Kaye E. Brock

Low vitamin D status is associated with physical inactivity, obesity and low vitamin D intake in a large US sample of healthy middle-aged men and women

The aim of this study was to investigate modifiable predictors of vitamin D status in healthy individuals, aged 55-74, and living across the USA. Vitamin D status [serum 25-hydroxyvitamin D (25(OH)D)] was measured along with age and season at blood collection, demographics, anthropometry, physical activity (PA), diet, and other lifestyle factors in 1357 male and 1264 female controls selected from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) cohort. Multivariate linear and logistic regression analyses were used to identify associations with vitamin D status. Three%, 29% and 79% of the population had serum 25(OH)D levels<25, <50 and <80 nmol/L, respectively. The major modifiable predictors of low vitamin D status were low vitamin D dietary and supplement intake, body mass index (BMI) >30 kg/m2, physical inactivity (PA) and low milk and calcium supplement intake. In men, 25(OH)D was determined more by milk intake on cereal and in women, by vitamin D and calcium supplement and menopausal hormone therapy (MHT) use. Thus targeting an increase in vigorous activity and vitamin D and calcium intake and decreasing obesity could be public health interventions independent of sun exposure to improve vitamin D status in middle-aged Americans.

Food, activity and family--environmental vs biochemical predictors of weight gain in children.

Objective: To identify whether measures of energy intake and expenditure predict excessive weight gain over time in children and to describe how these measures relate to similar measures in parents.Design: Prospective, descriptive study over 12 months with no intervention.Setting: University teaching hospital.Subjects: Children aged between 6.0 and 9.0 y. Recruitment was through advertisement. A total of 59 children (30 F), 41 mothers and 29 fathers. In all, 41 (69%) of the children were reviewed at 12 months (20 F).Results: No significant correlations were identified between body mass index (BMI) z-score change in children over 12 months for any dietary variable or for any measures of energy expenditure, including hours of television viewing or percent time spent in low-, moderate- or high-intensity activity. The BMI z-score change over 12 months was significantly correlated with LDL cholesterol and Apo B/ApoA-1 ratio, independent of percent body fat (r=0.45, P=0.01; r=0.37, P=0.03). A significant positive correlation was found for mothers and girls for percent time in moderate to high activity (r=0.44, P=0.03) and between fathers and children for percent time spent in low activity (r=0.43, P=0.005).Conclusions: The study has been unable to identify environmental predictors that indicate propensity to faster weight gain over time in this cohort of children, but has extended the evidence on lifestyle-influenced biochemical predictors that do. An overall lack of vigorous activity in this age group, and correlations between parental and child activity and inactivity have been identified.Sponsorship: The Australian Rotary Health Foundation, The Financial Markets Foundation for Children, The National Health and Medical Research Council.

Evidence for a Specific Uptake and retention Mechanism for 25- Hydroxyvitamin D (25OHD) in skeletal Muscle Cells

Little is known about the mechanism for the prolonged residence time of 25-hydroxyvitamin D (25OHD) in blood. Several lines of evidence led us to propose that skeletal muscle could function as the site of an extravascular pool of 25OHD. In vitro studies investigated the capacity of differentiated C2 murine muscle cells to take up and release 25OHD, in comparison with other cell types and the involvement of the membrane protein megalin in these mechanisms. When C2 cells are differentiated into myotubes, the time-dependent uptake of labeled 25OHD is 2-3 times higher than in undifferentiated myoblasts or nonmuscle osteoblastic MG63 cells (P < .001). During in vitro release experiments (after 25OHD uptake), myotubes released only 32% ± 6% stored 25OHD after 4 hours, whereas this figure was 60% ± 2% for osteoblasts (P < .01). Using immunofluorescence, C2 myotubes and primary rat muscle fibers were, for the first time, shown to express megalin and cubilin, endocytotic receptors for the vitamin D binding protein (DBP), which binds nearly all 25OHD in the blood. DBP has a high affinity for actin in skeletal muscle. A time-dependent uptake of Alexafluor-488-labeled DBP into mature muscle cells was observed by confocal microscopy. Incubation of C2 myotubes (for 24 hours) with receptor-associated protein, a megalin inhibitor, led to a 40% decrease in 25OHD uptake (P < .01). These data support the proposal that 25OHD, after uptake into mature muscle cells, is held there by DBP, which has been internalized via membrane megalin and is retained by binding to actin.

Effects of diet and exercise on plasma vitamin D (25(OH)D) levels in Vietnamese immigrant elderly in Sydney, Australia

Vitamin D deficiency may be associated with osteoporosis and fractures in the elderly. In Australia where there is a sizeable Vietnamese population, research has not yet clarified the roles of diet, exercise and sun exposure in determining vitamin D status. Plasma samples for 25-hydroxy-vitamin D (25(OH)D); dietary intake of vitamin D and calcium; muscle strength and sun exposure were measured and weekly dairy intake, exercise levels and smoking habits were surveyed in free-living elderly of Vietnamese and Australian/British origin. There was marginal vitamin D deficiency (<37 nmol/L 25(OH)D) in 63% of Vietnamese but only in 37% of Australian/British born. Low dairy intake and no vigorous exercise were best predictors of vitamin D deficiency in Vietnamese, taking into account age, gender, dietary intake and sun exposure. Since these migrant elderly may not get adequate sun exposure due to either clothing customs or cultural norms that encourage fair (untanned) skin, it is important to encourage increased exercise and dairy intake.

Predictors of vitamin D biochemical status in a large sample of middle-aged male smokers in Finland

Background/Objectives:As vitamin D deficiency is considered to be more common in regions with little solar ultraviolet (UV) light in winter, the aim of this study was to analyze predictors of vitamin D status by season within a large sample of male smokers from Finland, a country where there is negligible solar UV light in winter.Subjects/Methods:Vitamin D (measured by 25-hydroxyvitamin D (25(OH)D) nmol/l) and other serum constituents were assayed. Measured anthropometry, and self-reported dietary intake and physical activity (PA) were obtained and analyzed using stepwise multiple linear and logistic regression in 2271 middle-aged Finnish male smokers.Results:In all, 27% of the population in winter and 17% in summer had serum 25(OH)D levels of <25 nmol/l, respectively. In summer, in multiple logistic regression analyses with adjustment for confounding and other predictors, high vitamin D intake (odds ratios (OR) 3.6; 95% confidence interval (CI) 1.5–8.5), some leisure time PA (OR 2.0; 95% CI 1.3–3.1) and having a body mass index (BMI) of ⩾21 kg/m2 compared with <21 kg/m2 (OR 2.6; 95% CI 1.3–5.0), were associated with 25(OH)D ⩾25 nmol/l. In winter, additional modifiable factors were occupational PA (OR 1.6; 95% CI 1.1–2.5) and high fish (OR 3.1; 95% CI 1.7–6.2) or poultry consumption (OR 1.7; 95% CI 1.2–2.5). Predictors from linear regression analyses of continuous levels of 25(OH)D were similar to the logistic regression analyses of 25(OH)D ⩾25 nmol/l.Conclusion:In this Finnish sample more vitamin D intake, PA and having a BMI of ⩾21 may have important modifiable roles in maintaining an adequate vitamin D status.

The Relationship Between Obesity and Blood Pressure Differs by Ethnicity in Sydney School Children

BACKGROUND The objective of this study was to investigate the relationship between obesity and high systolic blood pressure (SBP) in Southeast Asian (SEAsian) and Australian children living in Australia. METHODS SBP, country of birth, and obesity indices (body mass index (BMI), waist circumference (WC), and percent body fat (%TBF)) were recorded in 1,232 9-year-old children from Sydney schools and remeasured 3 years later (n = 628). The relationship between SBP and obesity (both at baseline and longitudinally) was investigated by regression analyses. RESULTS Children of SEAsian origin had a significantly higher risk of high SBP with increases in obesity indices compared to those of Australian origin. At 9 years old, SBP increased 1.51 mm Hg for each of BMI increase for SEAsian children compared to 1.05 mm Hg for Australian children (P(interaction) = 0.03). These same significant analysis of variance (ANOVA) interactions were seen with WC (P(interaction) = 0.02) and %TBF (P(interaction) = 0.04) as predictors of SBP. These differences by ethnic background were also reflected in the 3-year longitudinal analysis where SEAsian children showed higher risk of increasing SBP with BMI increase (SBP increased 1.70 mm Hg for each unit of BMI increase for SEAsian children compared to 0.80 mm Hg for Australian children (P(interaction) = 0.02)) or with WC increase (P(interaction) = 0.01), whereas these increases were small and nonsignificant in Australian children. CONCLUSION These findings suggest that SEAsian children living in Australia are at higher risk of increasing SBP than their Australian counterparts when they become overweight or obese.

Diabetes prevalence is associated with serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D in US middle-aged Caucasian men and women: a cross-sectional analysis within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

Hypovitaminosis D may be associated with diabetes, hypertension and CHD. However, because studies examining the associations of all three chronic conditions with circulating 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) are limited, we examined these associations in the US Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial (n 2465). Caucasian PLCO participants selected as controls in previous nested case-control studies of 25(OH)D and 1,25(OH)(2)D were included in this analysis. Diabetes, CHD and hypertension prevalence, risk factors for these conditions and intake of vitamin D and Ca were collected from a baseline questionnaire. Results indicated that serum levels of 25(OH)D were low (< 50 nmol/l) in 29 % and very low (< 37 nmol/l) in 11 % of subjects. The prevalence of diabetes, hypertension and CHD was 7, 30 and 10 %, respectively. After adjustment for confounding by sex, geographical location, educational level, smoking history, BMI, physical activity, total dietary energy and vitamin D and Ca intake, only diabetes was significantly associated with lower 25(OH)D and 1,25(OH)(2)D levels. Caucasians who had 25(OH)D ≥ 80 nmol/l were half as likely to have diabetes (OR 0·5 (95 % CI 0·3, 0·9)) compared with those who had 25(OH)D < 37 nmol/l. Those in the highest quartile of 1,25(OH)(2)D (≥ 103 pmol/l) were less than half as likely to have diabetes (OR 0·3 (95 % CI 0·1, 0·7)) than those in the lowest quartile (< 72 pmol/l). In conclusion, the independent associations of 25(OH)D and 1,25(OH)(2)D with diabetes prevalence in a large population are new findings, and thus warrant confirmation in larger, prospective studies.

Reproductive health and access to healthcare facilities: risk factors for depression and anxiety in women with an earthquake experience

BackgroundThe reproductive and mental health of women contributes significantly to their overall well-being. Three of the eight Millennium Development Goals are directly related to reproductive and sexual health while mental disorders make up three of the ten leading causes of disease burden in low and middle-income countries. Among mental disorders, depression and anxiety are two of the most prevalent. In the context of slower progress in achieving Millennium Development Goals in developing countries and the ever-increasing man-made and natural disasters in these areas, it is important to understand the association between reproductive health and mental health among women with post-disaster experiences.MethodsThis was a cross-sectional study with a sample of 387 women of reproductive age (15-49 years) randomly selected from the October 2005 earthquake affected areas of Pakistan. Data on reproductive health was collected using the Centers for Disease Control reproductive health assessment toolkit. Depression and anxiety were measured using the Hopkins Symptom Checklist-25, while earthquake experiences were captured using the Harvard Trauma Questionnaire. The association of either depression or anxiety with socio-demographic variables, earthquake experiences, reproductive health and access to health facilities was estimated using multivariate logistic regression.ResultsPost-earthquake reproductive health events together with economic deprivation, lower family support and poorer access to health care facilities explained a significant proportion of differences in the experiencing of clinical levels of depression and anxiety. For instance, women losing resources for subsistence, separation from family and experiencing reproductive health events such as having a stillbirth, having had an abortion, having had abnormal vaginal discharge or having had genital ulcers, were at significant risk of depression and anxiety.ConclusionThe relationship between womens post-earthquake mental health and reproductive health, socio-economic status, and health care access is complex and explained largely by the socio-cultural role of women. It is suggested that interventions that consider gender differences and that are culturally appropriate are likely to reduce the incidence.

Culture and sun exposure in immigrant East Asian women living in Australia

In this qualitative study, researchers examined cultural and attitudinal factors that might be related to sun-exposure behaviors among East Asian women living in Australia. Researchers asked Chinese (n = 20) and Korean (n = 16) immigrant women who participated in a larger cross-sectional quantitative study of vitamin D blood levels to volunteer to participate in an in-depth interview in 2010. These women reported a number of cultural factors related to their attitudes and behaviors with regard to sun exposure. They expressed preference for fair skin, a tradition of covering skin when outdoors, and no sunbathing culture. They believed that fair skin was more beautiful than tanned skin. They reported that beauty was the reason for active avoidance of sunlight exposure. Although they reported knowledge of the need for sun avoidance due to skin cancer risk, few reported knowledge about the benefits of sun exposure for adequate vitamin D levels. These findings may provide some reasons for vitamin D deficiency previously reported in these populations. Thus, researchers recommend that these attitudes of excessive sun protection and limiting sun exposure be further investigated as they may have implications for planning and delivery of health promotion programs to this growing population of immigrants in Australia.

Prevalence, Awareness, Treatment and Control of Hypertension in Macau: Results From a Cross-Sectional Epidemiological Study in Macau, China

BACKGROUND Awareness of hypertension, as well as its prevalence, treatment, and control status, has not been comprehensively investigated in Macau Special Administrative Region (SAR), China. METHODS A survey was conducted on a randomly sampled population of 1,410 participants (n = 638 men) aged 18-93 years in 2012. Blood pressure was individually measured twice. Awareness, treatment, and control of hypertension were assessed by interview-administered questionnaire. RESULTS Prevalence of hypertension was 34% in Macau, similar to the United States (30%) and United Kingdom (31%). Among hypertensives, 69% were aware of their condition, 59% were treated, and 30% were adequately controlled. Older age (≥50 years; odds ratio (OR) = 5.3; 95% confidence interval (CI) = 4.6-6.1), being of the male sex (OR = 2.2; 95% CI = 1.9-2.5), having retired (OR = 2.0; 95% CI = 1.8-2.3), being married (OR = 1.5; 95% CI = 1.3-1.9), having a low level of education in women (OR = 1.5; 95% CI = 1.1-2.1), Pinteraction = 0.01), and lack of salt awareness (OR = 1.1; 95% CI = 1.0-1.3) were associated with hypertension. Older age, having retired, and being married were also associated with higher awareness and treatment rates. Those who were older and married were better controlled. These demographic factors differed by sex. Those who had some knowledge of salt intake were more likely to have higher hypertension awareness, treatment, and control rates. CONCLUSIONS The prevalence of hypertension in Macau in 2012 has increased compared with 2006 (28%) and is comparable with prevalence rates in developed countries. Specific health promotion campaigns related to knowledge of risk factors such as salt intake and smoking may be useful for hypertension prevention and to improve hypertension awareness, treatment, and control rates.