Jim Mann

Effects on coronary artery disease of lipid-lowering diet, or diet plus cholestyramine, in the St Thomas' Atherosclerosis Regression Study (STARS)

To assess the effect of dietary reduction of plasma cholesterol concentrations on coronary atherosclerosis, we set up a randomised, controlled, end-point-blinded trial based on quantitative image analysis of coronary angiograms in patients with angina or past myocardial infarction. Another intervention group received diet and cholestyramine, to determine the effect of a greater reduction in circulating cholesterol concentrations. 90 men with coronary heart disease (CHD), who had a mean (SD) plasma cholesterol of 7.23 (0.77) mmol/l were randomised to receive usual care (U, controls), dietary intervention (D), or diet plus cholestyramine (DC), with angiography at baseline and at 39 (SD 3.5) months. Mean plasma cholesterol during the trial period was 6.93 (U), 6.17 (D), and 5.56 (DC) mmol/l. The proportion of patients who showed overall progression of coronary narrowing was significantly reduced by both interventions (U 46%, D 15%, DC 12%), whereas the proportion who showed an increase in luminal diameter rose significantly (U 4%, D 38%, DC 33%). The mean absolute width of the coronary segments (MAWS) studied decreased by 0.201 mm in controls, increased by 0.003 mm in group D, and increased by 0.103 mm in group DC (p less than 0.05), with improvement also seen in the minimum width of segments, percentage diameter stenosis, and edge-irregularity index in intervention groups. The change in MAWS was independently and significantly correlated with LDL cholesterol concentration and LDL/HDL cholesterol ratio during the trial period. Both interventions significantly reduced the frequency of total cardiovascular events. Dietary change alone retarded overall progression and increased overall regression of coronary artery disease, and diet plus cholestyramine was additionally associated with a net increase in coronary lumen diameter. These findings support the use of a lipid-lowering diet, and if necessary of appropriate drug treatment, in men with CHD who have even mildly raised serum cholesterol concentrations.

Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies.

Objective To summarise evidence on the association between intake of dietary sugars and body weight in adults and children. Design Systematic review and meta-analysis of randomised controlled trials and prospective cohort studies. Data sources OVID Medline, Embase, PubMed, Cumulative Index to Nursing and Allied Health Literature, Scopus, and Web of Science (up to December 2011). Review methods Eligible studies reported the intake of total sugars, intake of a component of total sugars, or intake of sugar containing foods or beverages; and at least one measure of body fatness. Minimum duration was two weeks for trials and one year for cohort studies. Trials of weight loss or confounded by additional medical or lifestyle interventions were excluded. Study selection, assessment, validity, data extraction, and analysis were undertaken as specified by the Cochrane Collaboration and the GRADE working group. For trials, we pooled data for weight change using inverse variance models with random effects. We pooled cohort study data where possible to estimate effect sizes, expressed as odds ratios for risk of obesity or β coefficients for change in adiposity per unit of intake. Results 30 of 7895 trials and 38 of 9445 cohort studies were eligible. In trials of adults with ad libitum diets (that is, with no strict control of food intake), reduced intake of dietary sugars was associated with a decrease in body weight (0.80 kg, 95% confidence interval 0.39 to 1.21; P<0.001); increased sugars intake was associated with a comparable weight increase (0.75 kg, 0.30 to 1.19; P=0.001). Isoenergetic exchange of dietary sugars with other carbohydrates showed no change in body weight (0.04 kg, −0.04 to 0.13). Trials in children, which involved recommendations to reduce intake of sugar sweetened foods and beverages, had low participant compliance to dietary advice; these trials showed no overall change in body weight. However, in relation to intakes of sugar sweetened beverages after one year follow-up in prospective studies, the odds ratio for being overweight or obese increased was 1.55 (1.32 to 1.82) among groups with the highest intake compared with those with the lowest intake. Despite significant heterogeneity in one meta-analysis and potential bias in some trials, sensitivity analyses showed that the trends were consistent and associations remained after these studies were excluded. Conclusions Among free living people involving ad libitum diets, intake of free sugars or sugar sweetened beverages is a determinant of body weight. The change in body fatness that occurs with modifying intakes seems to be mediated via changes in energy intakes, since isoenergetic exchange of sugars with other carbohydrates was not associated with weight change.

Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies

We combined data from 5 prospective studies to compare the death rates from common diseases of vegetarians with those of nonvegetarians with similar lifestyles. A summary of these results was reported previously; we report here more details of the findings. Data for 76172 men and women were available. Vegetarians were those who did not eat any meat or fish (n = 27808). Death rate ratios at ages 16-89 y were calculated by Poisson regression and all results were adjusted for age, sex, and smoking status. A random-effects model was used to calculate pooled estimates of effect for all studies combined. There were 8330 deaths after a mean of 10.6 y of follow-up. Mortality from ischemic heart disease was 24% lower in vegetarians than in nonvegetarians (death rate ratio: 0.76; 95% CI: 0.62, 0.94; P<0.01). The lower mortality from ischemic heart disease among vegetarians was greater at younger ages and was restricted to those who had followed their current diet for >5 y. Further categorization of diets showed that, in comparison with regular meat eaters, mortality from ischemic heart disease was 20% lower in occasional meat eaters, 34% lower in people who ate fish but not meat, 34% lower in lactoovovegetarians, and 26% lower in vegans. There were no significant differences between vegetarians and nonvegetarians in mortality from cerebrovascular disease, stomach cancer, colorectal cancer, lung cancer, breast cancer, prostate cancer, or all other causes combined.

Cereal grains, legumes and diabetes

This review examines the evidence for the role of whole grain foods and legumes in the aetiology and management of diabetes. MedLine and SilverPlatter (‘Nutrition’ and ‘Food Science FSTA’) databases were searched to identify epidemiological and experimental studies relating to the effects of whole grain foods and legumes on indicators of carbohydrate metabolism. Epidemiological studies strongly support the suggestion that high intakes of whole grain foods protect against the development of type II diabetes mellitus (T2DM). People who consume ∼3 servings per day of whole grain foods are less likely to develop T2DM than low consumers (<3 servings per week) with a risk reduction in the order of 20–30%. The role of legumes in the prevention of diabetes is less clear, possibly because of the relatively low intake of leguminous foods in the populations studied. However, legumes share several qualities with whole grains of potential benefit to glycaemic control including slow release carbohydrate and a high fibre content. A substantial increase in dietary intake of legumes as replacement food for more rapidly digested carbohydrate might therefore be expected to improve glycaemic control and thus reduce incident diabetes. This is consistent with the results of dietary intervention studies that have found improvements in glycaemic control after increasing the dietary intake of whole grain foods, legumes, vegetables and fruit. The benefit has been attributed to an increase in soluble fibre intake. However, prospective studies have found that soluble fibre intake is not associated with a lower incidence of T2DM. On the contrary, it is cereal fibre that is largely insoluble that is associated with a reduced risk of developing T2DM. Despite this, the addition of wheat bran to the diets of diabetic people has not improved indicators of glycaemic control. These apparently contradictory findings might be explained by metabolic studies that have indicated improvement in glucose handling is associated with the intact structure of food. For both grains and legumes, fine grinding disrupts cell structures and renders starch more readily accessible for digestion. The extent to which the intact structure of grains and legumes or the composition of foods in terms of dietary fibre and other constituents contribute to the beneficial effect remains to be quantified. Other mechanisms to help explain improvements in glycaemic control when consuming whole grains and legumes relate to cooking, type of starch, satiety and nutrient retention. Thus, there is strong evidence to suggest that eating a variety of whole grain foods and legumes is beneficial in the prevention and management of diabetes. This is compatible with advice from around the world that recommends consumption of a wide range of carbohydrate foods from cereals, vegetables, legumes and fruits both for the general population and for people with diabetes.

Myocardial infarction in young women with special reference to oral contraceptive practice.

Sixty-three women discharged from hospital with a diagnosis of myocardial infarction and 189 control patients were studied. All were under 45 years of age at the time of admission. Current oral contraceptive use, heavy cigarette smoking, treated hypertension and diabetes, pre-eclamptic toxaemia, and obesity were all reported by, and type II hyperlipoproteinaemia was found more often in, patients with myocardial infarction than their controls. The relationship between myocardial infarction and oral contraceptives could not be explained in terms of an association between the use of these preparations and the other factors. The combined effect of the risk factors was clearly synergistic.

Determination of the glycaemic index of foods: interlaboratory study.

Objective: Practical use of the glycaemic index (GI), as recommended by the FAO/WHO, requires an evaluation of the recommended method. Our purpose was to determine the magnitude and sources of variation of the GI values obtained by experienced investigators in different international centres.Design: GI values of four centrally provided foods (instant potato, rice, spaghetti and barley) and locally obtained white bread were determined in 8–12 subjects in each of seven centres using the method recommended by FAO/WHO. Data analysis was performed centrally.Setting: University departments of nutrition.Subjects: Healthy subjects (28 male, 40 female) were studied.Results: The GI values of the five foods did not vary significantly in different centres nor was there a significant centre×food interaction. Within-subject variation from two centres using venous blood was twice that from five centres using capillary blood. The s.d. of centre mean GI values was reduced from 10.6 (range 6.8–12.8) to 9.0 (range 4.8–12.6) by excluding venous blood data. GI values were not significantly related to differences in method of glucose measurement or subject characteristics (age, sex, BMI, ethnicity or absolute glycaemic response). GI values for locally obtained bread were no more variable than those for centrally provided foods.Conclusions: The GI values of foods are more precisely determined using capillary than venous blood sampling, with mean between-laboratory s.d. of approximately 9.0. Finding ways to reduce within-subject variation of glycaemic responses may be the most effective strategy to improve the precision of measurement of GI values.

Diet, nutrition and the prevention of type 2 diabetes

OBJECTIVES The overall objective of this study was to evaluate and provide evidence and recommendations on current published literature about diet and lifestyle in the prevention of type 2 diabetes. DESIGN Epidemiological and experimental studies, focusing on nutritional intervention in the prevention of type 2 diabetes are used to make disease-specific recommendations. Long-term cohort studies are given the most weight as to strength of evidence available. SETTING AND SUBJECTS Numerous clinical trials and cohort studies in low, middle and high income countries are evaluated regarding recommendations for dietary prevention of type 2 diabetes. These include, among others, the Finnish Diabetes Prevention Study, US Diabetes Prevention Program, Da Qing Study; Pima Indian Study; Iowa Womens Health Study; and the study of the US Male Physicians. RESULTS There is convincing evidence for a decreased risk of diabetes in adults who are physically active and maintain a normal body mass index (BMI) throughout adulthood, and in overweight adults with impaired glucose tolerance who lose weight voluntarily. An increased risk for developing type 2 diabetes is associated with overweight and obesity; abdominal obesity; physical inactivity; and maternal diabetes. It is probable that a high intake of saturated fats and intrauterine growth retardation also contribute to an increased risk, while non-starch polysaccharides are likely to be associated with a decreased risk. From existing evidence it is also possible that omega-3 fatty acids, low glycaemic index foods and exclusive breastfeeding may play a protective role, and that total fat intake and trans fatty acids may contribute to the risk. However, insufficient evidence is currently available to provide convincing proof. CONCLUSIONS Based on the strength of available evidence regarding diet and lifestyle in the prevention of type 2 diabetes, it is recommended that a normal weight status in the lower BMI range (BMI 21-23) and regular physical activity be maintained throughout adulthood; abdominal obesity be prevented; and saturated fat intake be less than 7% of the total energy intake.

A Prospective Population-Based Study of Microalbuminuria as a Predictor of Mortality in NIDDM

Objective— To assess prospectively the relationship between microalbuminuria and mortality in a geographically defined population of NIDDM patients and to determine the relative importance of microalbuminuria as a risk factor for mortality. Research Design and Methods–A survey of known diabetes undertaken in 1982 identified a cohort of 249 NIDDM patients. Follow-up information was available for 246 patients who contributed 1498 person-yr exposure and were followed up for a mean period of 6.1 yr. The median age of the cohort at entry was 68 yr (range 28–89 yr), and the median duration of diabetes was 7 yr (range 1–41 yr). At baseline, a clinical examination was performed and a random daytime urine specimen was obtained for measurement of urinary albumin concentration. Results— UAC results were available for 236 patients: 45 (19%) patients had a UAC > 15- < 40 mg/L; 36 (15%) had a UAC 40–200 mg/L; 10 (4%) had a UAC > 200 mg/L; and 145 (61%) had a normal UAC < or = 15 mg/L. During the follow-up period, 93 patients died. All-causes mortality, expressed as standardized mortality ratio (SMR = 149) and coronary heart disease mortality (CHD SMR = 166) were significantly increased. This excess mortality was significant in women (all-causes SMR = 194, CHD SMR = 234) but not in men (all-causes SMR = 118, CHD SMR = 128). On univariate analysis, systolic blood pressure was the only significant association with albumin concentration (P = 0.0002). An age-stratified log-rank test was conducted to determine the effect of potential explanatory variables on survival. Survival distributions were significantly different for known duration of diabetes (P = 0.045), intermittent claudication (P = 0.012), severity of retinopathy, lens opacity (P < 0.001) and UAC (P = 0.013) and diastolic blood pressure approached significance (P = 0.051). After adjusting for the effects of these potentially confounding variables identified by the log-rank analysis, significant predictors of early mortality on multivariate survival analysis were age, UAC of 40–200 mg/L (relative risk = 2.2, 95% confidence interval 1.3–3.7), more severe retinopathy (relative risk = 3.4, 95% confidence interval 1.9–6.0), and lens opacity (relative risk = 2.4, 95% confidence interval 1.6–3.8). Conclusions— The findings from this population-based cohort confirm the predictive power of microalbuminuria as a risk factor for mortality in NIDDM. In contrast to prospective studies of conventional cardiovascular risk factors in NIDDM, consistent evidence indicates that microalbuminuria is an independent predictor of excess mortality regardless of the collection procedure used.

Diet and risk of coronary heart disease and type 2 diabetes

A high intake of saturated fat is an important risk factor for coronary heart disease (CHD) and type 2 diabetes. However the declining rates of CHD in many affluent societies and the steady increase in type 2 diabetes worldwide suggest that these important causes of serious morbidity and premature mortality have differing risk or protective factors worldwide. Changed macronutrient composition, reduced cigarette smoking, and improved treatment of risk factors and acute cardiac events might explain the reduction in risk of CHD, whereas the increasing rates of obesity are probably the most important explanation for the increase in diabetes. Coronary risk factors associated with diabetes could outweigh improvements in conventional cardiovascular risk factors such that the decline in CHD could be stopped or reversed unless rates of obesity can be reduced. Reduced intake of saturated fatty acids and other lifestyle interventions aimed at lowering rates of obesity are the changes most likely to reduce the epidemic numbers of people with type 2 diabetes and CHD.

Dietary determinants of ischaemic heart disease in health conscious individuals

Objective To investigate dietary determinants of ischaemic heart disease (IHD) in health conscious individuals to explain the reduced risk in vegetarians, and to examine the relation between IHD and body mass index (BMI) within the normal range. Design Prospective observation of vegetarians, semi-vegetarians, and meat eaters for whom baseline dietary data, reported weight and height information, social class, and smoking habits were recorded. Subjects 10 802 men and women in the UK aged between 16 and 79, mean duration of follow up 13.3 years. Main outcome measures Death rate ratios for IHD and total mortality in relation to dietary and other characteristics recorded at recruitment (reference category death rate = 100). Results IHD mortality was less than half that expected from the experience reported for all of England and Wales. An increase in mortality for IHD was observed with increasing intakes of total and saturated animal fat and dietary cholesterol—death rate ratios in the third tertile compared with the first tertile: 329, 95% confidence interval (CI) 150 to 721; 277, 95% CI 125 to 613; 353, 95% CI 157 to 796, respectively. No protective effects were observed for dietary fibre, fish or alcohol. Within the study, death rate ratios were increased among those in the upper half of the normal BMI range (22.5 to < 25) and those who were overweight (BMI ⩾ 25) compared with those with BMI 20 to < 22.5. Conclusions In these relatively health conscious individuals the deleterious effects of saturated animal fat and dietary cholesterol appear to be more important in the aetiology of IHD than the protective effect of dietary fibre. Reduced intakes of saturated animal fat and cholesterol may explain the lower rates of IHD among vegetarians compared with meat eaters. Increasing BMI within the normal range is associated with increased risk of IHD. The results have important public health implications.