The adolescent transition under energetic stress: Body composition tradeoffs among adolescent women in The Gambia

Background and objectives: Life history theory predicts a shift in energy allocation from growth to reproductive function as a consequence of puberty. During adolescence, linear growth tapers off and, in females, ovarian steroid production increases. In this model, acquisition of lean mass is associated with growth while investment in adiposity is associated with reproduction. This study examines the chronological and developmental predictors of energy allocation patterns among adolescent women under conditions of energy constraint. Methodology: Fifty post-menarcheal adolescent women between 14 and 20 years old were sampled for weight and body composition at the beginning and end of 1 month in an energy-adequate season and 1 month in the subsequent energy-constrained season in a rural province of The Gambia. Results: Chronologically and developmentally younger adolescent girls gain weight in the form of lean mass in both energy-adequate and energy-constrained seasons, whereas older adolescents lose lean mass under conditions of energetic stress (generalized estimating equation (GEE) Wald chi-square comparing youngest tertile with older two tertiles 9.750, P = 0.002; GEE Wald chi-square comparing fast- with slow-growing individuals for growth rate 19.806, P < 0.001). When energy is limited, younger adolescents lose and older adolescents maintain fat (GEE Wald chi-square for interaction of age and season 6.568, P = 0.010; GEE Wald chi-square comparing fast- with slow-growing individuals for interaction of growth rate and season 7.807, P = 0.005). Conclusions and implications: When energy is constrained, the physiology of younger adolescents invests in growth while that of older adolescent females privileges reproductively valuable adipose tissue

Predictors of intact and C-terminal fibroblast growth factor 23 in Gambian children

Elevated C-terminal fibroblast growth factor 23 (C-FGF23) concentrations have been reported in Gambian children with and without putative Ca-deficiency rickets. The aims of this study were to investigate whether i) elevated C-FGF23 concentrations in Gambian children persist long term; ii) they are associated with higher intact FGF23 concentrations (I-FGF23), poor iron status and shorter 25-hydroxyvitamin D half-life (25OHD-t1/2); and iii) the persistence and predictors of elevated FGF23 concentrations differ between children with and without a history of rickets. Children (8-16 years, n=64) with a history of rickets and a C-FGF23 concentration >125 RU/ml (bone deformity (BD), n=20) and local community children with a previously measured elevated C-FGF23 concentration (LC+, n=20) or a previously measured C-FGF23 concentration within the normal range (LC-, n=24) participated. BD children had no remaining signs of bone deformities. C-FGF23 concentration had normalised in BD children, but remained elevated in LC+ children. All the children had I-FGF23 concentration within the normal range, but I-FGF23 concentration was higher and iron status poorer in LC+ children. 1,25-dihydroxyvitamin D was the strongest negative predictor of I-FGF23 concentration (R(2)=18%; P=0.0006) and soluble transferrin receptor was the strongest positive predictor of C-FGF23 concentration (R(2)=33%; P≤0.0001). C-FGF23 and I-FGF23 concentrations were poorly correlated with each other (R(2)=5.3%; P=0.07). 25OHD-t1/2 was shorter in BD children than in LC- children (mean (s.d.): 24.5 (6.1) and 31.5 (11.5) days respectively; P=0.05). This study demonstrated that elevated C-FGF23 concentrations normalised over time in Gambian children with a history of rickets but not in local children, suggesting a different aetiology; that children with resolved rickets had a shorter 25OHD-t1/2, suggesting a long-standing increased expenditure of 25OHD, and that iron deficiency is a predictor of elevated C-FGF23 concentrations in both groups of Gambian children

Iron bioavailability: UK Food Standards Agency workshop report

The UK Food Standards Agency convened a group of expert scientists to review current research investigating factors affecting iron status and the bioavailability of dietary iron. Results presented at the workshop show menstrual blood loss to be the major determinant of body iron stores in premenopausal women. In the presence of abundant and varied food supplies, the health consequences of lower iron bioavailability are unclear and require further investigatio

Life course dietary patterns and bone health in later life in a British birth cohort study

Evidence for the contribution of individual foods and nutrients to bone health is weak. Few studies have considered hypothesis-based dietary patterns and bone health. We investigated whether a protein, calcium and potassium-rich (PrCaK-rich) dietary pattern over the adult life course, was positively associated with bone outcomes at 60-64 years of age. Diet diaries were collected at ages 36, 46, 53 and 60-64 years in 1263 participants (661 women) from the MRC National Survey of Health and Development. DXA and pQCT measurements were obtained at 60-64y, including size-adjusted bone mineral content (SA-BMC) and volumetric bone mineral density (vBMD). A food-based dietary pattern best explaining dietary calcium, potassium and protein intakes (g/1000?kcal) was identified using reduced rank regression. Dietary pattern z-scores were calculated for each individual, at each time point. Individual trajectories in dietary pattern z-scores were modelled to summarise changes in z-scores over the study period. Regression models examined associations between these trajectories and bone outcomes at 60-64y, adjusting for baseline dietary pattern z-score and other confounders. A consistent PrCaK-rich dietary pattern was identified within the population, over time. Mean [SD] dietary pattern z-scores at age 36 and 60-64 years were -0.32[0.97], 2.2[1.5] (women) and -0.35[0.98], 1.7[1.6] (men). Mean trajectory in dietary pattern z-scores [SD] was 0.07[0.02]SD units/year. Among women, a 0.02 SD unit/year higher trajectory in dietary pattern z-score over time was associated with higher SA-BMC (spine 1.40% [95% CI: 0.30,2.51]; hip 1.35% [95% CI: 0.48,2.23]) and vBMD (radius 1.81% [95% CI: 0.13,3.50]) at 60-64 y. No statistically significant associations were found in men. During adulthood, an increasing score for a dietary pattern rich in protein, calcium and potassium was associated with greater SA-BMC at fracture-prone sites in women. This study emphasises the importance of these nutrients, within the context of the whole diet, to bone healt

MAVIDOS Maternal Vitamin D Osteoporosis Study: study protocol for a randomized controlled trial. The MAVIDOS Study Group

UNLABELLED: MAVIDOS is a randomised, double-blind, placebo-controlled trial (ISRCTN82927713, registered 2008 Apr 11), funded by Arthritis Research UK, MRC, Bupa Foundation and NIHR. BACKGROUND: Osteoporosis is a major public health problem as a result of associated fragility fractures. Skeletal strength increases from birth to a peak in early adulthood. This peak predicts osteoporosis risk in later life. Vitamin D insufficiency in pregnancy is common (31% in a recent Southampton cohort) and predicts reduced bone mass in the offspring. In this study we aim to test whether offspring of mothers supplemented with vitamin D in pregnancy have higher bone mass at birth than those whose mothers were not supplemented. METHODS/DESIGN: Women have their vitamin D status assessed after ultrasound scanning in the twelfth week of pregnancy at 3 trial centres (Southampton, Sheffield, Oxford). Women with circulating 25(OH)-vitamin D levels 25-100 nmol/l are randomised in a double-blind design to either oral vitamin D supplement (1000 IU cholecalciferol/day, n = 477) or placebo at 14 weeks (n = 477). Questionnaire data include parity, sunlight exposure, dietary information, and cigarette and alcohol consumption. At 19 and 34 weeks maternal anthropometry is assessed and blood samples taken to measure 25(OH)-vitamin D, PTH and biochemistry. At delivery venous umbilical cord blood is collected, together with umbilical cord and placental tissue. The babies undergo DXA assessment of bone mass within the first 14 days after birth, with the primary outcome being whole body bone mineral content adjusted for gestational age and age. Children are then followed up with yearly assessment of health, diet, physical activity and anthropometric measures, with repeat assessment of bone mass by DXA at age 4 years. DISCUSSION: As far as we are aware, this randomised trial is one of the first ever tests of the early life origins hypothesis in human participants and has the potential to inform public health policy regarding vitamin D supplementation in pregnancy. It will also provide a valuable resource in which to study the influence of maternal vitamin D status on other childhood outcomes such as glucose tolerance, blood pressure, cardiovascular function, IQ and immunology

Energy and nutrient dietary reference values for children in Europe: methodological approaches and current nutritional recommendations

The Expert Group on the Methodological Approaches and Current Nutritional Recommendations in Children and Adolescents was convened to consider the current situation across Europe with regard to dietary recommendations and reference values for children aged 2-18 years. Information was obtained for twenty-nine of the thirty-nine countries in Europe and a comprehensive compilation was made of the dietary recommendations current up to September 2002. This report presents a review of the concepts of dietary reference values and a comparison of the methodological approaches used in each country. Attention is drawn to the special considerations that are needed for establishing dietary reference values for children and adolescents. Tables are provided of the current dietary reference values for energy and for the macronutrients, vitamins, minerals, trace elements and water. Brief critiques are included to indicate the scientific foundations of the reference values for children and to offer, where possible, an explanation for the wide differences that exist between countries. This compilation demonstrated that there are considerable disparities in the perceived nutritional requirements of European children and adolescents. Although some of this diversity can be attributed to real physiological and environmental differences, most is due to differences in philosophy about the best methodological approach to use and in the way the theoretical approaches are applied. The report highlights the main methodological and technological issues that will need to be resolved before harmonisation can be fully considered. Solving these issues may help to improve the quality and consistency of dietary reference values across Europe. However, there are also considerable scientific and political barriers that will need to be overcome and the question of whether harmonisation of dietary reference values for children and adolescents is a desirable or achievable goal for Europe requires further consideratio

Diurnal rhythms of vitamin D binding protein and total and free vitamin D metabolites

Vitamin D binding protein (DBP) concentration is known to influence the availability and bioactivity of vitamin D metabolites but its diurnal rhythm (DR), its inter-relationships with the DRs of vitamin D metabolites and its influence on free vitamin D metabolite concentrations are not well described. The DRs of plasma total 25(OH)D, total 1,25(OH)2D, DBP, albumin and calculated free 25(OH)D and free 1,25(OH)2D were measured in men and women aged 60–75 years and resident in the UK (n 30), Gambia (n 31) and China (n 30) with differences in lifestyle, dietary intake and vitamin D status. Blood samples were collected every 4 h for 24 h and DRs statistically analysed with Fourier regression. Gambians had significantly higher plasma concentrations of vitamin D metabolites and lower albumin concentration compared to the British and Chinese. Significant DRs were observed for all analytes and calculated free vitamin D metabolites (P < 0.01). The pattern of DRs was similar between countries. The magnitude of the DRs of free 1,25(OH)2D was attenuated compared to that of total 1,25(OH)2D whereas it was not different between total and free 25(OH)D. Relationships between the DRs were generally weak. There was no phase shift between 1,25(OH)2D and DBP with the strongest cross correlation at 0 h time lag (r = 0.15, P = < 0.001). In comparison, 25(OH)D correlated less well with DBP (1 h time lag, r = 0.07, P = 0.12). These data demonstrate a relationship between the DRs of 1,25(OH)2D and DBP, possibly to maintain free 1,25(OH)2D concentrations. In contrast, the DRs of total and free 25(OH)D appeared to be less influenced by DBP, suggesting that DBP has comparatively less effect on 25(OH)D concentration and 25(OH)D availability. This work highlights the importance of standardisation in timing of sample collection particularly for the assessment of plasma protein concentrations

"Living on Paper:" Georgia O'Keeffe and the Culture of Drawing and Watercolor in the Stieglitz Circle

Drawing and watercolor were important in shaping the modernism of artist Georgia O'Keeffe and photographer Alfred Stieglitz. In his gallery 291 and journal Camera Work, Stieglitz introduced European avant-garde art to early twentieth-century America and promoted American modernists including O'Keeffe. Stieglitz as a child collected drawings and watercolors and learned traditional drawing connoisseurship that valued revelation of the artist's character through the marks he made on paper. Stieglitz's journals Camera Notes and Camera Work asserted connections between photography and other graphic media. Stieglitz and Edward Steichen founded 291 as a pictorial photography gallery but later exhibited modern paintings and many drawings and watercolors. O'Keeffe studied academic art at the Art Institute of Chicago and the Art Students League in New York, but she wanted more creative freedom. Art educator Arthur Wesley Dow introduced O'Keeffe to abstract design principles and prepared her to appreciate modern art. While O'Keeffe was training as an art teacher at Columbia University Teachers College in New York in 1914 and 1915, she visited 291 and became interested in modern art. The modern art O'Keeffe had seen was mainly in form of drawings and watercolor at 291 and reproductions in modernist journals, so her original conception of modernism was graphic. Her first modern art works, made in South Carolina in 1915, were abstract charcoal drawings that combined academic drawing techniques with modernist approaches from charcoal drawings by Pablo Picasso and Marius de Zayas. Stieglitz interpreted O'Keeffe's drawings as naïve expressions of female sexuality and showed them at 291 in 1916. O'Keeffe taught art in Texas and made modernist watercolors of the Texas sky and landscape. Stieglitz showed her new works at 291 in 1917. In 1918 O'Keeffe returned to New York and moved in with Stieglitz. She concentrated on painting in oils for the rest of her career. Stieglitz photographed O'Keeffe with her drawings and watercolors, connecting the marks on paper with the artist's body, hands, and sexuality. While exhibiting O'Keeffe's oil paintings, Stieglitz continued for decades to show O'Keeffe's early drawings to critics and to stress her origins as a simple graphic artist