Marilyn Tseng

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.

Prevalence and correlates of vitamin D status in African American men

BackgroundFew studies have examined vitamin D insufficiency in African American men although they are at very high risk. We examined the prevalence and correlates of vitamin D insufficiency among African American men in Philadelphia.MethodsParticipants in this cross-sectional analysis were 194 African American men in the Philadelphia region who were enrolled in a risk assessment program for prostate cancer from 10/96–10/07. All participants completed diet and health history questionnaires and provided plasma samples, which were assessed for 25-hydroxyvitamin D (25(OH)D) concentrations. We used linear regression models to examine associations with 25(OH)D concentrations and logistic regression to estimate odds ratios (OR) for having 25(OH)D ≥ 15 ng/mL.ResultsMean 25(OH)D was 13.7 ng/mL, and 61% of men were classified as having vitamin D insufficiency (25(OH)D <15 ng/mL). Even among men with vitamin D intake ≥ 400 IU/day, 55% had 25(OH)D concentrations <15 ng/mL. In multivariate models, 25(OH)D concentrations were significantly associated with supplemental vitamin D intake (OR 4.3, 95% confidence interval (CI) 1.5, 12.4) for >400 vs. 0 IU/day), milk consumption (OR 5.9, 95% CI 2.2, 16.0 for ≥ 3.5 vs. <1 time per week), and blood collection in the summer. Additionally, 25(OH)D concentrations increased with more recreational physical activity (OR 1.3, 95% CI 1.1, 1.6 per hour). A significant inverse association of body mass index with 25(OH)D concentrations in bivariate analyses was attenuated with adjustment for season of blood collection.ConclusionThe problem of low vitamin D status in African American men may be more severe than previously reported. Future efforts to increase vitamin D recommendations and intake, such as through supplementation, are warranted to improve vitamin D status in this particularly vulnerable population.

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.

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.

Stress Is Associated with Unfavorable Patterns of Dietary Intake among Female Chinese Immigrants

BackgroundChinese immigrants experience increased risk for weight gain and chronic disease after US migration. Whether psychosocial stress affects their eating behavior is unknown.PurposeThe purpose of this study is to examine psychosocial stress and dietary intake among 426 Chinese immigrant women in the Philadelphia region.MethodsParticipants completed 4xa0days of dietary recalls and questionnaires assessing positive and negative life events in the past year and migration-related stressors.ResultsIn hierarchical linear regression models, positive life events were associated with higher energy intake (βu2009=u200921.1, pu2009=u20090.04). Migration-related stress was associated with lower total gram (βu2009=u2009−11.3, pu2009<u20090.0001) and overall grain (βu2009=u2009−0.18, pu2009=u20090.03) intake and higher energy density (βu2009=u20090.002, pu2009=u20090.04) and percent energy from fat (βu2009=u20090.06, pu2009=u20090.05).ConclusionsMigration-related stress did not increase overall intake in terms of energy and total grams but selectively increased fat intake and energy density. Such dietary habits may have implications for future chronic disease risk in this immigrant population.

Adolescent Lifestyle Factors and Adult Breast Density in U.S. Chinese Immigrant Women

We examined recalled measures of adolescent diet, physical activity, and body size in relation to adult breast density in 201 U.S. Chinese immigrant women recruited in January 2002 to May 2003 from Philadelphia region screening programs. Mammographic images were classified into 1 of 4 categories ranging from “entirely fatty” to “extremely dense.” Questionnaires assessed diet and physical activity between ages 12–17, relative weight and height at age 10, and weight at age 18. To estimate odds ratios (ORs), we conducted logistic regression analyses using proportional odds models for polychotomous outcomes. Higher adult breast density was significantly associated with adolescent red meat intake (adjusted 3rd vs. 1st tertile OR = 3.0, 95% confidence interval (CI) 1.5–6.4, trend P = 0.003) but not with other adolescent factors. For the association of adult acculturation with breast density, adjustment for adolescent red meat intake attenuated the OR for the highest vs. lowest level of acculturation from 2.5 (95% CI 1.2–5.3) to 1.9 (95% CI 0.9–4.0). Greater adolescent red meat intake may have increased adult breast density and partly accounted for the strong association between acculturation and breast density in this sample of immigrant Chinese women. If confirmed by further study, dietary prevention efforts for breast cancer should be considered earlier in life.

Adiposity, adult weight gain and mammographic breast density in US Chinese women

The association of adiposity with dense tissue area in the breast is unclear, but suggests a mechanism by which adiposity might increase breast cancer risk. We examined associations of body mass index (BMI), usual BMI from age 20 to 29, waist circumference and adult weight gain with breast density in a sample of premenopausal United States Chinese immigrant women. Analyses included 415 participants in a longitudinal breast density study in Philadelphia. In addition to detailed questionnaire information, data collection included measures of anthropometry, and assessment of mammographic breast density using a computer‐assisted method. We used multivariate linear regression to quantify cross‐sectional associations with dense and nondense tissue area and percent breast density assessed at baseline. In adjusted models, BMI and waist circumference were significantly positively associated with nondense tissue area and inversely associated with percent density. BMI was also significantly positively associated with dense tissue area. Adult weight gain was associated with dense tissue area after adjusting for weight from age 20 to 29. In stratified analyses, BMI and adult weight gain were significantly associated with dense tissue area among women with BMI < 23 kg/m2, and BMI was associated with nondense tissue area among women with BMI ≥ 23 kg/m2. In this sample, adiposity and weight gain were associated with dense breast tissue area, although associations differed by level of adiposity. Given the potential implications of these findings for breast cancer prevention in premenopausal women, comparable studies in other population groups and with longitudinal data are needed. Reasons for the noted differences in associations by level of adiposity also warrant further investigation.

Dairy Intake and 1,25-dihydroxyvitamin D Levels in Men at High Risk for Prostate Cancer

ObjectiveDairy food intake has been associated with prostate cancer in previous work, but the mechanism by which this occurs is unknown. Dairy calcium may suppress circulating levels of potentially cancer-protective 1,25-hydroxyvitamin D (1,25(OH)2D). We examined the associations of dairy, milk, calcium, and vitamin D intake with plasma 1,25(OH)2D levels among 296 men (194 black, 102 non-black) enrolled in a high risk program for prostate cancer from 10/96 to 10/07.MethodsAll participants completed diet and health history questionnaires and provided plasma samples, which were assessed for levels of 25-hydroxyvitamin D and 1,25(OH)2D. We used multivariate linear regression to examine associations with 1,25(OH)2D.ResultsAfter adjustment for age, race, energy intake, BMI, and alcohol intake, we observed no associations for any of our variables of interest with 1,25(OH)2D, or any meaningful differences in estimates by race or vitamin D status.ConclusionOur findings, in a sample including a large proportion of black participants, do not confirm previous findings showing an inverse association between calcium intake and 1,25(OH)2D levels. As such, they suggest that future work should explore other mechanisms by which dairy foods and calcium might increase prostate cancer risk.

Acculturation and dietary change among Chinese immigrant women in the United States

US Chinese immigrants undergo a transition to increased chronic disease risk commonly attributed to acculturative and dietary changes. Longitudinal data to confirm this are lacking. We examined acculturation and diet over time in 312 Chinese immigrant women in Philadelphia, recruited October 2005 to April 2008 and followed with interviews and dietary recalls until April 2010. Associations were modeled using generalized estimating equations to account for repeated measures over time. Increasing length of US residence was associated with a small (~1xa0%/year) but significant increase in acculturation score (pxa0<xa00.0001), which in turn was significantly associated with increased energy density of the diet, percent of energy from fat, and sugar intake, and lower dietary moderation score. These findings provide longitudinal evidence that acculturation increases with length of US residence and is accompanied by dietary changes. However, the changes were small enough that their health impact is unclear. Factors besides acculturation that affect immigrant health and that affect the acculturation trajectory itself warrant investigation.

Vitamin D status is associated with sun exposure, vitamin D and calcium intake, acculturation and attitudes in immigrant East Asian women living in Sydney

Known determinants of vitamin D status (measured in serum as 25(OH)Dnmol/L) are exposure to sunlight and intake of vitamin D, either from foods or vitamin supplements. Recently, low vitamin D status in East Asian Australian immigrants has been reported. Thus the aim of this study was to investigate associations with vitamin D status in East Asian Australian immigrant women. In this cross-sectional study of women (n=152 aged 18-92), 25(OH)D levels were measured from serum samples (radio-immuno assay). Demographics, sun exposure patterns, dietary intake and acculturation factors were obtained by questionnaire. In spring, 53% of the study population had serum 25(OH)D levels <50nmol/L (deficiency); whereas in summer only 19% were deficient. Associations with vitamin D deficiency were younger age, higher education, more sun protection behavior, fewer minutes of sun exposure on weekends, low vitamin D and calcium intake through foods or supplements and less acculturation to Australian lifestyle. After multivariate adjustment, those who had no intake of vitamin D supplements (OR=5.6, CI=1.4-22), less sunlight exposure on weekends (OR=2.7, CI=1.0-7.3) and lower acculturation to Australian lifestyle (OR=2.5, CI=1.0-6.3) had increased risk of being deficient in vitamin D. Thus there is a need for vitamin D education in this at-risk population. This article is part of a Special Issue entitled Vitamin D Workshop.