Could the sun be good for your heart?
-
0:00 - 0:03So, before I became a dermatologist,
-
0:03 - 0:05I started in general medicine,
-
0:05 - 0:08as most dermatologists do in Britain.
-
0:08 - 0:10At the end of that time, I went off to Australia,
-
0:10 - 0:11about 20 years ago.
-
0:11 - 0:14What you learn when you go to Australia
-
0:14 - 0:16is the Australians are very competitive.
-
0:16 - 0:18And they are not magnanimous in victory.
-
0:18 - 0:20And that happened a lot:
-
0:20 - 0:23"You pommies, you can't play cricket, rugby."
-
0:23 - 0:25I could accept that.
-
0:25 - 0:27But moving into work --
-
0:27 - 0:30and we have each week what's called a journal club,
-
0:30 - 0:32when you'd sit down with the other doctors
-
0:32 - 0:34and you'd study a scientific paper
-
0:34 - 0:36in relation to medicine.
-
0:36 - 0:39And after week one, it was about cardiovascular mortality,
-
0:39 - 0:43a dry subject -- how many people die of heart disease,
-
0:43 - 0:44what the rates are.
-
0:44 - 0:46And they were competitive about this:
-
0:46 - 0:49"You pommies, your rates of heart disease are shocking."
-
0:49 - 0:51And of course, they were right.
-
0:51 - 0:55Australians have about a third less heart disease than we do --
-
0:55 - 0:59less deaths from heart attacks, heart failure, less strokes --
-
0:59 - 1:01they're generally a healthier bunch.
-
1:01 - 1:03And of course they said this was because of
-
1:03 - 1:05their fine moral standing, their exercise,
-
1:05 - 1:09because they're Australians and we're weedy pommies, and so on.
-
1:09 - 1:14But it's not just Australia that has better health than Britain.
-
1:14 - 1:17Within Britain, there is a gradient of health --
-
1:17 - 1:19and this is what's called standardized mortality,
-
1:19 - 1:21basically your chances of dying.
-
1:21 - 1:25This is looking at data from the paper about 20 years ago,
-
1:25 - 1:26but it's true today.
-
1:26 - 1:29Comparing your rates of dying 50 degrees north --
-
1:29 - 1:31that's the South, that's London and places --
-
1:31 - 1:35by latitude, and 55 degrees --
-
1:35 - 1:37the bad news is that's here, Glasgow.
-
1:37 - 1:40I'm from Edinburgh. Worse news, that's even Edinburgh.
-
1:40 - 1:44(Laughter)
-
1:44 - 1:48So what accounts for this horrible space here
-
1:48 - 1:50between us up here in southern Scotland
-
1:50 - 1:51and the South?
-
1:51 - 1:52Now, we know about smoking,
-
1:52 - 1:55deep-fried Mars bars, chips -- the Glasgow diet.
-
1:55 - 1:56All of these things.
-
1:56 - 1:59But this graph is after taking into account
-
1:59 - 2:01all of these known risk factors.
-
2:01 - 2:05This is after accounting for smoking, social class, diet,
-
2:05 - 2:07all those other known risk factors.
-
2:07 - 2:09We are left with this missing space
-
2:09 - 2:13of increased deaths the further north you go.
-
2:13 - 2:15Now, sunlight, of course, comes into this.
-
2:15 - 2:18And vitamin D has had a great deal of press,
-
2:18 - 2:20and a lot of people get concerned about it.
-
2:20 - 2:24And we need vitamin D. It's now a requirement that children have a certain amount.
-
2:24 - 2:26My grandmother grew up in Glasgow,
-
2:26 - 2:29back in the 1920s and '30s when rickets was a real problem
-
2:29 - 2:32and cod liver oil was brought in.
-
2:32 - 2:36And that really prevented the rickets that used to be common in this city.
-
2:36 - 2:39And I as a child was fed cod liver oil by my grandmother.
-
2:39 - 2:42I distinctly -- nobody forgets cod liver oil.
-
2:42 - 2:47But an association: The higher people's blood levels of vitamin D are,
-
2:47 - 2:51the less heart disease they have, the less cancer.
-
2:51 - 2:54There seems to be a lot of data suggesting that vitamin D is very good for you.
-
2:54 - 2:57And it is, to prevent rickets and so on.
-
2:57 - 2:59But if you give people vitamin D supplements,
-
2:59 - 3:03you don't change that high rate of heart disease.
-
3:03 - 3:07And the evidence for it preventing cancers is not yet great.
-
3:07 - 3:11So what I'm going to suggest is that vitamin D is not the only story in town.
-
3:11 - 3:15It's not the only reason preventing heart disease.
-
3:15 - 3:19High vitamin D levels, I think, are a marker for sunlight exposure,
-
3:19 - 3:22and sunlight exposure, in methods I'm going to show,
-
3:22 - 3:25is good for heart disease.
-
3:25 - 3:27Anyway, I came back from Australia,
-
3:27 - 3:30and despite the obvious risks to my health, I moved to Aberdeen.
-
3:30 - 3:33(Laughter)
-
3:33 - 3:36Now, in Aberdeen, I started my dermatology training.
-
3:36 - 3:38But I also became interested in research,
-
3:38 - 3:41and in particular I became interested in this substance, nitric oxide.
-
3:41 - 3:42Now these three guys up here,
-
3:42 - 3:44Furchgott, Ignarro and Murad,
-
3:44 - 3:47won the Nobel Prize for medicine back in 1998.
-
3:47 - 3:49And they were the first people to describe
-
3:49 - 3:53this new chemical transmitter, nitric oxide.
-
3:53 - 3:56What nitric oxide does is it dilates blood vessels,
-
3:56 - 3:58so it lowers your blood pressure.
-
3:58 - 4:02It also dilates the coronary arteries, so it stops angina.
-
4:02 - 4:03And what was remarkable about it
-
4:03 - 4:07was in the past when we think of chemical messengers within the body,
-
4:07 - 4:10we thought of complicated things like estrogen and insulin,
-
4:10 - 4:12or nerve transmission.
-
4:12 - 4:15Very complex processes with very complex chemicals
-
4:15 - 4:18that fit into very complex receptors.
-
4:18 - 4:20And here's this incredibly simple molecule,
-
4:20 - 4:23a nitrogen and an oxygen that are stuck together,
-
4:23 - 4:28and yet these are hugely important for [unclear] our low blood pressure,
-
4:28 - 4:30for neurotransmission, for many, many things,
-
4:30 - 4:34but particularly cardiovascular health.
-
4:34 - 4:37And I started doing research, and we found, very excitingly,
-
4:37 - 4:40that the skin produces nitric oxide.
-
4:40 - 4:43So it's not just in the cardiovascular system it arises.
-
4:43 - 4:45It arises in the skin.
-
4:45 - 4:46Well, having found that and published that,
-
4:46 - 4:48I thought, well, what's it doing?
-
4:48 - 4:50How do you have low blood pressure in your skin?
-
4:50 - 4:52It's not the heart. What do you do?
-
4:52 - 4:56So I went off to the States, as many people do if they're going to do research,
-
4:56 - 5:00and I spent a few years in Pittsburgh. This is Pittsburgh.
-
5:00 - 5:02And I was interested in these really complex systems.
-
5:02 - 5:06We thought that maybe nitric oxide affected cell death,
-
5:06 - 5:09and how cells survive, and their resistance to other things.
-
5:09 - 5:12And I first off started work in cell culture, growing cells,
-
5:12 - 5:14and then I was using knockout mouse models --
-
5:14 - 5:16mice that couldn't make the gene.
-
5:16 - 5:21We worked out a mechanism, which -- NO was helping cells survive.
-
5:21 - 5:24And I then moved back to Edinburgh.
-
5:24 - 5:27And in Edinburgh, the experimental animal we use is the medical student.
-
5:27 - 5:29It's a species close to human,
-
5:29 - 5:31with several advantages over mice:
-
5:31 - 5:35They're free, you don't shave them, they feed themselves,
-
5:35 - 5:37and nobody pickets your office saying,
-
5:37 - 5:39"Save the lab medical student."
-
5:39 - 5:42So they're really an ideal model.
-
5:42 - 5:44But what we found
-
5:44 - 5:49was that we couldn't reproduce in man the data we had shown in mice.
-
5:49 - 5:52It seemed we couldn't turn off the production
-
5:52 - 5:55of nitric oxide in the skin of humans.
-
5:55 - 5:58We put on creams that blocked the enzyme that made it,
-
5:58 - 6:02we injected things. We couldn't turn off the nitric oxide.
-
6:02 - 6:06And the reason for this, it turned out, after two or three years' work,
-
6:06 - 6:10was that in the skin we have huge stores
-
6:10 - 6:13not of nitric oxide, because nitric oxide is a gas,
-
6:13 - 6:16and it's released -- (Poof!) -- and in a few seconds it's away,
-
6:16 - 6:19but it can be turned into these forms of nitric oxide --
-
6:19 - 6:23nitrate, NO3; nitrite, NO2; nitrosothiols.
-
6:23 - 6:24And these are more stable,
-
6:24 - 6:28and your skin has got really large stores of NO.
-
6:28 - 6:31And we then thought to ourselves, with those big stores,
-
6:31 - 6:35I wonder if sunlight might activate those stores
-
6:35 - 6:36and release them from the skin,
-
6:36 - 6:40where the stores are about 10 times as big as what's in the circulation.
-
6:40 - 6:43Could the sun activate those stores into the circulation,
-
6:43 - 6:48and there in the circulation do its good things for your cardiovascular system?
-
6:48 - 6:50Well, I'm an experimental dermatologist,
-
6:50 - 6:52so what we did was we thought
-
6:52 - 6:55we'd have to expose our experimental animals to sunlight.
-
6:55 - 6:59And so what we did was we took a bunch of volunteers
-
6:59 - 7:02and we exposed them to ultraviolet light.
-
7:02 - 7:04So these are kind of sunlamps.
-
7:04 - 7:06Now, what we were careful to do was,
-
7:06 - 7:09vitamin D is made by ultraviolet B rays
-
7:09 - 7:13and we wanted to separate our story from the vitamin D story.
-
7:13 - 7:17So we used ultraviolet A, which doesn't make vitamin D.
-
7:17 - 7:19When we put people under a lamp
-
7:19 - 7:25for the equivalent of about 30 minutes of sunshine in summer in Edinburgh,
-
7:25 - 7:27what we produced was, we produced a rise
-
7:27 - 7:29in circulating nitric oxide.
-
7:29 - 7:32So we put patients with these subjects under the UV,
-
7:32 - 7:34and their NO levels do go up,
-
7:34 - 7:36and their blood pressure goes down.
-
7:36 - 7:39Not by much, as an individual level,
-
7:39 - 7:41but enough at a population level
-
7:41 - 7:45to shift the rates of heart disease in a whole population.
-
7:45 - 7:47And when we shone UV at them,
-
7:47 - 7:51or when we warmed them up to the same level as the lamps,
-
7:51 - 7:54but didn't actually let the rays hit the skin, this didn't happen.
-
7:54 - 7:58So this seems to be a feature of ultraviolet rays hitting the skin.
-
7:58 - 8:00Now, we're still collecting data.
-
8:00 - 8:01A few good things here:
-
8:01 - 8:05This appeared to be more marked in older people.
-
8:05 - 8:06I'm not sure exactly how much.
-
8:06 - 8:08One of the subjects here was my mother-in-law,
-
8:08 - 8:11and clearly I do not know her age.
-
8:11 - 8:14But certainly in people older than my wife,
-
8:14 - 8:17this appears to be a more marked effect.
-
8:17 - 8:19And the other thing I should mention
-
8:19 - 8:21was there was no change in vitamin D.
-
8:21 - 8:23This is separate from vitamin D.
-
8:23 - 8:24So vitamin D is good for you -- it stops rickets,
-
8:24 - 8:27it prevents calcium metabolism, important stuff.
-
8:27 - 8:30But this is a separate mechanism from vitamin D.
-
8:30 - 8:32Now, one of the problems with looking at blood pressure
-
8:32 - 8:34is your body does everything it can
-
8:34 - 8:35to keep your blood pressure at the same place.
-
8:35 - 8:37If your leg is chopped off and you lose blood,
-
8:37 - 8:40your body will clamp down, increase the heart rate,
-
8:40 - 8:42do everything it can to keep your blood pressure up.
-
8:42 - 8:45That is an absolutely fundamental physiological principle.
-
8:45 - 8:47So what we've next done
-
8:47 - 8:51is we've moved on to looking at blood vessel dilatation.
-
8:51 - 8:52So we've measured -- this is again,
-
8:52 - 8:57notice no tail and hairless, this is a medical student.
-
8:57 - 9:00In the arm, you can measure blood flow in the arm
-
9:00 - 9:03by how much it swells up as some blood flows into it.
-
9:03 - 9:07And what we've shown is that doing a sham irradiation --
-
9:07 - 9:08this is the thick line here --
-
9:08 - 9:11this is shining UV on the arm so it warms up
-
9:11 - 9:13but keeping it covered so the rays don't hit the skin.
-
9:13 - 9:17There is no change in blood flow, in dilatation of the blood vessels.
-
9:17 - 9:19But the active irradiation,
-
9:19 - 9:23during the UV and for an hour after it,
-
9:23 - 9:25there is dilation of the blood vessels.
-
9:25 - 9:27This is the mechanism by which you lower blood pressure,
-
9:27 - 9:30by which you dilate the coronary arteries also,
-
9:30 - 9:31to let the blood be supplied with the heart.
-
9:31 - 9:36So here, further data that ultraviolet -- that's sunlight --
-
9:36 - 9:41has benefits on the blood flow and the cardiovascular system.
-
9:41 - 9:43So we thought we'd just kind of model --
-
9:43 - 9:49Different amounts of UV hit different parts of the Earth at different times of year,
-
9:49 - 9:53so you can actually work out those stores of nitric oxide --
-
9:53 - 9:55the nitrates, nitrites, nitrosothiols in the skin --
-
9:55 - 9:58cleave to release NO.
-
9:58 - 10:02Different wavelengths of light have different activities of doing that.
-
10:02 - 10:04So you can look at the wavelengths of light that do that.
-
10:04 - 10:08And you can look -- So, if you live on the equator, the sun comes straight overhead,
-
10:08 - 10:10it comes through a very thin bit of atmosphere.
-
10:10 - 10:13In winter or summer, it's the same amount of light.
-
10:13 - 10:15If you live up here, in summer
-
10:15 - 10:18the sun is coming fairly directly down,
-
10:18 - 10:21but in winter it's coming through a huge amount of atmosphere,
-
10:21 - 10:24and much of the ultraviolet is weeded out,
-
10:24 - 10:27and the range of wavelengths that hit the Earth
-
10:27 - 10:29are different from summer to winter.
-
10:29 - 10:31So what you can do is you can multiply those data
-
10:31 - 10:33by the NO that's released
-
10:33 - 10:36and you can calculate how much nitric oxide
-
10:36 - 10:39would be released from the skin into the circulation.
-
10:39 - 10:41Now, if you're on the equator here --
-
10:41 - 10:45that's these two lines here, the red line and the purple line --
-
10:45 - 10:49the amount of nitric oxide that's released is the area under the curve,
-
10:49 - 10:51it's the area in this space here.
-
10:51 - 10:54So if you're on the equator, December or June,
-
10:54 - 10:57you've got masses of NO being released from the skin.
-
10:57 - 10:59So Ventura is in southern California.
-
10:59 - 11:02In summer, you might as well be at the equator.
-
11:02 - 11:04It's great. Lots of NO is released.
-
11:04 - 11:08Ventura mid-winter, well, there's still a decent amount.
-
11:08 - 11:12Edinburgh in summer, the area beneath the curve is pretty good,
-
11:12 - 11:16but Edinburgh in winter, the amount of NO that can be released
-
11:16 - 11:20is next to nothing, tiny amounts.
-
11:20 - 11:21So what do we think?
-
11:21 - 11:23We're still working at this story,
-
11:23 - 11:25we're still developing it, we're still expanding it.
-
11:25 - 11:27We think it's very important.
-
11:27 - 11:30We think it probably accounts for a lot of the north-south health divide within Britain,
-
11:30 - 11:32It's of relevance to us.
-
11:32 - 11:34We think that the skin --
-
11:34 - 11:36well, we know that the skin has got very large stores
-
11:36 - 11:39of nitric oxide as these various other forms.
-
11:39 - 11:41We suspect a lot of these come from diet,
-
11:41 - 11:43green leafy vegetables, beetroot, lettuce
-
11:43 - 11:46has a lot of these nitric oxides that we think go to the skin.
-
11:46 - 11:48We think they're then stored in the skin,
-
11:48 - 11:51and we think the sunlight releases this
-
11:51 - 11:53where it has generally beneficial effects.
-
11:53 - 11:56And this is ongoing work, but dermatologists --
-
11:56 - 11:58I mean, I'm a dermatologist.
-
11:58 - 12:00My day job is saying to people, "You've got skin cancer,
-
12:00 - 12:02it's caused by sunlight, don't go in the sun."
-
12:02 - 12:05I actually think a far more important message
-
12:05 - 12:08is that there are benefits as well as risks to sunlight.
-
12:08 - 12:14Yes, sunlight is the major alterable risk factor for skin cancer,
-
12:14 - 12:17but deaths from heart disease are a hundred times higher
-
12:17 - 12:19than deaths from skin cancer.
-
12:19 - 12:21And I think that we need to be more aware of,
-
12:21 - 12:23and we need to find the risk-benefit ratio.
-
12:23 - 12:25How much sunlight is safe,
-
12:25 - 12:29and how can we finesse this best for our general health?
-
12:29 - 12:31So, thank you very much indeed.
-
12:31 - 12:38(Applause)
- Title:
- Could the sun be good for your heart?
- Speaker:
- Richard Weller
- Description:
-
Our bodies get Vitamin D from the sun, but as dermatologist Richard Weller suggests, sunlight may confer another surprising benefit too. New research by his team shows that nitric oxide, a chemical transmitter stored in huge reserves in the skin, can be released by UV light, to great benefit for blood pressure and the cardiovascular system. What does it mean? Well, it might begin to explain why Scots get sick more than Australians ...
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 12:59
Thu-Huong Ha edited English subtitles for Could the sun be good for your heart? | ||
Thu-Huong Ha approved English subtitles for Could the sun be good for your heart? | ||
Thu-Huong Ha accepted English subtitles for Could the sun be good for your heart? | ||
Thu-Huong Ha edited English subtitles for Could the sun be good for your heart? | ||
Thu-Huong Ha edited English subtitles for Could the sun be good for your heart? | ||
Morton Bast added a translation |