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Sun bathing for cancer prevention

Phew, what a scorcher! Well, if you are even close to my age you’ll remember a few hot summers back in the day when the newspapers ran those headlines, and it certainly feels like that this week. I am sitting outside at my laptop typing this in 33 degrees and the black plastic keyboard is getting so hot it hurts my hands to type! I may have to retire inside before I finish this post!

I want to write about the benefits of sun exposure. In last week’s Weekly Weigh-In I explained that the benefits of regular, responsible sun exposure vastly outweigh the risks, and I explained the responsible bit, which I suggest you go back and read again! The goal is to spend some time outside every day, exposing some skin and making vitamin D naturally. The goal is not to stay inside for 50 weeks of the year and then burn for two weeks on holiday! And tanning beds are not the answer either!

I’m pretty much going to just repeat that message (it is worth repeating, as we swelter in summer heat) in this post, but before you close this and stop reading, we’ll add a bit more detail and back it up with a little bit more science.

Multiple studies show than overall, adequate levels of vitamin D have a protective effect against several common cancers, including some of the most common, such as breast cancer, colorectal cancer and prostate cancer. Breast cancer and prostate cancer are the most common cancers in women and men (respectively) in the UK.

Personally, I think it is important to remember that while skin cancers are quite common, they are also among the easier cancers to detect and treat, so survival rates are high. Skin cancer mortality in the UK is very low compared to breast, prostate and bowel cancer. In my opinion, if good high levels of vitamin D offer proven protection from breast, prostate and bowel cancer, then the small risk of occasionally burning and possibly promoting skin cancer is a risk well worth taking. Especially if we factor in all the other benefits of sun exposure and good vitamin D levels.

As an aside, it’s also worth noting that while adequate levels of vitamin D are recommended for cancer prevention and many other benefits, it’s not always a case of ‘more is better’. There seems to be no evidence so far that excessive vitamin D offers any proven benefits, and indeed at extremely high levels, vitamin D can prove toxic. I don’t want to sound like I am saying ‘Mother Nature knows best’ but it seems she does! The perfect level of vitamin D is the level you would have is you spent your life outside as a hunter-gatherer, as our ancient ancestors did for hundreds of thousands of years. Before we built buildings and cars, before we invented tanning beds and sunscreen, before we had desk jobs and worked in windowless warehouses…when we lived in tune with Nature, our sun exposure and vitamin D levels were spot on. Who knew!

Sun bathing yes…sun beds no

Now here comes an interesting twist. While regular responsible sun exposure is proven to be beneficial and reduce all-cause mortality (regular sun means you’ll live longer), it seems use of tanning beds has the very opposite effect, and increases all-cause mortality (regular sun beds and you’ll die younger).

At this point, scientists cannot give us a definitive reason why. Sun exposure is a positive gain, and we know that vitamin D is the mechanism. We also know that vitamin D supplementation offers similar benefits with little or no down sides, and it is cheap as well as effective. While here at Mother Nature’s Diet you will very rarely find us recommending any supplements, we do support vitamin D supplementation, as it seems to tick all the boxes. It works, most of us need it, and it’s cheap and easy. For us folks living up here in Northern Europe, I recommend taking a moderate-dose high quality vitamin D for the winter half of the year.

You can buy a quality daily 5,000 IU supplement online for just five or ten pounds and one bottle will last you the entire winter. So in the summer half of the year you get out and get some sun, and in the winter half of the year you still get outside every day, because it’s good for you, but the sun over the UK is not strong enough in winter to stimulate vitamin D production, and the weather is usually too cold to get your short off anyway, so for ten quid per year, you take a supplement. There, that’s easy, right?

But we have to wonder why sun exposure is broadly good and increases mortality, yet tanning beds are broadly bad and decrease mortality? Ummm…there is no definitive answer, but I’ll take a stab and give you my best guess, then you can decide for yourself.

We know that natural sunlight is made up of a broad spectrum of light wavelengths, including visible light (enabling me to sit here and type this right now!), infrared light, and ultraviolet (UV) light. We know that the UV light is made up of UV-A, UV-B, and UV-C.

[I could hypothesize that maybe there are further elements to the invisible light spectrum that we just have not detected yet. Possible, right? I mean, science is constantly making new discoveries. Once we thought atoms were the smallest thing, then we went down to electrons…down to quarks…down to the Planck length…we just keep discovering smaller things! As the sun is the most massive radioactive generator around, and we have never flown there and stuck probes on it (yikes!) who knows what we are yet to discover about sunlight. Just an idea!]

The sun generates UV-A, UV-B and UV-C (though no appreciable amount of UV-C reaches the earth’s surface), and tanning beds generate UV radiation that attempts to emulate this, producing mostly UV-A and a small amount of UV-B. I suspect that there are differences in the make up of wavelengths in natural sunlight, and tanning bed light. It seems to me highly likely that the artificial light from tanning beds is slightly different to the natural light we get form the sun, and as such our DNA does not recognise the light from tanning beds as sunlight. Instead, our skin sees a source of ultraviolet radiation, a known class 1 carcinogen, and this is harmful. (You see alcohol on that list of known class 1 carcinogens too? #justsayin’)

Some people say that the use of sunscreen is actually making skin cancers worse, not better. Experts say the jury is out from a scientific point of view, but they are not happy allowing sunscreen manufacturers to claim sunscreen offers any protection from skin cancer.

I do not like sunscreen, as I am broadly not in favour of covering our skin with chemicals, some of which we absorb into our blood stream, so I admit that maybe my opinion is a little biased here. However, I think sunscreens work by blocking much of the UV-B of sunlight, but allowing most of the UV-A to still get through. Now, just like with tanning beds, the result is that sunlight filtered through a sunscreen, ends in a version of ultraviolet light that your DNA does not recognise reaching your skin. Your DNA will not know what this is, just that it is a potentially carcinogenic form of ultraviolet light. Confusion for your DNA, and a possible cancer risk in my opinion.

Given all that we have looked at, I wonder if the reality is that:

  • Natural sunlight benefits us because it helps us make vitamin D in perfect amounts
  • Dietary vitamin D can help, so eat that oily fish!
  • And supplements can help too, so in our society where most people are somewhat vitamin D deficient, taking a supplement for the winter half of the year is probably a good idea
  • However, tanning beds cause problems because they produce an artificial light, which our DNA does not recognise as sunlight, but instead our DNA sees it as a carcinogen
  • Sunscreen also results in an artificial light reaching our skin, so while sunscreens stop sun burn, they end up delivering a light that our DNA does not know what to make of, and is in fact a potential carcinogen

I don’t know all the answers, not for sure, but I think the Mother Nature’s Diet way is best - make time to get outside every day; enjoy the sunshine and fresh air of the great outdoors all year round. When it’s warm and sunny, get outside even more and show some skin, just ten minutes with your shirt off in warm sun will make more vitamin D than the best diet can generate in a week. Use a good quality vitamin D supplement in the winter half of the year, and make sure you have some oily fish in your diet. Be responsible in the sun, try not to use sunscreen, but instead when you feel you have had enough, or when you are starting to go pink, cover up or move into the shade. Little and often works, build up your skin colour over a period of time.

To your good health!


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