Is sunshine healthy again?

  • New study claims avoiding the sun is as dangerous as smoking
  • Study found women in Sweden who had greatest sun exposure had lowest risk of dying from heart disease/stroke and death overall
  • But study failed to consider exercise as possible cause of improved health in cohort
  • UV exposure clearly linked to cancer risk
  • Safe sun exposure for most people still a few minutes of sunlight to face, arms and hands in the morning and evening

I live in Queensland.  Queensland is the Sunshine State, so named because we boast about having the most hours of sunshine than any other state in Australia (we actually don’t have the most sunshine in Australia, but we like to remain pleasantly deluded).

We’re blessed with temperatures that vary from pleasantly warm to oppressive and humid, but with an outdoor climate and a coastline that boasts some of the world’s most beautiful beaches, traditionally, Queenslanders have enjoyed lots of time in the sun.

In the 1960’s and 70’s, it was fashionable, and even considered healthy, to have a deep brown tan, even if that meant burning yourself to a lobster-red colour in order to achieve it.  Then in the 1980’s, we had a rethink because of the large number of skin cancers that were appearing.  I remember being at school in the 1980’s and being indoctrinated with the “Slip Slop Slap” mantra, “Slip on a shirt, slop on some sunscreen, and slap on a hat”.

Now, in the mid twenty-teens, the trend in sun avoidance behaviour has almost led us back to the Victorian era of full body swimsuits, enormous hats and constant shade seeking.  Tan’s are considered unhealthy, and if you get burnt enough to peel, everyone tells you that you’re going to die of melanoma.

If the trend continues, the next generation will be anaemic zombies whose only light exposure will be from LED devices.  Actually, come to think of it, that IS the current generation …

Given our carcinophobic sun-avoidance, I was surprised to see an article come across my social media feed entitled, “Avoiding sun as dangerous as smoking”.

Oh my goodness, was this another thing we’ve been get wrong all these years?  Should I start promoting tans again?  Should I be in my backyard in my underwear trying to get one myself?

As it turns out, I can keep my clothes on, much to the relief of my neighbours.

The study in question is a 20 year follow up of nearly 30,000 women in Sweden [1].  They measured their sun exposure habits at entry to the study, and throughout the two decades of follow up, and they found a nice linear relationship between their sun exposure and their overall mortality.

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The authors stated that, “Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking.”

This is sometimes where reading medical literature can be confusing.  I can imagine some people thinking, “Well, that means if I want to spend all day on the beach, I can protect myself by taking up smoking.”  So let’s take a step back here before we swap our sunblock for a packet of ciggies.  We have to be careful in how we apply this information from this study.

For a start, this research was done on women living in Sweden, where the climate is slightly different from living in the tropics.  There isn’t much sun in Sweden, and when it does come out, it’s not very intense.  That’s a big different from living in climates like Queensland where standing in the sun for an hour does to us what my microwave does to my leftovers.

We know that UV radiation is bad for us.  Tanning beds increase the risk of melanoma [2] and sunscreen decreases it [3].  When the current study broke down their numbers, the all-cause mortality related to sun-exposure was lower, but the cancer risk was higher.

Despite the risk of cancer increasing with sun-exposure, the cardiovascular causes of death were much lower, but this may be nothing to do with sun-exposure at all, but may be all to do with exercise, something the study failed to account for as an independent variable.  Time outside is usually going to be active time – exercising, gardening, walking, etc., and it may simply have been that those women who had the most sun exposure also did the most exercise or were the most active, which is common sense.

So the article isn’t able to prove that the health benefits which they ascribe to sunlight aren’t from something else.  Their cohort of subjects also doesn’t allow for a broad application of the results given their lack of UV intensity in their climate compared to other parts of the world.

I don’t think this study is enough to reverse the current wisdom about sun exposure.  It’s ok to have a few minutes of exposure to sunlight on your face, arms and hands most of the year, although some people in areas of higher latitudes (closer to the poles than the Equator) may need some more sun exposure in winter.  Look at information from a cancer council in your area for locally appropriate information.

So, keep your pants on, and the rest of your clothes for that matter.  We don’t need to expose ourselves and get a tan to live a longer life.

References

[1]        Lindqvist PG, Epstein E, Nielsen K, Landin-Olsson M, Ingvar C, Olsson H. Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort. Journal of internal medicine 2016 Mar 16.
[2]        Boniol M, Autier P, Boyle P, Gandini S. Cutaneous melanoma attributable to sunbed use: systematic review and meta-analysis. Bmj 2012;345:e4757.
[3]        Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up. Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2011 Jan 20;29(3):257-63.

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Dr Caroline Leaf and the matter of mind over genes

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I think I might have to throw away my genetics textbook.

I was always taught that genes were the main driver behind health and disease, and I always thought it was a pretty good theory.

But not according to Dr Caroline Leaf, communication pathologist and self-titled cognitive neuroscientist, who said on her social media feeds today, “Our health is not controlled by genetics – our health is controlled by our mind.”

Taking her statement at face value, she appears to be saying that genes have nothing to do with our health. Dr Leaf has made some asinine statements in the past, but to suggest that genes are irrelevant to human health seemed so stupid that no one in their right mind would suggest such a thing.

Perhaps I was taking her statement the wrong way? I wanted to make sure I didn’t jump to any rash conclusions about Dr Leaf’s statement, so I pondered it at length. Could she be referring to ‘control’ in the absolute sense? How much control do genes have on our health? What about the mind?

After deliberating for a while, I still came to the conclusion that Dr Leaf’s statement was nonsense.

Unfortunately, Dr Leaf’s statement is, like so many of her previous Facebook memes, so vague as to be misleading. The meaning of ‘health’ and ‘controlled’ could be taken so many ways … which part of our health? How much regulation constitutes ‘control’? What about genetics?

Looking at her statement in more depth, it becomes clear that no matter which way Dr Leaf meant it, it’s still wrong. For example, all of human health is controlled, in part, by genetics. That’s because life itself is controlled by genetics. The human genome provides a blueprint for the construction of all of the proteins in all of the cells in our entire body. The expression of those genes determines exactly how our body will run. If the genes are wrong, if the translation of the gene code into a protein is wrong, or if too much or too little of a protein is made, all determines whether our body is functioning at its optimum level or not.

The stimulus for the expression of our genes is influenced by the environment in which we live. If I go out into the sun a lot, the UV light triggers my skin cells to make the protein melanin, which makes my skin go darker and helps to provide some protection against the damaging effects of the UV light.

While the environment plays a part of the expression of some genes, it’s wrong to say that genetics doesn’t control the process. If I go into the sun too much, I risk developing a melanoma, because the sun damages the genes in some of my skin cells, causing them to grow without control.

Genes are still responsible for the disease itself. Sometimes the trigger is from the environment, sometimes it’s not. There are some people with genes for melanoma who don’t need an environmental trigger, because they develop melanoma on skin that’s exposed to very little UV light, like the genital skin.

So fundamentally, even taking the environment into account, our health is controlled by our genetics.

The other part of Dr Leaf’s meme is also wrong. Our health is not controlled by our mind. Our genes are influenced by “the environment”, which according to the seminal paper by Ottman, “The environmental risk factor can be an exposure, either physical (e.g., radiation, temperature), chemical (e.g., polycyclic aromatic hydrocarbons), or biological (e.g., a virus); a behavior pattern (e.g., late age at first pregnancy); or a “life event” (e.g., job loss, injury). This is not intended as an exhaustive taxonomy of risk factors, but indicates as broad a definition as possible of environmental exposures.” [1]

Even if one considers the mind as part of the sub classification of “a behavior pattern”, it’s still pretty clear that most of the factors that make up our environment are not related to our mind at all but are related to the external world, of which we have minimal or no control over. Sure, we make choices, but our choices aren’t truly free. They’re constrained by the environment in which we find ourselves. In the same way, our mind may have some tiny influence on our health, but only insofar as our environment and our genes will allow.

When it all boils down, this meme of Dr Leaf’s is rested on her foundational presumption that our mind can control matter, a very strong theme throughout her most recent book [2], but which is still preposterous. Our thoughts are simply a function of our brain, which is in turn determined by the function of our nerve cells, which is in turn a function of our genes and their expression.

Our mind doesn’t control matter. Matter controls our mind.

I can keep my genetics textbooks after all.

References

  1. Ottman, R., Gene-environment interaction: definitions and study designs. Prev Med, 1996. 25(6): 764-70 http://www.ncbi.nlm.nih.gov/pubmed/8936580
  2. Leaf, C.M., Switch On Your Brain : The Key to Peak Happiness, Thinking, and Health. 2013, Baker Books, Grand Rapids, Michigan: