Case study
Effect of smoking on lipid profile
R.S.Trivedi1,A.K.Anand2- Jamnagar( Gujarat)
Introduction
The habit of smoking is increasing particularly in developing
nations. There is considerable evidence that tobacco
consumption either in smokable or in smokeless form is
associated with increased risk of cardiovascular disease
(CVD). The present study was conducted to find out
differences in the serum lipoprotein profile between smokers
and nonsmokers. Study included 50 smokers and 50 non
smokers. Smokers were divided into three classes- Mild (1-10
cigarettes per day), Moderate (11-20 cigarettes per day) and
Heavy (more than 20 cigarettes per day). The mean serum
total cholesterol was significantly higher in smokers than non
smokers. The mean serum HDL-cholesterol was significantly
lower in smokers than non smokers. The mean serum LDL,
mean serum triglyceride and mean serum VLDL were
significantly higher in smokers than non smokers although
the increase was insignificant in mild smoking. In present
study, the overall assessment has been that smoking is
associated with an unfavorable serum lipid profile. India is
world's third largest tobacco-producer and its product
consumer, after China and United States. Tobacco is smoked
and chewed in variety of ways and all forms of tobacco use are
reported to carry equal serious health consequences.
However, most Indian smokers, particularly in the lower
socio-economic classes, smoke bidis. Bidis (the "Indian
Cigarettes") are made from tobacco which is rolled by hand in
a tendu leaf. Now the habit of cigarette smoking is rising in
rural India. Key words:
Smoking, Lipid profile
Material and methods
The study was carried out in Department of Physiology, M.P.
Shah Medical College and Guru Gobind Singh Hospital,
Jamnagar. 50 healthy smokers and 50 healthy non smoker
subjects were included in the study. All the subjects in both the
samples were in the age group 30 to 60 years belonging to
middle socio-economic class. The control groups (nonsmokers) were comparable in age, sex, physical activity and
body mass index to study group (smokers). For studying
exclusively the effect of smoking on lipid profile, the subjects
having risk factors that affect lipid profile, were excluded.1
Exclusion criteria Persons having any of following criteria
were excluded. (1)Alcohol intake,(2) Ex-smoker,(3) Obesity
(BMI 30 in males and 28.6 in females)2,(4) Diabetes
mellitus,(5) Hypothyroidism(6) Renal diseases: Renal
failure, Nephrotic syndrome,(7) Liver diseases: Obstructive
liver diseases, Acute hepatitis,(8) Drugs: Estrogen,
Progesterone, - Blockers, Glucocorticoids etc. (9) Systemic
lupus erythematosus (SLE),(10) Multiple myeloma,
Lymphoma. Complete detailed history of each subject
including weight and height, number of cigarettes smoked per
day, duration of smoking, types of cigarettes taken, any
specific symptoms (if any) were noted as shown in Performa.
After detail history, pulse and blood pressure were recorded in
supine position after rest for five minutes in each person.
General and systemic examinations were done thoroughly.
Venous blood were collected after overnight fasting of 12
hours in all the subjects for estimation of serum total
cholesterol, HDL cholesterol, LDL cholesterol, VLDL
cholesterol and serum triglycerides. Serum was separated
from blood samples by centrifugation. Serum cholesterol,
serum triglyceride and serum HDL were measured. LDL and
VLDL cholesterol were calculated from these three values.
After taking complete detailed history and performing
complete clinical examination, venous blood was collected
(after overnight fasting) in all the subjects and estimation of
serum total cholesterol, triglycerides, HDL-cholesterol, LDL
and VLDL-cholesterol were done.All the subjects were
divided into four groups according to the number of cigarettes
/ bidis smoked per day.3, Group I:Non smoker: Subjects who
never smoked, Group II: Mild smoker: Subjects smoking 1-10
cigarettes or 1-15 bidis per day, Group III : Moderate smoker:
Subjects smoking 11-20 cigarettes or 16-30 bidis per day,
Group IV: Heavy smoker: Subjects smoking more than 20
cigarettes or 30 bidis per day. The data collected were
statistically analyzed.
Results and observations
The study, which was carried out on 50 healthy smokers and
50 healthy non smokers, showed following results: General
examination and systemic examination of all the subjects
were normal. Neither smokers nor nonsmokers were obese,
the body mass index (BMI) being less than 26.4 in smokers
and 26.2 in nonsmokers. The changes in mean age, pulse rate
and blood pressure in smokers and non smokers were nonsignificant statistically. i) Mean level of total cholesterol, LDL
cholesterol, VLDL Cholesterol and triglycerides were
1
Associate Professor Physiology,2Ex Prof & Head Physiology, M.P.Shah Govt. Medical College Jamnagar
13
National Journal of Otorhinolaryngology and Head & Neck Surgery, Vol. 1(10) No. 2, August 2013
significantly increased (p< 0.01) in smokers than nonsmokers.ii) Mean level of HDL-cholesterol was significantly
low (p< 0.01) in smokers (43.5 5.6 mg/dl) than non-smokers
(47.0 6.8 mg/dl).iii) Mean level of serum triglyceride and
VLDL were much more significantly increased (p< 0.001) in
smokers as compared to other values.iv) Mean total
cholesterol was 15.0 mg/dl and 6.5 mg/dl higher in heavy
smokers as compared to mild and moderate smokers.v)Mean
HDL-cholesterol was 3.4 mg/dl and 2.1 mg/dl lower in heavy
smokers as compared to mild and moderate smokers.
vi) Mean LDL-cholesterol was 12.5 mg/dl and 2.4 mg/dl
higher in heavy smokers as compared to mild and moderate
smokers.vii) Mean triglyceride was 36.2 mg/dl and 16.5
mg/dl higher in heavy smokers as compared to mild and
moderate smokers.
viii) Mean VLDL was 6.6 mg/dl and 3.4 mg/dl higher in
heavy smokers as compared to mild and moderate
smokers.ix) Although the values of total cholesterol, LDLcholesterol, triglyceride and VLDL-cholesterol were higher
in mild smokers than non smokers but increase were
statistically insignificant.x) The increased value of total
cholesterol, LDL-cholesterol, triglyceride and VLDLcholesterol in moderate and heavy smokers were statistically
significant.
xi) The decreased level of HDL-cholesterol in mild, moderate
and heavy smokers than non smokers was statistically
significant.
Lipid profile of non smokers and smokers of mean 8 years
Duration of various categories-i) There was increased in the
level of mean total cholesterol (173.0 34.6 mg/dl), LDL cholesterol (96.5 24.4 mg/dl), triglyceride (140.2 30.6
mg/dl) and VLDL (30.4 8.2 mg/dl) in mild smokers than non
smokers but statistically insignificant.ii) There was decrease
in the level of mean HDL-cholesterol in mild smokers (45.0
3.8 mg/dl) than non smokers (47.0 6.8 mg/dl) but statistically
insignificant.iii) There was significant decrease in the level of
mean HDL-cholesterol in moderate smokers (42.5 4.2 mg/dl)
than mild smokers (45.0 3.8 mg/dl) and non smoker (47.0
6.8 mg/dl).iv) Increase in the level of total cholesterol in
moderate smokers (179.2 30.8 mg/dl) than mild smokers
(173.0 34.6 mg/dl) and non smokers (164.0 16.8 mg/dl) was
statistically insignificant.v) Increase in the level of serum
triglyceride, LDL and VLDL-cholesterol in moderate
smokers (154.0 28.2, 109.0 20.2, 32.5 7.2 mg/dl) than mild
smokers (140.2 30.6, 96.5 24.4, 30.4 8.2 mg/dl) and non
smokers (129.0 28.6 ,92.8 20.4, 27.2 8.8 mg/dl) were
statistically significant.
Discussion
Both the smokers and non smokers were comparable in terms
14
of age, height, weight, body mass index and dietary habits.
The mean age (in years) of smokers was 46.2 10.2 and that of
non smokers was 45.0 11.4 which was not significant
statistically (P>0.05). Neither the smokers nor the nonsmokers were obese. General examination and systemic
examination of all the subjects were normal. The exact
mechanism by which smoking induces atherosclerosis is not
clear. Many studies have shown that cigarette smoking leads
to increased serum level of total cholesterol, LDL cholesterol,
triglyceride level and decreased level of antiatherogenic
HDL. Even exposure to environmental tobacco smoke i.e.
passive smoking result in decreased levels of HDL cholesterol
in children of smoker parents.
The mechanism by which
smoking alters lipoprotein metabolism is not clear. The
various mechanisms postulated are: Cigarette smoking Absorption of nicotine into the body-Secretion of
catecholamine and other hormones (cortisol, growth
hormone)-Activation of Adenyl cyclase in adipose tissueRelease of free fatty acids from adipose tissue into plasma
bound to albumin-Increased synthesis of triglycerides and
VLDL by liver-Decreased HDL.(1) Nicotine by stimulating
sympathoadrenal system leads to lipolysis, increased serum
free fatty acid (FFA) levels and increased synthesis of
VLDL.(2) Smoking has an additional indirect effect on
lipoprotein metabolism by affecting lipoprotein lipase, which
is an important factor in the metabolism of cholesterol and
triglycerides. (3) Repressive action of smoking on the
estrogen level which in turn leads to increased cholesterol.
Lower levels of estrogen are noted in smoking women as a
result of accelerated estrogen catabolism and formation.
Postmenopausal women taking estrogens have lower serum
estrogen levels if they smoke cigarettes. (4) Smokers are
known to consume diet rich in fat and cholesterol and poorer
in fibre and cereals.(5)Difference in oral fat handling between
smokers and non smokers (6) An antigenic glycoprotein
component of cigarette smoke, associated with immune
reactions, may also produce endothelial injury along with
other factors. Smoking reduces HDL cholesterol which is
considered the best predictor of atherosclerotic events.
Smoking cessation trials have documented a significant rise
in HDL after smoking cessation, and the expected rise after
continued cessation is 6 to 8 mg/dL Comparison of serum
cholesterol:The mean serum total cholesterol value among
non smokers was 164.0 16.8 mg/dl while in smokers it was
180.0 29.4 mg/dl. The values are significantly higher in
smokers. These findings are comparable with the
observations of other workers. Sinha et al4 observed
significant changes in cholesterol level in smokers and that is
comparable with present study.Rastogi et al3 found high level
National Journal of Otorhinolaryngology and Head & Neck Surgery, Vol. 1(10) No. 2, August 2013
of serum cholesterol because it was estimated by different
method.Brischetto et al5 did not found much difference of
serum cholesterol in mild smokers than non smokers but in
moderate and heavy smokers, it was significantly raised than
non smokers.Bulliya G.6 observed significant increase in
cholesterol level than non smokers. Comparison of serum hdlcholesterol:The mean serum HDL-cholesterol level in non
smokers was 47.0 6.8 mg/dl and that of smokers was 43.5 5.6
mg/dl. The value was significantly lower in smokers.The
findings suggest that serum HDL-cholesterol is significantly
lower in smokers as compared to non smokers and also it is
significantly lower in moderate (42.1 4.6 mg/dl) and heavy
smokers (40.0 4.1 mg/dl) as compared to mild smoker (43.4
5.4 mg/dl). These findings are in accordance to the
observations made in other studies. Comparison of serum
ldl:The mean LDL-cholesterol level was 92.8 20.4 mg/dl in
non smokers and 103.4 29.8 mg/dl in smokers which was
significant statistically. The increase in LDL-cholesterol in
mild smokers (97.5 20.8 mg/dl) was insignificant as
compared to non smokers where as in moderate (107.6 22.6
mg/dl) and heavy smokers (110.0 8.4 mg/dl), the change
were significant.Sinha et al4 observed that changes in LDLcholesterol in mild smokers as compared to non smokers was
insignificant whereas in moderate and heavy smokers that
were significant as in present study. Comparison of serum
triglycerides: Rastogi et al3 observed that changes in value of
S. VLDL is significant in mild smokers as compared to non
smokers but changes were significant in moderate and heavy
smokers as in present study.
Conclusions
Our study included 50 smokers and 50 non smokers. All were
healthy and non-obese. The means age of smokers was 46.2
10.4 years and that of non smokers was 45.0 11.4 years. The
mean pulse rate in non smokers was 74.2 5.2 per minute
where as in smokers it was 77.4 6.0 per minute. The higher
pulse rate in smokers suggests increased sympatho adrenal
drive. The mean blood pressure in smokers was 118.6 12.4 /
76.2 9.2 mm of Hg whereas in non smoker it was 116.8 12.8 /
75.6 8.8 mm of Hg. The change was not statistically
significant. The mean serum total cholesterol was
significantly higher in smokers than non smokers. The
increase was insignificant in mild smokers whereas it was
significant in moderate and heavy smokers. The mean serum
HDL-cholesterol was significantly lower in smokers than non
smokers. The mean serum LDL was significantly higher in
smokers than non smokers although the increase was
insignificant in mild smokers. The mean serum triglyceride
was much significantly higher in smokers. The increase was
15
insignificant in mild smokers. The mean serum VLDL was
significantly higher in smokers than non smokers. Therefore,
it can be concluded that alteration in lipid profile are higher in
persons smoking greater than 20 cigarettes per day (heavy
smokers) and those smoking 11-20 cigarettes per day
(moderate smokers) than those smoking 1-10 cigarettes per
day (mild smokers)
References
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Address for correspondence
Dr. R.S.Trivedi
Associate Professor Physiology
M .P. Shah Govt. Medical College
Jamnagar, Gujarat
Cell +91 9426465897
E-mail: drrstrivedi@yahoo.com
National Journal of Otorhinolaryngology and Head & Neck Surgery, Vol. 1(10) No. 2, August 2013