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Biomedical subjects

M J Gibney

Publications and source records attributed to M J Gibney.

At least 55 records · Page 3Linked to original sources
PubMed2000

Effect of long-chain n-3 polyunsaturated fatty acids on fasting and postprandial triacylglycerol metabolism.

Elevated plasma triacylglycerol concentrations have been associated with increased risk of coronary heart disease (CHD). In the past, the epidemiologic evidence about the causal role of triacylglycerols in CHD has not been well regarded, but recent prospective evidence shows that nonfasting plasma triacylglycerol concentration is a strong and independent predictor of future myocardial infarction. Elevated plasma triacylglycerol concentrations are associated with other CHD risk factors, namely reduced HDL-cholesterol concentrations and a preponderance of highly atherogenic, small, dense LDL particles. Plasma triacylglycerol concentrations increase after the ingestion of a fat-containing meal, and elevated postprandial triacylglycerolemia leads to a series of metabolic reactions that reduce HDL-cholesterol concentrations and promote the formation of small, dense LDL particles. The magnitude of the postprandial response is largely determined by fasting plasma triacylglycerol concentrations. Metabolism of plasma triacylglycerols also influences postprandial factor VII activation and the postprandial lipemic responsiveness to dietary cholesterol. Therefore, dietary factors that improve fasting plasma triacylglycerol concentrations must have a role in a healthy diet. Eicosapentaenoic and docosahexaenoic acids are n-3 polyunsaturated fatty acids (PUFAs) in fish oil that effectively reduce plasma triacylglycerol concentrations. Because n-3 PUFAs are effective at low doses (1 g n-3 PUFA/d), they provide a realistic option for the optimization of plasma triacylglycerol metabolism.

Cholesterol, HDL↗
PubMed2000

The impact of postprandial lipemia in accelerating atherothrombosis.

Several clinical studies have shown that the magnitude and duration of postprandial lipemia is positively related to the pathogenesis and progression of coronary heart disease. Postprandial lipid metabolism refers to the series of metabolic events that occur following the ingestion of a meal containing fat. Dietary fat is principally composed of triacylglycerol, postprandial lipaemia therefore being characterized by an increase in plasma triacylglycerol concentration. This review will describe the nature of the postprandial response and show the direct and indirect pro-atherogenic effects of triacylglycerol-rich lipoprotein metabolism. An elevated postprandial lipemic response precipitates a number of adverse metabolic events, including the production of atherogenic chylomicron remnants, the formation of the highly atherogenic small, dense low-density lipoprotein particles, and a reduction in the concentration of the cardioprotective high-density lipoprotein fraction. Postprandial lipemia also interacts with the process of thrombosis, in that an elevated postprandial triacylglycerol-rich lipoprotein concentration has the ability to activate the coagulation factor VII and plasminogen activator inhibitor. In the light of the potential impact of an elevated postprandial lipemia on atherothrombosis, the genetic determinants of the magnitude of the postprandial response will be identified. Finally, the nutritional factors that modulate the postprandial response will also be discussed.

Coronary Artery Disease↗
PubMed2000

Postprandial factor VII metabolism: the effect of the R353Q and 10 bp polymorphisms.

Elevated levels of coagulation factor VII activity (FVIIc) are associated with increased risk of CHD. FVIIc is strongly determined by two polymorphisms (R353Q and 0/10 base pairs (bp)) and plasma triacylglycerol (TAG) concentrations. The Q and 10 bp polymorphisms show strong linkage disequilibrium and have been associated with lower levels of fasting FVII, but there has been little investigation of the effect of these genotypes on the postprandial FVII metabolism. The present study demonstrated that fasting activated factor VII (FVIIa) and factor VII antigen (FVIIag) levels were significantly lower in the heterozygotes carrying the Q and 10 bp alleles (n 12), than in the R/0 bp homozygotes (n 12) (43.0 (SE 4.8) v. 23.9 (SE 6.5) mU/ml and 85.7 (SE 5.4) v. 71.6 (SE 7.5)% respectively). During postprandial lipaemia there was a significant increase in FVIIa in R/0 bp homozygotes but not in the heterozygotes carrying the Q and 10 bp alleles. The proportion of FVIIa (FVIIa:FVIIag) increased in the homozygotes but not in the heterozygotes (2.04 (SE 0.35) v. 1.20 (SE 0.26) respectively). Therefore possession of the relatively common Q and 10 bp alleles is not associated with postprandial activation of FVII, which may in turn have a protective effect against CHD.

Adult↗
PubMed2000

Effect of postprandial lipaemia and Taq 1B polymorphism of the cholesteryl ester transfer protein (CETP) gene on CETP mass, activity, associated lipoproteins and plasma lipids.

A large number of studies in recent years have investigated the effects of hyperlipidaemias and diabetes on cholesteryl ester transfer protein (CETP) on neutral lipid transfer activity and plasma lipids. There has been an ongoing debate as to whether CETP is pro- or anti-atherogenic as it provides a mechanism for the transfer of cholesterol from the cardioprotective HDL subfraction to the potentially atherogenic LDL subfraction. This study was designed to investigate whether there was significant variability of CETP mass and activity in a large normolipidaemic population and whether there is an association between CETP and plasma lipoprotein composition. The presence of a known polymorphism of CETP gene (Taq 1B) was investigated to see if there was any association between this polymorphism and CETP mass and activity, and plasma lipids. There was significant (P < 0.0001) increase in CETP mass and activity in plasma postprandially at 6 h. Using multiple stepwise regression analysis there was significant association with fasting CETP mass and activity (beta = 0.055; P = 0.002) and triacylglycerol-rich lipoprotein (beta = 0.013; P = 0.005) and postprandial CETP mass (beta = 0.254; P = 0.007). Repeated-measures analysis showed a strong association between the absence of Taq 1B polymorphism and low CETP mass and elevated HDL- and HDL2-cholesterol and HDL-phospholipid concentrations than did those who were homozygous or heterozygous for the presence of the restriction site.

Adult↗
PubMed2000

Underestimation of body mass index through perceived body image as compared to self-reported body mass index in the European Union.

An observational, cross-sectional study was conducted in a representative sample of the European Union (7155 men and 8077 women) to calculate the underestimation of body weight as assessed by body image among the overweight and obese population and identify the associated factors to this behavior. Participants were older than 15 years and they were living in the 15 European Union countries. Body mass index (BMI) was grouped into 4 categories using the cutpoints established by the WHO, while perceived body image (PBI) was assessed using a nine-silhouettes drawing. The degree of underestimation between PBI as compared to BMI was identified in overweight and obesity categories of BMI. A multivariable logistic regression model for each gender was used to adjust for potentially confounding variables. Men classified themselves worse than women, being more likely to underestimate their body weight (65.2% of men underestimated their weight vs 32.2% women), regardless of other socioeconomic and attitudinal variables. The greatest degree of underestimation was observed in Mediterranean individuals (68.7% of men and 37.9% of women underestimated their weight). The subjects in the 'maintenance' stage of physical activity tended more often to wrongly select their actual image (71.8% for men and 38.7% for women).

Adolescent↗
PubMed1999

Dietary intake methods for estimating food additive intake.

Given the wide array of demands on food intake databases for estimating food chemical intake, there is no possibility of an all-embracing methodology. Whereas initial estimates should always begin at a crude level, when more refined estimates are needed methodologies range from indirect (household, national level) to direct (retrospective or prospective, individual level). The indirect methods cannot provide data on consumer-only intakes but percentage households purchasing can be used as a surrogate for percentage individuals consuming. For the direct methods, the greater the duration, the higher the estimate of percentage consumers and the lower the estimate of intakes among consumers only. In considering excursions above the acceptable daily intake (ADI), databases need to be constructed which allow estimates of intake per eating occasion, where intakes at each eating occasion through the day or days are collapsed into intake per day or week, and the possibility of measuring excursions above the ADI is lost.

Diet Surveys↗
PubMed1999

Long-chain n-3 polyunsaturated fatty acids and triacylglycerol metabolism in the postprandial state.

Elevated plasma triacylglycerol (TG; triglyceride) concentrations, especially in the postprandial state, have been associated with an increased risk of coronary heart disease (CHD). Postprandial lipemia represents a complex series of reactions which occur following the ingestion of a meal containing fat and is associated with a number of adverse metabolic events including the production of atherogenic chylomicron remnants, the formation of the highly atherogenic small dense low density lipoprotein particles, a reduction in the concentration of the cardioprotective high density lipoprotein fraction and the activation of coagulation factor VII. Fish oils are a rich source of the long-chain n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid and docosahexaenoic acid. Long chain n-3 PUFA are effective hypotriglyceridemic agents, lowering both fasting and postprandial TG concentrations. There is a large body of evidence which shows that n-3 PUFA reduces plasma TG concentrations through reduced endogenous very low density lipoprotein production. This in turn may account for the reduced postprandial lipemic response following n-3 PUFA supplementation. However, this does not preclude a contribution of enhanced chylomicron clearance, which may be mediated through altered chylomicron size, structure or chemical composition, or altered lipoprotein lipase metabolism in terms of enzyme concentration, activity, or affinity for chylomicrons. However the precise biochemical nature of this effect remains to be established. The reduction of postprandial plasma TG concentrations by n-3 PUFA may partly explain why n-3 PUFA intake is inversely related to CHD mortality.

Cardiotonic Agents↗
PubMed1999

Optimal macronutrient balance.

There is at present a justifiable debate as to the optimum level of total dietary fat which will reduce the risk of obesity without an elevation of plasma triacylglycerol or a depression of plasma HDL-cholesterol. Total plasma cholesterol and LDL-cholesterol levels are lowered and risk of fatal myocardial infarction is lowered when either saturated or trans-unsaturated fatty acids are replaced isoenergetically by either monounsaturated or polyunsaturated fatty acids. The triacylglycerol-raising and HDL-lowering effects of low-fat high-carbohydrate diets can be overcome with low intakes of n-3 polyunsaturated fatty acids and moderate exercise. Whilst a reduction in dietary fat is being attained in many countries, the reduction is uniform across all fatty acids, leaving dietary fat composition unchanged. The ability of low-fat diets to reduce cholesterol and cause a fall in body weight is not influenced by the carbohydrate ratio starch: sugars in the diet. However, weight-gain susceptibility to high intakes of dietary fat and the plasma cholesterol responsiveness to diet are considerably influenced by common genetic polymorphisms.

Cholesterol↗
PubMed1999

Methods used to conduct the pan-European Union survey on consumer attitudes to physical activity, body weight and health.

OBJECTIVE: The purpose of conducting this survey was to identify data on consumer attitudes towards and beliefs about physical activity, body weight and health among the 15 countries of the EU. DESIGN: A cross-sectional study to get a picture of the attitudes to physical activity, body weight and health in the EU. For this, it was considered important that samples be nationally representative so that inferences drawn from the data could be applied to the population in each country as well as to the EU population as a whole. Using a non-probability sampling method employing quota controls (and the national weight) we obtained large sample sizes from each country which were nationally representative in terms of the variables age, sex and regional distribution. To ensure samples were truly nationally representative a national weight was used when analysing the data using the same characteristics as those used to define quotas. When examining pooled estimates for the total EU sample a population weight was applied. RESULTS: In total, 15,239 subjects aged 15 years and upwards in the EU completed the survey. This article gives details on the methods used in carrying out the survey from design of the questionnaire to sample selection, questionnaire administration and analysis of the data. The methods and their limitations are discussed.

Adolescent↗
PubMed1999

Nutrition, physical activity and health status in Europe: an overview.

INTRODUCTION: The European diet is characterized by a wide variation in every aspect of eating from the timing of meals to the composition of meals. In general, there is a tendency in terms of dietary advice towards lower fat intakes in order to reduce saturated fatty acid intake and to reduce the risk of obesity. Such diets are most successful and yield the most favourable metabolic profile when there is an adequate level of physical activity. OBJECTIVE: The aim of the present paper was to explore how the composition of dietary fat changes across the EU with low- and high-fat diets and to explore levels of physical activity and attitudes to physical activity across the EU. DESIGN: The paper draws on data contained in reports and supplements of the Institute of European Food Studies in the EU. RESULTS: There is a clear trend for southern EU states to have higher MUFA intakes and lower SFA intakes than northern ELJ states. However, for both geographic regions, the fatty acid composition of dietary fat was similar in groups with lower or higher dietary fat intakes. Physical activity was ranked low by consumers (n= 15,000) for its importance in relation to health and the prevention of weight-gain. Some 47% agreed that their present level of physical activity is sufficient. 78% agreed that being 13 kg heavier would not be detrimental to health and 30% agreed that the main benefit of physical activity was to relieve stress. CONCLUSIONS: (i) The present strategy of lowering dietary fat intake does not alter dietary fat composition and (ii) there is a high level of ignorance among consumers of the benefits of physical activity and the adverse effects of excess body-weight.

Attitude to Health↗
PubMed1999

Perceptions about body weight and weight reduction in Spain.

OBJECTIVE: To assess the more prevalent beliefs about body weight and the factors involved in weight changes in the Spanish adult population. DESIGN: A national survey was carried out according to an established protocol on Spanish subjects selected by a multistage procedure following a random route model, which was quota-controlled for several sociodemographic variables. This study was undertaken by the Spanish arm of a pan-European survey and was performed with a validated questionnaire. It contained questions to evaluate some aspects concerning the relationship between obesity, physical activity and health. We also estimated the proportion of self-reported overweight and obesity. SETTING: Spain. SUBJECTS: The sample included 1,000 subjects aged 15 years or older. RESULTS: Eleven per cent of the sample were obese (body mass index, BMI > 30 kg/m-2) and an additional 32% were overweight (BMI > 25 and < 30 kg/m-2). Obesity prevalence was higher among older individuals, those with lower education and socioeconomic levels, and among housewives and retired or unemployed people. Most Spanish people believed that fat intake (51%) and the amount of food consumption (44%) were the major factors involved in weight gain, while physical activity was less mentioned (12%). The method most frequently used to lose weight was diet (9%). Individuals from central and southern regions payed more attention to genetics (20-27%) and physical activity (12-20%) as determinants of weight gain than people living in the north or northwest regions (15-17% and 8-9%, respectively). Normal weight people participated more often in some physical activity during their leisure time. CONCLUSIONS: The Spanish population is not familiar with factors influencing weight gain. Health promotion strategies should emphasize the role of physical activity, especially among older individuals, retired or unemployed subjects, those from lower educational or socioeconomic levels and among people living in the north or northwest of Spain.

Adolescent↗
PubMed1999

Physical inactivity, sedentary lifestyle and obesity in the European Union.

BACKGROUND: Diverging trends of decreasing energy intake and increasing prevalence of obesity suggest that physical inactivity and sedentary lifestyle may be one of the key determinants of the growing rates of overweight/obesity in Western populations information about the impact of physical inactivity and sedentary lifestyles on the prevalence of obesity among the general adult population in the European Union is sparse. OBJECTIVES: To estimate the association of leisure-time sedentary and non-sedentary activities with body mass index (BMI, kg/m2) and with the prevalence of obesity (BMI>30 kg/m2) in a sample of the 15 member states of the European Union. METHODS: Professional interviewers administered standardized in-home questionnaires to 15,239 men and women aged 15 years upwards, selected by a multi-stage stratified cluster sampling with quotas applied to ensure national and European representativeness. Energy expenditure during leisure time was calculated based on data on frequency of and amount of time participating in various physical activities, assigning metabolic equivalents (METS) to each activity. Sedentary lifestyle was assessed by means of self-reported hours spent sitting down during leisure time. Multiple linear regression models with BMI as the dependent variable, and logistic regression models with obesity (BMI>30 kg/m2) as the outcome, were fitted. RESULTS: Independent associations of leisure-time physical activity (inverse) and amount of time spent sitting down (direct) with BMI were found. The adjusted prevalence odds ratio (OR) for obesity was 0.52 [95% confidence interval (CI): 0.43-0.64, P<0.001] for the upper quintile of physical activity (>30 METS) compared with the most physically inactive quintile (<1.75 METS). A positive independent association was also evident for the time spent sitting down, with an adjusted OR= 1.61(95% CI: 1.33-1.95, P<0.001) for those who spent more than 35 h of their leisure time sitting down compared with those who spent less than 15 h. CONCLUSIONS: Obesity and higher body weight are strongly associated with a sedentary lifestyle and lack of physical activity in the adult population of the European Union. These results, however, need to be interpreted with caution due to the cross-sectional design. Nonetheless, they are consistent with the view that a reduction in energy expenditure during leisure time may be the main determinant of the current epidemic of obesity.

Adolescent↗
PubMed1999

Strategies for altering population intakes of fats and fatty acids.

Quantitative dietary guidelines for fats were first issued in 1977 in the USA and these guidelines have changed little since then. In the UK only 14% of the population achieve the dietary goal for fat (33% energy) and only 3% achieve the target (10% energy) from saturated fatty acids. Analysis of the Dietary and Nutritional Survey of British Adults reveals that across quartiles of decreasing total fat intake, the actual fatty acid composition of this fat does not alter; i.e. when total fat is lowered, all fatty acid categories are equally lowered. This arises because 85% of total fat and of each of the categories of fatty acids are provided by just five foods (milk, meat, cereals, spreads and vegetables). When total fat in the UK is lowered, the intake of polyunsaturated fatty acids is lowered. The problem is that if the intake of polyunsaturated fatty acids falls below a threshold of about 5% energy, the cholesterol-raising properties of certain saturated fatty acids, e.g. myristic acid, are greatly augmented. In order to alter the balance of dietary fatty acids, more data are needed on food choices of those in the population achieving particular targets. These targets cannot be based on existing dietary goals, since so few people attain them. A new set of 'interim attainable dietary guidelines', based on prevailing dietary intakes, must be the basis for establishing sensible food-based dietary guidelines.

Adult↗
PubMed1999

The effect of low and moderate fat intakes on the postprandial lipaemic and hormonal responses in healthy volunteers.

Present literature indicates that whereas an acute fat intake of 5 g does not elicit a postprandial triacylglycerolaemic response, 20 g of fat does. Since 67% of fat intake occasions involve fat doses of less than 20 g, the present study examined the effect of a relatively low-fat (LF) meal (0.2 g/kg body weight; mean 14 g) on postprandial triacylglycerol (TAG) metabolism, compared with a high-fat (HF) meal (0.6 g/kg body weight; mean 43 g), a fat dose which is more typical of laboratory studies. Plasma- and chylomicron-TAG concentrations increased significantly (P < or = 0.001) following both meals, and the increase was significantly (P < or = 0.02) greater after the HF meal. The postprandial areas under the curves and maximal postprandial TAG concentrations for plasma- and chylomicron-TAG were significantly higher following the HF meal (P < or = 0.05). Postprandial plasma insulin and gastric inhibitory polypeptide concentrations increased significantly (P < or = 0.001) after each meal, but there was no difference between the two meals. These data show that modest amounts of fat in a meal will elicit a measurable postprandial TAG response. Since postprandial lipaemia affects the composition and concentration of the TAG- and cholesterol-rich lipoproteins, controlling dietary TAG supply may influence the metabolic fate of these lipoproteins.

Adult↗
PubMed1999

Cholesterol reduction using manufactured foods high in monounsaturated fatty acids: a randomized crossover study.

In two separate studies, the cholesterol-lowering efficacy of a diet high in monounsaturated fatty acids (MUFA) was evaluated by means of a randomized crossover trial. In both studies subjects were randomized to receive either a high-MUFA diet or the control diet first, which they followed for a period of 8 weeks; following a washout period of 4-6 weeks they were transferred onto the opposing diet for a further period of 8 weeks. In one study subjects were healthy middle-aged men (n 30), and in the other they were young men (n 23) with a family history of CHD recruited from two centres (Guildford and Dublin). The two studies were conducted over the same time period using identical foods and study designs. Subjects consumed 38% energy as fat, with 18% energy as MUFA and 10% as saturated fatty acids (MUFA diet), or 13% energy as MUFA and 16% as saturated fatty acids (control diet). The polyunsaturated fatty acid content of each diet was 7%. The diets were achieved by providing subjects with manufactured foods such as spreads, 'ready meals', biscuits, puddings and breads, which, apart from their fatty acid compositions, were identical for both diets. Subjects were blind to which of the diets they were following on both arms of the study. Weight changes on the diets were less than 1 kg. In the groups combined (n 53) mean total and LDL-cholesterol levels were significantly lower at the end of the MUFA diet than the control diet by 0.29 (SD 0.61) mmol/l (P < 0.001) and 0.38 (SD 0.64) mmol/l (P < 0.0001) respectively. In middle-aged men these differences were due to a mean reduction in LDL-cholesterol of -11 (SD 12)% on the MUFA diet with no change on the control diet (-1.1 (SD 10)%). In young men the differences were due to an increase in LDL-cholesterol concentration on the control diet of +6.2 (SD 13)% and a decrease on the MUFA diet of -7.8 (SD 20)%. Differences in the responses of middle-aged and young men to the two diets did not appear to be due to differences in their habitual baseline diets which were generally similar, but appeared to reflect the lower baseline cholesterol concentrations in the younger men. There was a moderately strong and statistically significant inverse correlation between the change in LDL-cholesterol concentration on each diet and the baseline fasting LDL-cholesterol concentration (r -0.49; P < 0.0005). In conclusion, diets in which saturated fat is partially replaced by MUFA can achieve significant reductions in total and LDL-cholesterol concentrations, even when total fat and energy intakes are maintained. The dietary approach used to alter fatty acid intakes would be appropriate for achieving reductions in saturated fat intakes in whole populations.

Adult↗