Mj Ball

Serum leptin levels are associated with bone mass in nonobese women

Both serum leptin and bone mineral density are positively correlated with body fat, generating the hypothesis that leptin may be a systemic and/or local regulator of bone mass. We investigated 214 healthy, nonobese Australian women aged 20-91 yr. Bone mineral content, projected bone area, and body fat mass were measured by dual energy x-ray absorptiometry and fasting serum leptin levels by RIA. Associations between bone mineral content (adjusted for age, body weight, body fat mass, and bone area) and the natural logarithm of serum leptin concentrations were analyzed by multiple regression techniques. There was a significant positive association at the lateral spine, two proximal femur sites (Wards triangle and trochanter), and whole body (partial r(2) = 0.019 to 0.036; all P < 0.05). Similar trends were observed at the femoral neck and posterior-anterior-spine. With bone mineral density the dependent variable (adjusted for age, body weight, and body fat mass), the association with the natural logarithm of leptin remained significant at the lateral spine (partial r(2) = 0.030; P = 0.011), was of borderline significance at the proximal femur sites (partial r(2) = 0.012 to 0.017; P = 0.058 to 0.120), and was not significant at the other sites. Our results demonstrate an association between serum leptin levels and bone mass consistent with the hypothesis that circulating leptin may play a role in regulating bone mass.

Relationships between single nucleotide polymorphisms of antioxidant enzymes and disease

The presence and progression of numerous diseases have been linked to deficiencies in antioxidant systems. The relationships between single nucleotide polymorphisms (SNPs) arising from specific antioxidant enzymes and diseases associated with elevated oxidative stress have been studied with the rationale that they may be useful in screening for diseases. The purpose of this narrative review is to analyse evidence from these studies. The antioxidant enzyme SNPs selected for analysis are based on those most frequently investigated in relation to diseases in humans: superoxide dismutase (SOD2) Ala16Val (80 studies), glutathione peroxidise (GPx1) Pro197Leu (24 studies) and catalase C-262T (22 studies). Although the majority of evidence supports associations between the SOD2 Ala16Val SNP and diseases such as breast, prostate and lung cancers, diabetes and cardiovascular disease, the presence of the SOD2 Ala16Val SNP confers only a small, clinically insignificant reduction (if any) in the risk of these diseases. Other diseases such as bladder cancer, liver disease, nervous system pathologies and asthma have not been consistently related to this SOD SNP genotype. The GPx1 Pro197Leu and catalase C-262T SNP genotypes have been associated with breast cancer, but only in a small number of studies. Thus, currently available evidence suggests antioxidant enzyme SNP genotypes are not useful for screening for diseases in humans.

The association of diet and thrombotic risk factors in healthy male vegetarians and meat-eaters

Objective: The aim of this study was to assess thrombosis tendency in subjects who were habitual meat-eaters compared with those who were habitual vegetarians.Design: Cross-sectional comparision of habitual meat-eaters and habitual vegetarians.Setting: Free living subjects.Subjects: One hundred and thirty-nine healthy male subjects (vegans n=18, ovolacto vegetarians n=43, moderate-meat-eaters n=60 and high-meat-eaters n=18) aged 20–55 y who were recruited in Melbourne.Outcome measures: Dietary intake was assessed using a semi-quantitative Food Frequency Questionnaire. The parameters of thrombosis were measured by standard methods.Results: Saturated fat and cholesterol intakes were significantly higher and polyunsaturated fat (PUFA) was significantly lower in the meat-eaters compared with vegetarians. In the meat-eaters, the platelet phospholipids AA levels were significantly higher than in the vegetarians, but there was no increase in ex vivo platelet aggregation and plasma 11-dehydro thromboxane B2 levels. Vegetarians, especially the vegans, had a significantly increased mean collagen and ADP stimulated ex vivo whole blood platelet aggregation compared with meat-eaters. The vegan group had a significantly higher mean platelet volume than the other three dietary groups. However, meat-eaters had a significantly higher cluster of cardiovascular risk factors compared with vegetarians, including increased body mass index, waist to hip ratio, plasma total cholesterol (TC), triacylglycerol and LDL-C levels, ratio of TC/HDL-C and LDL-C/HDL-C and plasma factor VII activity.Conclusions: Consumption of meat is not associated with an increased platelet aggregation compared with vegetarian subjects.Sponsorship: Meat Research Corporation, Australia.

Chickpeas may influence fatty acid and fiber intake in an ad libitum diet, leading to small improvements in serum lipid profile and glycemic control.

Optimal replacement macronutrient/s for dietary saturated fat to reduce cardiovascular disease risk remains controversial. Chickpeas are rich in dietary fiber and polyunsaturated fatty acids. This exploratory study, conducted from September 2004 to May 2005, assessed the effect of incorporating chickpeas in the ad libitum diet of 45 free-living adults. Participants consumed a minimum of 728 g of canned, drained chickpeas per week (the amount in four 300-g cans) as part of their habitual diet for 12 weeks (chickpea phase), followed by 4 weeks of habitual diet without chickpeas (usual phase). In the chickpea phase, mean dietary fiber intake was 6.77 g/day more and mean polyunsaturated fatty acid consumption (as a percentage of total fat) was 2.66% more (both P<0.001), causing the polyunsaturated to saturated fatty acids ratio to change from 0.39 to 0.47 (P=0.045). Serum total cholesterol and low-density lipoprotein cholesterol were 7.7 mg/dL (0.20 mmol/L) and 7.3 mg/dL (0.19 mmol/L) less, respectively, after the chickpea phase (P<or=0.01), fasting insulin was 0.75 microIU/mL (5.21 pmol/L) less (P=0.045), and the homeostasis assessment model of insulin resistance was 0.21 less (P=0.01). Univariate analysis revealed that dietary fiber had the greatest single effect, reducing serum total cholesterol by 15.8 mg/dL (0.41 mmol/L) (P=0.01). Polyunsaturated and saturated fatty acids had equivalent but opposing effects on serum total cholesterol and insulin. Larger studies on populations with greater degrees of hypercholesterolemia and/or hyperglycemia than the participants in this study are warranted.

Effects of replacing meat with soyabean in the diet on sex hormone concentrations in healthy adult males

A randomised crossover dietary intervention study was performed to evaluate the effects of replacing meat protein in the diet with a soyabean product, tofu, on blood concentrations of testosterone, dihydrotestosterone, androstanediol glucuronide, oestradiol, sex hormone-binding globulin (SHBG), and the free androgen index (total testosterone concentration/SHBG concentration x 100; FAI). Forty-two healthy adult males aged 35-62 years were studied. Diets were isoenergetic, with either 150 g lean meat or 290 g tofu daily providing an equivalent amount of macronutrients, with only the source of protein differing between the two diets. Each diet lasted for 4 weeks, with a 2-week interval between interventions. Fasting blood samples were taken between 07.00 and 09.30 hours. Urinary excretion of genistein and daidzein was significantly higher after the tofu diet (P < 0.001). Blood concentrations of sex hormones did not differ after the two diets, but the mean testosterone:oestradiol value was 10% higher (P = 0.06) after the meat diet. SHBG was 3% higher (P = 0.07), whereas the FAI was 7% lower (P = 0.06), after the tofu diet compared with the meat diet. There was a significant correlation between the difference in SHBG and testosterone:oestradiol and weight change. Adjusting for weight change revealed SHBG to be 8.8% higher on the tofu diet (mean difference 3 (95% CI 0.7, 5.2) nmol/l; P = 0.01) and testosterone:oestradiol to be significantly lower, P = 0.049). Thus, replacement of meat protein with soyabean protein, as tofu, may have a minor effect on biologically-active sex hormones, which could influence prostate cancer risk. However, other factors or mechanisms may also be responsible for the different incidence rates in men on different diets.

A prospective randomized, controlled trial of intravenous versus oral iron for moderate iron deficiency anaemia of pregnancy.

Abstract.  Khalafallah A, Dennis A, Bates J, Bates G, Robertson IK, Smith L, Ball MJ, Seaton D, Brain T, Rasko JEJ Launceston General Hospital (LGH), Australia; University of Tasmania, Australia; and Centenary Institute, University of Sydney, NSW, Australia) A prospective randomized, controlled trial of intravenous versus oral iron for moderate iron deficiency anaemia of pregnancy. J Intern Med 2010; 268: 286–295.

Effect of dietary cholesterol on plasma cholesterol concentration in subjects following reduced fat, high fibre diet.

One hundred and sixty eight subjects participated in a randomised crossover study to determine whether halving or doubling the present dietary cholesterol intake from eggs had any influence on blood cholesterol concentration in people following current dietary recommendations. During the first eight weeks all participants were advised to follow a reduced fat diet (26% total energy for hyperlipidaemic patients, 35% total energy for normolipidaemic volunteers) with an increased ratio of polyunsaturated to saturated fatty acids. This background diet was continued throughout the 16 week experimental period, during which participants ate either two or seven eggs a week. A small but significant increase in total cholesterol was seen after four weeks in the group eating seven eggs a week compared with that in the group eating two eggs a week, but this was no longer apparent after eight weeks. Previous studies suggesting that dietary cholesterol has a greater effect on the serum cholesterol concentration either have been carried out against a background of a higher fat intake or have contrasted extreme cholesterol intakes. A further reduction in dietary cholesterol seems to be unnecessary in those people who have already reduced their intake of saturated fat and increased the ratio of polyunsaturated to saturated fatty acids and fibre rich carbohydrate.

Acute effects of food on postprandial blood pressure and measures of arterial stiffness in healthy humans

BACKGROUND Recent research suggests that central pulse pressure may be a better indicator of cardiovascular disease outcomes than brachial pressure. Little information is available regarding the effect of food intake on postprandial central pressure and other measures of arterial stiffness when measured with a noninvasive pulse wave analysis (PWA) technique. OBJECTIVE The objective was to investigate the effects of water and food plus water intake on brachial and central blood pressure (BP) and measures of arterial stiffness, including augmentation pressure and augmentation index, by using the PWA technique. DESIGN Measurements of BP and PWA were made at fasting and for 2 h after the intake of water or breakfast (1300 kJ) in random order in 35 subjects. RESULTS Baseline fasting measures of BP and arterial stiffness were not significantly different before the 2 interventions. Consumption of food plus water, compared with water alone, led to a significantly lower (all P < 0.01) brachial diastolic pressure (difference: -3.8 mm Hg), central BP (difference: systolic, -6.1 mm Hg; diastolic, -3.8 mm Hg), central pulse pressure (difference: -2.4 mm Hg), mean arterial pressure (difference: -4.6 mm Hg), augmentation pressure (difference: -2.9 mm Hg), and augmentation index (difference: -5.3 mm Hg). CONCLUSIONS Markers of central hemodynamics are sensitive to feeding state and therefore should be measured at fasting to avoid variability due to recent (within 2-3 h) food intake. This is especially important when measurements are repeated over time to assess the effect of medication or lifestyle changes on cardiovascular disease risk factors.

Lupin kernel fibre-enriched foods beneficially modify serum lipids in men

AbstractObjective:To examine the effect of a diet containing a novel legume food ingredient, Australian sweet lupin (Lupinus angustifolius) kernel fibre (LKFibre), compared to a control diet without the addition of LKFibre, on serum lipids in men.Design:Randomized crossover dietary intervention study.Setting:Melbourne, Australia — Free-living men.Subjects:A total of 38 healthy males between the ages of 24 and 64 y completed the intervention.Intervention:Subjects consumed an LKFibre and a control diet for 1 month each. Both diets had the same background menus with seven additional experimental foods that either contained LKFibre or did not. Depending on energy intake, the LKFibre diet was designed to contain an additional 17 to 30 g/day fibre beyond that of the control diet.Results:Compared to the control diet, the LKFibre diet reduced total cholesterol (TC) (mean±s.e.m.; 4.5±1.7%; P=0.001), low-density lipoprotein cholesterol (LDL-C) (5.4±2.2%; P=0.001), TC: high-density lipoprotein cholesterol (HDL-C) (3.0±2.0%; P=0.006) and LDL-C:HDL-C (3.8±2.6%; P=0.003). No effects on HDL-C, triacylglycerols, glucose or insulin were observed.Conclusions:Addition of LKFibre to the diet provided favourable changes to some serum lipid measures in men, which, combined with its high palatability, suggest this novel ingredient may be useful in the dietary reduction of coronary heart disease risk.Sponsorship:Grains Research and Development Corporation, Australian Research Council and the Department of Agriculture Western Australia.

Nutrient intake and iron status of Australian male vegetarians

Objective: The study was designed to investigate the iron intake and status of Australian, male vegetarians aged between 20 and 50 y.Design: Cross-sectional comparison of male vegetarians and age/sex matched omnivores.Setting: Free-living community subjects.Subjects: 39 ovolactovegetarians, 10 vegans and 25 omnivores were recruited by local advertisement.Outcome measures: A 12-d semiquantitative dietary record to assess iron and zinc intake. Iron status was assessed by measurement of serum ferritin and haemoglobin concentrations.Results: Mean (s.d.) daily iron intakes of both the ovolactovegetarians (20.4 (7.7) mg/d) and vegans (22.9 (6.2) mg/d), were significantly higher than the omnivores’ intake of 15.8 (4.5) mg/d. Ovo-lactovegetarians and vegans had significantly (P<0.001 and P<0.05, respectively) lower serum ferritin concentrations than omnivores: mean (s.d.): 64 (46.9), 65 (49.9) and 121 (72.5) ng/ml, respectively. Significantly more ovolactovegetarians and vegans than omnivores had serum ferritin concentrations below 25 ng/ml and below 12 ng/ml (P<0.05). A higher proportion of omnivores had concentrations above 200 ng/ml (P<0.05). The differences in serum ferritin concentrations between the vegetarians and omnivores remained significant even after exclusion of iron supplement users.Conclusion: Australian male vegetarians had iron intakes higher than those of omnivores and above recommended levels, but their iron status was significantly lower.Sponsorship: Deakin University.