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