Susan J. Whiting

Calcium Accretion in Girls and Boys During Puberty: A Longitudinal Analysis

The primary purpose of this study was to estimate the magnitude and variability of peak calcium accretion rates in the skeletons of healthy white adolescents. Total‐body bone mineral content (BMC) was measured annually on six occasions by dual‐energy X‐ray absorptiometry (DXA; Hologic 2000, array mode), a BMC velocity curve was generated for each child by a cubic spline fit, and peak accretion rates were determined. Anthropometric measures were collected every 6 months and a 24‐h dietary recall was recorded two to three times per year. Of the 113 boys and 115 girls initially enrolled in the study, 60 boys and 53 girls who had peak height velocity (PHV) and peak BMC velocity values were used in this longitudinal analysis. When the individual BMC velocity curves were aligned on the age of peak bone mineral velocity, the resulting mean peak bone mineral accrual rate was 407 g/year for boys (SD, 92 g/year; range, 226–651 g/year) and 322 g/year for girls (SD, 66 g/year; range, 194–520 g/year). Using 32.2% as the fraction of calcium in bone mineral, as determined by neutron activation analysis (Ellis et al., J Bone Miner Res 1996;11:843‐848), these corresponded to peak calcium accretion rates of 359 mg/day for boys (81 mg/day; 199–574 mg/day) and 284 mg/day for girls (58 mg/day; 171–459 mg/day). These longitudinal results are 27–34% higher than our previous cross‐sectional analysis in which we reported mean values of 282 mg/day for boys and 212 mg/day for girls (Martin et al., Am J Clin Nutr 1997;66:611‐615). Mean age of peak calcium accretion was 14.0 years for the boys (1.0 years; 12.0‐15.9 years), and 12.5 years for the girls (0.9 years; 10.5‐14.6 years). Dietary calcium intake, determined as the mean of all assessments up to the age of peak accretion was 1140 mg/day (SD, 392 mg/day) for boys and 1113 mg/day (SD, 378 mg/day) for girls. We estimate that 26% of adult calcium is laid down during the 2 adolescent years of peak skeletal growth. This period of rapid growth requires high accretion rates of calcium, achieved in part by increased retention efficiency of dietary calcium.

13th Workshop consensus for vitamin D nutritional guidelines.

1Department of Biochemistry and Division of Biomedical Sciences, University of California, Riverside, CA USA 2Laboratory of General Endocrinology, Onderwijs en Navorsing, Leuven, Belgium 3Nutrition and Dietetics, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada 4Department of Nutritional Sciences, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Canada 5Department of Endocrinology, VU University Medical Center, Amsterdam, The Netherlands

Vitamin D in adult health and disease: a review and guideline statement from Osteoporosis Canada - summary

CMAJ • SEPTEMBER 7, 2010 • 182(12)

The vitamin D status of Canadians relative to the 2011 Dietary Reference Intakes: an examination in children and adults with and without supplement use

BACKGROUND The 2011 Dietary Reference Intakes (DRIs) for vitamin D use 25-hydroxyvitamin D [25(OH)D] concentrations to define vitamin D deficiency (<30 nmol/L), the Estimated Average Requirement (40 nmol/L), and the Recommended Dietary Allowance (RDA; 50 nmol/L). The Canadian population has not yet been assessed according to these recommendations. OBJECTIVE We determined the prevalence of meeting DRI recommendations and the role of vitamin D supplement use among Canadians aged 6-79 y. DESIGN Plasma 25(OH)D from a representative sample of Canadians in the Canadian Health Measures Survey-Cycle 1 (n = 5306) were used. Supplement use was assessed by household interview. Concentrations of 25(OH)D were compared in supplement users and nonusers by season and race. RESULTS Overall, 5.4%, 12.7%, and 25.7% of the participants had 25(OH)D concentrations below the 30-, 40-, and 50-nmol/L cutoffs, respectively. In white Canadians, plasma 25(OH)D concentrations ranged from an undetectable percentage with concentrations <30 nmol/L in summer to 24.5% with concentrations <50 nmol/L in winter; the corresponding values ranged from 12.5% to 53.1% in nonwhite Canadians. Supplement users had significantly higher 25(OH)D concentrations than did nonusers, and no seasonal differences were found. In nonsupplement users, the prevalence of 25(OH)D concentrations <50 nmol/L in winter was 37.2% overall and was 60.7% in nonwhites. CONCLUSIONS One-quarter of Canadians did not meet the RDA, but the use of vitamin D supplements contributed to a better 25(OH)D status. Nonwhite Canadians had the highest risk of not achieving DRI recommendations. More than one-third of Canadians not using supplements did not meet the RDA in winter. This suggests that current food choices alone are insufficient to maintain 25(OH)D concentrations of 50 nmol/L in many Canadians, especially in winter.

Health effects with consumption of the flax lignan secoisolariciresinol diglucoside.

Flaxseed is the richest source of the lignan secoisolariciresinol diglucoside (SDG). After ingestion, SDG is converted to secoisolariciresinol, which is further metabolised to the mammalian lignans enterodiol and enterolactone. A growing body of evidence suggests that SDG metabolites may provide health benefits due to their weak oestrogenic or anti-oestrogenic effects, antioxidant activity, ability to induce phase 2 proteins and/or inhibit the activity of certain enzymes, or by mechanisms yet unidentified. Human and animal studies identify the benefits of SDG consumption. SDG metabolites may protect against CVD and the metabolic syndrome by reducing lipid and glucose concentrations, lowering blood pressure, and decreasing oxidative stress and inflammation. Flax lignans may also reduce cancer risk by preventing pre-cancerous cellular changes and by reducing angiogenesis and metastasis. Thus, dietary SDG has the potential to decrease the incidence of several chronic diseases that result in significant morbidity and mortality in industrialised countries. The available literature, though, makes it difficult to clearly identify SDG health effects because of the wide variability in study methods. However, the current evidence suggests that a dose of at least 500 mg SDG/d for approximately 8 weeks is needed to observe positive effects on cardiovascular risk factors in human patients. Flaxseed and its lignan extracts appear to be safe for most adult populations, though animal studies suggest that pregnant women should limit their exposure. The present review discusses the potential health benefits of SDG in humans, with supporting evidence from animal studies, and offers suggestions for future research.

Despite mandatory fortification of staple foods, vitamin D intakes of Canadian children and adults are inadequate☆

Vitamin D is largely obtained through sun-induced skin synthesis and less from dietary sources, but during Canadian winters, skin synthesis is non-existent. The objective of this study was to estimate vitamin D intakes in Canadians from food sources. Data used in this study included food intakes of Canadians reported in the 2004 Canadian Community Health Survey Cycle 2.2 (CCHS 2.2), a nationally representative sample of 34,789 persons over the age of 1 year. The mean+/-SD dietary intake of vitamin D from food of Canadians was 5.8+/-0.1 microg/day, with males 9-18 years having the highest mean intakes (7.5+/-0.2 microg/day) and females 51-70 years having the lowest intakes (5.2+/-0.3 microg/day). Males in all age groups had higher intakes than females and White Canadians had higher vitamin D intakes than Non-Whites in most age sex groups. Milk products contributed 49% of dietary vitamin D followed by meat and meat-alternatives (31.1%). The majority of Canadians consume less than current recommended intake of vitamin D from food. Consideration should be given to strategies to improve vitamin D intake of Canadians by increasing both the amount of vitamin D added to foods and range of foods eligible for fortification.

Positive effects of vegetable and fruit consumption and calcium intake on bone mineral accrual in boys during growth from childhood to adolescence : the University of Saskatchewan Pediatric Bone Mineral Accrual Study

BACKGROUND Nutrition is an important modifiable factor in the development of bone mass during adolescence. Recent studies of children and adolescents examined the effects of foods such as milk products and fruit and vegetables on bone growth; however, few studies included both boys and girls. OBJECTIVE The purpose was to ascertain the role of consumption of milk products and vegetables and fruit in the accrual of total-body bone mineral content (TBBMC) in boys and girls from childhood to late adolescence. DESIGN Seven-year longitudinal data were obtained from 85 boys and 67 girls aged 8-20 y. Biological maturity was defined by the number of years from the age at peak height velocity. Dietary intake was assessed by serial 24-h recalls. Anthropometric measurements and physical activity were assessed every 6 mo. TBBMC assessed with dual-energy X-ray absorptiometry in the fall of each year was the indicator of bone mass. RESULTS Most boys (87.8%) met Canadian recommendations for milk product intake. Few subjects (<30%) consumed vegetables and fruit in recommended amounts. Using a multilevel modeling statistical approach containing important biological and environmental factors, we found that vegetable and fruit intakes, calcium intake, and physical activity were significant independent environmental predictors of TBBMC in boys but not in girls. CONCLUSIONS In addition to adequate dietary calcium intake, appropriate intakes of vegetables and fruit have a beneficial effect on TBBMC in boys aged 8-20 y. Underreporting of dietary intake by girls may explain why this effect was not apparent in girls.

Low wintertime vitamin D levels in a sample of healthy young adults of diverse ancestry living in the Toronto area: associations with vitamin D intake and skin pigmentation

BackgroundVitamin D plays a critical role in bone metabolism and many cellular and immunological processes. Recent research indicates that concentrations of serum 25-hydroxyvitamin D [25(OH)D], the main indicator of vitamin D status, should be in excess of 75 nmol/L. Low levels of 25(OH)D have been associated with several chronic and infectious diseases. Previous studies have reported that many otherwise healthy adults of European ancestry living in Canada have low vitamin D concentrations during the wintertime. However, those of non-European ancestry are at a higher risk of having low vitamin D levels. The main goal of this study was to examine the vitamin D status and vitamin D intake of young Canadian adults of diverse ancestry during the winter months.MethodsOne hundred and seven (107) healthy young adults self-reporting their ancestry were recruited for this study. Each participant was tested for serum 25(OH)D concentrations and related biochemistry, skin pigmentation indices and basic anthropometric measures. A seven-day food diary was used to assess their vitamin D intake. An ANOVA was used to test for significant differences in the variables among groups of different ancestry. Linear regression was employed to assess the impact of relevant variables on serum 25(OH)D concentrations.ResultsMore than 93% of the total sample had concentrations below 75 nmol/L. Almost three-quarters of the subjects had concentrations below 50 nmol/L. There were significant differences in serum 25(OH)D levels (p < 0.001) and vitamin D intake (p = 0.034) between population groups. Only the European group had a mean vitamin D intake exceeding the current Recommended Adequate Intake (RAI = 200 IU/day). Total vitamin D intake (from diet and supplements) was significantly associated with 25(OH)D levels (p < 0.001). Skin pigmentation, assessed by measuring skin melanin content, showed an inverse relationship with serum 25(OH)D (p = 0.033).ConclusionWe observe that low vitamin D levels are more prevalent in our sample of young healthy adults than previously reported, particularly amongst those of non-European ancestry. Major factors influencing 25(OH)D levels were vitamin D intake and skin pigmentation. These data suggest a need to increase vitamin D intake either through improved fortification and/or supplementation.

Dietary Protein, Phosphorus and Potassium Are Beneficial to Bone Mineral Density in Adult Men Consuming Adequate Dietary Calcium

Objective: The purpose of this study was to determine relationships of calcium (Ca), protein (Pr), phosphorus (P) and potassium (K) to measures of bone mineral density in adult men. Methods: Cross-sectional analysis of 57 men ages 39 to 42 years who were participants in an ongoing study. Dietary assessment was conducted using the Block food frequency questionnaire (FFQ). BMD of total body (TB), hip and lumbar spine (LS) were measured with dual X-ray absorptiometry (DXA). Results: Ca, Pr, P and K, as well as lean body mass (LBM), showed significant correlation with BMD at the total body, hip and lumbar spine. Stepwise forward regression selection method identified LBM, height and fat mass as significant predictors of TB-BMD, LBM and height as significant predictors of hip BMD, and LBM as a significant predictor of LS-BMD. As the nutrients tested correlated significantly with each other, only one nutrient was entered into the regression model at a time to accommodate the potential for multicollinearity. In regression analysis, adjusted for site-specific anthropometric variables and energy intake, K, Pr and P intake accounted for significant (p < 0.05) prediction of TB-BMD and LS-BMD values by 7% to 13%. No bone-related nutrient added significantly to the prediction of hip BMD. Ca intake was not significantly associated with BMD at any site in the adjusted models. Conclusions: Our analysis provides support that a moderate protein (1.2 g/kg) diet, plentiful in potassium (>100 mmol/day) and phosphorus (1741 ± 535 mg) is beneficial for maintaining bone mineral density in adult men when Ca intake was adequate (1200 ± 515 mg).

Relationship between carbonated and other low nutrient dense beverages and bone mineral content of adolescents

Abstract Low nutrient dense beverages such as carbonated drinks are increasing in the adolescents diet, and concern has been raised that these beverages, particularly colas, reduce bone mass. We determined whether the type of low nutrient dense beverage as well as the amount was related to bone mineral content and accumulation during the two years spanning the time of peak bone mass accrual in adolescence. Total body bone mineral content (BMC) and dietary intakes were obtained for 59 boys and 53 girls when each subject was ± one year of his or her measured age of peak rate of BMC. Consumption of low nutrient dense beverages was negatively related to BMC (r = −0.256, P=0.03) and accrual (r = −0.227, P=0.05) for adolescent girls but not boys. Milk beverage intake in both boys and girls was inversely related to low nutrient dense beverage consumption (r = −0.343, P=0.01; r=−0.244, P=0.08, respectively). Low nutrient dense beverage ingestion by adolescents appeared to reduce bone mineral accrual and BMC in teenage girls by replacing milk beverages.