Dr. Paul Mason - 'Sunlight and health - from Vitamin D to Fish oil'

today I'd like to take you on a journey looking at the potential health benefits of the Sun and I was really heartened to see so many hands go up indicating that you had actually been out in the Sun this morning because sunshine is actually really very good for our health and what might surprise a lot of you is that it's not all about vitamin D in fact when we have a look at the data probably very little of the benefit is about vitamin D and in the process of this exploration we're going to uncover some surprising facts not the least of which is that even having a skin cancer is often associated with no decrease in our mortality so we're then going to explore different ways that we can expose ourselves to the Sun to make it safer as with all my lectures this should not be considered personal medical advice this is my personal interpretation of the science and if you want personal advice then please consult your physician now I want to start by talking about sunshine there's something special about sunshine that makes us live longer even after accounting for skin cancer sunshine reduces the rate of death from a number of conditions and it's probably not an effect of vitamin D this is a graph from the World Health Organization and it shows death rates between the two hemispheres and what you'll see here in the red line the southern hemisphere which is where we are is that the mortality rate peaks in July our winter and we can see the reverse in the northern hemisphere and predictably the equatorial countries shown in gray have much less variation and this trend still persists even when we statistically control for things like influenza now this is not conclusive evidence of a benefit of sunshine but it certainly does give food for thought let's take a look at a Swedish study that had over 38,000 females and all of them 415 years and it assessed sun exposure and their chance of dying or mortality and this was from the results table of that study and it compared those with a history of sunbathing vacations and yes in Europe that is a thing compared with those who had never been on a sunbathing vacation and what they found was that there was a statistically significant trend for lower mortality in those who had been on sunbathing vacations and perhaps even more surprisingly was they had a similar finding with the history of sunburn those people without a history of sunburn had a higher death rate than some of those with a history of sunburn so in a similar vein let's have a look at another study but rather than looking at sun exposure let's look at Sun avoidance this was also asked where you stayed and it looked at almost 30,000 females over 20 years and it compared some exposure behaviors to mortality and the different shades of grey you can see here in the graph represent different causes of mortality and this first graph shows the mortality over a 20-year period in those with the most active avoidance of the Sun this second graph shows the mortality rate in those with moderate sun exposure and as you can see the rate of mortality is clearly less than in the first group and finally this is the group with the most active sun exposure and you can see even further a larger reduction in mortality now to appreciate how large this effect was smokers who had the highest level of sun exposure had an equivalent level of mortality as non-smokers who have the lowest this suggests that the magnitude of effect of avoiding the Sun could actually be comparable to smoking which is really quite astonishing now again this doesn't prove causation but it certainly gets us thinking so let's now address the big elephant in the room when it comes to sun exposure and that's skin cancer we need to balance the harms and risks of the Sun and UV radiation has been clearly associated with skin cancer in a dose-dependent fashion that is the more sun exposure we have the more likely we are to have skin cancer but on the other side of the coin UV radiation is associated with a reduced risk of about 14 other different types of cancers as well as reducing the risk of heart disease and diabetes so let's have a look at a study that looked in particular at skin cancer and mortality and this study was based on the entire Danish population over the age of 40 40 years all 4.4 million of them so this graph here compares the mortality rate in those with a diagnosis of melanoma skin cancer compared to those without a history of any skin cancer so the light gray line here shows those with melanomas and the darker line here shows people without any skin cancer and you'll notice that there's very little variation between the two groups having a melanoma in this population didn't seem to significantly impact on lifespan what about non melanoma skin cancer squamous cell carcinoma in basal cell carcinoma well you can see here in the light grey line that those with non-melanoma skin cancers on average lived longer than those without any skin cancer repeat those with non melanoma skin cancer lived longer than those without and by some margin - comparing the age of death along the bottom scale there you can see there's almost 10 years difference between the two groups now not every study has replicated this finding its population does and the experience of an individual could be different but it does indirectly indicate that even in the presence of skin cancer sun exposure might be beneficial and to understand why sun exposure could be so helpful we need to understand a little bit more about ultraviolet radiation ultraviolet radiation has a smaller wavelength than visible light and we divided into three categories UVA UVB and UVC which you can see on the left hand side UVA which you can see in yellow easily penetrates the atmosphere and most of it reaches the ground in contrast a lot of the ultraviolet B radiation is attenuated by the ozone layer before it reaches the ground and this point is really important because it means that the thicker the layer of atmosphere that it passes through the less of it that will end up striking the ground and that means that at different times of day a relative exposure to UVB can be significantly different and having a look at UVC we can see that none of it strikes the ground at all so we don't have to worry about that from here so when the Sun is directly overhead it's passing through the shortest amount of atmosphere before it reaches us so we're getting relatively proportional amounts of UVA and UVB exposure but when the Sun is lower in the sky as in earlier in the day and later in the day the UV radiation passes through a much greater massive atmosphere and especially the ozone layer and this mostly affects UVB levels so you can see here in this graphic that when the sun's coming up in the morning the amount of ultraviolet B radiation is actually far less but the amount of UVA radiation is relatively preserved so let's take a closer look at UVB radiation this is the main cause of sunburn and it's the principal cause of skin cancer both accumulated UVB exposure and intermittent intense exposure have been shown to contribute to different types of skin cancer on the other side of the coin though UVB is what leads to the production of vitamin D and a skin from cholesterol and it's this vitamin D that many people attribute the health effects of the Sun to but as we're about to learn while vitamin D is really important for a bone health it significantly impact our lifespan in a way that we've seen from the previous studies UVA in contrast is far less implicated in skin cancer to a degree it can cause a slight increase in risk but much less than with UVB it does play a role in skin aging especially with pigmentation changes and it might also contribute to wrinkles but this is one of the most important things that I'm going to say today UVA radiation releases a substance called nitric oxide in the skin and this is a substance which actually helps you live longer I'll repeat UVA radiation releases a substance called nitric oxide into the skin and it's this nitric oxide which explains the link between reduced mortality and sun exposure these pictures here show how nitric oxide is increased by increasing exposure to UVA radiation now when we get exposed to the Sun we get both UVA and UVB radiation so we produce vitamin D and we release nitric oxide at the same time so it's quite logical that our vitamin D levels to a degree would reflect all cause mortality if indeed that's what that's where we're getting the benefit but just remember the benefit comes from nitric oxide not vitamin D the vitamin D is just a surrogate marker that's not to say vitamin D is not important because it is so this here is an x-ray of a six-year-old boy with a condition called rickets and this is a problem that's caused by vitamin D deficiency it results in deficient mineralization of the bone and that's why these bones have bent because they're soft they can't support his weight without bending now it used to be thought that rickets was a condition of a bygone era something that we shouldn't really see in modern medical practice I've diagnosed two cases in just the last three months so vitamin D deficiency is still a very relevant public health issue in Australia today the problem is vitamin D just doesn't explain the ink last man it is incredibly important for bone health but it doesn't give us the huge mortality benefits that we saw from the other epidemiological studies so where does vitamin D come from well we can get about five to ten percent of our daily requirements from food now very few foods naturally contain vitamin D fatty fish liver and eggs but what's that you say well as margarine here well in Australia table margarine is mandated to be fortified with vitamin D and perhaps concerning lis it ends up being one of the major sources of dietary vitamin D in the Australian population it's clear though that most people don't get enough vitamin D from the diet so another source is needed and as you now know that sources of sunshine UVB rays strike the skin and convert cholesterol in the skin to vitamin D and it's also when the Sun strikes our skin we get a little bit of UVA exposure and that produces nitric oxide but as we said vitamin D could be predicted to be associated with all cause mortality because it's also associated with nitric oxide release and this is indeed what we see this graph here is from a meta-analysis which pulled the results of 32 individual studies comparing the risk of dying between individuals with varying levels of vitamin D on the left you can see the risk of dying and along the bottom you can see the vitamin D levels and what you can see is that in those with the low vitamin D the risk of dying is almost double that of people with high levels of vitamin D and this is from a cohort study of almost 10,000 German men between the ages of 50 and 74 and it followed them for nine and a half years and they compared their death rates in two different groups based on whether they had low vitamin D levels less than 30 nano moles the leader or higher vitamin D levels more than 15 animals a leader and the decrease in height of the line represents increasing mortality in other words the more than line drops the more people died and what you can clearly see here is that those with lower levels of vitamin D had a much higher rate of death than those people with a higher wall so then what does this mean when I test the vitamin D of one of my patients and it comes back low as in this lady what do I do is it worth me supplementing her with vitamin D this was a 44 year old office worker and she didn't see much Sun and when she did she was always very careful she always covered up wore a hat wore sunscreen she made sure that she looked after her skin so in this case should I give her a vitamin D supplement let's see what the evidence shows now remember the big difference in lifespan that you saw with very high and very low levels of vitamin D well let's see what happens when we give vitamin D as a supplement this was a study of more than 2,600 subjects and they were randomized to receive either 800 international units of vitamin D a day or a placebo and then they were followed for five years and the two lines here measured the death rate the higher the line the higher the death rate and you can see there's virtually no difference between the supplemented group represented by the solid line and the placebo group represented by the dashed line and this finding has been replicated many times these are two systematic reviews both of which found no significant benefit from vitamin D supplementation with respect to mortality the top one reviewed 13 observational studies and 18 experimental trials and found no significant benefit the lower one looked at 290 prospective cohort studies and 172 randomized trials and also found a big discrepancy between the benefits seen in observational studies and the benefits seen in the interventional studies that is those studies in which people were given vitamin D tablets so this leads us to conclude that vitamin D is probably not the answer so let's take a closer look at nitric oxide the substance that's released in the skin in response to UVA exposure this is the study in which participants were exposed to either real or sham ultraviolet radiation of the UVA type and the effect on blood pressure was monitored and you can see here that the real UVA exposure in the lower line led to a much more significant drop in blood pressure than the Sham UVA and this effect occurs because nitric oxide which is released from UVA exposure to the skin actually relaxes our blood vessels and this also impacts our blood pressure outside of the laboratory remember the graph from the World Health Organization showing that mortality rate is actually lower in summer well this also happens with blood pressure where we see lower blood pressure in summer than in winter and it's got a very tight correlation with UVA exposure and this is really important because high blood pressure or hypertension is a major risk factor for heart attack for stroke and a host of other vascular diseases which is why we see this peak in heart attacks in the winter now nitric oxide also benefits our blood glucose level by improving the sensitivity of insulin and high blood sugar is known as a respecter in many diseases heart attacks stroke dementia and here we can see that the addition of sodium nitroprusside which breaks down to nitric oxide allows insulin to remove sugar more effectively from the circulation so then we might predict that blood sugar control would be better in summer than winter and that's exactly what we see this is a measurement of average blood sugar using a test called hba1c and that measures how much glucose is in the circulation over a period at about four to six weeks and this graph from a northern hemisphere studies shows that hba1c is significantly lower in the soul and understand that hba1c is one of the most powerful markers of disease that we have a reduction in hba1c is very significant so if indeed nitric oxide where's that blood pressure and improves our blood sugar control the question is how do we get more of it from sun exposure while minimizing our risk of skin cancer now remember when the sun's lower in the sky learn receiving proportionately more UVA and UVB and it's that UVA that produces more nitric oxide well it then makes sense to expose ourselves to the Sun more when the Sun is lower in the sky and this craft demonstrates that ratio is much better earlier and later in the day than when the sun's overhead that solar noon now to put the flipside on to this if we get a optimal exposure of UVA at the extremes of the day then right in the middle of the day we probably have a suboptimal exposure to UVB and that's shown by this which is called the UV index now the UV index is basically something that reflects the tendency of the Sun to cause sunburn and because of that because it's UVB especially shortwave UVB that causes sunburn the UV index is heavily weighted to shortwave UV the UVB variety now it's a linear scale so that means that a UV index of 10 will burn you twice as quickly as a UV index of 5 and so on generally if the index is 2 or under there's no risk of sunburn in most individuals and if it UV index is 3 or 4 then most individuals could spend an hour in the Sun without protection without significant risk of sunburn it goes without saying though that your personal skin type does come into that so you do need to be cautious and some people taking certain medications will sensitize them to the sun exposure so that shouldn't be taken as a concrete rule now what happens if you're outside and you don't know what the UV index is well you can use the length of your shadow as a pretty good surrogate marker remember that when the sun's low in the sky you're getting proportionately more UVA unless UVB and that's when a longer shot always be cast now there's various interpretations of what shadow lengths you should be concerned about but generally speaking if your shadow is as tall as you are you should be able to spend at least half an hour in the Sun without any protection now many people conflate temperature with UV exposure now what do I mean by that it's your outside and it feels hot so your assume you're getting more UV radiation so I'd like you to look for a moment at the blacklight here which represents the UV radiation and you can see that it peaks at about one o'clock now I want you to have a look at the red line representing temperature and you can see that that's peaking at about 6:30 but at the time the temperature Peaks it's actually associated with quite a low level of radiation so don't rely on temperature using your showing will be a much better guide so now I'd like to move on to have a look at other means of reducing skin cancer risk primarily supplements and medications the risk of skin cancer is much higher in people with diabetes there is a silver lining though one of the drugs most commonly used to treat diabetes metformin might actually reduce the risk of skin cancer so this was from a study published earlier this year and it compares the rate of skin cancer against total lifetime dose of metformin and it found that those who had a higher type total lifetime dose had a much lower risk of skin cancer and you can see that the group who never used metformin had more than four times the risk of skin cancer than the group who used at the most so good news for some diabetics let's have a look at something called nicotinamide or vitamin b3 this was an excellent study done here in Sydney actually and 386 participants with a history of non melanoma skin cancer were randomly allocated to either receive a placebo or this vitamin d3 500 milligrams twice a day for 12 months and what they found was that there was a significant reduction in skincare mainly due to a reduction in squamous carcinomas and squamous cell carcinomas and this indicated that if you had a history of non melanoma skin cancer it would probably be worthwhile supplementing with this I want to now move on to one of my favorite topics omega-3 found in fish oil in this study 15 volunteers took high doses of fish oil for up to six months and they're tended to for sunburn was assessed now how do you assess that well we do it by exposing them to varying amounts of ultraviolet B radiation and then reviewing them 24 hours later to see the skin response and the smallest amount of UV radiation that it takes to cause the detectable reddening of the skin basically a sunburn is recorded the technical term for this is minimal erythema dose and this process was done before and after supplementing with fish oil for six months and the effect was significant on the left side here you can see the dose of radiation causing sunburn before there's the supplementation and as you go down to the right you can see that the dose of radiation required to cause this burn damage to the skin significantly increase so it more than doubled after six months so effectively that meant that you could spend twice as long in the Sun without getting burnt the benefit wore off pretty quickly after stopping the fish although so it seems that a continuous dose of fish oil is probably necessary and there's another benefit of omega-3 fat supplementation which is very relevant to skin cancer and that's got to do with the immune system the immune system doesn't just attack pathogens like bacteria and viruses it can also play a role in identifying and neutralizing abnormal cancer cells so anything that leads to impairment of the immune system potentially increases the risk of cancer and it's well known that people on immune suppression therapy like those people have had organ transplants have a much higher rate of skin cancer and we know that UV radiation impairs the immune system and many people experience this after they've been out in a weekend and they get an outbreak of cold sores and studies have shown that if we expose mice to chronic doses of ultraviolet radiation they're not able to reject transplant and tumors like healthy mice so the immune suppressant effect of UV on the skin is really significant when it comes to skin cancer and in this study they explored the immune suppressing effect in people taking fish oil and those without there was a study of 79 females and what they found was a significant reduction in the immune suppressing effect in those who took fish oil for three months and this is a combined meta-analysis and systematic review that compiled the data from 11 observational interventional and mechanistic studies on the risk of skin cancer and omega-3 supplementation and it found that the consumption of high levels of omega-3 fats was associated with a 48% risk reduction in melanoma and this fits very well with the data we've seen on sunburn and immune suppression so this then leads to the logical question how do we optimize the level of omega-3 fats in ourselves and it's at this point of a story I'd like to introduce a villain this is vegetable oil except it doesn't come from vegetables the council seeds and before it found its way into our food supply it used to be used as a machine lubricant but that's not the problem the problem is vegetable oils are very rich in omega-6 oils omega-6 oils are shown here in yellow and you can see that vegetable oils by and large have very large quantities of them and correspondingly very small volumes of omega-3s shown in orange and the problem is that omega-6 fats are quite common in skin cancer they increase the production of among other things something called the series two prostaglandins and these increase the inflammation and carcinogenic expression within the skin in response to ultraviolet exposure omega-3 fats on the other hand they lead to the production of series 3 prostaglandins which inhibit these processes and if we increase our omega-6 level well this leads to a reduction in our omega-3 level so remember that marjorine well it might have been fortified with vitamin D but it was loaded with omega-6 reducing your ability to spend time in the Sun so maybe it wasn't such a good deal after all let's take a look now at how we can use the relationship between omega-3 and omega-6 to our advantage this was from a dietary intervention study no supplements were used just changes in diet and in this part of the study participants were placed on a low omega-6 diet the kind without vegetable and seed oils no margarine let's first of all look at the omega-3 index shown here in white and what we can see is that over 12 weeks the omega-3 EPA in our red blood cells increased by 21 percent and if we have a look at the omega-6 levels in red we can see there's a corresponding reduction of about 21 percent 26 percent all in all that's not too bad but it's not amazing either let's see what happened when we increase the omega-3 intake now we see a massive increase of omega-3 of two hundred and seventy one percent and normally double the reduction in omega-6 the 50 percent and remember these changes occurred with diet alone no supplements were used so the combination of both reducing omega-6 and increasing omega-3 is very effective and almost certainly will help to protect from some of the damage caused by ultraviolet VIII radiation so let's recap what we've covered today firstly the UVA radiation from Sun Shine releases nitric oxide which seems to be associated with a mortality benefit it's mainly ultraviolet irradiation that cause the sunburn and most of the skin cancer risk and we can reduce our exposure to UVB while still getting enough UV by exposing ourselves to the Sun when it's lower in the sky perhaps by using a shadow as a proxy and of course if we're concerned that we're not getting enough vitamin D due to the reduced UVB exposure we can always supplement and if you're diabetic you can probably reduce your risk of skin cancer by taking that Foreman and if you have a history of skin cancer taking nicotinamide seems to reduce the risk as well and getting the right balance between omega-6 fats and omega-3 fats seems to be incredibly beneficial reducing our risk of melanoma and also increasing our resistance to sunburn so in closing appropriate sunshine exposure is actually good for our health and militantly avoiding it probably caused us more harm than good and if we do want to expose ourselves to the Sun and then there's ways and means that things that we can do to make it safer thank you

Channel: Low Carb Down Under

Views: 144,347

Rating: 4.8849001 out of 5

Keywords: Low Carb Down Under, LCDU, www.lowcarbdownunder.com.au, Low Carb Sydney November 2018, #LowCarbSyd, Vitamin D, Fish Oil, Omega 3, Omega 6, Diabetes, sun exposure, skin cancer, UVA, UVB, Low Carb Doctors, Nitric Oxide, cardiovascular disease, UV Index, metformin

Id: Kvh4D_osFXs

Length: 29min 49sec (1789 seconds)

Published: Wed Feb 20 2019

Reddit Comments

[u/unibball]

He's very engaging and has great info. I just wish more presenters and writers would be more assiduous about the difference between "linoleic" acid and "linolenic" acid. Not being careful about that difference makes the presentations appear a bit sloppy with the info.