The Effect of Diet and Exercise on Health - Essay Example

? Biomedical Analysis: Assignment Topic: The effect of diet and exercise on cholesterol, triglycerides (TG’s) and high density lipoproteins (HDL). Contents: Page 3 - Abstract Page 4 – Introduction Page 6 – Method Page 7- Results Page 14- Discussion Page 15- References Abstract The present study was conducted to see the effect of individuals’diet and exercise on their levels of cholesterol, triglycerides (TGs) and high density lipoproteins (HDL) in blood. The results show a direct effect of higher fat intake on the levels of total cholesterol and triglycerides indicating an increased risk of cardiovascular disease. As compared to those subjects consuming a low fat diet, the subjects who reported having a normal daily diet with medium amounts of fat had nearly 13% higher blood total cholesterol, and those having a diet with high fat content showed 42% higher blood cholesterol. Similarly, the medium fat consumers had 31% higher TG levels and high fat consumers had 60% higher TG levels compared to the low fat consumers. However, there was no significant difference in HDL concentrations in blood on the basis of dietary fat consumption. The results of the present study further showed that moderate exercise (1-2 times a week) reduces total cholesterol and TG, and increases HDL slightly, thereby reducing the risk of cardiovascular disease. The statistical analysis showed a direct relationship between cholesterol, TG and HDL levels in blood and diet/exercise. The results support the hypothesis diet and exercise affect cholesterol, high density lipoprotein and triglycerides in blood, and, consequently, could reduce the risk of cardiovascular disease. Introduction Accumulation of unnecessary fat in the abdominal region of the body is considered a risk for cardiovascular disease. The key reasons for cardiovascular disease (CVD) are lack of exercise and unchecked eating. CVD is one of the main impediments in maintaining health of common people and is a major cause of mortality in the U.S. (Fox et al., 1996). Lipids are organic substances present in all living organisms. They possess mostly carbon hydrogen bonds and are commonly called fats. They are a rich source of energy and an efficient way for storing excess calories. Because of their unique physical properties, lipids are also an integral part of cell membranes and therefore, also play an important structural role in cells. (Marshall and Bangert, 2008). Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids also encompass molecules such as fatty acids diets their derivatives (including tri-, di-, and monoglycerides and phospholipids) as well as other sterol- containing metabolites such as cholesterol (Harvey, 2003). The main plasma lipids include fatty acids, triglycerides, cholesterols and lipoproteins. The fatty acids are made of a hydrocarbon chain that terminates with a carboxylic acid group this arrangement confers the molecule with a polar, hydrophilic end that is insoluble in water. The fatty acid structure is one of the most fundamental categories of biological lipids, and is commonly used as a building block of more structurally complex lipids. The carbon chain, typically between 4 to 24 carbons long, may be saturated or unsaturated, and may be attached to functional groups containing oxygen, halogens, nitrogen and sulphur. Where a double bond exists, there is the possibility of either a cis or trans geometric isomerism, which significantly affects the molecule’s molecular configuration. cis- double bonds cause the fatty acid chain to bend. This effect is directly proportional to the number of double bounds in the chain. This in turn plays an important role in the structure and function of cell membranes. Most naturally occurring fatty acids are of the cis configuration, although the trans form does exist in some natural and partially hydrogenated fats and oils. (Hunter, 2006). The triglyceride (TG) molecule comprises one glycerol and three fatty acid molecules. TGs, containing saturated fatty acid without bends, packed together closely and tend to be solid at room temperature. Most plant derived TGs comprise primarily poly unsaturated fatty acid, oriented in the cis formation, and are in lipid form even at 40?C. TGs from animal sources are mostly present in the liver and other tissue. The high energy TG molecules, which constitute 95% of lipoprotein fats, are called chylomicrons or VLDL. (Mayne et al., 1994). Cholesterol is an unsaturated steroid alcohol of high molecular weight, consisting of a tetracyclic cyclopentaphenanthrene ring and a side chain of 8 carbon atoms at carbon 17. Holestrol is found exelusively in animals which is used for the manufacture and repair of cell membrane, for synthesis of bile acid and vitamin D. Sources of cholesterol are both exogenous (dietary that contributes 100mg to 700mg cholesterol per day) and endogenous (primarily hepatic). Also it can be produced in the liver and other tissues, and the biliary cholesterol is secreted in to the intestine daily and about 50% of which is reabsorbed in to the blood (Mayne et al., 1994; Carl et al.,1987). The cholesterol levels in blood are influenced by many factors including diet, weight, activity, heredity, age and sex (www.medicinenet.com). Saturated fat and trans fatty acids significantly raise the low-density lipoprotein (LDL) cholesterol level in blood. Excessive body weight leads to increased total cholesterol and LDL levels, and lower high-density lipoprotein (HDL) level. Lack of exercise can generally leads to weight gain resulting in increased LDL cholesterol levels and low HDL levels. Exercise increases HDL which has a protective action in the arteries against the atherosclerosis process (www.medicinenet.com). It extracts cholesterol particles from the artery walls and transports them to the liver for excretion through the bile. HDL also acts against the accumulation of LDL cholesterol in the artery walls. Improvements in lipid profiles have been reported after following an energy restricting diet (Nieman et al., 2002). An inherited genetic condition known as familial hypercholesterolemia is characterised by very high LDL cholesterol levels which cannot be controlled by either diet or exercise (www.medicinenet.com). The lipid profile evaluates the status of fat metabolism in the body. The key enzymes involved in lipoprotein metabolism are lipoprotein lipase (LPL), hepatic lipase (HL), lecithin-cholesterol acyltransferase (LCAT) and cholesterol ester transfer protein (CETP). Lipolysis and LPL activity have been shown to increase after exercise (Ferguson and Alderson, 1998; Magkos et al., 2005). Subjects, Materials and Methods The present study was conducted to investigate the effect of diet and exercise on the lipid profile in blood which is an indicator of risk for cardiovascular disease. The blood samples were taken from 10 healthy female subjects by finger prick technique using standard procedures and observing standard safety measures under the guidance of the supervisor. The required background information such as age, type of diet, physical exercise, alcohol consumption, smoking habits, weight and height was recorded on specific proformas. Blood samples were taken from subjects after 12 hours of fasting, by pricking three fingers of each subject using a Roche Accu-Chek® Softclix® Pro lancing device for cholesterol, HDL and TG analyses. Approximately 3000?l of each blood sample were collected in a plastic capillary which was labelled and used for HDL test. Samples were collected in specially adapted Eppendorf microcentrifuge tube and spun at ~3,000rpm for 5 minutes in a centrifuge. A 33?l sample of plasma was removed using a 10-100ul micropipette for HDL test and placed on the Reflotron HDL Cholesterol Test Strips and analysed for 2 minutes using Reflotron Clinical Biochemistry Analyser. The blood sample for the TGs and cholesterol test was stored unclotted until the completion of the experiment. Cholesterol analysis was carried out for 1? minutes using the same micropipette and analyser and following the same method as in the case of HDL analysis. The same procedure and equipment was used for TG analysis as well. In the final step, all the test materials were safely disposed of into clinical waste bags. Results The present study was undertaken to see the effect of diet and exercise on the blood lipid profile in women. Data were obtained by analysing fasting blood levels of total cholesterol, triglycerides and high density lipoproteins in 10 female healthy subjects. Table 1 gives the background information, including family history of cardiovascular disease, pertaining to the 10 female subjects. Information on the subjects’ normal diet indicates that six out of ten (that is 60%) subjects were consuming medium amounts of fat while 20% each of the subjects formed the category of those consuming low and high fat diets, respectively. Five out of ten subjects were exercising 1-2 times a week while 4 out of 10 subjects were not excercising at all. Only one subject was undertaking moderately heavy exercise i.e. 3-4 times a week. Half of the participants indicated a family history rising lipid levels. The differences in fat intake may be due to the amount of total food (calories) consumed by the subjects, their feeding habits e.g. vegetarian/non-vegetarian, or their reaction towards different food e.g. lactose intolerance. The analysis of the data indicated an inverse relationship between diet/exercise and cholesterol and triglycerides, and a direct relationship of diet/exercise and high density lipoproteins. Table 1. Type of diet, amount of fat consumed, frequency of exercise and family history of subjects Lifestyle & family history of participants Partipant No. 1 2 3 4 5 6 7 8 9 10 Normal diet yes yes yes yes yes yes yes yes yes yes Intake of fat medium high medium high medium medium medium medium low Low Exercise (number of times/week) 1 - 2 1-2 3 - 4 1 - 2 no no no no 1-2 1-2 Family history no no no yes no yes yes yes yes no The results of the analyses of cholesterol, TGs, HDL in the partipants’ blood samples are shown in Table 2. Table 2. Results of analysis of cholesterol, TGs, HDL in partipant blood samples. Participant Cholesterol (m mol/L) Triglycerides (m mol/L) HDL (m mol/L) 1 3.90 0.84 2.18 2 6.43 1.69 1.89 3 4.08 0.80 1.78 4 4.79 1.06 1.86 5 3.16 1.99 1.59 6 5.95 0.82 2.18 7 4.70 1.43 1.49 8 4.90 0.87 2.60 9 4.34 0.92 1.60 10 3.25 0.80 2.00 Figure 1 depicts the mean (+ s.d.) cholesterol levels measured in the various blood samples categorized on the basis of the dietary fat intake. Fig.1. Mean cholesterol concentration (+ s.d.) measured in the blood of participants grouped on the basis of their normal dietary fat intake as low, medium and high. ** P>0.1, F-test (when compared to low fat intake) The triglyceride values (mean values + s.d.) obtained in the various blood samples categorized on the basis of the dietary fat intake are shown in Figure 2. Fig. 2. Mean triglyceride concentration (+ s.d.) measured in the blood of participants grouped on the basis of their normal dietary fat intake as low, medium and high. ** P=0.12, F-test (when compared to low fat intake) The evaluated HDL values (mean values + s.d.) of the various blood samples categorized on the basis of the dietary fat intake are shown in Figure 3. Fig.3. Mean high density lipoprotein (HDL) concentration (+ s.d.) obtained in the blood of participants grouped on the basis of their normal dietary fat intake as low, medium and high. *** P=0.49, F-test (when compared to low fat intake). The effect of exercise on the various blood lipid parameters are shown in Figure 4. Fig. 4. The concentrations of cholesterol, triglycerides (TG) and high-density lipoproteins (HDL) measured in exercising and non-exercising subjects. **P=0.17, ***P=0.42, F-test Discussion The amount of fat consumed through diet was seen to influence the blood cholesterol level as seen in the case of Participant No.2 whose normal diet consists of high fat (Table 1). Blood cholesterol concentration of this participant was 6.43mmol/l (Table 2) which is much higher than the normal value of Read More