smoking and skin health

[Rupal Pandit]

 

Smoking is associated with a range of detrimental health effects, the
most well known of which are lung cancer and cardiovascular disease.
There are many lesser known health effects as well, including effects
on the skin.
In many cases, these changes to skin are not life threatening, though
they can change the physical appearance of the smoker. For example,
smoking is associated with premature ageing and wrinkles. Smoking is
also associated with very serious skin conditions, including squamous
cell carcinoma of the skin (a type of skin cancer) and psoriasis.
Awareness of the changes to physical appearance and the serious skin
conditions associated with smoking may help motivate individuals to
quit smoking.
 
How smoking affects the skin
The precise ways in which tobacco smoke damages or changes skin are
not fully understood, though scientific studies have produced evidence
about a number of possible ways. Studies suggest that tobacco smoke
exposure decreases capillary and arteriolar blood flow, possibly
damaging connective tissues that help maintain healthy skin. Skin
fibroblasts (the cells in connective tissue that form collagen and
elastin) are damaged by tobacco smoke.
There is also evidence that tobacco smoke is phototoxic. Smoke becomes
more toxic in the presence of ultraviolet light (UV), such as is found
in sunlight, and causes more damage to skin cells than either smoke or
UV would cause on their own.
 
Changes to physical appearance
Ageing
As people age, their skin also ages. The ageing process is influenced
by a number of environmental factors. Sun exposure is the most
prominent risk factor for premature ageing. Although it is much less
well known, cigarette smoking is also a risk factor for premature skin
ageing.
Several studies have reported that cigarette smoking causes an
individual's skin to age even more than exposure to sunlight does.
Studies have also reported that the effect of exposure to tobacco
smoke and sunlight at the same time is more dangerous than the
combined effect of either exposure alone, and that women are at
greater risk than men.
The ageing of skin can be measured by a number of features. Most
obviously, skin becomes wrinkled. Wrinkling is caused by changes to
skin elasticity and concentrations of skin components such as collagen
and elastin. Differences in skin features between individuals who do
and do not smoke can therefore be measured by physical appearance, or
by analysing skin tissues for concentrations of components.
 
Wrinkles
Numerous studies have found that premature wrinkling is associated
with smoking. There is evidence that the more an individual smokes,
the more the premature ageing effect occurs, so heavy smokers will
experience more premature wrinkles than those who only smoke
occasionally. One study, in which eight judges individually rated the
age of smokers and non-smokers from their photographs, reported that
smokers were, on average, rated as being 2.7 years older than their
actual age, while non-smokers were rated at 0.7 years younger than
their actual age.
Another study reported that moderate smokers were almost twice as
likely to wrinkle prematurely than non-smokers, and heavy smokers were
almost three times more likely to wrinkle prematurely.
Other studies have examined exposure to both cigarettes and sunlight,
to assess the relative importance of each of these exposures in the
development of wrinkles. Evidence from these studies suggests that
smoking may be a more important factor in the development of wrinkles
than sun exposure.
There is evidence that individuals exposed to both tobacco smoke and
sunlight prematurely winkle more than individulas exposed to tobacco
smoke or sunlight alone. One study found that smokers were 5.8 times
more likely to develop wrinkles than non-smokers, while those with
excessive sun exposure (i.e. more than two hours per day) were only
2.65 times more likely to wrinkle than those who were not excessively
exposed to sunlight. Individuals who smoked heavily (35 pack years or
more) and had excessive sun exposure were 11.4 times more likely than
non-smokers with less than two hours per day of sun exposure to
develop wrinkles. This is a considerably greater risk than the
combined individual risks of exposure (i.e. 5.8 for tobacco + 2.65 for
sunlight = 8.45 times more likely). As tobacco smoke is phototoxic,
this synergistic effect of combined tobacco smoke and sun exposure is
unsurprising.
Another study reported that smoking more than 20 cigarettes per day
was associated with an almost 10-year increase in skin ageing. The
study found no significant association between sun exposure and
wrinkles.
There is some evidence that women's skin is more affected by tobacco
smoke exposure than men's skin. One study reporting a premature ageing
effect in both sexes found that smoking men were 2.3 times more likely
than non-smoking men, and smoking women more than 3 times as likely as
non-smoking women, to age prematurely. The study did not explore the
possible reasons why women's skin was more sensitive to the
detrimental effects of tobacco smoke than men's skin.
 Poor wound healing
There is evidence that smoking tobacco decreases the ability of skin
to regenerate and repair wounds. This is particularly evident in
patients undergoing surgery. For example, smokers who undergo face
lift surgery are more likely than non-smokers to experience
unsatisfactory wound healing.
There are a number of possible ways by which exposure to tobacco smoke
may inhibit the skin's ability to regenerate and repair. Nicotine, one
of the toxic components of tobacco smoke, is a vasoconstrictor (an
agent which causes the blood vessels to contract). When blood vessels
are constricted they transport less blood through the body, and
therefore reduce the supply of nutrients upon which the skin depends
to regenerate. Similarly, carbon monoxide, another toxic component in
tobacco smoke, reduces oxygen flow through the body, thus reducing the
supply of oxygen needed by damaged cells to regenerate.
 
General skin changes
Moisture
Dry skin can feel uncomfortable because it is less flexible than
moisturised skin. Unmoisturised skin becomes unattractive and may take
on a red, flaky or scaly appearance. Dry skin is also more likely to
crack or itch than well-moisturised skin.
Evidence about the effects of smoking on the moisture content of skin
is limited, but the available evidence suggests that smoking reduces
moisture in the skin. An Israeli study examining skin moisture found
that women who smoked more than ten cigarettes per day had
significantly lower mean moisture values than non-smokers.
 
Skin blood flow
Cigarette smoking reduces skin blood flow by increasing the release of
a hormone called vasopressin. Vasopressin is produced naturally by
humans. One of its functions is to reduce blood flow. Studies have
shown that concentrations of vasopressin in the blood rise immediately
after smoking tobacco.
 
Skin lesions
A review of all published studies examining the associations between
skin health and smoking reported that smoking increases the risk of
skin lesions in people with diabetes, lupus and AIDS.
 
Skin cancer
Exposure to sunlight is the predominant risk factor for squamous cell
carcinoma of the skin (a type of skin cancer). There is considerable
evidence that smoking also increases the risk of skin cancer. A Dutch
study found that cigarette and pipe smokers were twice as likely as
non-smokers to develop squamous cell carcinoma of the skin, when other
risk factors (e.g. age and sun exposure) were taken into account.
Interestingly, there was no significant association between cigar
smoking and squamous cell carcinoma. The same study reported that
current smokers were more likely to develop the condition than former
smokers.
The Nurses' Health Study, a large study conducted amongst nurses from
the US, found that nurses who smoked were 50% more likely to develop
squamous cell carcinoma of the skin, compared to non-smoking nurses. A
number of other studies have also identified smoking as a risk factor
for squamous cell carcinoma of the skin.
 
Psoriasis
Tobacco smoke exposure increases the risk of developing psoriasis, a
rare skin condition characterised by the formation of silvery, plaque-
like scales on the arms and legs (particularly at the elbows and
knees). Smokers with psoriasis are less likely than non-smokers to
improve following treatment.
A recent review of literature on the topic reported that women who
smoked were 3.3 times more likely to develop psoriasis than non-
smoking women. While no significant association between smoking and
development of psoriasis in men was found, there was evidence that men
who smoked at least ten cigarettes per day were more likely to have
severe psoriasis. Decreased improvement rates following treatment were
noted in both men and women.