Kyong Park

Dietary Supplements and Mortality Rate in Older Women: The Iowa Women's Health Study

BACKGROUND Although dietary supplements are commonly taken to prevent chronic disease, the long-term health consequences of many compounds are unknown. METHODS We assessed the use of vitamin and mineral supplements in relation to total mortality in 38,772 older women in the Iowa Womens Health Study; mean age was 61.6 years at baseline in 1986. Supplement use was self-reported in 1986, 1997, and 2004. Through December 31, 2008, a total of 15,594 deaths (40.2%) were identified through the State Health Registry of Iowa and the National Death Index. RESULTS In multivariable adjusted proportional hazards regression models, the use of multivitamins (hazard ratio, 1.06; 95% CI, 1.02-1.10; absolute risk increase, 2.4%), vitamin B(6) (1.10; 1.01-1.21; 4.1%), folic acid (1.15; 1.00-1.32; 5.9%), iron (1.10; 1.03-1.17; 3.9%), magnesium (1.08; 1.01-1.15; 3.6%), zinc (1.08; 1.01-1.15; 3.0%), and copper (1.45; 1.20-1.75; 18.0%) were associated with increased risk of total mortality when compared with corresponding nonuse. Use of calcium was inversely related (hazard ratio, 0.91; 95% confidence interval, 0.88-0.94; absolute risk reduction, 3.8%). Findings for iron and calcium were replicated in separate, shorter-term analyses (10-year, 6-year, and 4-year follow-up), each with approximately 15% of the original participants having died, starting in 1986, 1997, and 2004. CONCLUSIONS In older women, several commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk; this association is strongest with supplemental iron. In contrast to the findings of many studies, calcium is associated with decreased risk.

Dietary Supplements and Mortality Rate in Older Women

BACKGROUND Although dietary supplements are commonly taken to prevent chronic disease, the long-term health consequences of many compounds are unknown. METHODS We assessed the use of vitamin and mineral supplements in relation to total mortality in 38,772 older women in the Iowa Womens Health Study; mean age was 61.6 years at baseline in 1986. Supplement use was self-reported in 1986, 1997, and 2004. Through December 31, 2008, a total of 15,594 deaths (40.2%) were identified through the State Health Registry of Iowa and the National Death Index. RESULTS In multivariable adjusted proportional hazards regression models, the use of multivitamins (hazard ratio, 1.06; 95% CI, 1.02-1.10; absolute risk increase, 2.4%), vitamin B(6) (1.10; 1.01-1.21; 4.1%), folic acid (1.15; 1.00-1.32; 5.9%), iron (1.10; 1.03-1.17; 3.9%), magnesium (1.08; 1.01-1.15; 3.6%), zinc (1.08; 1.01-1.15; 3.0%), and copper (1.45; 1.20-1.75; 18.0%) were associated with increased risk of total mortality when compared with corresponding nonuse. Use of calcium was inversely related (hazard ratio, 0.91; 95% confidence interval, 0.88-0.94; absolute risk reduction, 3.8%). Findings for iron and calcium were replicated in separate, shorter-term analyses (10-year, 6-year, and 4-year follow-up), each with approximately 15% of the original participants having died, starting in 1986, 1997, and 2004. CONCLUSIONS In older women, several commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk; this association is strongest with supplemental iron. In contrast to the findings of many studies, calcium is associated with decreased risk.

Transition to Adulthood: Delays and Unmet Needs among Adolescents and Young Adults with Asthma

OBJECTIVE To examine the effect of the transition to adulthood on financial and non-financial barriers to care in youth with asthma. STUDY DESIGN With National Health Interview Survey data from 2000 to 2005, we examined delays and unmet needs because of financial and non-financial barriers, evaluating the effect of adolescent (age, 12-17 years; n = 1539) versus young adult age (age, 18-24 years; N = 833), controlling for insurance, usual source of care, and sociodemographic characteristics. We also simulated the effects of providing public insurance to uninsured patients and a usual source of care to patients without one. RESULTS More young adults than adolescents encountered financial barriers resulting in delays (18.6% versus 8%, P < .05) and unmet needs (26.6% versus 11.4%, P < .05), although delays caused by non-financial barriers were similar (17.3% versus 14.9%, P = not significant). In logistic models young adults were more likely than adolescents to report delays (odds ratio [OR], 1.45; 95% CI, 1.02-2.08) and unmet needs (OR, 1.8; 95% CI, 1.29-2.52) caused by financial barriers. CONCLUSIONS Delays and unmet needs for care caused by financial reasons are significantly higher for young adults than they are for adolescents with asthma.

Oxidative Stress and Insulin Resistance The Coronary Artery Risk Development in Young Adults study

OBJECTIVE Although cumulative evidence suggests that increased oxidative stress may lead to insulin resistance in vivo or in vitro, community-based studies are scarce. This study examined the longitudinal relationships of oxidative stress biomarkers with the development of insulin resistance and whether these relationships were independent of obesity in nondiabetic young adults. RESEARCH DESIGN AND METHODS Biomarkers of oxidative stress (F2-isoprostanes [F2Isop] and oxidized LDL [oxLDL]), insulin resistance (the homeostasis model assessment of insulin resistance [HOMA-IR]), and various fatness measures (BMI, waist circumference, and estimated percent fat) were obtained in a population-based observational study (Coronary Artery Risk Development in Young Adults) and its ancillary study (Young Adult Longitudinal Trends in Antioxidants) during 2000–2006. RESULTS There were substantial increases in estimated mean HOMA-IR over time. OxLDL and F2Isop showed little association with each other. Mean evolving HOMA-IR increased with increasing levels of oxidative stress markers (P < 0.001 for oxLDL and P = 0.06 for F2Isop), measured in 2000–2001. After additional adjustment for adiposity, a positive association between oxLDL and HOMA-IR was strongly evident, whereas the association between F2Isop and HOMA-IR was not. CONCLUSIONS We observed positive associations between each of two oxidative stress markers and insulin resistance. The association with oxidized LDL was independent of obesity, but that with F2Isop was not.

Household food insecurity is a risk factor for iron-deficiency anaemia in a multi-ethnic, low-income sample of infants and toddlers.

OBJECTIVE The present study examines the relationships of household food security status with Fe deficiency (ID) and Fe-deficiency anaemia (IDA) among children less than 3 years of age, and associated factors that contribute to ID and IDA. DESIGN Cross-sectional study and chart review. The US Food Security Survey Module was administered to adult caregivers as part of the Childrens Sentinel Nutrition Assessment Project (C-SNAP). Haematological data were obtained from medical records. SETTING A large metropolitan medical centre in Minneapolis, Minnesota, USA. SUBJECTS A multi-ethnic sample of 2853 low-income children aged <36 months who received care at the medical centre. RESULTS Among the caregivers, 23.3 % reported low household food security and 11.6 % reported very low household food security (VLFS). After controlling for background factors, children from households with VLFS were almost twice as likely to have IDA than were children from households with high or marginal food security (OR = 1.98, 95 % CI 1.11, 3.53); the corresponding associations for ID were not statistically significant. CONCLUSIONS The prevalence of IDA in early childhood is significantly larger in low-income infants and toddlers living in VLFS households. Asian, Hispanic and African-American children have elevated prevalences of ID and IDA. Breast-feeding may be associated with elevated ID and IDA, while participation in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) may be protective for ID.

Toenail Selenium and Incidence of Type 2 Diabetes in U.S. Men and Women

OBJECTIVE Compelling biological pathways suggest that selenium (Se) may lower onset of type 2 diabetes mellitus (T2DM), but very few studies have evaluated this relationship, with mixed results. We examined the association between toenail Se and incidence of T2DM. RESEARCH DESIGN AND METHODS We performed prospective analyses in two separate U.S. cohorts, including 3,630 women and 3,535 men, who were free of prevalent T2DM and heart disease at baseline in 1982–1983 and 1986–1987, respectively. Toenail Se concentration was quantified using neutron activation analysis, and diabetes cases were identified by biennial questionnaires and confirmed by a detailed supplementary questionnaire. Hazard ratios of incident T2DM according to Se levels were calculated using Cox proportional hazards. RESULTS During 142,550 person-years of follow-up through 2008, 780 cases of incident T2DM occurred. After multivariable adjustment, the risk of T2DM was lower across increasing quintiles of Se, with pooled relative risks across the two cohorts of 1.0 (reference), 0.91 (95% CI 0.73–1.14), 0.78 (0.62–0.99), 0.72 (0.57–0.91), and 0.76 (0.60–0.97), respectively (P for trend = 0.01). Results were similar excluding the few individuals (4%) who used Se supplements. In semiparametric analyses, the inverse relationship between Se levels and T2DM risk appeared to be linear. CONCLUSIONS At dietary levels of intake, individuals with higher toenail Se levels are at lower risk for T2DM. Further research is required to determine whether varying results in this study versus prior trials relate to differences in dose, source, statistical power, residual confounding factors, or underlying population risk.

Omega-3 Fatty Acids, Mercury, and Selenium in Fish and the Risk of Cardiovascular Diseases

Fish consumption is associated with lower risk of cardiovascular disease. Some fish species also contain methylmercury, which may increase cardiovascular risk, as well as selenium, a trace element that could counter the effects of methylmercury or have beneficial effects itself. These potentially conflicting effects have created public confusion about the risks and benefits of fish consumption in adults. We examined the evidence for cardiovascular effects of fish consumption, particularly effects of marine omega-3 fatty acids, methylmercury, and selenium. Compelling evidence indicates that modest fish consumption substantially reduces cardiovascular risk, in particular cardiac mortality, related at least partly to benefits of omega-3 fatty acids. In contrast, observational studies and (for selenium) clinical trials demonstrate mixed and inconclusive results for cardiovascular effects of methylmercury and selenium. Net health benefits of overall fish consumption in adults are clear. Quantitative risk-benefit analyses of cardiovascular effects of consuming specific fish species, based on joint contents of fatty acids, methylmercury, and selenium, cannot currently be performed until the cardiovascular effects of methylmercury and selenium are established.

Instant coffee consumption may be associated with higher risk of metabolic syndrome in Korean adults.

AIMS Cumulative evidence suggests that coffee consumption may have beneficial effects on metabolic diseases; however, few previous studies have considered the types of coffee consumed and the additives used. We investigated the relationship between coffee consumption and metabolic syndrome (MetSyn) and its components. METHODS We analyzed 17,953 Korean adults, aged 19-65 years, using cross-sectional data from the Korean National Health and Nutrition Examination Survey (KNHANES, 2007-2011). Coffee consumption level, types of coffee consumed, and the additives used were assessed based on a food frequency questionnaire and 24-h recall. Demographic and lifestyle factors were assessed using self-administered questionnaires. Data on metabolic biomarkers were obtained from a health examination. Multivariable logistic regression was used to determine the odds ratios of prevalent metabolic syndrome and its components according to frequency and type of coffee consumption. RESULTS We found that 76% of the subjects were habitual coffee drinkers, most of whom consumed instant coffee mix containing sugar and powder creamer. After multivariable adjustment, the odds ratios (95% CI) comparing those who consumed coffee ≥3 times/day with those who consumed coffee <1 time/week were 1.37 (1.15-1.63) for obesity, 1.33 (1.11-1.59) for abdominal obesity, 1.28 (1.09-1.51) for hypo-HDL cholesterolemia, and 1.37 (1.10-1.72) for metabolic syndrome. Instant-coffee drinkers were observed to have elevated risks of these metabolic conditions. CONCLUSIONS Consumption of coffee, particularly instant coffee mix, may have harmful effects on MetSyn, perhaps partly deriving from excessive intake of sugar and powder creamer.

Menarche and assessment of body mass index in adolescent girls.

OBJECTIVES To determine whether menarcheal status in individual girls biases assessments of overweight and obesity when using body mass index (BMI) criteria from age-based reference data. STUDY DESIGN Data were analyzed for 2145 girls aged 8.00 to 16.99 years was examined from 1999 to 2002 as part of the National Health and Nutrition Examination Survey (NHANES). RESULTS An estimate of the menarche-related effect on BMI assessment at each age was calculated as K = (m-M)beta, in which m = the menarcheal status of a girl (0,1); M = the prevalence of menarcheal status; and beta = the regression coefficient of BMI on m. At levels of BMI near the percentile cutoff points defining overweight and obesity (85th, 95th) the prevalence of menarcheal status is higher and the BMI differences between menarcheal and premenarcheal girls (beta) are smaller than those observed when all girls are considered. The average effects on BMI of menarche that occurs earlier than the population mean age or of menarche that occurs later than the population mean age generally are <or= +/- 1.00 kg/m(2) for individual girls whose BMI is near the cutoff values defining overweight and obesity. CONCLUSION The average effects of menarcheal status on BMI assessments of overweight and obesity are small and usually should not be clinically important.

Demographic and lifestyle factors and selenium levels in men and women in the U.S.

Selenium is an antioxidant trace element linked to cardiovascular disease and cancer. Although diet is a major source, relatively little else is known about independent determinants of selenium levels in free-living humans. In this study, we aimed to investigate the independent demographic, lifestyle, and dietary determinants of selenium levels in 1,997 men and 1,905 women in two large prospective U.S. cohorts. Toenail selenium levels were quantified using neutron activation analysis. Diet, geographic residence, demographic, and environmental factors were assessed by validated self-administered questionnaires. Multivariate generalized linear models were conducted to assess the independent relations of these factors with toenail selenium levels, correcting for measurement error in the diet. In multivariable-adjusted analyses, independent predictors of higher selenium were male gender (6.3% higher levels); living in West and Northern-Midwest U.S. regions (8.9% and 7.4% higher than Southern-Midwest regions, respectively); consumption of beef and bread products (between 0.7 - 2.5% higher per daily serving); and selenium supplement use (6.9% higher than non-users); whereas cigarette smoking (5-10% lower than never smokers) , older age (0.6% lower per 5 years), and consumption of eggs, white rice, dairy products, coffee, and alcohol (between 0.1 to 2.0% lower per daily serving) were associated with lower selenium. Multiple dietary and non-dietary factors independently predicted selenium levels, suggesting that both consumption and non-dietary processes (e.g., related to oxidant status) may affect levels. Significant geographic variation in selenium levels exists in the US.