No abstract

In addition to its recognized role in bone health, recent studies point to vitamin D functions in other tissues, including the pancreas. We tested the association between the vitamin D status and glucose and lipid homeostasis in a school-based, cross-sectional survey of a representative sample of youth. We measured fasting plasma insulin, glucose, total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDL-C) apolipoproteins (apo) A1 and B, and 25-hydroxyvitamin D [25(OH)D] concentrations in 878 boys and 867 girls. The 25(OH)D concentrations (mean +/- SD) were 45.9 +/- 12.2 nmol/L in boys and 45.9 +/- 13.0 nmol/L in girls. More than 93% of youth had suboptimal (<75 nmol/L) vitamin D concentrations. There was a slightly lower glycemia, -0.5% (P = 0.015) and -0.4% (P = 0.025), and homeostasis model assessment of insulin resistance, -2.8% (P = 0.043) and -2.3% (P = 0.050), for each 10-nmol/L increase in plasma 25(OH)D in boys and girls, respectively. In contrast, in girls only there were modest increases in plasma TC (1.1%; P = 0.017), TG (2.9%; P = 0.004), apoA1 (1.2%; P < 0.001), and apoB (1.5%; P = 0.023). We observed no association between the presence of at least 2 cardiometabolic risk factors (borderline/unfavorable fasting concentrations of apoB, HDL-C, TG, insulin, and glucose) and 25(OH)D concentrations in either boys or girls. Although the observed associations between 25(OH)D concentrations and fasting glucose, and variables of lipid metabolism are modest, they may have a potential long-term impact on cardiovascular risk.

BACKGROUND:Adequate vitamin D status is important for bone growth and mineralization and has been implicated in the regulation of autoimmunity, metabolic function, and cancer prevention. There are no reports of population-based studies on the vitamin D status of Canadian youth, a population with mandatory fortification of foods.

here are important health disparities by income in Canada and the US. 1,2 Disadvantaged children are at greater risk of infant mortality, incidence of death from infectious diseases and accidental deaths. 3 Older youth in disadvantaged settings may be more exposed to smoking, poor diet and sedentary behaviour, contributing to an increased risk of chronic disease in adulthood. 4,5 Moreover, the contribution of these exposures to increased morbidity and mortality appears to be additive, 6 and clustering of risk behaviours is observed among Canadian youth from low-income households. 7 The contribution of diet to an increased risk of chronic disease in youth is not well understood. 8 Among youth from low-income households, food insecurity may be associated with an additional level of deprivation. 9 Food insecurity is an inability to access, at all times, enough food for an active, healthy life. 10 A recent report from the Canadian Community Health Survey (CCHS, Cycle 2.2) found that teenage girls living in food-insecure households consumed fewer milk products, fruits and vegetables compared to food-secure girls. 9 Because food insecurity is observed in middle-income households, 9,11 the combined effect of low income and food insecurity should be assessed to determine if their association with dietary indicators and anthropometric measurements is additive.We examined the influence of income and the conjoint influence of low income and food insecurity on several dietary indicators in a representative sample of Canadian youth aged 9-18 years. We chose to examine milk, calcium and vitamin D intakes as they are implicated in bone health in youth, and there is considerable vitamin D deficiency among Canadian youth. [12][13][14] We studied sweetened beverage consumption because of its association with obesity, 15 and fruit and vegetable consumption, which is associated with numerous health benefits. 16 We also examined longer-term nutritional indicators such as height and overweight status. METHODSThe CCHS Cycle 2.2 targeted persons of all ages living in private dwellings in Canada's ten provinces. Residents of the three territories, persons living on First Nations reserves or Crown lands, persons living in institutions, and residents of some remote regions were excluded. Our study population included 8,938 youth aged 9-18 years. We excluded pregnant and breastfeeding girls.Data were collected in person in all months of 2004, using a computerassisted interviewing method. Interviewers received 3 days of training.

Twenty obese inpatients who claimed to crave carbohydrate-rich foods were given d-fenfluramine f 15 mg P.o., twice daily) or its placebo, double-blind, for two consecutive eight-day periods. Food choices were measured on treatment days 1, 7, and 8 by giving the subjects access to unlimited portions of six isocaloric meal foods (three high in carbohydrate and three high in protein) and of 10 isocaloric snack foods (five high in protein and five high in carbohydrate) available 24 hours a day in a computerized vending machine. d-fenfluramine reduced mealtime calorie intake by only 16% (from 1940 ? 94 to 1630 & 92; p < .OO 1), mealtime carbohydrate by 22%, and had no significant effect on mealtime protein consumption; in contrast, snack calorie intake was reduced by 4 1 % (from 707 2 97 to 4 14 * 46; p < .OO I ) , and snack carbohydrate intake by the same proportion. The mean number of carbohydrate-rich snacks consumed per day decreased from 5.8 & 0.8 to 3.4 & 0.4 (p < .O I), while that of protein-rich snacks failed to change significantly (i.e., from 0.7 2 0.2 to 0.5 2 0.2).