Evaluation of plasma and erythrocyte fatty acids C15:0, t-C16:1n-7 and C17:0 as biomarkers of dairy fat consumption in adolescents.

INTRODUCTION: Pentadecanoic (C15:0), heptadecanoic (C17:0) and trans-palmitoleic (t-C16:1n-7) fatty acids (FAs) are often used as biomarkers for dairy fat in adults. This study aimed to investigate the relationship between dairy product intake and these FAs in adolescents. MATERIAL AND METHODS: Healthy adolescents were randomized to one of three groups (Group 1: control; Group 2: consume 3 dairy servings/day; and Group 3: consume ≥ 4 servings/d). C15:0, C17:0 and t-C16:1n-7 were quantified using gas chromatography. Dietary intakes were assessed by 24 h diet recalls. RESULTS: No difference was observed in FAs at baseline or 6 months (mo), however, at 12 mo, erythrocyte C15:0 increased in group 3 (+0.37 µg/ml, p = 0.01). Dairy intake increased in both intervention groups (Group 2: +1.4 servings/d; Group 3: +2.4 servings/d, p < 0.0001) and positively correlated with erythrocyte C15:0 at 12 mo. CONCLUSION: Erythrocyte FAs appear to be associated with increasing dairy intakes during adolescence.

Litter quality and microtopography as key drivers to topsoil properties and understorey plant diversity in ancient broadleaved forests on decalcified marl.

In forest ecosystems, litter quality is a major driver for soil and understorey characteristics, but elevation, microtopography and subsoil properties may also be important. We tested the importance of each factor in two ancient mixed forests on decalcified marl, dominated by trees with different litter quality such as European hornbeam, with high-palatable litter, and beech, with low-palatable litter. We mapped elevation, differences in local height (microtopography), tree distribution and understorey cover on slopes ranging from crest to bottom, and sampled 200 7 × 7 m grid cells for characteristics of litter input, understorey, topsoil and subsoil. In both forests, elevation decreased gradually, but microtopography showed irregular patterns of depressions and mounds of a few cm below or above average local height. Tree distribution was not affected by elevation or subsoil properties, but clearly by microtopography. Adult beech was abundant on local mounds, while hornbeam was more common in local depressions. Topsoil and understorey characteristics were mainly affected by litter quality (tree species dominance) and microtopography. Litter quality had separate effects from microtopography, but could reinforce this. High litter quality (hornbeam) and low local height both led to high earthworm activity, low litter mass, high erosion, impermeable clay layers close to the surface, high pH, high soil moisture and high diversity of the understorey. Low litter quality (beech) and high local height both led to low earthworm activity, high litter mass, low erosion, low pH, low soil moisture and low plant diversity. Beech and hornbeam may act as ecosystem engineers, which change habitat conditions and local hydrology, and make habitats more suitable to themselves, and/or unsuitable to the other. However, they also increased spatial complexity of the forest and length of the habitat gradient. This may increase forest biodiversity as a whole, but also resilience to prolonged wet or dry periods.

Diet diversity, growth and adiposity in healthy breastfed infants fed homemade complementary foods.

BACKGROUND/OBJECTIVES: Infant complementary feeding is important for establishing food preferences. Few studies exist on the effects of infant complementary feeding choices (food preparation methods) on dietary intake, growth or adiposity. We examined whether provision of homemade complementary food is associated with the development of dietary diversity, nutrient intakes and quality of infant growth. SUBJECTS/METHODS: Secondary analysis of feeding practices from a randomized trial of vitamin D supplementation in 132 healthy breastfed 1-month-old infants from Montréal, Canada. This longitudinal study used diet records, anthropometric and body composition data (dual-energy X-ray absorptiometry) from assessments that occurred when infants were 6, 9, 12 and 36 months of age. Infants were grouped into three categories of food preparation method on the basis of whether or not they had consumed homemade or commercial meat or fruit and vegetable by 9 months (homemade, commercial and both). Multivariable regression controlled for family income, maternal education and infant sex. RESULTS: Dietary data were available for 65 infants. By 9 months, 22% of infants had exclusively received homemade (n=14), 14 infants had exclusively received commercial and 37 infants had received both. The development of dietary diversity (number of World Health Organization-recommended food groups) was higher (0.76 (95% confidence interval (CI): 0.14, 1.38); P<0.05) in the homemade group versus commercial. Energy and nutrient intakes did not differ by group over time. The homemade group had 773 g (-1364, -182; P<0.01) lower whole-body fat mass and 7.1% (-12.6, -1.6; P<0.05) lower % body fat at 12 months compared with the reference group (both homemade and commercial). Reduced whole-body fat mass in the homemade group persisted at 36 months (-696 g (95% CI: -1341, -52); P<0.05). There were no differences between groups for changes in growth Z-scores (length-for-age, weight-for-age and body mass index-for-age). CONCLUSIONS: Provision of homemade complementary food is associated with increased dietary diversity during the first year of life and reduced adiposity.

Vitamin D supplementation trial in infancy: body composition effects at 3 years of age in a prospective follow-up study from Montréal.

BACKGROUND: The impact of vitamin D status on body composition is not well understood. OBJECTIVES: Evaluate how vitamin D supplementation in infancy affects body composition at 3 years of age. METHODS: Double-blind randomized trial of 132, 1-month-old healthy, breastfed infants randomly assigned to receive oral vitamin D3 supplements of 400, 800, 1200 or 1600 IU d-1 for 11 months. In the present analysis, 87 (66%) returned at 3 years of age. Body composition was measured using dual-energy x-ray absorptiometry and plasma 25-hydroxyvitamin D [25(OH)D] concentrations by liquid chromatography tandem mass spectrometry. RESULTS: Anthropometry, body composition, diet, activity and demographics were similar across dosage groups at 3 years. Mean 25(OH)D concentration from 1 month to 3 years was higher (P < 0.001) in the 1200 IU group than 800 and 400 IU groups. Children with 25(OH)D concentrations above 75 nmol L-1 had lower fat mass (~450 g; P = 0.049). In multiple linear regression, mean 25(OH)D was associated with lean mass percent (ß = 0.06; CI: 0.00, 0.12; P = 0.042), fat mass (ß = -11.29; CI: -22.06, -0.52; P = 0.048) and body fat percent (ß = -0.06; CI: -0.12, -0.01; P = 0.045). CONCLUSIONS: Higher vitamin D status from infancy through to 3 years of age associates with leaner body composition.

Vitamin D supplementation in breastfed infants from Montréal, Canada: 25-hydroxyvitamin D and bone health effects from a follow-up study at 3 years of age.

UNLABELLED: Whether infant vitamin D supplementation may have long-term bone benefits is unclear. In this study, breastfed infants who received vitamin dosages greater than 400 IU/day did not have higher bone mineralization at 3 years. This study provides important data to inform pediatric public health recommendations for vitamin D. INTRODUCTION: North American health agencies recommend breastfed infants should be supplemented with 400 IU of vitamin D/day to support bone health. Few studies examined the long-term benefits of early life vitamin D supplementation on bone mineralization. The objective of this study was to determine if a dose-response relationship exists between infant vitamin D supplementation, vitamin D status, and bone outcomes at 3 years of age. METHODS: This was a double-blind randomized trial of 132, 1-month-old healthy, breastfed infants from Montréal, Canada, between 2007 and 2010. In this longitudinal analysis, 87 infants (66 %) returned for follow-up at 3 years of age, between 2010 and 2013. At 1 month of age, participants were randomly assigned to receive oral cholecalciferol (vitamin D3) supplements of 400, 800, 1200, or 1600 IU/day until 12 months of age. Lumbar spine vertebrae 1-4 (LS) bone mineral density (BMD), LS and whole body bone mineral content (BMC), and mineral accretion were measured by dual-energy x-ray absorptiometry at 3 years. RESULTS: At follow-up, the treatment groups were similar in terms of diet, sun exposure, and demographics. There were no significant differences among the groups in LS or whole body BMC, BMD, or accretion. Although, 25(OH)D concentrations were not different among the groups, higher doses (1200 and 1600 IU/day) achieved higher 25(OH)D area under the curve from 1 to 36 months vs. 400 IU/day. CONCLUSIONS: This is the first longitudinal follow-up of an infant vitamin D dose-response study which examines bone mineralization at 3 years of age. Dosages higher than 400 IU/day do not appear to provide additional benefits to the bone at follow-up. Larger studies with more ethnically diverse groups are needed to confirm these results.

Physical activity assessment tools for use in overweight and obese children.

The prevalence of excess weight in children and adults worldwide has increased rapidly in the last 25 years. Obesity is positively associated with increased risk for many health issues such as type 2 diabetes, cardiovascular disease and psychosocial problems. This review focuses on child populations, as it is known that the sedentary behaviors of overweight/obese youth often endure into adulthood. Assessment of physical activity (PA), among other factors such as diet and socio-economic status, is important in understanding weight variation and in designing interventions. This review highlights common subjective and objective PA assessment tools, the validity of these methods and acceptable ways of collecting and interpreting PA data. The aim is to provide an update on PA assessment in overweight/obese children, highlighting current knowledge and any gaps in the literature, in order to facilitate the use of PA assessments and interventions by health-care professionals as well as suggest future research in this area.

Concurrent nematode infection and pregnancy induce physiological responses that impair linear growth in the murine foetus.

This study examined concurrent stresses of nematode infection and pregnancy using pregnant and non-pregnant CD1 mice infected 3 times with 0, 50 or 100 Heligmosomoides bakeri larvae. Physiological, energetic, immunological and skeletal responses were measured in maternal and foetal compartments. Resting metabolic rate (RMR) was elevated by pregnancy, but not by the trickle infection. Energy demands during pregnancy were met through increased food intake and fat utilization whereas mice lowered their body temperature during infection. Both infection and pregnancy increased visceral organ mass and both altered regional bone area and mineralization. During pregnancy, lumbar mineralization was lower but femur area and mineralization were higher. On the other hand, infection lowered maternal femur bone area and this was associated with higher IFN-gamma in maternal serum of heavily infected pregnant mice. Infection also reduced foetal crown-rump length which was associated with higher amniotic fluid IL-1 beta.

Feeding flaxseed oil but not secoisolariciresinol diglucoside results in higher bone mass in healthy rats and rats with kidney disease.

Flaxseed's oil and lignan, secoisolariciresinol diglucoside (SDG), are implicated in attainment of health and treatment of renal injury and osteoporosis. To test for these benefits, weanling Han:SPRD-cy rats (n=171) with or without kidney disease were randomized to diets made with either corn oil or flaxseed oil and with or without SDG for 12 weeks. In females, weight was lower with the SDG diet. In males fed flaxseed oil, lean mass was higher and fat % was lower. In both sexes, fat % was lower in diseased rats. Bone mineral content (BMC) and density were higher in rats fed flaxseed oil and lower in diseased rats, additionally; BMC was lower in SDG-supplemented females. The benefit of flaxseed oil on body composition is sex specific but the effect on bone mass is not. Lastly, reduced weight due to early rat kidney disease is not due to loss of lean body mass.

Bone density and bone area in Canadian Aboriginal women: the First Nations Bone Health Study.

INTRODUCTION: Canadian Aboriginal women are at increased risk of fracture compared with the general population. HYPOTHESIS: There is disproportionately reduced bone density in Aboriginal women as compared to white females of similar age. METHODS: A random age-stratified (25-39, 40-59 and 60-75) sample of Aboriginal women (n=258) and white women (n=181) was recruited. All subjects had calcaneus and distal forearm bone density measurements, and urban participants (n=397 [90.4%]) also had measurements of the lumbar spine, hip and total body. RESULTS: Unadjusted measurements were similar in the two groups apart from the distal forearm which showed a significantly lower mean Z-score in the Aboriginal women (p=0.03). Aboriginal women were heavier than white women (81.0+/-18.0 kg vs. 76.0+/-18.0 kg, p=0.02). Weight was directly associated with BMD at all measurement sites (p<0.00001) and potentially confounded the assessment of ethnicity on bone mass measurements. Weight-adjusted ANCOVA models demonstrated significantly lower bone density in Aboriginal than white women for the calcaneus, distal forearm, and total body (all p<0.05), but not at the other sites. ANCOVA models (adjusted for age, height and weight) were used to explore differences in bone area and bone mineral content (BMC). There was a significant effect of ethnicity on bone area with Aboriginal women having larger adjusted mean values than white women (lumbar spine p=0.038, total hip p=0.0004, total body p=0.020). In contrast, there was no detectable effect of ethnicity on BMC (all p>0.2). CONCLUSIONS: We identified significant site-specific differences in age-and weight-adjusted bone density for Aboriginal and white women. Larger bone area, rather than a reduction in BMC, appeared to be primarily responsible. Further work is needed to define how these differences in bone density and geometry affect indices of bone strength.

Growth and bone mineralization of young adults weighing less than 1500 g at birth.

BACKGROUND: Preterm infants are at risk for suboptimal growth and bone mineralization compared to infants born at term but long-term outcomes into early adulthood are unclear. AIMS: To determine (1) if growth and nutrition in the first year of life significantly predict the outcomes measured at adulthood and (2) whole body and regional bone mineral content (BMC) of young adults who were born preterm and weighing <1500 g. STUDY DESIGN AND SUBJECTS: In this descriptive follow-up study, subjects were born preterm and weighing <1500 g (n=25, 17.2+/-1.2 years of age) and originally participated in a 1-year follow-up study of infant growth or subjects born at term (n=25, 17.3+/-1.4 years of age). OUTCOME MEASURES: In the preterm group, relationships of growth and nutrition in the first year of life with adult anthropometry and BMC were identified using correlation and regression analysis. Birth groups were compared for measurements of anthropometry and whole body and regional BMC obtained at adulthood using t-tests. RESULTS: After correcting for the effects of bone area using regression, rate of weight gain had a positive relationship and days to regain birth weight a negative relationship to adult BMC. Young adults, born preterm, were significantly shorter with lower whole body BMC than of those born at term, but BMC was appropriate for size. CONCLUSIONS: Growth early in life predicts subsequent attainment of growth and bone mass. Premature birth results in lower attainment of height achieved by young adult age but bone mass is appropriate for body size.

Percent body fat and bone mass in healthy Canadian females 10 to 19 years of age.

The primary aim of the investigation was to assess the relationship between whole-body fat expressed as a percentage of body weight with whole-body bone mineral content relative to age and anthropometry. Sixty females between 10 and 19 years of age were recruited to this cross-sectional study, which included measurements of weight and height and whole-body fat and bone mineral content using dual-energy X-ray absorptiometry. To assess bone mineral content, data were expressed as a weight or standard deviation scores using age and bone area. Relationships between outcome variables were determined using multiple correlation analysis followed by multiple linear regression with age, weight, height, and fat as predictor variables for outcomes of bone mineral content and density. Correlation analysis indicated that whole-body fat expressed as a percent was significantly related to weight (p < 0.01), but was not related to age or bone mineral content or density unless bone mineral content was corrected to age or bone area using standard deviation scores. In addition, body fat was associated with bone area for age and height (p < 0.01). However, multiple linear regression yielded opposite results. When included in regression, body fat had a negative impact on bone mineral content (p = 0.003), mineral content corrected to bone area (p = 0.02), and bone density (p = 0.003), while age, weight, and height had positive impacts on these outcome measurements. The data suggest that for younger children, the relative influence of percent body fat will be greater and could be linked with suboptimal attainment of peak bone mass. The females in this study appeared to be within reference limits for percent body fat. However, greater amounts of body fat relative to weight could be a marker for lifestyles that do not support attainment of optimal peak bone mass.

Dietary supplementation of arachidonic acid is associated with higher whole body weight and bone mineral density in growing pigs.

Essential fatty acids are fundamental to normal growth and development, but North American formulas do not contain arachidonic (AA) and docosahexaenoic acid (DHA). The main objective of the present study was to determine whether addition of AA and DHA to formula elevates growth and bone mineralization in piglets. A secondary objective was to establish whether liver fatty acid composition is related to that of bone. Twelve 10-d-old male piglets were randomized to receive either a standard formula with an n-6:n-3 fatty acid ratio of 4.9:1.0 or the same formula made with an equal amount of fat but containing AA (0.5% wt/wt total fat) and DHA (0.1% wt/wt total fat) for 14 d. Piglets in the supplemented group had significantly (p < 0.05) higher weight and greater bone mineral density of the whole body, lumbar spine, and femur. No differences were observed in whole body length, calcium absorption, or biochemical markers of bone metabolism. Feeding AA resulted in lower linoleic acid (p < 0.05) and higher (p < 0.05) AA in liver total lipid (% wt/wt) and bone FFA (% wt/wt) but no change to DHA. Liver AA (% wt/wt total lipid) was positively related (p < 0.05) to growth, free AA (% wt/wt) in bone, bone mineral content, bone mineral density, and urinary prostaglandin E2 but negatively related (p < 0.05) to free linoleic acid in bone. Inverse relationships were observed when liver linoleic acid was substituted for liver AA as the independent variable. These data indicate that feeding AA is associated with elevated weight and higher whole body and regional bone mineral density.

Modification of polycystic kidney disease and fatty acid status by soy protein diet.

UNLABELLED: Modification of polycystic kidney disease and fatty acid status by soy protein diet. BACKGROUND: Previous studies have demonstrated that soy protein can slow progression of renal injury in the Han:SPRD-cy rat. We undertook a study to establish whether this benefit was independent of any nutritional deprivation, and whether or not it was associated with changes in polyunsaturated fatty acid status that have been previously linked to the anti-inflammatory or antineoplastic potential of soy diets. METHODS: Male Han:SPRD-cy rats were pair fed a 20% casein or 20% soy protein diet for six weeks from weaning. Tissue was harvested for analysis of cystic change, cell proliferation, macrophage infiltration, and fibrosis. Renal and hepatic tissues were also harvested for lipid analysis using gas chromatography. RESULTS: Animals thrived on both diets. Soy protein feeding was associated with reduced cystic change (4.3 vs. 7.0 mL/kg, P < 0.0001), epithelial cell proliferation (15.7 vs. 21.0 cells/mm epithelium, P < 0.0001), macrophage infiltration (25.3 vs. 43.5 cells/high-power field, P < 0.0001), and fibrosis (0.6 vs. 1.07 mL/kg, P < 0.0001). The soy diet prevented a significant elevation in serum creatinine in diseased versus normal animals. Soy feeding was associated with higher renal and hepatic linoleic acid content and higher hepatic alpha-linolenic acid, but lower hepatic arachidonic acid content. CONCLUSIONS: Isocaloric soy protein feeding ameliorates both epithelial and interstitial changes in the Han:SPRD-cy rat independent of a hypocholesterolemic effect. The histologic benefit is associated with changes in polyunsaturated fatty acid metabolism that may influence both inflammatory and proliferative pathways.

Improvement in the accuracy of dual energy x-ray absorptiometry for whole body and regional analysis of body composition: validation using piglets and methodologic considerations in infants.

Previously, we conducted dual energy x-ray absorptiometry (DXA) (Hologic QDR-1000/W) scans and carcass analysis of piglets to evaluate the Pediatric Whole Body software (PedWB) (V5.35) for use in infants. A software upgrade designed for infant whole body (InfWB) (V5.56) led to a reassessment of DXA by: 1) reanalysis of the original scans using InfWB software and 2) comparison of InfWB-estimates of bone mineral content (BMC) and lean and fat mass with chemical analysis. Other assessments included 1) methods of regional analysis and 2) artifacts and the Infant Table Pad in the scan field. The mean coefficients of variation for InfWB whole body measures in small piglets (n = 10, weight 1575 +/- 73 g) and large piglets (n = 10, weight 5894 +/- 208 g) were less than 2.6% except for fat mass which was higher (8.0% versus 6.3% and 6.6% versus 3.5%, respectively) compared with PedWB. In large piglets InfWB produced good estimates of BMC, lean and fat masses. In small piglets, fat mass by InfWB was correlated with chemical analysis, but not by PedWB. There was improvement in the estimation of BMC with InfWB, from 27 +/- 2.2 g to 32 +/- 2.3 g (carcass ash = 38 +/- 3.3 g). Femur BMC analysis by InfWB was precise and was accurate when compared with chemical analysis. Artifacts in the DXA scan field (diapers and blankets) resulted in an increase of the DXA-estimated fat and lean masses. The Infant Table Pad increased the estimate of fat mass in a small piglet by 50%, thus further study is required before it is used routinely. Improvements of the DXA technology have resulted in a more accurate tool, if scanning procedures are carefully implemented.

Longitudinal assessment of growth and bone mineral accretion in prematurely born infants treated for chronic lung disease with dexamethasone.

The objective of this study in premature infants was to assess the relationship between dexamethasone, growth and bone mineral accretion. Nine appropriate size for gestational age premature infants treated for chronic lung disease with tapering doses of dexamethasone (0.5-0.1 mg/kg/day over 37 +/- 7 days) were individually matched to a comparison infant by sex, gestational age, birth-weight, and type of feed. Infant growth and bone mineral accretion were measured at equivalent gestational ages from recruitment until 6 months corrected age. During hospitalization, mean rate of weight, length and head circumference growth and bone mineral accretion in the distal radius were significantly lower in the dexamethasone-treated infants in spite of similar nutrient intakes. Dexamethasone infants had significantly lower plasma phosphorus, and urinary calcium, pyridinoline and N-telopeptide excretion. Dexamethasone affected absolute length, but not weight, throughout the study. No significant differences were observed in body composition or absolute radial and whole body bone mineral content. The results indicate that dexamethasone therapy compromises growth and bone mineral accretion in small premature infants. 'Catch-up' linear growth was not evident at 6 months of age and reflects the importance of early nutrition interventions.

Whole body lean mass is altered by dexamethasone treatment through reductions in protein and energy utilization in piglets.

The objective of this study was to assess the effect of dexamethasone on growth, body composition and protein metabolism using the piglet as a model for rapidly growing premature infants. Seven-day-old male pigs (n = 18) were randomized to 0.5 mg/kg/day oral dexamethasone or placebo for 15 consecutive days. Weight and length gains and weight gained per energy or protein consumed were significantly lower in the dexamethasone group. Serum urea nitrogen was significantly higher in the dexamethasone group by day 15 of the study. No differences were observed between groups for urinary creatinine. The whole body percent lean mass was significantly lower and percent fat mass was significantly higher in the dexamethasone piglets, as measured by dual energy X-ray absorptiometry. In young piglets, dexamethasone, at doses similar to those in premature infants, induces protein catabolism, impairs growth and alters its composition.

Dexamethasone treatment impairs calcium regulation and reduces bone mineralization in infant pigs.

Calcium and vitamin D metabolism, bone mineralization, and growth were studied in piglets randomly assigned to 15 d of dexamethasone (0.5 mg.kg-1.d-1, orally) or placebo. Growth velocity was significantly reduced by dexamethasone treatment (P < 0.001). Pigs in the dexamethasone group demonstrated lower 45Ca absorption by in situ intestinal perfusion (P < 0.01). Plasma 25-hydroxycholecalciferol (calcidiol) and 1,25-dihydroxycholecalciferol (calcitriol) were lower (P < 0.05) and the urinary ratio of calcium to creatinine was higher (P < 0.05) after 15 d of dexamethasone compared with placebo. Differences between pre- and postosteocalcin (P < 0.01) and pyridinoline (P < 0.01) were higher and wholebody, lumbar, and femur bone mineral density were lower (P < 0.05) in dexamethasone-treated piglets. Dexamethasone-induced reductions in bone mineral mass likely result from reduced vitamin D status, reduced intestinal calcium absorption, elevated urinary calcium loss and direct effects of the steroid on bone. When dexamethasone is used in premature infants to improve lung function, negative effects on growth and bone metabolism could occur.