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Biomedical subjects

J I Mann

Publications and source records attributed to J I Mann.

At least 37 records · Page 2Linked to original sources
PubMed2001

Determinants of overweight and obesity in patients with bipolar disorder.

OBJECTIVE: To examine lifestyle-related determinants of the excess adiposity observed in patients with bipolar disorder. METHOD: Eighty-nine male and female patients with DSM-IV bipolar disorder who were attending a specialist bipolar clinic or another psychiatric outpatient clinic (19% with body mass index [BMI] > or = 30) and 445 age- and sex-matched reference subjects (12% with BMI > or = 30) participated in a cross-sectional study of nutrient intake and physical activity. Main outcome measures included macronutrient intakes (assessed with 24-hour recall), percentage of energy derived from various food sources, and physical activity levels (assessed with the Life in New Zealand Questionnaire). RESULTS: Mean total energy intake was higher in female patients than in reference subjects: 8468 kJ compared with 6980 kJ (95% confidence interval [CI] = 583 to 2392 kJ). Total daily sucrose and percentage of energy from carbohydrate were higher in patients than in reference subjects; for women, 73 g and 49% (95% CI = 20 to 56 g, 3% to 10) and for men, 89 g and 47% (95% CI = 15 to 59 g, 3% to 9%). Total fluid intake and intake of sweetened drinks were higher in patients than in reference subjects (ratio of geometric means: women, 1.2 and 2.3, respectively [95% CI = 1.1 to 1.4, 1.9 to 2.8]; men, 1.1 and 2.1, respectively [95% CI = 1.0 to 1.23, 1.8 to 2.41). Patients reported fewer episodes of low- to moderate-intensity and high-intensity physical activity as compared with reference subjects (p < or = .05). CONCLUSION: This study confirms that drug-induced changes in food preference can lead to an excessive energy intake largely as a result of a high intake of sucrose. Dietary advice regarding the use of energy-rich beverages along with encouragement to increase levels of physical activity may help prevent weight gain in bipolar patients. The findings also have some bearing on dietary advice aimed at avoiding overweight and obesity in the general population.

Adult↗
PubMed2000

Genetic factors associated with response of LDL subfractions to change in the nature of dietary fat.

A preponderance of dense low density lipoprotein (LDL) particles is associated with an increased risk of coronary heart disease. It has been shown that dense LDL levels can be modified by diet. We investigated the contribution of polymorphisms in the genes for apolipoprotein (apo) B, apo AIV, lipoprotein lipase (LPL) and cholesterol ester transfer protein (CETP) to variation in the changes in plasma concentrations of dense LDL between a high saturated and a high polyunsaturated fatty acid diet. A total of 46 freeliving individuals (19 men and 27 women) completed a crossover trial with two dietary interventions of 4 weeks each, a high saturated fat diet (providing 21% energy from saturated fat and 3% energy from polyunsaturated fat) and a high polyunsaturated fat diet (providing 11% energy as saturated fat and 10% energy as polyunsaturated fat). Overall, the change in dense LDL between the saturated and polyunsaturated fat period was 0.17+/-0.33 mmol/L and this change was similar in men and women. Of the polymorphisms studied only variation in the apo AIV gene causing the substitution of histidine for glutamine at position 360 (Q360H) was associated with significant differences in the change in dense LDL concentration. Apo AIV Q/H individuals (n=6) showed a three-fold greater change in dense LDL cholesterol unadjusted for Lp(a) levels than Q/Q individuals (0.46+/-0.27 versus 0.12+/-0.31 mmol/L, p=0.02). The greater decrease in dense LDL cholesterol with an increase in polyunsaturated fat seen in those with the apo AIV H360 variant, who represent roughly 10% of the general population, suggests that they may benefit most from a PUFA rich lipid lowering diet.

Adult↗
PubMed2000

Variants in the cholesterol ester transfer protein and lipoprotein lipase genes are predictors of plasma cholesterol response to dietary change.

There are no definitive explanations as to why individuals with hypercholesterolemia, a major cardiovascular risk factor, respond differently to dietary change. Fifty five free-living individuals completed a double crossover trial with two dietary regimens, a high saturated fat diet (providing 21% energy from saturated fat and 3% energy from polyunsaturated fat) and a high polyunsaturated fat diet (providing 11% energy as saturated fat and 10% energy as polyunsaturated fat), each phase continuing for 4 weeks. Extensive genotyping and several measures of dietary compliance have provided further insights regarding the determinants of extent of cholesterol response to changes in the nature of dietary fat. Individuals with the CETP B1B1 genotype and the LPL X447+ allele showed an average 0. 44 (95% CI: 0.22, 0.66) and 0.45 (95% CI: 0.18, 0.72) mmol/l greater change in total cholesterol, respectively, than those with one or more CETP B2 allele or homozygous for the LPL S447 allele when comparing diets high and low in saturated fat. Indices of dietary compliance including changes in reported saturated and polyunsaturated fat intake and change in triglyceride linoleate were not significantly different between the CETP genotypes. Change in reported saturated (r=0.36, P=0.04) and polyunsaturated (r=0.22, P=0. 05) fat intake and change in triglyceride linoleate (reflecting polyunsaturated fat intake) (r=0.21, P=0.07), also predicted total cholesterol response to dietary fat changes. In multivariate analyses, variation in the cholesterol ester transfer protein and lipoprotein lipase genes predicted response independent of measures of dietary compliance, suggesting that these two genes are important determinants of variation in cholesterol response to dietary change in free-living individuals.

Adult↗
PubMed2000

Can dietary intervention produce long-term reduction in insulin resistance?

Insulin sensitivity is potentially enhanced by a range of diet-related changes including reduction of visceral adiposity, a reduction in saturated fatty acids, and possibly a redistribution of the proportions of various unsaturated fatty acids. While there is evidence to suggest that lifestyle changes can reduce the risk of progression of impaired glucose tolerance to type 2 diabetes, there are no clinical trials which have conclusively demonstrated that any measure can reduce insulin resistance in the long term to an extent that can prevent the development of type 2 diabetes and other clinical complications. Evidence concerning the possibilities for reducing visceral adiposity and altering the nature of dietary fat are therefore considered. Attempts to achieve prolonged and substantial weight reduction in adults have not been encouraging, and it may be that preventing further weight gain is the most realistic target in this age group. In childhood the attempts have been more successful. The development of new approaches to achieving behavioural change and an environment which facilitates physical activity and appropriate food choices will be essential for more successful individual and population attempts to facilitate reduction in insulin resistance by weight loss. Changes in the nature of dietary fat appear to be more easily achieved. This is already a component of dietary advice aimed at cardiovascular risk reduction, and should be reinforced now with a view to also achieving a reduction in insulin resistance.

Adipose Tissue↗
PubMed2000

A definition for dietary fibre.

The objective of this paper is to present a definition for dietary fibre based on recent advances that have taken place not only in human nutrition but also in plant cell-wall science and animal nutrition. We propose a physiologically based framework definition but, recognizing the diversity of dietary fibre, we have proposed further classifications within this framework. We also suggest that dietary fibre be removed from the carbohydrate group of nutrients because some compounds defined as dietary fibre are not chemically carbohydrates. The definition and classification system clearly highlight areas where further studies are needed.

Cell Wall↗
PubMed2000

Dietary strategies for lowering homocysteine concentrations.

BACKGROUND: Elevated plasma total homocysteine (tHcy) concentrations are associated with increased risk of vascular disease, and there is a strong inverse association between dietary and blood folate and blood tHcy concentrations. Increased folate consumption may lower the risk of tHcy-mediated cardiovascular disease. OBJECTIVES: The objective was to determine the most appropriate means of increasing dietary folate to reduce plasma tHcy. DESIGN: Sixty-five free-living subjects aged 36-71 y with tHcy concentrations >/=9 micromol/L participated in a randomized, controlled trial to compare 3 approaches for increasing dietary folate to approximately 600 microg/d: folic acid supplementation, consumption of folic acid-fortified breakfast cereals, and increased consumption of folate-rich foods. RESULTS: An intake of 437 microg folic acid/d from supplements resulted in a 27-nmol/L increase in serum folate and a 21% reduction in tHcy, relative to the change in a control group. In subjects who consumed folic acid-fortified breakfast cereal, folate intake increased by an average of 298 microg, serum folate increased by 21 nmol/L, and tHcy concentrations decreased by 24%. Increased intakes of folate-rich foods resulted in a 418-microg increase in dietary folate, a 7-nmol/L increase in serum folate, and a 9% reduction in tHcy concentrations. The decrease in tHcy was negatively correlated (r = -0.66) with the increase in serum folate. CONCLUSIONS: Daily consumption of folic acid-fortified breakfast cereals and the use of folic acid supplements appear to be the most effective means of reducing tHcy concentrations. The reduction in tHcy was significantly negatively correlated with the increase in serum folate, which may be a useful marker for measuring dietary change.

Adult↗
PubMed2000

Effect of supplementation with tomato juice, vitamin E, and vitamin C on LDL oxidation and products of inflammatory activity in type 2 diabetes.

OBJECTIVE: To compare the effects of short-term dietary supplementation with tomato juice, vitamin E, and vitamin C on susceptibility of LDL to oxidation and circulating levels of C-reactive protein (C-RP) and cell adhesion molecules in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: There were 57 patients with well-controlled type 2 diabetes aged <75 years treated with placebo for 4 weeks and then randomized to receive tomato juice (500 ml/day), vitamin E (800 U/day), vitamin C (500 mg/day), or continued placebo treatment for 4 weeks. Susceptibility of LDL to oxidation (lag time) and plasma concentrations of lycopene, vitamin E, vitamin C, C-RP, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 were measured at the beginning of the study, after the placebo phase, and at the end of the study. RESULTS: Plasma lycopene levels increased nearly 3-fold (P = 0.001), and the lag time in isolated LDL oxidation by copper ions increased by 42% (P = 0.001) in patients during supplementation with tomato juice. The magnitude of this increase in lag time was comparable with the corresponding increase during supplementation with vitamin E (54%). Plasma C-RP levels decreased significantly (-49%, P = 0.004) in patients who received vitamin E. Circulating levels of cell adhesion molecules and plasma glucose did not change significantly during the study. CONCLUSIONS: This study indicates that consumption of commercial tomato juice increases plasma lycopene levels and the intrinsic resistance of LDL to oxidation almost as effectively as supplementation with a high dose of vitamin E, which also decreases plasma levels of C-RP, a risk factor for myocardial infarction, in patients with diabetes. These findings may be relevant to strategies aimed at reducing risk of myocardial infarction in patients with diabetes.

Aged↗
PubMed2000

Prevalence of overweight and obesity in bipolar patients.

BACKGROUND: Patients who receive pharmacologic treatment for bipolar illness frequently gain weight. This study evaluated the prevalence of overweight and obesity in an unselected group of bipolar patients and matched reference subjects. METHOD: The prevalence of overweight, obesity, and central adiposity was evaluated in 89 euthymic bipolar (DSM-IV) patients and 445 reference subjects, matched for age and sex, using a cross-sectional study design. RESULTS: Female patients were more often overweight and obese than female reference subjects (chi2 = 9.18, df = 2, p = .01). The frequency of overweight was similar in male patients and male reference subjects, but male patients were more likely to be obese. Patients were more centrally obese than the general population in women (chi2 = 32.21, df = 1, p = <.001) and in men (chi2= 8.81, df = 1, p = .003). Patients treated with antipsychotic drugs were more obese than patients not receiving these drugs (chi2= 4.7, df = 1, p = .03). CONCLUSION: Body fat is more centrally distributed in pharmacologically treated bipolar patients than in matched population controls. Obesity is more prevalent in patients than in the general population. Obesity prevalence is clearly related to the administration of antipsychotic drugs.

Adipose Tissue↗
PubMed1999

Homocysteine levels in healthy New Zealanders and those with vascular disease.

AIMS: Levels of plasma homocysteine (tHcy) have been shown to vary between populations. The aim of the present study was to determine tHcy levels in a New Zealand population to facilitate interpretation of international reference ranges. METHODS: Fasting tHcy levels were determined in 431 volunteer men and women, aged between 17 and 83 years, from the greater Otago region. Subjects with self-reported incidences of vascular disease (n=138) were compared with healthy control subjects (n=293). RESULTS: Mean (SD) fasting tHcy level of the entire population was 8.3(3.5) micromol/L and men had significantly higher levels than women (9.0(3.4) and 7.8(3.5) micromol/L, respectively, p<0.05). Levels increased significantly with increasing age (0.5 micromol/L for every ten years). There was a small but non-significant difference in tHcy levels between subjects with and without vascular disease (difference after excluding two outliers and adjusting for age and gender; 0.63, 95% CI, -0.03,1.29). tHcy levels were not significantly correlated with lipid or lipoprotein levels. CONCLUSION: Levels of tHcy in a group of volunteers from the greater Otago region were similar to those reported in other populations at high risk of cardiovascular disease. Reference ranges derived from these populations would appear to be applicable for New Zealanders. tHcy measurements should be made when assessing individuals at high risk of vascular disease and intervention strategies considered.

Adolescent↗
PubMed1999

The Oxford Vegetarian Study: an overview.

The Oxford Vegetarian Study is a prospective study of 6000 vegetarians and 5000 nonvegetarian control subjects recruited in the United Kingdom between 1980 and 1984. Cross-sectional analyses of study data showed that vegans had lower total- and LDL-cholesterol concentrations than did meat eaters; vegetarians and fish eaters had intermediate and similar values. Meat and cheese consumption were positively associated, and dietary fiber intake was inversely associated, with total-cholesterol concentration in both men and women. After 12 y of follow-up, all-cause mortality in the whole cohort was roughly half that in the population of England and Wales (standardized mortality ratio, 0.46; 95% CI, 0.42, 0.51). After adjusting for smoking, body mass index, and social class, death rates were lower in non-meat-eaters than in meat eaters for each of the mortality endpoints studied [relative risks and 95% CIs: 0.80 (0. 65, 0.99) for all causes of death, 0.72 (0.47, 1.10) for ischemic heart disease, and 0.61 (0.44, 0.84) for all malignant neoplasms]. Mortality from ischemic heart disease was also positively associated with estimated intakes of total animal fat, saturated animal fat, and dietary cholesterol. Other analyses showed that non-meat-eaters had only half the risk of meat eaters of requiring an emergency appendectomy, and that vegans in Britain may be at risk for iodine deficiency. Thus, the health of vegetarians in this study is generally good and compares favorably with that of the nonvegetarian control subjects. Larger studies are needed to examine rates of specific cancers and other diseases among vegetarians.

Cholesterol↗
PubMed1999

Variation in plasma cholesterol response to dietary change.

BACKGROUND AND AIMS: Previous studies have suggested that some individuals show an appreciably larger change in total cholesterol in response to dietary change (hyper-responders) than others (minimal responders), and also that some people are more likely to respond consistently. We have examined the role of individual dietary compliance in determining total cholesterol response to changes in the nature of dietary fat. METHODS AND RESULTS: Participants completed a randomised double dietary crossover trial with a diet high in saturated fat and a diet high in polyunsaturated fat. Each period continued for four weeks without washouts. Plasma lipoproteins were measured at the end of each period. Dietary compliance was assessed by change in the reported polyunsaturated:saturated fat ratio calculated from three-day diet records, and change in polyunsaturated fat intake, determined by change in plasma triglyceride linoleate. A wide range of individual responses was observed with no evidence of two distinct populations of hyper- and minimal responders. Variation in response to the three crossovers appeared to be due mainly to variation in compliance. CONCLUSIONS: The results of this study do not support earlier suggestions of two separate populations of hyper and minimal responders to change in the nature of dietary fat, rather there is a graded range of response. In a free-living population, the extent to which individuals comply with dietary advice varies considerably and this contributes to the magnitude of cholesterol response as well as consistency on repeated dietary challenges.

Adult↗
PubMed1998

The effect of a low-fat, high-carbohydrate diet on serum high density lipoprotein cholesterol and triglyceride.

OBJECTIVE: To determine whether substituting carbohydrate for saturated fat has any adverse effects on serum high density lipoprotein (HDL) cholesterol and triglycerides in free-living individuals. DESIGN: Randomised crossover trial. SETTING: General community. SUBJECTS: Volunteer sample of 38 healthy free-living men with mean (s.d.) age 37 (7) y, moderately elevated serum total cholesterol 5.51 (0.93) mmol/l and body mass index 26.0 (3.6) kg/m2. INTERVENTIONS: Participants completed two six week experimental periods during which they consumed either a traditional Western diet (36%, 18%, and 43% energy from total, saturated, and carbohydrate, respectively) or a low-saturated fat high-carbohydrate diet (22%, 6% and 59% energy from total, saturated, and carbohydrate, respectively). Dietary principles were reinforced regularly, but food choices were self-selected during each experimental period. MAIN OUTCOME MEASURES: Serum lipids, body weight and plasma fatty acids. RESULTS: Reported energy and nutrient intakes, plasma fatty acids, and a drop in weight from 79.1 (12.5) kg on the Western diet to 77.6 (12.0) kg on the high-carbohydrate diet (P < 0.001) confirmed a high level of compliance with experimental diets. Total and low density lipoprotein (LDL) cholesterol fell from 5.52 (1.04) mmol/l and 3.64 (0.88) mmol/l, respectively on the Western diet to 4.76 (1.10) mmol/l and 2.97 (0.94) mmol/l on the high-carbohydrate diet (P < 0.001). HDL cholesterol fell from 1.21 (0.27) mmol/l on the Western diet to 1.07 (0.23) mmol/l on the high-carbohydrate diet (P = 0.057), but the LDL:HDL cholesterol ratio improved from 3.17 (1.05) on the Western diet to 2.88 (0.97) on the high-carbohydrate diet (P = 0.004). Fasting triglyceride levels were unchanged throughout the study. CONCLUSIONS: Replacement of saturated fat with carbohydrate from grains, vegetables, legumes, and fruit reduces total and LDL cholesterol with only a minor effect on HDL cholesterol and triglyceride. It seems that when free living individuals change to a fibre rich high-carbohydrate diet appropriate food choices lead to a modest weight reduction. This may explain why the marked elevation of triglyceride and reduction of HDL cholesterol observed on strictly controlled high-carbohydrate diets may not occur when such diets are followed in practice.

Adult↗
PubMed1998

Low body mass index in non-meat eaters: the possible roles of animal fat, dietary fibre and alcohol.

OBJECTIVE: To examine the associations of diet and other lifestyle factors with body mass index (BMI) using data from the Oxford Vegetarian Study. SUBJECTS: 1914 male and 3378 female non-smokers aged 20-89 y at recruitment to the study. MEASUREMENTS: All subjects completed a diet/lifestyle questionnaire at recruitment giving details of their usual diet and other characteristics including height and weight, smoking and drinking habits, amount of exercise, occupation and reproductive history. Answers to the food frequency questionnaire were used to classify subjects as either meat eaters or non-meat eaters, and to estimate intakes of animal fat and dietary fibre. Subjects were further classified according to their alcohol consumption, exercise level, social class, past smoking habits and parity. RESULTS: Mean BMI was lower in non-meat eaters than in meat eaters in all age groups for both men and women. Overall age-adjusted mean BMIs in kg/m2 were 23.18 and 22.05 for male meat eaters and non-meat eaters respectively (P < 0.0001) and 22.32 and 21.32 for female meat eaters and non-meat eaters respectively (P < 0.0001). In addition to meat consumption, dietary fibre intake, animal fat intake, social class and past smoking were all independently associated with BMI in both men and women; alcohol consumption was independently associated with BMI in men, and parity was independently associated with BMI in women. After adjusting for these factors, the differences in mean BMI between meat eaters and non-meat eaters were reduced by 36% in men and 31% in women. CONCLUSIONS: Non-meat eaters are thinner than meat eaters. This may be partly due to a higher intake of dietary fibre, a lower intake of animal fat, and only in men a lower intake of alcohol.

Adult↗
PubMed1997

Lifestyle intervention in people with insulin-dependent diabetes mellitus (IDDM).

OBJECTIVE: To investigate the impact of intensive lifestyle education on dietary practices, exercise and metabolic measurements in people with insulin-dependent diabetes mellitus (IDDM). DESIGN: Sixty-one volunteer subjects with IDDM were randomised to intensive (Group 1) or standard (Group 2) education programmes for six months. During a second six month period of observation Group 1 subjects received routine surveillance for their condition and those in Group 2 were given intensive advice (phase 2). Current insulin regimens were modified to optimise glycaemic control before the start of the intervention phase. Nutrient intakes, weight, blood pressure, glycated haemoglobin (HbA1), plasma lipids, lipoproteins and maximal oxygen consumption (VO2 max) were measured at the time of recruitment and at three monthly intervals during the trial and phase 2. SETTING: Department of Human Nutrition at the University of Otago. RESULTS: Glycated haemoglobin decreased significantly in both groups between recruitment and randomisation, the improvement being sustained during the six months of the randomised trial and for group 1 during the six months of post trial observation. A further decrease was seen in Group 2 during the second six month period when they were given intensive advice. Comparable changes were seen with total and low density lipoprotein (LDL) cholesterol in Group 1 during the trial, but significant decreases were only seen in Group 2 in association with intensive intervention (phase 2). These changes occurred in parallel with increases in intakes of carbohydrate and monounsaturated fatty acids, a reduction in intakes of total and saturated fat, and an improvement in maximum oxygen consumption. CONCLUSIONS: A lifestyle programme for people with IDDM results in modest changes in diet and exercise habits sufficient to improve measures of glycaemic control and lipoprotein mediated risk of coronary heart disease independent of changes in insulin regime. More innovative approaches to achieve lifestyle changes are required to meet current recommendations which in turn are likely to produce even greater beneficial changes than those observed here.

Adult↗
PubMed1997

Dietary effects on plasma LDL and HDL.

The effects of diet on lipoproteins have been studied for many decades. Current research is focused on the effects of individual fatty acids, the extent to which diet influences lipoprotein (a) and the degree to which postprandial lipoprotein metabolism can be influenced. Practical implementation of dietary recommendations aimed at reducing lipoprotein-mediated risk of coronary heart disease remains an important issue.

Diet↗