A Biochemical Study of High-Density Lipoprotein Cholesterol (HDL-C) Changes in Middle Aged Common People with Different Lifestyle

: HDL cholesterol is one of the 5 major groups of lipoproteins cholesterol, which enable lipids like cholesterol and TG to be transported within the water based blood stream. In healthy persons, about thirty percent of blood cholesterol is carried by HDL cholesterol. HDL-C is a potent predictor of coronary heart disease. Genetic as well as environmental factors including lifestyle factors play a role as determinants of its level in the blood. To examine the effects of certain lifestyle factors on serum level of high density lipoprotein cholesterol in young adult people HDL cholesterol seems to protect against CVD which increases the risk for heart disease. Three hundred and twenty five young adult subjects of both sexes aged 18-45 years asymptomatic for cardiovascular diseases were interviewed according to special questionnaire including information on lifestyle habits. Physical examination was done, height, body weight and blood pressure measurements were performed. Blood analysis to determine the blood level of high density lipoprotein cholesterol was done after 12 hours fasting. Smoking and obesity were the most significant risk factors associated with a decreased level of high density lipoprotein cholesterol. The level of HDL-C was 50.5±11.5 mg/dl in smokers compared with 57.7±12.5 mg/dl in non-smokers. Its level was 48.5 ±8.5 mg/dl in obese individuals compared to 57.5±11.7mg/dl in normal body weight subjects. Physical activity was not significantly associated with low level of HDL-C analysis, but it was found to be significantly associated with its level by the multiple regression analysis. High-density lipoprotein cholesterol level was a function of many factors, some of them were lifestyle related such as smoking, physical activity and obesity. Therefore, efforts to encourage more physical activity, quitting smoking, consuming low fat diet and keeping ideal body weight are recommended.


INTRODUCTION
have low levels of HDL-C [less than 1 mmol/L] as the Strong evidence from epidemiological and clinical HDL-C are multi factorial and many possibilities are trials had supported an inverse relationship between suggested; HDL-C may prevent oxidation of LDL-C, so it HDL-C and risk of coronary heart disease (CHD) [1][2][3][4][5][6][7][8].
protects against excess lipid accumulation in the blood For every 1mg/dl increase in serum HDL-C, there vessel wall. [3,10] It provides a reverse cholesterol appears to be a corresponding 2% to 3% decrease in transport from the tissues to the liver for metabolic CHD risk and 4% to 5% decrease in cardiovascular conversion and excretion [3,11]. It has also been diseases mortality [7]. Approximately one quarter to hypothesized that cholesterol efflux from atherosclerotic one third of patients with pre-existing coronary disease lesion is promoted by HDL-C, possibly through a receptor and desirable total cholesterol [less than 5.2 mmol/L] related mechanism [4,12].
primary abnormality [2, 3,9]. The protective effects of In addition to constitutional determinants such as  considered as constantly sedentary which nearly equals  age, sex, ethnicity and genetic factors, other variables  to 1 hour of light aerobic activity/ week. Those who have  such as dietary fat, obesity and other lifestyle factors an index of 15-85 were considered moderately active [13]. including physical activity, alcohol consumption and Height and weight were measured and the body mass smoking habit are known to affect serum HDL-C level.
index (BMI) was calculated using the Quetlet index [5, [13][14][15][16][17]. There are many studies worldwide which [BMI = weight in Kg/height in m ][20] Non obese: studied the influence of lifestyle on serum lipids BMI < 30kg/m , overweight: BMI 30-34.2 kg/ m and (including HDL-C) [15][16][17], but studies which examined the obese if BMI was >35 kg/ m [21]. Clinical heart relation between lifestyle factors and HDL-C serum levels examination and pulse rate measurements were done to in young adults asymptomatic for coronary heart diseases detect any heart abnormality. Biochemical measurements are scarce in Karaikal, India., after obtaining the approval regarding serum HDL-C estimation was performed after Institutional research and ethical committee, this cross-12 hours fasting. Serum HDL measurement was done by sectional study was conducted in the department of the Random Access Clinical chemistry analyzer (Model: Biochemistry, Vinayaka Missions Medical college and XL-300) Low level of HDL-C was considered if the level hospital, Karaikal, India between (January to march 2015) was < 40 mg / dl [22,23]. to examine the effect of certain lifestyle factors on serum HDL-C level.
Statistical Analysis: Data was represented as mean and used when appropriate. Multiple regression analysis was apparently healthy, with no history of cardiovascular used to determine whether observed differences in diseases, who were selected randomly from three outcomes remained while controlling for potentially colleges nearby to the Vinayaka Missions medical confounding variables. A P-value of <0.05 was considered college and hospital, Karaikal and from College Bus significant. drivers.

Methods:
Interviewing was performed according to a special questionnaire form which covers the following Table 1 demonstrates selected socio-demographic aspects; Socio-demographic characteristics, medical characteristics of the study population. The majority history, aspects of dietary habits, alcohol consumption, were in their early twenties. While those who were above physical activity and smoking. Smoking habits: non-45 years of age formed only 3.38% of the total studied smokers defined by those who never smoke, Ex-smokers population. Regarding sex composition, the majority were included those who stopped smoking before more than 3 men. 64.3% were with higher secondary school level of months, while Current smokers were those who smoke education and 11.6% were with basic degree or more level regularly. Diet was classified on the type of food that of education. individuals consumed, those who consumed a well known Tabl 2 shows the frequency of the lifestyle factors fatty diet such as butter, cream, cheese, solid fat etc, among the studied subjects. The fatty diet consumption on most days of the week were considered to be on fatty was the most prevalent lifestyle among the study diet. Physical activity was measured by using a population. It was prevalent in 37.84% of them, followed combined index of leisure time physical activity which was by smoking which was prevalent in 27.69%. Obese and calculated from the product of intensity, estimated inactive subjects formed 7.6% and 15.38% of the total duration of exercise and monthly frequency using the studied population respectively. Reliable information method reported by Raitakan et al. [18,19]. Subjects with concerning alcohol intake was difficult to obtain from index of equal or higher than 80 were considered as interviewees, therefore, the results were undependable. constantly active, which nearly equals to an intensive Only 3 individuals (1.53%) mentioned they were on physical activity for more than 2 hours/week. Subjects alcohol-intake, so no further analysis was carried out with an index value of less than or equals to 17 were regarding this variable [24][25][26][27][28][29][30][31][32][33].    As shown in Table 3, HDL-C level was inversely associated with smoking and body mass index with a highly significant difference. HDL-C serum level was 50.5 ± 11.5mg/dl in smokers in comparison with 57.5 ± 12.5mg/dl in non-smokers and its level was 55.7 ± 11.7mg/dl in normal weight individuals compared 48.5 ± 8.5mg/dl in obese persons. While HDL-C level was lower in fatty diet consumers (55.2 ± 12.5mg/dl) and sedentary individuals (54.5±12.3 mg/dl) in comparison with non-fatty diet consumers (56.03±13.5 mg/dl) and active individuals (56.8±11.9 mg/dl) respectively, but the differences were not significant.

RESULTS
To investigate the independent effects of selected risk factors on HDL-C level, a stepwise linear multiple regression analysis was performed (Table 4) the examined risk factors were the lifestyle determinants (i.e. smoking, physical activity, diet and body mass index) in addition to age and sex. Body mass index, smoking and physical activity in addition to sex (females showed higher HDL-C level) and age were noticed to have highly significant effects on HDL-C concentration. BMI appears to be the strongest variable that explained 5.9% of the variability in In conclusion, HDL-C level was primarily a function of HDL-C concentration, together with the other variables, many factors, some of them are lifestyle related such as they explained 17.9% of the variation in HDL-C smoking, physical activity and obesity. The results of this concentration and about 82% of the variation is still left study clearly demonstrated the need to initiate preventive unaccounted for. efforts early in life to encourage more physical activity,

DISCUSSION
consuming healthy diet.
This study has shown different contributions to the REFERENCES risk of low level of HDL-C from the major lifestyle factors.
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