Could the sun be good for your heart Richard Weller

so before I became a dermatologist I

started in general medicine as as most

dermatologists do in Britain at the end

of that time I went off to Australia

about 20 years ago what you learn when

you go to Australia is the Australians

are very competitive and and they are

not magnanimous in victory and and that

happened a lot I knew Pommies you can’t

play cricket rugby I I could accept that

but moving into work and we have each

week what’s called a journal Club when

you’d sit down with the other doctors

and you’d study a scientific paper in

relation to medicine and after week one

it was about cardiovascular mortality a

dry subject how many people die of heart

disease what the rates are and they were

competitive about this you Pommies

you’re rates of heart disease are

shocking and of course they were right

Australians have about 1/3 less heart

disease than we do less deaths from

heart attacks heart failure less strokes

they’re generally healthier Bunch and of

course they said this was because of

their fine moral standing their exercise

because they’re Australians and we’re we

easy Pommies and so on but you know it’s

not just Australia that has better

health than Britain within Britain there

is a gradient of health and this is

what’s called standardized mortality

basically your chances of dying this is

looking at data from the paper about 20

years ago but it’s true today comparing

your rates of dying at 50 degrees north

that’s the South that’s London and

places um by latitude and 55 degrees the

bad news is that’s here Glasgow I’m from

Edinburgh worst news that’s even

Edinburgh okay so there is

so what accounts for this horrible space

here between us up here in southern

Scotland and the south now we know about

smoking deep-fried Mars bars trips the

Glasgow diet all of these things but

this graph is after taking into account

all of these known risk factors this is

after accounting for smoking social

class diet all those other known

respects we are left with this missing

space of increased deaths the further

north you gaze now sunlight of course

comes into this and vitamin D has had a

great deal of press and a lot of people

get concerned about it and we need

vitamin D it’s now a requirement that

children have a certain amount my

grandmother grew up in Glasgow back in

the 1920s and 30s when rickets was a

real problem and cod liver oil was

brought in and that really prevented the

rickets that used to be common in this

city and I as a child was fed cod liver

oil by my grandmother I distinctly

nobody forgets cod liver oil but an

association the higher people’s blood

levels of vitamin D are the less heart

disease they have the less cancer there

seems to be a lot of data suggesting

that vitamin D is very good for you and

it is to prevent rickets and so on but

if you give people vitamin D supplements

you don’t change that high rate of heart

disease and the evidence for it

preventing cancers is not yet great so

what I’m going to suggest is that

vitamin D is not the only story in town

it’s not the only reason preventing

heart disease high vitamin D levels I

think are a marker for sunlight exposure

and sunlight exposure in methods I’m

gonna show is good for heart disease

anyway I came back from Australia and

despite the obvious risks to my health I

moved to Aberdeen

now in Aberdeen I started my dermatology

training but I also became interested in

research and in particular I became

interested in this substance nitric

oxide now these three guys up here first

got big marrow Murad won the Nobel Prize

for medicine back in 1998 and they were

the first people to describe this new

chemical transmitter nitric oxide what

nitric oxide does is it dilates blood

vessels so it lowers your blood pressure

it also dilates the coronary arteries

stops angina and what was remarkable

about it was in the past when we think

of chemical messengers or in the body we

thought of complicated things like

estrogen and insulin or nerve

transmission very complex processes with

very complex chemicals that fit into

very complex receptors and here’s this

incredibly simple molecule a nitrogen

and an oxygen that have stuck together

and yet these are hugely important for

painting our low blood pressure for

neurotransmission for many many things

but particularly cardiovascular health

and I started doing research and we

found very excitingly that the skin

produces nitric oxide so it’s not just

in the cardiovascular system that arises

it arises in the skin while having found

that and published that I thought well

what’s it doing how do you have a low

blood pressure in your skin you know

it’s not the heart what do you do

so I went off to the States as many

people do if they’re going to do

research and I spent a few years in

Pittsburgh

um this is Pittsburgh and I was

interested in these really kind of

complex systems we fought them maybe

nitric oxide affected cell death and how

cells survive and their resistance to

other things and I first of all started

working in cell culture growing cells

and then as using knockout mouse models

mice that couldn’t make me the gene we

worked out a mechanism which I know was

helping cells survive and I then moved

back to Edinburgh and in Edinburgh the

experimental animal we use is the

medical student it’s a species close to

human with several advantages over mice

they’re free you don’t shave them they

feed themselves and nobody pickets your

office saying save the lab medical

student so they’re really an ideal an

ideal model

but what we found was that we couldn’t

reproduce in man the data we had shown

in mice it seemed we couldn’t turn off

the production of nitric oxide in the

skin of humans we put on creams that

block the enzyme that made it and we

injected things we couldn’t turn off the

the nitric oxide and the reason for this

it turned out after two or three years

work was in the skin

we have huge stores not of nitric oxide

because nitric oxide is a gas and it’s

released and in a few seconds it’s away

but it can be turned into these forms of

nitric oxide nitrate no3 nitrite no.2

might raise with us and these are more

stable and your skin has got really

large stores of Na and we then thought

to ourselves all those big stores

I wonder if sunlight might activate

those stores and release them from the

skin where the stores are about ten

times as big as what’s in the

circulation could the Sun activate those

stores into the circulation and they’re

in the circulation can do it’s good

things for your cardiovascular system

well I’m an experimental dermatologist

so what we did was we thought we have to

expose our experimental animals to

sunlight and so what we did was we took

a bunch of volunteers and we expose them

to ultraviolet light so these are kind

of Sun lamps

now what we were careful to do was

vitamin D is made by ultraviolet B rays

and we wanted to separate our story from

the vitamin D story so we used

ultraviolet a which doesn’t make vitamin

D when we put people under a lamp for

the equivalent of about 30 minutes of

sunshine in summer in Edinburgh what we

produced was removed a rise in

circulating nitric oxide so we put

patients with these subjects under the

UV and then enno levels do go up and

their blood pressure goes down not by

much as an individual level but enough

at a population level to shift the rates

of heart disease in a whole population

and when we Shawn UV at them or when we

warmed them up to the same level as the

Lambs but didn’t actually that the rays

hit the skin this didn’t happen so this

seems to be a feature of ultraviolet

rays hitting the skin now we’re still

collecting data a few good things here

where this appeared to be more marked in

older people I’m not sure exactly how

much one of the subjects here was my

mother-in-law and clearly I do not know

her age but certainly in people older

than my wife this appears to be a more

marked effect and the other thing I

should mention was there was no change

in bitumen D this is separate from

vitamin D so vitamin D is good for you

it stops rickets it provides calcium

atados important stuff but this is a

separate mechanism from vitamin D now

one of the problems are looking at blood

pressure is your body does everything it

can to keep your blood pressure at the

same place if your leg is chopped off

and you lose blood your body will clamp

down increase the heart rate do

everything it can to keep your blood

pressure up that is an absolutely

fundamental physiological principle so

what we’ve next done is we’ve moved on

to looking at blood vessel dilatation so

we’ve measured this is again notice no

tail and and hairless this is a medical

student okay in the arm you can measure

how Doug flow in the arm by how much it

swells up as some blood flows into it

and what we’ve shown is adding a sham

irradiation this is the thick line here

this is shining UV on the arms that

warms up but keeping it cupboards the

Rays don’t hit the skin there is no

change in blood flow in in dilatation of

the blood vessels but the act of

irradiation during the UV and for an

hour after it there is dilation of the

blood vessels this is the mechanism by

which you lower blood pressure by which

you dilate the coronary arteries also to

let the blood be supplied with heart so

here further data that ultraviolet that

sunlight has benefits on the blood flow

and the cardiovascular system so we

thought were just kind of model at

different amounts of UV hit the earth at

different parts of the earth at

different times of year so you can

actually work out those stores of nitric

oxide the nitrates nitrites might rosa

files on the skin release a cleave to

release n-no different wavelengths of

light have different activities of doing

that so you can look at the wavelengths

that like to do that and you can look

if you live on the equator the Sun comes

straight overhead it comes to a very

thin bit of atmosphere and winter or

summer it’s the same amount of light if

you live up here in summer sun’s coming

fairly directly down but in winter it’s

coming through a huge amount of

atmosphere and much of the ultraviolet

is weeded out and that range of

wavelengths he earth are different in

summer to winter so what you can is you

can multiply those data by the n oh

that’s released and you can calculate

how much nitric oxide would be released

from the skin into the circulation now

if you’re on the equator here that’s

these two lines here the red line and

the Purple Line and the amount of nitric

oxide that’s released is the area under

the curve is the area in this space here

so if you’re on the equator December or

June you’ve got masses of n Oh being

released from the skin so Ventura is in

Southern California in summer you might

as well be at the equator it’s great

lots of air no it’s released for

interior mid winter well there’s still

you know a decent amount Edinburgh in

summer the area beneath the curve is

really good but Edinburgh in winter you

know the amount of air no that can be

released is next to nothing tiny amounts

so what do we think we’re still working

at this story we’re still developing it

with SIL expanding it we think it’s very

important and we think it probably

accounts for a lot of the north-south

health divide within Britain it’s of

relevance to us we think that the skin

well we know that the skin has got very

large stores of nitric oxide as is

various other forms we suspect a lot of

these come from diet green leafy

vegetables beet roots lettuce has a lot

of these nitric oxides that we think go

to the skin we think they’re then stored

in the skin and we think the sunlight

releases this where it has generally

beneficial effects and this is ongoing

work but I mean dermatologists I’m and

I’m a dermatologist my day job is saying

to people you’ve got skin cancer it’s

caused by sunlight don’t go in the Sun I

actually think a far more important

message is that there are benefits as

well as risks to sunlight yes sunlight

is the is the major alterable

risk factor for skin cancer but deaths

from heart disease are a hundred times

higher than deaths from skin cancer and

I think that we need

to be more aware of and we need to find

the risk-benefit ratio how much sunlight

is safe how can we kind of finesse this

best for our general health so thank you

very much indeed