompaniment of relative cancer immunity in some way related to exposure to solar radiation”

Interesting research.  If you would like to read the full article check out the link below.

Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease Michael F Holick

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