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Biomedical subjects

James R Hebert

Publications and source records attributed to James R Hebert.

At least 19 recordsLinked to original sources

Racial disparities in colon cancer. Primary care endoscopy as a tool to increase screening rates among minority patients.

Colon cancer is a condition whose far-reaching effects have been well documented nationally and within the state of South Carolina. Fortunately, the disease is amenable to both primary and secondary prevention through screening colonoscopy. Despite the conceptual simplicity of recommending colonoscopy, barriers exist to universal (or even widespread) screening. Currently the infrastructure necessary to achieve screening goals set by the American Cancer Society (ACS), the American College of Gastroenterology (ACG), and the South Carolina Department of Health and Environmental Control (DHEC) has not been established. At current rates of training gastroenterologists, the medical community will not be able to come close to achieving widespread screening. Given the discrepancy between the public health benefit of achieving the goals and the deaths that have occurred because of the resource shortfall, we propose alternative measures to screen the at-risk population for consideration. This need is most acute in the black community, in which where screening rates tend to be lower and polyps have been found to progress more quickly than among white populations. In South Carolina, one model has used primary care physicians as the labor force to provide routine screening colonoscopy for their own patients. This model makes screening much more accessible to minority patients, as the wait is shorter and the cost typically lower. In combination with a faith-based partnership with minority religious organizations, this model has begun to make needed inroads toward addressing the disparities associated with colon cancer. Cancer 2007. (c) 2006 American Cancer Society.

Colonic Neoplasms↗

Methodology for adding glycemic index and glycemic load values to 24-hour dietary recall database.

OBJECTIVES: We describe a method of adding the glycemic index (GI) and glycemic load (GL) values to the nutrient database of the 24-hour dietary recall interview (24HR), a widely used dietary assessment. We also calculated daily GI and GL values from the 24HR. METHODS: Subjects were 641 healthy adults from central Massachusetts who completed 9067 24HRs. The 24HR-derived food data were matched to the International Table of Glycemic Index and Glycemic Load Values. The GI values for specific foods not in the table were estimated against similar foods according to physical and chemical factors that determine GI. Mixed foods were disaggregated into individual ingredients. RESULTS: Of 1261 carbohydrate-containing foods in the database, GI values of 602 foods were obtained from a direct match (47.7%), accounting for 22.36% of dietary carbohydrate. GI values from 656 foods (52.1%) were estimated, contributing to 77.64% of dietary carbohydrate. The GI values from three unknown foods (0.2%) could not be assigned. The average daily GI was 84 (SD 5.1, white bread as referent) and the average GL was 196 (SD 63). CONCLUSION: Using this methodology for adding GI and GL values to nutrient databases, it is possible to assess associations between GI and/or GL and body weight and chronic disease outcomes (diabetes, cancer, heart disease). This method can be used in clinical and survey research settings where 24HRs are a practical means for assessing diet. The implications for using this methodology compel a broader evaluation of diet with disease outcomes.

Blood Glucose↗

Conceptualization and development of a theory-based healthful eating and physical activity intervention for postpartum women who are low income.

Eating and physical activity behaviors that confer risk for chronic disease are prominent among women from varying ethnic and racial groups who are low income. Conceptualization and development of a theory-based behavioral intervention to address their unique needs during the first year following childbirth comprised four steps: (a) translating public health guidelines and emerging epidemiologic data into specific intervention messages; (b) developing practical strategies to operationalize theoretical constructs, in the context of a social ecological framework; (c) stating achievement-based objectives and writing scripts for five home visits; and (d) conducting formative research. Focus group participants expressed a desire for a "health mentor," not somebody who "nags" or "stresses you out." Paraprofessionals from the Expanded Food and Nutrition Education Program (EFNEP) were directly involved in pretesting the intervention and remain involved as health mentors. This intervention can serve as a basis for future organizational partnerships to benefit the health of populations who are low income.

Adult↗

Association between tobacco use and body mass index in urban Indian population: implications for public health in India.

BACKGROUND: Body mass index [BMI, weight (kg)/height (m2)], a measure of relative weight, is a good overall indicator of nutritional status and predictor of overall health. As in many developing countries, the high prevalence of very low BMIs in India represents an important public health risk. Tobacco, smoked in the form of cigarettes or bidis (handmade by rolling a dried rectangular piece of temburni leaf with 0.15-0.25 g of tobacco) or chewed, is another important determinant of health. Tobacco use also may exert a strong influence on BMI. METHODS: The relationship between very low BMI (< 18.5 kg/m2) and tobacco use was examined using data from a representative cross-sectional survey of 99,598 adults (40,071 men and 59,527 women) carried out in the city of Mumbai (formerly known as Bombay) in western India. Participants were men and women aged > or = 35 years who were residents of the main city of Mumbai. RESULTS: All forms of tobacco use were associated with low BMI. The prevalence of low BMI was highest in bidi-smokers (32% compared to 13% in non-users). For smokers, the adjusted odds ratio (OR) and 95% confidence interval (CI) were OR = 1.80(1.65 to 1.96) for men and OR = 1.59(1.09 to 2.32) for women, respectively, relative to non-users. For smokeless tobacco and mixed habits (smoking and smokeless tobacco), OR = 1.28(1.19 to 1.38) and OR = 1.83(1.67 to 2.00) for men and OR = 1.50(1.43 to 1.59) and OR = 2.19(1.90 to 3.41) for women, respectively. CONCLUSION: Tobacco use appears to be an independent risk factor for low BMI in this population. We conclude that in such populations tobacco control research and interventions will need to be conducted in concert with nutrition research and interventions in order to improve the overall health status of the population.

Adult↗

Association between carbohydrate intake and serum lipids.

BACKGROUND: The effect of dietary carbohydrate on blood lipids has received considerable attention in light of the current trend in lowering carbohydrate intake for weight loss. OBJECTIVES: To evaluate the association between carbohydrate intake and serum lipids. METHODS: Blood samples and 24-hour dietary and physical activity recall interviews were obtained from each subject at quarterly intervals for five consecutive quarters between 1994 and 1998 from 574 healthy adults in Central Massachusetts. Relationships between serum lipids and dietary carbohydrate factors were assessed using linear mixed models and adjusting for other risk factors known to be related to blood lipids. Both cross-sectional and longitudinal results were reported. RESULTS: Cross-sectional analysis results from this study suggest that higher total carbohydrate intake, percentage of calories from carbohydrate, glycemic index (GI) and/or glycemic load (GL) are related to lower high-density lipoprotein cholesterol (HDL-C) and higher serum triacylglycerol levels, while higher total carbohydrate intake and/or GL are related to lower total and low-density lipoprotein cholesterol (LDL-C) levels. In a one-year longitudinal analysis, GL was positively associated with total and LDL-C levels, and there was an inverse association between percentage of calories from carbohydrate and HDL-C levels. CONCLUSIONS: Results suggest that there is a complex and predominantly unfavorable effect of increased intake of highly processed carbohydrate on lipid profile, which may have implications for metabolic syndrome, diabetes, and coronary heart disease. Further studies in the form of randomized controlled trials are required to investigate these associations and determine the implications for lipid management.

Adult↗

Association of physical activity with hormone receptor status: the Shanghai Breast Cancer Study.

Evidence exists that breast tumors differing by estrogen receptor (ER) and progesterone receptor (PR) status may be phenotypically distinct diseases resulting from dissimilar etiologic processes. Few studies have attempted to examine the association of physical activity with breast cancer subtype. Such research may prove instructive into the biological mechanisms of activity. Consequently, this investigation was designed to assess the relationship between physical activity and hormone receptor-defined breast cancers in a population of Asian women in which the distribution of receptor types differed from traditional Western populations. Participants, ages 25 to 64 years, were recruited into this population-based, case-control study of breast cancer conducted in Shanghai, China from August 1996 to March 1998. Histologically confirmed breast cancer cases with available receptor status information (n = 1001) and age frequency-matched controls (n = 1,556) completed in-person interviews. Polytomous logistic regression was used to model the association between measures of activity with each breast cancer subtype (ER+/PR+, ER-/PR-, ER+/PR-, and ER-/PR+) using the control population as the reference group. Exercise in both adolescence and the last 10 years was associated with a decreased risk of both receptor-positive (ER+/PR+) and receptor-negative (ER-/PR-) breast cancers in both premenopausal and postmenopausal women (odds ratios, 0.44 and 0.51 and 0.43 and 0.21, respectively). Sweating during exercise within the last 10 years was also associated with decreased risk for receptor-positive and receptor-negative breast cancers among postmenopausal women (odds ratios, 0.58 and 0.28, respectively). These findings suggest that physical activity may reduce breast cancer risk through both hormonal and nonhormonal pathways.

Adult↗

Urinary estrogen metabolites, prostate specific antigen, and body mass index among African-American men in South Carolina.

INTRODUCTION: Estrogen metabolites have been linked to risk of breast cancer, and we were interested in whether they are associated with prostate specific antigen (PSA) and other factors associated with prostate cancer. African-American (AA) men in South Carolina have among the highest prostate cancer rates in the world, and thus provide an ideal population in which to investigate this hypothesis. METHODS: We recruited AA men attending prostate cancer screenings in and around Columbia, South Carolina. Because very few men had elevated PSAs, we restricted our study to the 77 men whose PSA was below the cutpoint used by the screening program to indicate need for diagnostic workup. These men provided spot urine samples and answered demographic and lifestyle questions including self-reported body weight, height, exercise, tobacco use, medications, cancer history and age. Levels of urinary 2-hydroxyestrone (2-OHE1) and 16alpha-hydroxyestrone (16alpha-OHE1), and their ratio (2/16) and blood PSA levels were determined. RESULTS: After adjusting for a statistically significant interaction between age and BMI, we found a reduction of 14.2% in 2-OHE1 for each 1.0 ng/ml increase in PSA (p=0.05). For obese AA men only (BMI> or =30 kg/m2), 2-OHE1 increased by 36% for each decade of age (p=0.009). CONCLUSIONS: Estrogen metabolites may be related to PSA level in AA men. Older men with BMIs greater than 30 kg/m2 had an unexpected increase in 2-OHE1, suggesting a dysregulation of this estrogen metabolism pathway. Further studies of estrogen metabolites may provide insights into prostate cancer risk factors.

Adult↗

Permeation and reservoir formation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P) across porcine esophageal tissue in the presence of ethanol and menthol.

Environmental influences may affect carcinogen absorption and residency in the tissues of the aero-digestive tract. We quantified the effect of ethanol and menthol on the rates of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P) absorption using a fully validated in vitro diffusion system, capable of accurately and precisely quantifying tobacco carcinogen permeation and reservoir formation in porcine esophageal mucosa. Confocal microscopy was employed to visualize the location of B[a]P in the exposed membranes. Markedly different extents of permeation and reservoir formation for the tobacco carcinogens were recorded in the presence of ethanol and menthol. The water-soluble NNK permeated the membrane rapidly, while the lipophilic B[a]P did not appreciably diffuse through the tissue. Significantly different extents of reservoir formation were observed for the different carcinogens and in the presence of the different penetration-enhancer solvents. Alcohol (at 5% concentration) did not influence the permeation or reservoir formation of NNK. A mentholated donor solution (0.08%) both decreased the flux of NNK and significantly increased the tissue reservoir formation. The magnitude of the reservoir formed by B[a]P was relatively extensive (even though membrane permeation rates were negligible), being greatest in the presence of both ethanol and menthol. This suggests synergy between the two penetration-enhancer species acting on this carcinogen. Confocal microscopy studies confirmed that there was an appreciable intra-cellular, and specifically nuclear, association of the B[a]P species during the reservoir formation process. The aqueous solubility of the diffusing species and the presence of penetration enhancers appeared to be key factors in the absorption and cellular binding processes. The results presented support the hypothesis that the use of mentholated cigarettes, or the concomitant consumption of alcohol while smoking, may have marked effects on the fate of tobacco chemicals. This finding may help to explain elevated rates of esophageal squamous cell carcinoma in African Americans.

Animals↗

Scale and shape issues in focused cluster power for count data.

BACKGROUND: Interest in the development of statistical methods for disease cluster detection has experienced rapid growth in recent years. Evaluations of statistical power provide important information for the selection of an appropriate statistical method in environmentally-related disease cluster investigations. Published power evaluations have not yet addressed the use of models for focused cluster detection and have not fully investigated the issues of disease cluster scale and shape. As meteorological and other factors can impact the dispersion of environmental toxicants, it follows that environmental exposures and associated diseases can be dispersed in a variety of spatial patterns. This study simulates disease clusters in a variety of shapes and scales around a centrally located single pollution source. We evaluate the power of a range of focused cluster tests and generalized linear models to detect these various cluster shapes and scales for count data. RESULTS: In general, the power of hypothesis tests and models to detect focused clusters improved when the test or model included parameters specific to the shape of cluster being examined (i.e. inclusion of a function for direction improved power of models to detect clustering with an angular effect). However, power to detect clusters where the risk peaked and then declined was limited. CONCLUSION: Findings from this investigation show sizeable changes in power according to the scale and shape of the cluster and the test or model applied. These findings demonstrate the importance of selecting a test or model with functions appropriate to detect the spatial pattern of the disease cluster.

Journal Article↗

Association between dietary carbohydrates and body weight.

The role of dietary carbohydrates in weight loss has received considerable attention in light of the current obesity epidemic. The authors investigated the association of body mass index (weight (kg)/height (m)(2)) with dietary intake of carbohydrates and with measures of the induced glycemic response, using data from an observational study of 572 healthy adults in central Massachusetts. Anthropometric measurements, 7-day dietary recalls, and physical activity recalls were collected quarterly from each subject throughout a 1-year study period. Data were collected between 1994 and 1998. Longitudinal analyses were conducted, and results were adjusted for other factors related to body habitus. Average body mass index was 27.4 kg/m(2) (standard deviation, 5.5), while the average percentage of calories from carbohydrates was 44.9 (standard deviation, 9.6). Mean daily dietary glycemic index was 81.7 (standard deviation, 5.5), and glycemic load was 197.8 (standard deviation, 105.2). Body mass index was found to be positively associated with glycemic index, a measure of the glycemic response associated with ingesting different types of carbohydrates, but not with daily carbohydrate intake, percentage of calories from carbohydrates, or glycemic load. Results suggest that the type of carbohydrate may be related to body weight. However, further research is required to elucidate this association and its implications for weight management.

Adult↗

The effect of social desirability and social approval on self-reports of physical activity.

The purpose of this investigation was to examine social desirability and social approval as sources of error in three self-reported physical activity assessments using objective measures of physical activity as reference measures. In 1997, women (n = 81) living in Worcester, Massachusetts, completed doubly labeled water measurements and wore an activity monitor for 14 days. They also completed seven interviewer-administered 24-hour physical activity recalls (PARs) and two different self-administered 7-day PARs. Measures of the personality traits "social desirability" and "social approval" were regressed on 1) the difference between physical activity energy expenditure estimated from doubly labeled water and each physical activity assessment instrument and 2) the difference between monitor-derived physical activity duration and each instrument. Social desirability was associated with overreporting of activity, resulting in overestimation of physical activity energy expenditure by 0.65 kcal/kg/day on the second 7-day PAR (95% confidence interval: 0.06, 1.25) and overestimation of activity durations by 4.15-11.30 minutes/day (both 7-day PARs). Social approval was weakly associated with underestimation of physical activity on the 24-hour PAR (-0.15 kcal/kg/day, 95% confidence interval: -0.30, 0.005). Body size was not associated with reporting bias in this study. The authors conclude that social desirability and social approval may influence self-reported physical activity on some survey instruments.

Adult↗

Prevention of head and neck cancer.

In the vast majority of cases, head and neck cancer is a preventable disease. The relationship between tobacco and alcohol and these cancers is well established. Despite efforts aimed at reduction of risk factor exposure and early detection methods, head and neck cancer remains one of the more common cancers worldwide. Recent advances in molecular techniques have provided a framework for future targets for early diagnosis and treatment of these malignancies. This review provides a summary of recent developments in primary and secondary prevention of head and neck cancer and innovative strategies aimed at a reduction in incidence and mortality from this disease. The future prevention of head and neck cancer will likely require solutions to the widespread use of tobacco products and innovative diagnostic techniques leading to improvements in overall survival.

Alcohol Drinking↗

Sources of variation in nutrient intakes among men in Shanghai, China.

BACKGROUND AND OBJECTIVE: Random errors, from any source, will attenuate epidemiological risk estimates. Before we launched the Shanghai Men's Health Study (SMHS), a large population-based cohort study investigating the diet-cancer association among Chinese men, a dietary calibration study was conducted among 96 men aged 40-75 years (mean age 56.5 years), with biweekly 24-hour dietary recalls (24HDRs) implemented over a 1-year period. Data from this study were analysed to evaluate the nature and magnitude of variances for intake of 26 nutrients among SMHS participants, to compare variance ratios of 26 nutrients among Chinese men and women and individuals in other studies, and to estimate the number of 24HDRs required for future dietary calibration studies in similar populations. DESIGN: Ninety-six healthy, free-living men in Shanghai were administered biweekly 24HDR interviews 24 times over a 1-year period. To assess between-individual and within-individual contributions to variance, a mixed effects model was fitted and ratios of within-individual to between-individual (sigma(w)(2)/sigma(b)(2)) dietary intake variances were computed. SETTING: Shanghai, China. RESULTS: In agreement with reports from studies conducted in the USA and many other countries, we found that within-individual variances were usually larger than between-individual variances in dietary intake for all nutrients. The sum of all other variation (e.g. weekday and weekend, seasonal, interviewer) accounted for less than 5% of total variation. Ratios of within- to between-individual variances (for log-transformed data) ranged from 1.25 for carbohydrate intake to near 8 for delta-tocopherol intake. CONCLUSIONS: The results of this study suggest that among middle-aged and elderly Chinese men in Shanghai, within- and between-individual variation account for more than 95% of the total variation for 26 nutrients. Further dietary validation studies in the same population could be adequately carried out with only 12 days of dietary recalls, if 100 participants were enrolled.

Adult↗

Dietary fat intake is associated with psychosocial and cognitive functioning of school-aged children in the United States.

Using cross-sectional data from the Third National Health and Nutrition Survey, 1988-1994, we examined whether dietary fat intake is associated with cognitive and psychosocial functioning in school-aged children. Based upon 24-h diet recall interviews, dietary intakes of total fat, SFA, monounsaturated fatty, PUFAs, and cholesterol were estimated in 3666 participants aged 6 to 16 y. Psychosocial functioning was evaluated in interviews of each child's mother. Cognitive functioning was measured using achievement and intelligence tests. Overall, total fat and saturated fat were unrelated to measures of cognitive and psychosocial functioning. Compared with equivalent energy intake from saturated fat or carbohydrate, each 5% increase in energy intake from PUFAs was associated with lower risks of poor performance on the digit span test (replacing SFA, OR = 0.58, 95% CI = 0.37-0.91; replacing carbohydrate, OR = 0.61, 95% CI = 0.43-0.88). Cholesterol intake was associated with an increased risk of poor performance on the digit span test (OR = 1.25, 95% CI = 1.11-1.42 for each 100-mg increment intake of cholesterol). The associations were independent of socioeconomic status, maternal education and marital status, and children's nutrition status and were consistent across different methods of energy adjustment in regression models. We conclude that high intake of PUFAs may contribute to an improved performance on the digit span test. In contrast, increased intake of cholesterol may be associated with a poorer performance.

Adolescent↗

Urban, rural, and regional variations in physical activity.

PURPOSE: There is some speculation about geographic differences in physical activity (PA) levels. We examined the prevalence of physical inactivity (PIA) and whether U.S. citizens met the recommended levels of PA across the United States. In addition, the association between PIA/PA and degree of urbanization in the 4 main U.S. regions (Northeast, Midwest, South, and West) was determined. METHODS: Participants were 178,161 respondents to the 2000 Behavioral Risk Factor Surveillance System (BRFSS). Data from 49 states and the District of Columbia were included (excluding Alaska). States were categorized by urban status according to the U.S. Department of Agriculture. Physical activity variables were those commonly used in national surveillance systems (PIA = no leisure-time PA; and PA = meeting a PA recommendation). RESULTS: Nationally, PA levels were higher in urban areas than in rural areas; correspondingly, PIA levels were higher in rural areas than in urban areas. Regionally, the urban-rural differences were most striking in the South and were, in fact, often absent in other regions. Demographic factors appeared to modify the association. CONCLUSION: The association between PA and degree of urbanization is evident and robust in the South but cannot be generalized to all regions of the United States. For the most part, the Midwest and the Northeast do not experience any relationship between PA and urbanization, whereas, in the West, the trend appears to be opposite of that observed in the South.

Activities of Daily Living↗

The cancer prevention and control research network.

The Cancer Prevention and Control Research Network is a national network recently established to focus on developing new interventions and disseminating and translating proven interventions into practice to reduce cancer burden and disparities, especially among minority and medically underserved populations. Jointly funded by the Centers for Disease Control and Prevention and the National Cancer Institute, the Cancer Prevention and Control Research Network consists of sites administered through Prevention Research Centers funded by the Centers for Disease Control and Prevention. The five sites are located in Kentucky, Massachusetts, South Carolina, Texas, Washington State, and West Virginia. The Cancer Prevention and Control Research Network's intervention areas include primary prevention of cancer through healthy eating, physical activity, sun avoidance, tobacco control, and early detection of cancer through screening. The Cancer Prevention and Control Research Network uses the methods of community-based participatory research and seeks to build on the cancer-relevant systematic reviews of the Guide to Community Preventive Services. Initial foci for the Cancer Prevention and Control Research Network's research work groups include projects to increase screening for breast, cervical, and colorectal cancers; to promote informed decision making for prostate cancer screening; and to validate educational materials developed for low-literacy populations.

Biomedical Research↗

The PPAR{gamma} Pro12Ala polymorphism and risk for incident sporadic colorectal adenomas.

Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear hormone receptor superfamily initially shown to be a key regulator of fat cell differentiation, can inhibit cell growth and induce apoptosis in colon cell lines. There are heterozygous loss of function mutations in the gene encoding PPARgamma in tumors from approximately 10% of human colon cancer patients. A common structural polymorphism has been detected in the PPARgamma gene at codon 12 (Pro12Ala). We investigated the hypothesis that the PPARgamma Pro12Ala polymorphism is associated with colorectal adenoma risk in a recently concluded case-control study of incident sporadic colorectal adenomas (163 cases and 212 controls). The multivariate-adjusted odds ratio (OR) for incident sporadic colorectal adenoma was 0.65 (95% CI 0.39-1.09) for those with the Pro12Ala or Ala12Ala genotype compared with those with the Pro12Pro genotype. Multivariate-adjusted inverse associations with the Ala12 variant were more pronounced among those who were female (OR 0.36, 95% CI 0.18-0.75) or did not take non-steroidal anti-inflammatory drugs (OR 0.38, 95% CI 0.14-1.00). Marginally significant results were observed among those with a lower waist:hip ratio (OR 0.52, 95% CI 0.24-1.12) or a lower body mass index (OR 0.46, 95% 0.20-1.05). Smoking was a very strong risk factor (OR 2.34, 95%CI 1.37-4.02) for colorectal adenoma among those with the wild-type (Pro12Ala) genotype, but not those with the Ala12 variant (OR 0.86, 95%CI 0.35-2.09). Larger studies are needed to validate these results, which suggest that the PPARgamma Pro12Ala polymorphism may interact with other factors to protect against colorectal adenoma.

Adenoma↗

Seasonal variation in serum cholesterol levels: treatment implications and possible mechanisms.

BACKGROUND: A variety of studies have noted seasonal variation in blood lipid levels. Although the mechanism for this phenomenon is not clear, such variation could result in larger numbers of people being diagnosed as having hypercholesterolemia during the winter. METHODS: We conducted a longitudinal study of seasonal variation in lipid levels in 517 healthy volunteers from a health maintenance organization serving central Massachusetts. Data collected during a 12-month period for each individual included baseline demographics and quarterly anthropometric, blood lipid, dietary, physical activity, light exposure, and behavioral information. Data were analyzed using sinusoidal regression modeling techniques. RESULTS: The average total cholesterol level was 222 mg/dL (5.75 mmol/L) in men and 213 mg/dL (5.52 mmol/L) in women. Amplitude of seasonal variation was 3.9 mg/dL (0.10 mmol/L) in men, with a peak in December, and 5.4 mg/dL (0.14 mmol/L) in women, with a peak in January. Seasonal amplitude was greater in hypercholesterolemic participants. Seasonal changes in plasma volume explained a substantial proportion of the observed variation. Overall, 22% more participants had total cholesterol levels of 240 mg/dL or greater (> or =6.22 mmol/L) in the winter than in the summer. CONCLUSIONS: This study confirms seasonal variation in blood lipid levels and suggests greater amplitude in seasonal variability in women and hypercholesterolemic individuals, with changes in plasma volume accounting for much of the variation. A relative plasma hypervolemia during the summer seems to be linked to increases in temperature and/or physical activity. These findings have implications for lipid screening guidelines. Further research is needed to better understand the effects of a relative winter hemoconcentration.

Adult↗