Rebecca C. Mollard

Dietary determinants of hepatic steatosis and visceral adiposity in overweight and obese youth at risk of type 2 diabetes

BACKGROUND Dietary determinants of hepatic steatosis, an important precursor for nonalcoholic fatty liver disease, are undefined. OBJECTIVE We explored the roles of sugar and fat intake as determinants of hepatic steatosis and visceral obesity in overweight adolescents at risk of type 2 diabetes. DESIGN This was a cross-sectional study of dietary patterns and adipose tissue distribution in 74 overweight adolescents (aged: 15.4 ± 1.8 y; body mass index z score: 2.2 ± 0.4). Main outcome measures were hepatic steatosis (≥5.5% fat:water) measured by magnetic resonance spectroscopy and visceral obesity (visceral-to-subcutaneous adipose tissue ratio ≥0.25) measured by magnetic resonance imaging. Main exposure variables were dietary intake and habits assessed by the Harvard Youth Adolescent Food Frequency Questionnaire. RESULTS Hepatic steatosis and visceral obesity were evident in 43% and 44% of the sample, respectively. Fried food consumption was more common in adolescents with hepatic steatosis than in adolescents without hepatic steatosis (41% compared with 18%; P = 0.04). Total fat intake (β = 0.51, P = 0.03) and the consumption of >35% of daily energy intake from fat (OR: 11.8; 95% CI: 1.6, 86.6; P = 0.02) were both positively associated with hepatic steatosis. Available carbohydrate (β = 0.54, P = 0.02) and the frequent consumption of soda were positively associated with visceral obesity (OR: 6.4; 95% CI: 1.2, 34.0; P = 0.03). Daily fiber intake was associated with reduced odds of visceral obesity (OR: 0.82; 95% CI: 0.68, 0.98; P = 0.02) but not hepatic steatosis. CONCLUSION Hepatic steatosis is associated with a greater intake of fat and fried foods, whereas visceral obesity is associated with increased consumption of sugar and reduced consumption of fiber in overweight and obese adolescents at risk of type 2 diabetes.

Zinc-deficient rats have more limited bone recovery during repletion than diet-restricted rats

The objective of this study was to investigate the effects of dietary zinc deficiency and diet restriction on bone development in growing rats, and to determine whether any adverse effects could be reversed by dietary repletion. Weanling rats were fed either a zinc-deficient diet ad libitum (ZD; <1 mg zinc/kg) or nutritionally complete diet (30 mg zinc/kg) either ad libitum (CTL) or pair-fed to the intake of the ZD group (DR; diet-restricted) for 3 weeks (deficiency phase) and then all groups were fed the zincadequate diet ad libitum for 3, 7, or 23 days (repletion phase). Excised femurs were analyzed for bone mineral density (BMD) using dual-energy x-ray absorptiometry, and plasma was analyzed for markers of bone formation (osteocalcin) and resorption (Ratlaps). After the deficiency phase, ZD had lower body weight and reduced femur BMD, zinc, and phosphorus concentrations compared with DR; and these parameters were lower in DR compared with CTL. Femur calcium concentrations were unchanged among the groups. Reduced plasma osteocalcin in ZD and elevated plasma Ratlaps in DR suggested that zinc deficiency limits bone formation while diet restriction accelerates bone resorption activity. After 23 days of repletion, femur size, BMD, and zinc concentrations remained lower in ZD compared with DR and CTL. Body weight and femur phosphorus concentrations remained lower in both ZD and DR compared with CTL after repletion. There were no differences in plasma osteocalcin concentrations after the repletion phase, but the plasma Ratlaps concentrations remained elevated in DR compared with CTL. In summary, both ZD and DR lead to osteopenia during rapid growth, but the mechanisms appear to be due to reduced modeling in ZD and higher turnover in DR. Zinc deficiency was associated with a greater impairment in bone development than diet restriction, and both deficiencies limited bone recovery during repletion in growing rats.

Vigorous intensity exercise for glycemic control in patients with type 1 diabetes.

Regular physical activity has substantial health benefits in persons with type 1 diabetes, including reduced risk of complications and cardiovascular mortality as well as improved self-rated quality of life. Despite these benefits, individuals with type 1 diabetes are often less active than their peers without diabetes. When factors such as time constraints, work pressure and environmental conditions are often cited as barriers to physical activity in the general population, 2 additional major factors may also explain the low rates of physical activity in young people with type 1 diabetes: (1) fear of hypoglycemia both during and after (particularly overnight) exercise and (2) a lack of empiric evidence for the efficacy of physical activity for achieving optimal glycemic control. A number of acute exercise trials recently showed that the inclusion of vigorous intensity physical activity in conventional moderate intensity (i.e. walking and light cycling) exercise sessions may overcome these barriers. No studies have tested the efficacy of high-intensity physical activity on glycemic control (A1C) or post-exercise hypoglycemia in a randomized controlled trial. This article summarizes the literature related to the role of physical activity for the management of blood glucose levels in individuals with type 1 diabetes and provides a rationale for the need of a randomized controlled trial examining the effects of vigorous-intensity physical activity on blood glucose control.

Conjugated linoleic acid reduces parathyroid hormone in health and in polycystic kidney disease in rats

BACKGROUND Feeding conjugated linoleic acid (CLA) is reported to reduce prostaglandin E(2) synthesis, which is required for parathyroid hormone (PTH) release. OBJECTIVE This study was undertaken to determine whether CLA would suppress hyperparathyroidism and the resulting high-turnover bone disease in a rat model of polycystic kidney disease (PKD). DESIGN Outcome measurements were conducted after 8 wk of feeding diets supplemented with and without CLA (1% of dietary fat) to Han:SPRD-cy male rats (n = 52). PTH, bone formation, and resorption were assessed in addition to femur bone mass with use of dual-energy X-ray absorptiometry. RESULTS CLA feeding resulted in attenuation of PTH concentrations in both PKD-affected and nonaffected rats (by 60%) but did not significantly alter bone formation and resorption. CONCLUSION Reduction in PTH may open possibilities for CLA as an adjunctive therapy in secondary hyperparathyroidism.

Outdoor Time Is Associated with Physical Activity, Sedentary Time, and Cardiorespiratory Fitness in Youth

OBJECTIVE To determine whether time spent outdoors was associated with increased moderate-to-vigorous physical activity (MVPA) and related health benefits in youth. STUDY DESIGN We performed a cross-sectional study of 306 youth aged 13.6 ± 1.4 years. The exposure of interest was self-reported time spent outdoors after school, stratified into three categories: none, some, and most/all of the time. The main outcome of interest was accelerometer-derived MVPA (Actical: 1500 to >6500 counts/min). Secondary outcomes included sedentary behavior, cardiorespiratory fitness, overweight status, and blood pressure. RESULTS Among the 306 youth studied, those who reported spending most/all of their after-school time outdoors (n = 120) participated in more MVPA (61.0 ± 24.3 vs 39.9 ± 19.1 min/day; adjusted P < .001), were more likely to achieve the recommended minimum 60 min/day of MVPA (aOR 2.8; 95% CI, 1.3-6.4), spent less time in sedentary activities (539 ± 97 min/day vs 610 ± 146 min/day; adjusted P < .001), and had higher cardiorespiratory fitness (49 ± 5 vs 45 ± 6 mL/kg/min; adjusted P < .001) than youth who reported no time outdoors (n = 52). No differences in overweight/obesity or blood pressure were observed across the groups. CONCLUSIONS Time spent outdoors is positively associated with MVPA and cardiorespiratory fitness in youth and negatively associated with sedentary behavior. Experimental trials are needed to determine whether strategies designed to increase time spent outdoors exert a positive influence on physical activity and fitness levels in youth.

Dietary Arachidonic Acid and Docosahexaenoic Acid Elevate Femur Calcium and Reduce Zinc Content in Piglets

Specific dietary polyunsaturated fatty acids (PUFAs) and long chain PUFAs (LCPUFAs) elevate femur calcium content and enhance calcium balance. Mothers milk is associated with enhanced calcium balance and contains LCPUFAs; arachidonic acid (AA), and docosahexanoic acid (DHA). However, the effect of AA and DHA on calcium metabolism and other bone minerals during infancy is unknown. Thus, piglets received one of four formulas (15 d): control or with AA:DHA (0.5:0.1 g, 1.0:0.2 g, or 2.0:0.4 g/100 g of fat). Calcium absorption, femur mineral composition, and urinary mineral excretion. Main effects identified using two-way analysis of variance (ANOVA) and post hoc analysis conducted using Duncans multiple range test. Significant effects of diet were observed in femur calcium and zinc content, but not calcium absorption, urinary mineral excretion, femur ash weight, femur phosphorus, or femur magnesium content. The piglets receiving AA:DHA as 1.0:0.2 g/100 g of fat had 1.9% higher mg calcium/g of ash, but 8.6% lower μg zinc/g of ash compared with control. Thus, AA:DHA in a ratio of 5:1 does not affect mineral accretion, but AA plus DHA, in amounts similar to the upper limit of human milk, might be detrimental to bone mineralization over time due to lower zinc.

Acute sodium ingestion has no effect on short-term food and water intake, subjective appetite, thirst, or glycemic response in healthy young men

The high intake of dietary sodium (Na(+)) has been associated with obesity and insulin resistance, sparking the hypothesis that the consumption of salty foods affects food intake (FI) and postprandial blood glucose (BG) response. Therefore, we conducted 2 randomized repeated-measures experiments to examine the acute effects of the Na(+) content of solid food and beverage on FI, water intake (WI), subjective appetite, thirst, and BG. FI and WI were measured at ad libitum pizza test meals; appetite, thirst, and BG were measured at baseline and at regular intervals before and after meals. In the first experiment, 16 males (mean body mass index (BMI), 22.2 kg·m(-2)) consumed a low-Na(+) (71 mg) bean preload (300 kcal) with or without 740 mg or 1480 mg of added Na(+) 120 min prior to the pizza meal. Participants ate 116 kcal more at the test meal after consuming beans with 740 mg of added Na(+) than after beans with 1480 mg of added Na(+). In the second experiment, 19 males (mean BMI, 23.2 kg·m(-2)) consumed a low-Na(+) (62 mg) tomato beverage (73 kcal) with or without 500, 1000, 1500, or 2000 mg of added Na(+) 30 min prior to a pizza meal. The beverage with 2000 mg of added Na(+) led to higher WI during the pizza meal than the beverage with 500 mg of added Na(+). However, compared with the control conditions (no added Na(+)), added Na(+) treatments had no effect on dependent measures in either experiment. In conclusion, the acute intake of Na(+), in a solid or liquid form, did not affect short-term subjective ratings of appetite or thirst, ad libitum FI or WI, or BG in healthy young men.

The Association Between Time Spent in Vigorous Physical Activity and Dietary Patterns in Adolescents: A Cross-Sectional Study

BACKGROUND Physical activity interventions targeting weight status have yielded mixed results. This variability may be attributed to compensatory changes in dietary patterns after increasing physical activity (PA) levels. Therefore, we sought to determine whether dietary patterns varied with time spent in vigorous-intensity PA in youth. METHODS Cross-sectional analysis of 330 youth enrolled in a school-based prospective cohort in central Alberta. Physical activity was assessed with waist mounted accelerometers (Actical) worn for 7 days. Main outcomes included consumption of unhealthy foods and the unhealthy food index obtained from a validated web-based 24-hour dietary recall instrument. Secondary outcomes included macronutrient intake, food group (Canadas Food Guide to Healthy Eating) intake, and diet quality. RESULTS Compared with youth participating in < 7 min/ day of vigorous physical activity, those achieving ≥ 7 min/day displayed no change in healthy or unhealthy food consumption. However, linear regression suggests a modest association between diet quality and vigorous-intensity PA. CONCLUSION These data demonstrate that in this cohort of Canadian youth, time spent being physically active is associated with healthier dietary patterns and not with increased consumption of unhealthy foods.

Canned Navy Bean Consumption Reduces Metabolic Risk Factors Associated with Obesity

The high prevalence of obesity and its metabolic co-morbidities require dietitians to promote lifestyle modifications that can be effectively implemented into practice and are feasible for customers to adhere to. The objective of this study was to determine the effect of commercially available ready-to-eat canned navy beans added to the habitual diet on risk factors associated with obesity. Fourteen overweight and obese adults consumed 5 cups of canned navy beans per week for 4 weeks. The study results demonstrated that bean consumption results in reduced waist circumference in females by 2.5 cm and males by 2.1 cm (P < 0.001). The effect of beans on pulse rate, total cholesterol (TC), and low-density lipoprotein cholesterol (LDL) were sex dependent (P < 0.05). In males, pulse rate, TC, and LDL were decreased by 6.5%, 11.5%, and 18%, respectively. In females, pulse rate increased by 9.6%, and TC and LDL were relatively unchanged. There was a trend for a decreased glucose AUC (P = 0.06) in response to a glucose load. This study demonstrates that consuming 5 cups per week of ready-to-eat canned navy beans for 4 weeks reduces metabolic risk factors associated with obesity and therefore can be used as a tool in dietetic practice.

Glycaemic and insulinaemic impact of oats soaked overnight in milk vs. cream of rice with and without sugar, nuts, and seeds: a randomized, controlled trial

Background/ObjectivesSoaking oats overnight in milk renders them ready to eat the next morning, however, it is unknown whether oats prepared this way will retain its relatively low glycaemic and insulinaemic impact. Therefore, we compared the glycaemic, insulinaemic and subjective hunger responses elicited by oats soaked overnight in 110 g skim-milk (ONO) vs. cooked cream of rice cereal (CR), both with and without inclusions.Subjects/MethodsThe project was performed at two research centers (Toronto, Winnipeg) as two separate studies each using a randomized, cross-over design with similar methods. The glycaemic and insulinaemic responses of overnight-fasted participants without diabetes (males:females: Toronto, 24:16; Winnipeg, 20:20) were measured for 3 h after consuming CR and ONO fed alone (Toronto) or with added sugar, nuts, and seeds (CRsns and ONOsns) (Winnipeg). Participants rated subjective hunger using visual analog scales. Data were analyzed by paired t-test. The primary endpoint was 0–2 h incremental area under the curve (iAUC) for glucose.ResultsMean glucose iAUC was 33% less, after ONO than CR (mean difference was 39 (51–27) mmol × min/l, p < 0.0001) and 24% less, after ONOsns than CRsns (mean difference was 43 (65–21) mmol × min/l, p = 0.0003). Serum-insulin iAUC was 33% less, after ONO than CR (mean difference 57 (81–40) pmol × hl, p < 0.0001) and 32% less, after ONOsns than CRsns (966 (1360–572) pmol × h/l, p < 0.0001). In both Toronto and Winnipeg, subjective hunger ratings were similar across the two treatments.ConclusionsOats prepared by soaking overnight in skimmed milk without and with inclusions retain their relatively low glycaemic and insulinaemic impact.