It’s NBT highlights time! Every week we’ll send you a short email containing the following:
One piece of simple, actionable advice to improve your health and performance.
Something we would like to give a different perspective on, and why.
One awesome thing that we think you’ll enjoy!
One action to add to your health routine this week:
Get more time in the sun without sunscreen.
Believe it or not, sun avoidance has become a major public health risk! Reducing sun exposure originally made sense as part of an effort to reduce skin cancer. However, the unintended consequences (such as increased vitamin D deficiency and a greater risk of many autoimmune diseases and other cancers) perhaps created an even larger problem than the one we were trying to fix. Though sunburn does increase the risk of all skin cancers, getting some sun exposure actually reduces the risk of melanoma! There are a number of potential mechanisms, including the effect of local vitamin D production in the skin. Other factors for melanoma should also be considered, such as genetics and family history.
Total time in the sun does increase the risk of non-melanoma skin cancers, but these can usually be treated with surgery, and they rarely metastasise. Balance that risk with data such as that from this study in Sweden, where complete sun avoidance was associated with the same mortality risk as being a smoker! In fact, the more Northern your latitude, the more beneficial (and less detrimental) chronic or occupational sun exposure appears to be. Not to mention the benefits of bright light from the sun on circadian rhythm, blood pressure, and production of serotonin and melatonin.
Part of the problem with our current approach to sun exposure may come from sunscreens and how we determine their effectiveness. The Sun Protection Factor (SPF) is based on the degree to which UVB light is blocked, but not UVA. Therefore, when you apply sunscreens, you’re definitely reducing your ability to produce vitamin D (which requires UVB), but you’re not necessarily blocking all the rays that can cause sunburn, skin cancer, or aging of the skin (also caused by UVA). In fact, that UVB you’re blocking is probably protective in terms of melanoma risk. Not to mention that some chemical sunscreens may have endocrine-disrupting effects. Or, as Chris put it: “that lovely smell of suntan cream is, in fact, the smell of your testosterone going down.”
The best overall approach to increasing sun exposure (especially in the summer) is to slowly build-up your tolerance without sunscreen to produce protective melanin (i.e. a “tan”), and use physical methods (clothes and shade) more frequently, to prevent burning. Most studies guage time in the sun based on personal “burn time” or “minimal erythemal dose” (MED). For instance, if you would burn in 20 minutes, spending half of that time (i.e. 10 minutes) with 50% of your body exposed to the sun will produce around 4,000IUs of vitamin D. Which 50% you expose is entirely up to you... This should be enough to reverse a borderline deficiency over time, and is probably a good target to avoid sunburn. Maintaining a healthy level of vitamin D (roughly 40-60 ng/ml) will probably require something like 25% of burn time (~2,000IUs of vitamin D), 2-3 times per week. Unfortunately (or not!), you can’t get all the health benefits of sun from a pill.
If you’re going to use sunscreen, we’d recommend Zinc or Titanium oxides. These are more inert than chemical sunscreens, do not degrade in sunlight, protect against UVA as well as UVB, and don’t tend to be absorbed through the skin in appreciable amounts. Of course, checking vitamin D sufficiency with blood levels of vitamin D and parathyroid hormone (PTH) is the best way to make sure you’re getting enough sun for your own personal requirements!
A different perspective:
Trying to increase your testosterone levels? That might not always be a good idea…
The internet is full of articles giving guys tips on how to “increase” or “hack” their testosterone levels. While it certainly looks like testosterone levels in the population are dropping (probably due to various aspects of the Western lifestyle), we’re not sure that more is always better. For instance, did you know that men in successful relationships tend to have lower testosterone levels? Or that prisoners with higher testosterone are more likely to commit violent or sexual crimes? This may be because of the effect that testosterone has on the frontal cortex, decreasing both empathy and the capacity for impulse control (though having a higher socioeconomic status does confer some protection).
When it comes to absolute testosterone levels, nobody’s really sure what “optimal” is. For men over 40 years old, staying in the top 25-50% of the population in terms of total testosterone levels (i.e. above ~500 ng/dl) is definitely a good idea for overall health and longevity. Beyond that, we’d resist the temptation to keep forcing testosterone levels higher. While there is definitely a place for testosterone boosters and testosterone replacement therapy (TRT) to improve health in men with hypogonadism, working hard to artificially increase your testosterone levels may just result in poorer decision making and a worse relationships! And if done inappropriately, may also increase the risk of cardiovascular disease.
The best approach is to focus on aspects of health that might be reducing your testosterone levels and sexual function such as poor sleep, job stress, chronic infections/inflammation, excess training stress, undereating, metabolic disease, refined carbohydrates, and exposure to endocrine-disrupting chemicals. This will allow your body to make the amount of testosterone it naturally wants to. We’ve had many guys who, after fixing their gut, stress, training, and circadian rhythm, are off the TRT and harder, faster, and recovering better than ever! No fancy hacking, pills, or creams required.
As well as testosterone, want to learn more about the things that affect our neurochemistry and decision making? We can’t recommend the work of Professor Robert Sapolsky highly enough! He recently made an awesome appearance on the Joe Rogan Experience podcast, has given numerous excellent talks, and also has a great Human Behavioural Biology course on iTunes.
Thanks for reading!
Tommy Wood, MD, PhD
P.S Got anything that you think is a highlight? We’d love to hear from you! Send your thoughts to email@example.com.
P.P.S If you’ve been diligently adding our highlights tips and other things to your health and fitness routine and you’re still not happy with your results, then some testing may be in order. At Nourish Balance Thrive, we’ve helped over 1,000 athletes identify and resolve the root causes killing their performance. Book a free consultation, and we’ll take a look at your history and share how we’d work with you as part of our “Elite Performance Program.”
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