9 — Sunlight & Vitamin D

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Episode Transcript

This is the Eat Ancestral podcast number nine. So I spend a lot of my time thinking about and talking about food. I think it's one of the most important things to get right, if you're wanting to live a healthy, functional life and avoid chronic disease, and a lot of preventable issues. But one of the things that we don't talk often enough about are other inputs that might be just as important as our nutrition. I think maybe nutrition has the edge, let's say, but I think these other things are also super important. And if we don't get them, then things certainly will not be optimised. One of those things is sunlight. I think it's a it's an essential input that our physiology is expecting. And I think if we don't get enough of it, then a lot of things will go wrong. People know about the vitamin D-sunlight connection, but vitamin D, even though that would be enough of a reason to get sunlight, as it's involved in pretty much all of our most critical biological functions, Vitamin D is only a fraction of the benefit of sun exposure. So today, I wanted to sit down, or I'm actually standing at my desk here, and talk about the benefits of sunlight and safe sun exposure. I grew up in Queensland, Australia, it's pretty hot there. My ancestors, recent ancestors, are from the Netherlands, and Scotland. So as you can imagine, there's a bit of a mismatch between my biology and the environment, I have red hair, and fair skin and freckles. And growing up in Australia, under the hot sun, it was a bit of a challenge, you know. We also like to spend a lot of time outside. So really, your options are quite limited; wear sun cream, like put it everywhere, even on your feet, basically. Haha. And, and then, you know, wear these big wide brimmed hats, you know, wear a rashguard when you go swimming, this kind of thing. These were our options; it was sun cream, or stay out of the sun or wear, you know, clothing that would help to protect you from the sun while you're swimming or whatever. And you know, it worked reasonably well. I don't think I got too many bad sunburns. My mum, when she was younger, had a melanoma on the back of a leg, which was a bit worrying. And so along with that, and my own experience, just not feeling very tolerant of the sun, and couple that with the public healthcare messaging, which was all about slip, slop, slap, and not not going out in the sun during the middle of the day. This all created in my mind, and I think has created for wider society, a bit of fear around sun exposure. And we think that if you are getting a tan that that's uncool and irresponsible, and if you're not wearing sun cream, and you're not covering up and you're not, you know, avoiding the sun during the middle of the day, then that you're gonna suffer in the future, you're gonna get skin cancer, you're going to have, you're going to have problems. And I just don't think it's that simple. And I don't think that messaging is very helpful. And I don't think it's very helpful because we know that sunlight is essential to many life forms. And it seems very, very important for our own physiology, for our own human biology to function optimally. And vitamin D is a good example here of the essentiality, the necessity of sunlight; it is our best source of vitamin D. And it's really hard to get enough vitamin D in our food, especially if you're not eating animal foods, animal fats, where you get these fat soluble vitamins in small amounts. But even if you are, the best place to get vitamin D is from the sun. If you're not getting sunlight, you're probably not getting adequate amounts of vitamin D, among other things. But if we don't get enough vitamin D alone, then all of our most critical functions won't happen. Vitamin D is so important. It's involved in so many different things. We think that almost every cell in our body has vitamin D receptors. And we know that it's involved in the regulation of a couple of thousand genes. Okay, so that seems pretty important. And that's just one benefit. That's one example of one benefit of sun exposure. And so I think we can say with a lot of confidence that sunlight is essential to human health, and vitality. And if we don't get enough of it, then a lot of things will go wrong. Now, on the flip side, we also know that overexposure to sunlight can result in skin burns, tissue damage, DNA damage, and possibly long term complications with things like skin cancers. So I guess where we have come to then is to realise that we can't avoid the sun completely. And we can't get too much of it. We need to find a little bit of balance; we need to find our individual tolerance and go from there. So I have a paper here from Baggarly et al., from 2015. And it's called Sunlight and Vitamin D: Necessary for Public Health. I thought they did a really good job of summarising some of the main points here and offering some interpretation. And I just wanted to go through a bit of their introduction just to give you a third party perspective. And then I will jump in and talk about some of the benefits and try and break it down and make it more digestible. So the introduction to this paper kicks off by saying; "The World Health Organization's International Agency for Research on Cancer recommends avoiding outdoor activities at midday, wearing clothing to cover the whole body and daily use of sunscreen on usually exposed skin. The American Cancer Society advocates Slip Slop, Slap and Wrap, to make sure skin is covered in clothing or sunscreen and to avoid exposure to the sun between 10am and 4pm. The US Surgeon General has issued a call to action focused on reducing ultraviolet exposure, whether from indoor UV or from the sun. Though these recommendations all focused on reduction of skin cancer are accompanied by brief acknowledgement of the importance of vitamin D for health, they persist in urging avoidance of the sun at the precise times when vitamin D can be synthesised in the skin, the hours between 10am and 3pm, and suggest that all necessary vitamin D can be obtained through food and dietary supplements." So that's interesting. So we're all focused on reducing skin cancer. As we can agree that is a good objective to have. However, in doing so, we have created a situation where we recommended that people avoid the sun during the precise hours where the body is able to leverage sunlight to manufacture vitamin D, which is involved in many important physiological processes. They're also suggesting by doing so that all necessary vitamin D can be obtained through food and dietary supplements. Listen, anyone who's telling you that you need supplements in order to get adequate nutrients.... unless those supplements are food, like organ supplements, then they're probably full of shit, I think you should be able to get pretty much all your nutrients from food. One major exception here is vitamin D, because our best source of vitamin D is not our food. You can find small amounts of it in animal foods, and it might help you get through the winter. But at the end of the day, our best source of vitamin D is from sunlight. So if we're not getting sunlight, we're not getting it during the hours, in which our body can actually synthesise vitamin D from it, then we're gonna run into problems. And these recommendations therefore, are a bit out of whack. They're a bit myopic. We're focusing on one thing and saying that, in order to prevent skin cancer, we should avoid the sun especially during these hours. But then when you pick that apart a little bit more you realise that, oh, okay, so if we avoid the sun during the middle of the day, we're definitely not getting enough vitamin D. And then we're going to have all these other problems. So it kind of makes sense, but it's a bit short sighted. So back to the paper here. "These recommendations are understandable from the viewpoint of preventing the 3.5 million new cases of and 2000 deaths from nonmelanoma skin cancer in the United States each year. But they neglect the fact that we have a long cultural history of appreciation of the sun, and use of UV radiation for healing purposes. Moreover, they neglect that we have evolved with physiological adaptations to help protect the skin from the sun when we are mindful of exposure and do not burn. They neglect the fact that increased sun exposure based on latitude has been associated with protection from several different types of cancer, Type 1 diabetes, multiple sclerosis, and other diseases. They also neglect the fact that exposure to the sun induces beneficial physiological changes beyond the production of vitamin D." So we know that vitamin D is critical to our most critical biological functions, if we don't get enough vitamin D, our gut health, our reproductive health, our metabolic health, our musculoskeletal health, our neurological health, our immune function, none of it will work as it should. And that is just a fraction of the benefit of sunlight. So I think, as I pointed out here, we've been a little myopic, in suggesting that we should avoid the sun, especially during those times. And that there's more here, there's more to this story than meets the eye. So let's stick with the vitamin D theme for just a little longer. I think it's really interesting to almost use vitamin D as a gauge for how much sunlight we might consider appropriate for our biology. And a bit further down in this paper, the authors are doing a bit of a cost-benefit analysis here. And they say that of the 30 leading causes of death in the United States in 2010, 19 were linked to low vitamin D status, including various forms of cardiovascular disease, various cancers, diabetes mellitus (that's Type 2 diabetes), Alzheimer's disease, and then falls and fractures in the elderly. And they said, if we were able to get vitamin D levels above a certain point, we would see massive reductions in deaths and massive savings in health care costs. And that raising vitamin D levels alone would be one of the most efficient and most cost effective ways of reducing the burden of disease across a wide range of diseases, and for increasing life expectancy, as well. And that a lot of the reason for this widespread vitamin D deficiency are these messages that we're receiving from the from the health authorities who are promoting avoidance of sun exposure and covering the skin with clothing and sunscreen, etc. The authors go on to talk about vitamin D and how how important it is for optimal health. And I thought this would be worth reading out because it does encapsulate a lot of these ideas with regards to vitamin D and why would be so important so foundational to human health and well being. And so I'm gonna read this section out from the paper. It says "In common with many other micronutrients, Vitamin D is a necessary but not sufficient factor for key cell biologic processes. That is, it is an enabler, it must be present for those processes to occur, but it does not itself stimulate or cause them. In brief, low vitamin D status does not so much cause disease or dysfunction, as it impairs cellular response to both internal and external signals. It is now recognised that essentially every tissue and cell in the body has vitamin D receptors. Furthermore, most cells also have the capability of converting 25 hydroxy vitamin D to its active form 1,25 dihydroxy vitamin D, and most of our daily vitamin D consumption occurs in this way. This conversion in the cell allows for allows each tissue to use vitamin D added as it is needed. It also follows that in the absence of vitamin D, none of our bodily systems can work at their optimal potential. Thus, it becomes clear that low vitamin D status would inevitably be involved in In a wide range of dysfunctions and diseases." So the next thing that the researchers go on to discuss is the issue of how much vitamin D is necessary for optimal health. And something they point out here, which I thought was quite interesting was that we need to consider our desired end-points. Because if our goal is just to avoid known diseases like tuberculosis and rickets, then we might undershoot the amount of vitamin D that is optimal. I don't know about you, but I am not interested in just getting by in life. I don't want to be anywhere near rickets. I don't want my immune system to be compromised. I want to optimise everything. So these researchers are speaking my language. Two of the ways that they are approximating optimal vitamin D status in humans is firstly by looking at two African tribes, the Maasai, and then the Hadza, who live in East Africa, where humans are thought to have originated and have daily sun exposure approximating that of early humans. And what they found is that these groups have an average 25 seram, 25 hydroxy vitamin D status of 46 ng/mL, If you're not living in America, this means 112 nmol/L. And I think that's really helpful because that can indicate to us how much on a daily basis we might need to be getting in order to gain that long term vitamin D status. And later on in the paper, the second way they've sort of tried to approximate the optimal level of vitamin D levels of vitamin D for humans, is by looking at pregnancy and childhood and growth and development. And what they are suggesting is that humans need about 6000 IU's of vitamin D per day, for normal physiologic functions, and pregnant mothers, nursing mothers might need a bit more, because if the mother doesn't have enough vitamin D herself, then it might not be passed on in adequate amounts to the foetus or to the child through breast milk. So these quite quite important parts of life. And we know that nutrient deficiencies during these critical times of growth and development, result in a wide range of a wide range of dysfunction, and diseases. And so I think this is a pretty interesting way of figuring this out. Because if you get roughly 6000 IU's of vitamin D per day, eventually, over the long term, if you put in the work day after day and get your daily sun exposure, then you will end up with a vitamin D concentration, which is on par with, or something similar to, these groups of humans who are approximating the lifestyle and sun exposure of our early human ancestors. So I think that's an interesting way of figuring out how much vitamin D might be necessary / might be optimal for humans. And that's what I'm personally shooting for, is somewhere in between 100 to 120 nmol/L, which is, you know, 40 to 50 ng/mL in the American lingo. And yeah, that roughly boils down to, I don't know, 4 or 5 or 6000 IU's of vitamin D per day, which I think makes it quite practical for us, because at the end of the day, it's not that long to be outside in the sun. You know, it could be, depending on your skin type, it could be 30 minutes, could be 45, 60 minutes. And, again, that makes it very practical for us in terms of our daily behaviours, and I think that's pretty easily obtainable for most people. Okay, so the benefits of sunlight obviously extend far beyond that of just vitamin D. And I wanted to go through a few examples of those now. So the first thing to understand is a little bit about sunlight. And you might find the graphic, the visual guide that I've put together, helpful here. And if you go to the show notes, you can hit a link, that'll take you straight to it. But basically, sunlight is composed of multiple wavelengths of light, it is not one entity. Now, these wavelengths as a group, we call the spectrum of solar radiation. And it starts with ultraviolet light wavelengths on the left, all the way over to infrared on the right. Only some of these wavelengths are visible to human eyes. So we can't actually see ultraviolet, like bees can, for example, and we can't see infrared either, but we can see the blue, the green and the reds in the middle. And it's interesting to note this because each of these wavelengths has unique effects on our physiology, so they don't all do the same things. And even though we can't see them, that doesn't mean it's not happening. So what are some of these physiological responses? First of all, UVA exposure triggers the release of nitric oxide, which triggers vasodilation, which improves blood flow and significantly lowers our blood pressure. So this is really important. Blood flow, the dilation of our blood vessels and the lowering of our blood pressure. High blood pressure, hypertension, is one of the biggest risk factors for cardiovascular disease specifically, but it's also involved in a lot of other dysfunction. And it's one of our biggest issues in the modern world is high blood pressure, especially in young males. So UVA also triggers melanin production, which is an increase in skin pigmentation. This is the tan that I was referencing earlier. And it also triggers the thickening of our skin. So it causes thickening of the stratum corneum, which is the outermost layer of our skin. So this increased skin thickness, and melanin, is this type of built in sun protection. And this response protects our skin from burning, and protects our deeper tissues from DNA damage. So that's quite cool. And yeah, the body has ways of protecting itself, we just need to know about them and to sort of encourage that to happen in a safe manner. Okay, so moving on from UVA, up next up we have UVB. And UVB is what actually is triggering vitamin D synthesis in our skin. And by the way, Vitamin D is more like a steroid hormone than a vitamin. And as you know, most of us are deficient in it. And this has system wide implications, right... gut health and immune function, brain health, bone health, our muscle health, reproductive health, it is critical. And so we all need to be making sure we get enough of that. I think this is a good moment to introduce the idea you might be already aware of this, that UVB is not available year round. So in the winter, depending on where you live, you might not be getting exposed to UVB. So you need to be aware of this and perhaps lean more on your dietary sources of vitamin D, or potentially even some supplements during that time of year. So for example, if you live in Northern Europe or North America, there's a period of time for about three months of the year through the winter, where UVB will not be in the atmosphere, meaning that you will not be able to synthesise vitamin D during those times. Another effect of UVB exposure is the triggering of beta-endorphin release, which is an opioid peptide that promotes relaxation, feelings of well being and helps out with our immune function as well. Moving on from the ultraviolet wavelengths. Next up we have blue light, which helps to regulate our melatonin production. And this is sensed through the photoreceptors in our eyes. So light signals received through the eyes helped to regulate melatonin production. And melatonin plays a key role in our circadian rhythms, which are our internal body clocks, and this has a lot of implications for things like sleep quality, recovery from exercise, hormone balance, immune function. Melatonin is colloquially known as, or popularly known as the sleep hormone. But it does a lot more than that. But one of the most important things we can do with regards to melatonin, and blue light is to get outside in the morning as early as possible after waking up and get some light in our eyes. Don't wear sunnies as soon as you walk out the door, otherwise, you won't be getting this signalling. And I, I forget who it was, but years and years ago, I remember one of my mentors said something about how a good night's sleep starts in the morning. And if you do this, and you get outside, and you get exposed to light, early in the morning, especially in the eyes and on the skin, this will really help you out with your sleep quality and a bunch of other things as well. So moving on from blue light, we're moving into the red and infrared part of the spectrum now. So red and infrared wavelengths had been found to relieve pain, reduce inflammation, and to promote wound healing. That is also very fascinating. You might have seen these red light devices that are on the market these days, these devices are leveraging these particular wavelengths, these red, these deep red and infrared way wavelengths. And there's a lot of impressive research behind this. But basically, you can get these effects from the sun, you do not need these fancy devices. But they can be used specifically in very interesting and helpful ways. So a couple of last minute ones here, sunlight triggers serotonin production, helps with our mood, and psychological health, and also is involved in the production of melatonin, as well. And last one here, sunlight enhances our energy production via the mitochondria. So some of these wavelengths can actually penetrate down into our deeper tissues and interact with our mitochondria, and enable our mitochondria to produce more ATP than they otherwise would have. So ATP is the energy currency of the body. And who'd have thought, sunlight helps you enhance ATP production. So I guess there are many more examples we could look at. And I bet there's a bunch more that we don't even know about yet. But I think at this point, the question is, what else do you need to know? Like sunlight is clearly essential for humans, in many ways is clearly very beneficial. I think that's why it feels so damn good to get out in the sunlight. Obviously, our job now is just to get the right amount. And so we must be careful, like with many things in life not to over indulge, we need to remember that excess sun exposure can cause skin skin burns, lead to tissue damage, DNA damage, and potentially skin cancer. So we obviously need to be mindful of our individual tolerance, and to practice safe or non burning sun exposure. And if you want to try and optimise your sun exposure, or you're typically someone who has spent a lot of time indoors and you have a lighter complexion than you, you're going to want to ease your way into it. Too much too soon, is a recipe for a sunburn. But you should be confident knowing that over time with intentional strategic exposure to sunlight, your body will adapt in many different ways, and it will benefit in many different ways. And I think the early morning sun is a great opportunity. It's much less intense than during the middle of the day. The evening sunlight is also similar in that way. But just remember the best time to get vitamin D from the UVB is during the middle of the day. So we should probably be getting a bit of both. Okay to wrap things up, I wanted to go back to the paper very briefly and read out their conclusion, or part of their conclusion here. They say; "The full solar spectrum is essential to optimal health and well being. Humans are physiologically adapted to produce vitamin D in response to sun exposure, specifically, UVB radiation, other regions of the spectrum seem to confer benefit as well. Though some vitamin D comes from our diet, and more recently from supplements, we should not ignore the natural capacity that we possess to produce our own. We are of the opinion that moderate sun exposure (less than the time required to burn, to the arms, shoulders, trunk, and legs) should be sought rather than avoided. Once that limited time has been achieved, se agree that covering the skin or seeking shade may be appropriate. The benefits of such exposure go beyond production of vitamin D, and include other physiological responses to sunlight still inadequately explored, including the release of nitric oxide, production of beta endorphin and regulation of circadian rhythms, all important components of lifelong health and wellbeing. The current policy of sun avoidance is creating probable harm for the general population." Okay, well there you have it. I hope you have found that valuable. Please let me know. if you have any suggestions, or feedback, I’d be happy to hear from you. If you would like to get in touch, if you want to work together, if you need some support, you can check out my Services page on my website, or just shoot me an email. There’ll be links in the show notes for those. Anyway, that’s enough for me today. My name is Ben, this has been the Eat Ancestral podcast, and we have been talking about sunlight. Take care, i’ll talk with you soon.

Transcribed by https://otter.ai