Jenni-star
Tue, Feb-15-05, 22:46
I Dont know if this is of interest to those SAD people out there, but i thought i'd post it in case you are interested. :wave:
Transcript from ABC Radio National, Australia
with Norman Swan
Vitamin D
7 February 2005
A leading laboratory at the University of Sydney has been investigating Vitamin D for many years. Associate Professor Rebecca Mason talks about their work.
Program Transcript
Vitamin D is turning out to be an amazing vitamin – not just because of its supposed effects on cancer. Just round the corner from Bruce’s office is a leading laboratory which has been investigating vitamin D for many years. They’ve findings which support the results from these studies on cancer. Associate Professor Rebecca Mason is Deputy Director of Sydney University’s Institute for Biomedical Research and Head of the Physiology Department.
Rebecca Mason: Vitamin D as you say is made in the skin. The skin accumulates a compound which on interaction with the UVB component of sunlight is converted to pre-vitamin D which in the skin gets then converted into vitamin D. You can’t make too much vitamin D from sunlight because the vitamin D then gets converted into what are called over irradiation products which -
Norman Swan: It’s a feedback mechanism which stops any more being produced.
Rebecca Mason: Yes, stops too much being produced so you can’t make too much vitamin D from being in sunlight. Small amounts of sunlight seem to make enough vitamin D, the vitamin D is then absorbed into the body, it’s converted into 25 hydroxy D in the liver, that’s what we measure to see if you’ve got enough vitamin D. So when you go to the doctor and say have I got enough vitamin D that’s what he measures. And then it gets converted into the hormonal form of vitamin D which is called 1,25 dihydroxy vitamin D or calcitriol.
Norman Swan: And when you give these numbers and letters it’s essentially just the different chemical structure?
Rebecca Mason: A different chemical structure but most of the hormonal effects of vitamin D are due to this calcitriol.
Norman Swan: So you’re calling Vitamin D a hormone?
Rebecca Mason: It is indeed a hormone and calcitriol is made in the kidney, mostly for its hormonal effects on bone.
Norman Swan: Meaning it’s a chemical messenger, it sends a message to different parts of the body?
Rebecca Mason: It sends a message to different parts of the body and as far as bone health is concerned that’s most of the story. But there’s a lot more of the story that I’ll tell you about in a moment.
Norman Swan: So vitamin D builds bone essentially?
Rebecca Mason: Vitamin D builds bone, it probably also has important effects in muscle. Now vitamin D builds bone because mainly it helps calcium absorption from the gut.
Norman Swan: So if you’ve got enough vitamin D on board, enough calcitriol from your kidney then your bowel is completely if you like more porous to calcium – it allows more in.
Rebecca Mason: It allows more in, you can absorb more of the calcium that you take in food and that calcium goes to bone and it stops bone breakdown because then bone doesn’t have to be broken down to provide enough calcium for other essential needs.
Norman Swan: Now there’s this fascinating story that people with enough vitamin D on board don’t break their hips as much as people who don’t have enough vitamin D and people like you believe that it’s much more than just the bone effect?
Rebecca Mason: That’s right.
Norman Swan: In other words they don’t fall over as much.
Rebecca Mason: They don’t fall over as much and that seems to be due to a couple of effects. One is their muscles are stronger and secondly they’re starting to accumulate evidence that they’re better co-ordinated. They don’t seem to sway as much and if you ask them to do tasks that involve co-ordination, they’re better able to do it.
Norman Swan: Now is that an effect on the brain or is that an effect on the muscles, that the muscles are better co-ordinated?
Rebecca Mason: We don’t know precisely yet but we know that the machinery exists for the brain to respond. The three hallmarks of things that we all need to do to make good bones and good muscle strength are adequate vitamin D, adequate calcium in our diets and adequate exercise.
Norman Swan: From an early age.
Rebecca Mason: From an early age so we build up peak bone mass, peak muscle mass and continuing throughout life so we keep it.
Norman Swan: We’ll come back to vitamin D and sunlight in a minute. Let’s look at skin cause you made some remarkable findings in skin which are almost counter intuitive.
Rebecca Mason: Yes indeed. We make vitamin D in skin and we’ve got some evidence that when you make vitamin D in skin the vitamin D that you produce actually contributes to protection from the damage that UV does in skin.
Norman Swan: In other words the sunlight that causes the damages also induces the vitamin D – there’s a feedback loop and protection.
Rebecca Mason: It does indeed – we think that it contributes in a similar way to the production of pigment that produces a tan and the epidermal thickness that you get from the beginning of summer, you start to increase your epidermal thickness that also protects you from sunlight and we think that vitamin D contributes in a similar way.
Norman Swan: So through increased thickness and increased tanning or is it through another mechanism?
Rebecca Mason: No, it seems to be through another mechanism. We have evidence that the vitamin D that is produced contributes to an enhanced protection from DNA damage. Probably through enhanced DNA repair. We certainly know that after you’ve irradiated skin with UV you get a lot of DNA damage, in the presence of added vitamin D you get less DNA damage. The tan that you get doesn’t protect you against the current episode of sun exposure, it protects you against the sun exposure that you get the next day or the day after. Remember that in the natural state after winter you get exposed to increasing amounts of sunlight and the small amount of increasing sunlight gradually builds up the pigment and the skin thickening and the vitamin D.
Remember although I said that vitamin D gets produced the active hormone of vitamin D gets produced in the kidney, we have evidence and there’s a lot of data now that the active hormone of vitamin D is produced in the skin and is produced in many other tissues. And so the active hormone of vitamin D is produced in the skin, it takes some hours but it would gradually build up and be protective against the increasing build up of sunlight. This is what would happen in the natural state.
Norman Swan: So that the hunter/gatherer in the temperate zones which is where most of us have evolved would have been white in winter and then progressively turn more brown as summer went in. It wasn’t just a sudden trip to the Gold Coast that did it?
Rebecca Mason: Exactly. It’s the current arrangement of sudden hits of sunlight instead of being gradually able to build up your defences over a longer period of time and the defences are tanning, skin thickening and we also think the defences are building up the active vitamin D hormone in skin.
Norman Swan: Have you looked at the cancer and vitamin D story? I mean I’ve covered this now for many years, the evidence seems extremely strong and it just seems to get stronger. The latest on melanoma is just a bit surprising in a sense because it’s a sun caused disease. But have you looked at that?
Rebecca Mason: We were in this actually about 15 years ago only we didn’t really know it at the time. We’d published studies showing that 1,25 D the active hormone enhanced the conversion of melanoma cells to much more benign type of cells, reduced their rate of proliferation. We showed that melanoma cells produced the active hormone of vitamin D. All of these things that people believe now contribute to the reduction in cancers associated with vitamin D.
Norman Swan: And it’s the DNA repair story again do you think?
Rebecca Mason: It may be associated with DNA repair but it’s probably more important mechanisms including inhibition of angiogenesis that’s tumours need blood vessels to survive and vitamin D appears to be one of those factors that inhibit blood vessel development. Vitamin D in internal tumours seems to enhance the ability of the immune system and other cells to cause killing of tumour cells.
Norman Swan: Is there any difference between vitamin D that you get from sunlight and swallowing it from a bottle?
Rebecca Mason: That’s an interesting question and a lot of people have debated this for some time. There is a chemical difference between the vitamin D that you get from and most of the vitamin D that you get from a bottle in Australia which is vitamin D 2. There are small chemical differences – vitamin D2 is a plant form of vitamin D, it probably isn’t bound as well by the protein the carries it in the blood, it doesn’t bind as well to the protein that it acts on in cells. That being said the differences are likely to be relatively small. At this stage if you were not able to make vitamin D by going out into the sun and that’s difficult for some people. For a start older people don’t make vitamin D very efficiently, people with dark skin or who have to cover up modestly for ethnic or religious reasons, then taking a tablet is certainly better than not taking any vitamin D at all. And as far as we can tell it’s reasonably efficient.
Norman Swan: And of course as you said earlier the margin of safety is greater, it’s much easier to take too much by the bottle.
Rebecca Mason: It is much easier to take too much by the bottle but not generally in the amounts that are available.
Norman Swan: Let’s say we wanted to save money and go and take the safe route which is sunlight. We’ve had decades now of people saying stay out of the sunlight, this is poison, a tanned skin is not a good thing to have etc. etc. etc. So what are heretics like you going to advise?
Rebecca Mason: OK, they’re still right in a sense. A tanned skin is not a good thing to have and staying out in the sun is not a good thing to do. Australia is still the skin cancer capital of the world, you don’t need much sun exposure to get adequate vitamin D. What the Australian and NZ Bone and Mineral Council are suggesting and what Osteoporosis Australia are suggesting and we’ve done this in consultation with the Cancer Council is small amounts of sun exposure considerably less than would be required to produce even minor degrees of redness. So in summer about 5 to 7 minutes in a place like Australia and outside the witching hours of 10am to 2 pm standard time which is 11am to 3 pm summer time to face, arms and hands about 15% body surface most days would give you ample amounts of vitamin D.
Norman Swan: I interviewed another vitamin D person Michael Hollick a few years ago from Boston University and he was arguing that you’ve got to be exposed in winter too, it’s got to be even through the year.
Rebecca Mason: If possible in winter and sort of incidental exposure would be nice so hanging up clothes, doing gardening, maybe going for a little bit of a walk, playing a bit of morning or afternoon sport would be nice. That would be great in terms of getting you out and about, maybe doing a bit of exercise as well which would help other things. Not deliberately going out into the sun but incidental exposure and avoiding the really key problems of 10am to 2pm or 11am to 3pm.
Norman Swan: Could we see vitamin D being used therapeutically for some cancers?
Rebecca Mason: We have in fact started to see the very preliminary therapeutic trials of the active hormone. There’s a problem though with using the active hormone in that to use it in sufficient doses to have an effect on tumours -
Norman Swan: The calcium levels go up too much.
Rebecca Mason: There’s a problem with high calcium,. What have been developed though over the past few years are analogues of vitamin D which have anti-cancer effects but without so much of the calcium effects and they’re the ones which are now being developed for use as anti-tumour agents. The first clinical trial has been reported recently which was not particularly successful but it was with an early analogue and certainly there’s a great deal of interest.
Norman Swan: You were telling me before we started that you’ve been having discussions in the United States about this and there’s a fair bit of resistance to the sun is OK story.
Rebecca Mason: There is. The idea that you can never be too rich, too thin or have too little sun exposure is still alive and well in the United States. I got up recently and said that the attitudes were changing in Australia and someone from the FDA came up to me afterwards and said they’re going to be extremely upset but I think the mood is changing even over there.
Norman Swan: Associate Professor Rebecca Mason is Deputy Director of Sydney University’s Institute for Biomedical Research, I’m Norman Swan and you’ve been listening to the Health Report.
References:
Wong G et al. 1,25-Dihydroxyvitamin D and three low calcemic analogs decrease UV-induced DNA damage via the rapid response pathway. J Steroid Biochem Mol Biol 2004; 89-90C:567-570
Nowson CA et al. Vitamin D in Australia: Issues and recommendations. Australian Family Physician 2004;33:133-138
Guests on this program:
Associate Professor Rebecca Mason
Deputy Director
Sydney University's Institute for Biomedical Research
and Head of the Physiology Department
University of Sydney
Sydney, New South Wales
Further information:
Diet and nutrition - Health Library A-Z
http://abc.net.au/health/library/diet.htm
Skin cancer fact file - ABC Health Matters
http://abc.net.au/health/regions/library/skincancer_ff.htm
Presenter: Norman Swan
Producer: Brigitte Seega
Transcript from ABC Radio National, Australia
with Norman Swan
Vitamin D
7 February 2005
A leading laboratory at the University of Sydney has been investigating Vitamin D for many years. Associate Professor Rebecca Mason talks about their work.
Program Transcript
Vitamin D is turning out to be an amazing vitamin – not just because of its supposed effects on cancer. Just round the corner from Bruce’s office is a leading laboratory which has been investigating vitamin D for many years. They’ve findings which support the results from these studies on cancer. Associate Professor Rebecca Mason is Deputy Director of Sydney University’s Institute for Biomedical Research and Head of the Physiology Department.
Rebecca Mason: Vitamin D as you say is made in the skin. The skin accumulates a compound which on interaction with the UVB component of sunlight is converted to pre-vitamin D which in the skin gets then converted into vitamin D. You can’t make too much vitamin D from sunlight because the vitamin D then gets converted into what are called over irradiation products which -
Norman Swan: It’s a feedback mechanism which stops any more being produced.
Rebecca Mason: Yes, stops too much being produced so you can’t make too much vitamin D from being in sunlight. Small amounts of sunlight seem to make enough vitamin D, the vitamin D is then absorbed into the body, it’s converted into 25 hydroxy D in the liver, that’s what we measure to see if you’ve got enough vitamin D. So when you go to the doctor and say have I got enough vitamin D that’s what he measures. And then it gets converted into the hormonal form of vitamin D which is called 1,25 dihydroxy vitamin D or calcitriol.
Norman Swan: And when you give these numbers and letters it’s essentially just the different chemical structure?
Rebecca Mason: A different chemical structure but most of the hormonal effects of vitamin D are due to this calcitriol.
Norman Swan: So you’re calling Vitamin D a hormone?
Rebecca Mason: It is indeed a hormone and calcitriol is made in the kidney, mostly for its hormonal effects on bone.
Norman Swan: Meaning it’s a chemical messenger, it sends a message to different parts of the body?
Rebecca Mason: It sends a message to different parts of the body and as far as bone health is concerned that’s most of the story. But there’s a lot more of the story that I’ll tell you about in a moment.
Norman Swan: So vitamin D builds bone essentially?
Rebecca Mason: Vitamin D builds bone, it probably also has important effects in muscle. Now vitamin D builds bone because mainly it helps calcium absorption from the gut.
Norman Swan: So if you’ve got enough vitamin D on board, enough calcitriol from your kidney then your bowel is completely if you like more porous to calcium – it allows more in.
Rebecca Mason: It allows more in, you can absorb more of the calcium that you take in food and that calcium goes to bone and it stops bone breakdown because then bone doesn’t have to be broken down to provide enough calcium for other essential needs.
Norman Swan: Now there’s this fascinating story that people with enough vitamin D on board don’t break their hips as much as people who don’t have enough vitamin D and people like you believe that it’s much more than just the bone effect?
Rebecca Mason: That’s right.
Norman Swan: In other words they don’t fall over as much.
Rebecca Mason: They don’t fall over as much and that seems to be due to a couple of effects. One is their muscles are stronger and secondly they’re starting to accumulate evidence that they’re better co-ordinated. They don’t seem to sway as much and if you ask them to do tasks that involve co-ordination, they’re better able to do it.
Norman Swan: Now is that an effect on the brain or is that an effect on the muscles, that the muscles are better co-ordinated?
Rebecca Mason: We don’t know precisely yet but we know that the machinery exists for the brain to respond. The three hallmarks of things that we all need to do to make good bones and good muscle strength are adequate vitamin D, adequate calcium in our diets and adequate exercise.
Norman Swan: From an early age.
Rebecca Mason: From an early age so we build up peak bone mass, peak muscle mass and continuing throughout life so we keep it.
Norman Swan: We’ll come back to vitamin D and sunlight in a minute. Let’s look at skin cause you made some remarkable findings in skin which are almost counter intuitive.
Rebecca Mason: Yes indeed. We make vitamin D in skin and we’ve got some evidence that when you make vitamin D in skin the vitamin D that you produce actually contributes to protection from the damage that UV does in skin.
Norman Swan: In other words the sunlight that causes the damages also induces the vitamin D – there’s a feedback loop and protection.
Rebecca Mason: It does indeed – we think that it contributes in a similar way to the production of pigment that produces a tan and the epidermal thickness that you get from the beginning of summer, you start to increase your epidermal thickness that also protects you from sunlight and we think that vitamin D contributes in a similar way.
Norman Swan: So through increased thickness and increased tanning or is it through another mechanism?
Rebecca Mason: No, it seems to be through another mechanism. We have evidence that the vitamin D that is produced contributes to an enhanced protection from DNA damage. Probably through enhanced DNA repair. We certainly know that after you’ve irradiated skin with UV you get a lot of DNA damage, in the presence of added vitamin D you get less DNA damage. The tan that you get doesn’t protect you against the current episode of sun exposure, it protects you against the sun exposure that you get the next day or the day after. Remember that in the natural state after winter you get exposed to increasing amounts of sunlight and the small amount of increasing sunlight gradually builds up the pigment and the skin thickening and the vitamin D.
Remember although I said that vitamin D gets produced the active hormone of vitamin D gets produced in the kidney, we have evidence and there’s a lot of data now that the active hormone of vitamin D is produced in the skin and is produced in many other tissues. And so the active hormone of vitamin D is produced in the skin, it takes some hours but it would gradually build up and be protective against the increasing build up of sunlight. This is what would happen in the natural state.
Norman Swan: So that the hunter/gatherer in the temperate zones which is where most of us have evolved would have been white in winter and then progressively turn more brown as summer went in. It wasn’t just a sudden trip to the Gold Coast that did it?
Rebecca Mason: Exactly. It’s the current arrangement of sudden hits of sunlight instead of being gradually able to build up your defences over a longer period of time and the defences are tanning, skin thickening and we also think the defences are building up the active vitamin D hormone in skin.
Norman Swan: Have you looked at the cancer and vitamin D story? I mean I’ve covered this now for many years, the evidence seems extremely strong and it just seems to get stronger. The latest on melanoma is just a bit surprising in a sense because it’s a sun caused disease. But have you looked at that?
Rebecca Mason: We were in this actually about 15 years ago only we didn’t really know it at the time. We’d published studies showing that 1,25 D the active hormone enhanced the conversion of melanoma cells to much more benign type of cells, reduced their rate of proliferation. We showed that melanoma cells produced the active hormone of vitamin D. All of these things that people believe now contribute to the reduction in cancers associated with vitamin D.
Norman Swan: And it’s the DNA repair story again do you think?
Rebecca Mason: It may be associated with DNA repair but it’s probably more important mechanisms including inhibition of angiogenesis that’s tumours need blood vessels to survive and vitamin D appears to be one of those factors that inhibit blood vessel development. Vitamin D in internal tumours seems to enhance the ability of the immune system and other cells to cause killing of tumour cells.
Norman Swan: Is there any difference between vitamin D that you get from sunlight and swallowing it from a bottle?
Rebecca Mason: That’s an interesting question and a lot of people have debated this for some time. There is a chemical difference between the vitamin D that you get from and most of the vitamin D that you get from a bottle in Australia which is vitamin D 2. There are small chemical differences – vitamin D2 is a plant form of vitamin D, it probably isn’t bound as well by the protein the carries it in the blood, it doesn’t bind as well to the protein that it acts on in cells. That being said the differences are likely to be relatively small. At this stage if you were not able to make vitamin D by going out into the sun and that’s difficult for some people. For a start older people don’t make vitamin D very efficiently, people with dark skin or who have to cover up modestly for ethnic or religious reasons, then taking a tablet is certainly better than not taking any vitamin D at all. And as far as we can tell it’s reasonably efficient.
Norman Swan: And of course as you said earlier the margin of safety is greater, it’s much easier to take too much by the bottle.
Rebecca Mason: It is much easier to take too much by the bottle but not generally in the amounts that are available.
Norman Swan: Let’s say we wanted to save money and go and take the safe route which is sunlight. We’ve had decades now of people saying stay out of the sunlight, this is poison, a tanned skin is not a good thing to have etc. etc. etc. So what are heretics like you going to advise?
Rebecca Mason: OK, they’re still right in a sense. A tanned skin is not a good thing to have and staying out in the sun is not a good thing to do. Australia is still the skin cancer capital of the world, you don’t need much sun exposure to get adequate vitamin D. What the Australian and NZ Bone and Mineral Council are suggesting and what Osteoporosis Australia are suggesting and we’ve done this in consultation with the Cancer Council is small amounts of sun exposure considerably less than would be required to produce even minor degrees of redness. So in summer about 5 to 7 minutes in a place like Australia and outside the witching hours of 10am to 2 pm standard time which is 11am to 3 pm summer time to face, arms and hands about 15% body surface most days would give you ample amounts of vitamin D.
Norman Swan: I interviewed another vitamin D person Michael Hollick a few years ago from Boston University and he was arguing that you’ve got to be exposed in winter too, it’s got to be even through the year.
Rebecca Mason: If possible in winter and sort of incidental exposure would be nice so hanging up clothes, doing gardening, maybe going for a little bit of a walk, playing a bit of morning or afternoon sport would be nice. That would be great in terms of getting you out and about, maybe doing a bit of exercise as well which would help other things. Not deliberately going out into the sun but incidental exposure and avoiding the really key problems of 10am to 2pm or 11am to 3pm.
Norman Swan: Could we see vitamin D being used therapeutically for some cancers?
Rebecca Mason: We have in fact started to see the very preliminary therapeutic trials of the active hormone. There’s a problem though with using the active hormone in that to use it in sufficient doses to have an effect on tumours -
Norman Swan: The calcium levels go up too much.
Rebecca Mason: There’s a problem with high calcium,. What have been developed though over the past few years are analogues of vitamin D which have anti-cancer effects but without so much of the calcium effects and they’re the ones which are now being developed for use as anti-tumour agents. The first clinical trial has been reported recently which was not particularly successful but it was with an early analogue and certainly there’s a great deal of interest.
Norman Swan: You were telling me before we started that you’ve been having discussions in the United States about this and there’s a fair bit of resistance to the sun is OK story.
Rebecca Mason: There is. The idea that you can never be too rich, too thin or have too little sun exposure is still alive and well in the United States. I got up recently and said that the attitudes were changing in Australia and someone from the FDA came up to me afterwards and said they’re going to be extremely upset but I think the mood is changing even over there.
Norman Swan: Associate Professor Rebecca Mason is Deputy Director of Sydney University’s Institute for Biomedical Research, I’m Norman Swan and you’ve been listening to the Health Report.
References:
Wong G et al. 1,25-Dihydroxyvitamin D and three low calcemic analogs decrease UV-induced DNA damage via the rapid response pathway. J Steroid Biochem Mol Biol 2004; 89-90C:567-570
Nowson CA et al. Vitamin D in Australia: Issues and recommendations. Australian Family Physician 2004;33:133-138
Guests on this program:
Associate Professor Rebecca Mason
Deputy Director
Sydney University's Institute for Biomedical Research
and Head of the Physiology Department
University of Sydney
Sydney, New South Wales
Further information:
Diet and nutrition - Health Library A-Z
http://abc.net.au/health/library/diet.htm
Skin cancer fact file - ABC Health Matters
http://abc.net.au/health/regions/library/skincancer_ff.htm
Presenter: Norman Swan
Producer: Brigitte Seega