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Lisa Harnack

Publications and source records attributed to Lisa Harnack.

At least 19 recordsLinked to original sources
PubMed2006

Dietary carotenoids and risk of colorectal cancer in a pooled analysis of 11 cohort studies.

Dietary carotenoids have been hypothesized to protect against epithelial cancers. The authors analyzed the associations between intakes of specific carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein + zeaxanthin, and lycopene) and risk of colorectal cancer using the primary data from 11 cohort studies carried out in North America and Europe. Carotenoid intakes were estimated from food frequency questionnaires administered at baseline in each study. During 6-20 years of follow-up between 1980 and 2003, 7,885 incident cases of colorectal cancer were diagnosed among 702,647 participants. The authors calculated study-specific multivariate relative risks and then combined them using a random-effects model. In general, intakes of specific carotenoids were not associated with colorectal cancer risk. The pooled multivariate relative risks of colorectal cancer comparing the highest quintile of intake with the lowest ranged from 0.92 for lutein + zeaxanthin to 1.04 for lycopene; only for lutein + zeaxanthin intake was the result borderline statistically significant (95% confidence interval: 0.84, 1.00). The associations observed were generally similar across studies, for both sexes, and for colon cancer and rectal cancer. These pooled data did not suggest that carotenoids play an important role in the etiology of colorectal cancer.

Carotenoids↗
PubMed2006

Methods for pooling results of epidemiologic studies: the Pooling Project of Prospective Studies of Diet and Cancer.

With the growing number of epidemiologic publications on the relation between dietary factors and cancer risk, pooled analyses that summarize results from multiple studies are becoming more common. Here, the authors describe the methods being used to summarize data on diet-cancer associations within the ongoing Pooling Project of Prospective Studies of Diet and Cancer, begun in 1991. In the Pooling Project, the primary data from prospective cohort studies meeting prespecified inclusion criteria are analyzed using standardized criteria for modeling of exposure, confounding, and outcome variables. In addition to evaluating main exposure-disease associations, analyses are also conducted to evaluate whether exposure-disease associations are modified by other dietary and nondietary factors or vary among population subgroups or particular cancer subtypes. Study-specific relative risks are calculated using the Cox proportional hazards model and then pooled using a random- or mixed-effects model. The study-specific estimates are weighted by the inverse of their variances in forming summary estimates. Most of the methods used in the Pooling Project may be adapted for examining associations with dietary and nondietary factors in pooled analyses of case-control studies or case-control and cohort studies combined.

Diet↗
PubMed2006

Adolescents involved in weight-related and power team sports have better eating patterns and nutrient intakes than non-sport-involved adolescents.

OBJECTIVE: To examine eating habits and energy and nutrient intake among adolescents participating in weight-related and power team sports and non-sport-involved adolescents. DESIGN: Data were drawn from Project EAT (Eating Among Teens), which was conducted with 4,746 adolescents from 31 middle and high schools in the Minneapolis/St Paul metropolitan area. SETTING: Urban secondary schools. SUBJECTS: Adolescents reporting participation in a weight-related sport, a power team sport, or no consistent participation in a sport. MAIN OUTCOME MEASURES: Meal and snack frequency, mean energy and nutrient intake, and mean physical activity. STATISTICAL ANALYSES PERFORMED: Analyses were conducted by sex across the three groups. General linear models were used to compare mean energy and nutrient intake, composite nutrient adequacy, and mean physical activity across the three groups. Percentages of youth meeting nutrient recommendations were compared across the three groups using chi(2) tests. RESULTS: For both males and females, youth involved in weight-related sports ate breakfast more frequently than non-sport-involved peers (females: 3.6 and 3.2 times per week, respectively, P<0.01; males: 4.7 and 3.7 times per week, respectively, P<0.01). Weight-related and power team sport-involved youth also had higher mean protein, calcium, iron, and zinc intakes than non-sport-involved peers. However, adolescent females had low calcium intake, regardless of sports involvement (weight-related sports 1,091 mg/day, power team sports 1,070 mg/day, and non-sport-involved 1,028 mg/day, P<0.05). CONCLUSIONS: Sport-involved adolescents have better eating habits and nutrient intake than their non-sport-involved peers. However, they are still in need of nutrition interventions, particularly around calcium intake.

Adolescent↗
PubMed2006

Internet food marketing strategies aimed at children and adolescents: a content analysis of food and beverage brand web sites.

Americans are spending an increasing amount of time using "new media" like the Internet. There has been little research examining food and beverage Web sites' content and marketing practices, especially those that attract children and adolescents. The purpose of this study was to conduct a content analysis of food- and beverage-brand Web sites and the marketing techniques and advertising strategies present on these sites. The top five brands in eight food and beverage categories, 40 brands in total, were selected based on annual sales data from Brandweek magazine's annual "Superbrands" report. Data were collected using a standardized coding form. The results show a wide variety of Internet marketing techniques and advertising strategies targeting children and adolescents. "Advergaming" (games in which the advertised product is part of the game) was present on 63% of the Web sites. Half or more of the Web sites used cartoon characters (50%) or spokescharacters (55%), or had a specially designated children's area (58%) with a direct link from the homepage. With interactive media still in its developmental stage, there is a need to develop safeguards for children. Food and nutrition professionals need to advocate for responsible marketing techniques that will support the health of children.

Adolescent↗
PubMed2006

Incidence of colorectal cancer in relation to glycemic index and load in a cohort of women.

BACKGROUND: Dietary glycemic index (GI) and glycemic load (GL) affect circulating insulin concentrations. Elevated circulating insulin concentrations can increase insulin-like growth factor-1, and both of these hormones may have growth-promoting effects within the colorectum. METHODS: We examined associations of GI and GL with colorectal cancer (CRC) among participants in the Iowa Women's Health Study (n = 35,197; ages 55-69 years at baseline in 1986). Over 15 years of follow-up, we identified 757 cases of colon cancer and 209 cases of rectal cancer (954 CRC cases). RESULTS: Overall, neither GI nor GL were significantly associated with incident CRC. However, among obese women (baseline body mass index >/=30 kg/m(2)) CRC incidence was increased in the highest versus lowest quintiles of GI (relative risk, 1.66; 95% confidence intervals, 1.13-2.43; P for trend = 0.02) and GL (relative risk, 1.79; 95% confidence intervals, 1.19-2.70; P for trend < 0.01). This pattern of increased risk for obese women with high GI or GL tended to hold for both colon cancer and rectal cancer, and for nondiabetic women as well. No statistically significant associations were observed between GI or GL and CRC among subjects whose baseline body mass index was <30 kg/m(2). CONCLUSION: Our findings suggest that high GI or GL are not major CRC risk factors among older women in general, but may increase CRC risk among women who are obese.

Aged↗
PubMed2006

The association of physical activity with lung cancer incidence in a cohort of older women: the Iowa Women's Health Study.

BACKGROUND: We examined the potential association between physical activity and lung cancer in women. METHODS: In 1986, 36,929 women from Iowa, who were free of prior cancer, completed a questionnaire regarding physical activity, smoking, body mass index, and other life-style factors. Women were followed through 2002 for cancer incidence. RESULTS: After adjusting for potential confounders, women with high physical activity levels were less likely [hazard ratio, 0.77; 95% confidence intervals (CI), 0.64-0.94] to develop lung cancer than women with low activity levels. This hazard ratio was 0.72 (95% CI, 0.55-0.94) in current smokers and 0.63 (95% CI, 0.43-0.92) in former smokers, but was not significant in never smokers. CONCLUSION: These results suggest that physical activity might reduce the risk of lung cancer in women who are current or former smokers.

Aged↗
PubMed2005

Dietary fiber intake and risk of colorectal cancer: a pooled analysis of prospective cohort studies.

CONTEXT: Inconsistent findings from observational studies have continued the controversy over the effects of dietary fiber on colorectal cancer. OBJECTIVE: To evaluate the association between dietary fiber intake and risk of colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS: From 13 prospective cohort studies included in the Pooling Project of Prospective Studies of Diet and Cancer, 725,628 men and women were followed up for 6 to 20 years across studies. Study- and sex-specific relative risks (RRs) were estimated with the Cox proportional hazards model and were subsequently pooled using a random-effects model. MAIN OUTCOME MEASURE: Incident colorectal cancer. RESULTS: During 6 to 20 years of follow-up across studies, 8081 colorectal cancer cases were identified. For comparison of the highest vs lowest study- and sex-specific quintile of dietary fiber intake, a significant inverse association was found in the age-adjusted model (pooled RR = 0.84; 95% confidence interval [CI], 0.77-0.92). However, the association was attenuated and no longer statistically significant after adjusting for other risk factors (pooled multivariate RR = 0.94; 95% CI, 0.86-1.03). In categorical analyses compared with dietary fiber intake of 10 to <15 g/d, the pooled multivariate RR was 1.18 (95% CI, 1.05-1.31) for less than 10 g/d (11% of the overall study population); and RR, 1.00 (95% CI, 0.85-1.17) for 30 or more g/d. Fiber intake from cereals, fruits, and vegetables was not associated with risk of colorectal cancer. The pooled multivariate RRs comparing the highest vs lowest study- and sex-specific quintile of dietary fiber intake were 1.00 (95% CI, 0.90-1.11) for colon cancer and 0.85 (95% CI, 0.72-1.01) for rectal cancer (P for common effects by tumor site = .07). CONCLUSIONS: In this large pooled analysis, dietary fiber intake was inversely associated with risk of colorectal cancer in age-adjusted analyses. However, after accounting for other dietary risk factors, high dietary fiber intake was not associated with a reduced risk of colorectal cancer.

Colorectal Neoplasms↗
PubMed2005

Alcohol consumption and risk of lung cancer: a pooled analysis of cohort studies.

BACKGROUND: Although smoking is the primary cause of lung cancer, much is unknown about lung cancer etiology, including risk determinants for nonsmokers and modifying factors for smokers. OBJECTIVE: We hypothesized that alcohol consumption contributes to lung cancer risk. DESIGN: We conducted a pooled analysis using standardized exposure and covariate data from 7 prospective studies with 399,767 participants and 3137 lung cancer cases. Study-specific relative risks (RRs) and CIs were estimated and then combined to calculate pooled multivariate RRs by using a random-effects model. RESULTS: We found a slightly greater risk for the consumption of > or = 30 g alcohol/d than for that of 0 g alcohol/d in men (RR: 1.21; 95% CI: 0.91, 1.61; P for trend = 0.03) and in women (RR: 1.16; 95% CI: 0.94, 1.43; P for trend = 0.03). In male never smokers, the RR for consumption of > or = 15 g alcohol/d rather than 0 g alcohol/d was 6.38 (95% CI: 2.74, 14.9; P for trend < 0.001). In women, there were few never-smoking cases and no evidence of greater risk (RR: 1.35; 95% CI: 0.64, 2.87). Because of possible residual confounding by smoking, we performed sensitivity analyses by reclassifying the never smokers in the highest drinking category as former smokers. Resulting associations for alcohol consumption were somewhat attenuated, but P for trend = 0.05 for men, which was near the original P = 0.03. CONCLUSIONS: A slightly greater risk of lung cancer was associated with the consumption of > or = 30 g alcohol/d than with no alcohol consumption. Alcohol consumption was strongly associated with greater risk in male never smokers. Residual confounding by smoking may explain part of the observed relation.

Alcohol Drinking↗
PubMed2005

Dietary intake of heterocyclic amines and benzo(a)pyrene: associations with pancreatic cancer.

OBJECTIVE: Heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons, formed in temperature- and time-dependent manners during the cooking of meat, are mutagens and carcinogens. We sought to assess the association between dietary intake of HCA and benzo(a)pyrene [B(a)P] and exocrine pancreatic cancer in a population-based case-control study. METHODS: Subjects (193 cases and 674 controls) provided information on their usual meat intake and preparation method, e.g., stewed, fried, or grilled/barbecued, etc. Meat doneness preferences were measured using photographs that showed internal doneness and external brownness. We used a meat-derived HCA, B(a)P, and mutagen database with a questionnaire to estimate intake of PhIP, DiMeIQx, MeIQx, B(a)P, and mutagenic activity (revertants/g of daily meat intake). Data were analyzed with unconditional logistic regression. RESULTS: In analyses adjusted for age, sex, smoking, education, race, and diabetes, the odds ratio and 95% confidence interval for the highest compared with the lowest quintile were as follows: PhIP, 1.8 (1.0-3.1); DiMeIQx, 2.0 (1.2-3.5); MeIQx, 1.5 (0.9-2.7); B(a)P, 2.2 (1.2-4.0); and mutagenic activity, 2.4 (1.3-4.3). CONCLUSIONS: HCAs and B(a)P from well-done barbecued and pan-fried meats may be associated with increased risk for pancreatic cancer.

Aged↗
PubMed2005

Feasibility of using accelerometers to measure physical activity in young adolescents.

PURPOSE: Accelerometers may provide valid measures of physical activity, but the feasibility of using accelerometers with large groups of children is unknown. We assessed feasibility in the Eating and Activity Survey Trial (Project EAST), a study designed to develop valid tools to assess eating and physical activity patterns among middle school children. METHODS: Two hundred eighty-two Project EAST participants in grades 6-8 wore an accelerometer (Manufacturing Technologies, Inc., Fort Walton Beach, FL) for seven consecutive days. Multiple strategies were employed to encourage compliance and return of the accelerometer: 1) staff demonstrated how to wear the device properly; 2) students were given written and verbal instructions; 3) staff visited the students twice during 7 d to remind them to wear the devices and return them on time; and 4) movie tickets were given to students who returned the accelerometers on time. RESULTS: Data from 27 accelerometers were lost as a result of mechanical and nontechnical problems, resulting in unusable data for 8.5% of students. Days of data for the remaining 255 students were considered incomplete if the accelerometer registered less than three consecutive waking hours of zero counts. The percentage of students with complete accelerometer data for 3-7 d of data were > or = 3 d, 92%; > or = 4 d, 86%; > or = 5 d, 75%; > or = 6 d, 67%; and 7 d, 50%. Twenty-eight students (10%) returned their accelerometers late. Overweight children were significantly more likely to have 7 d of complete data than nonoverweight children. CONCLUSION: Our findings suggest that accelerometers are acceptable to most students. However, researchers working with middle school students should carefully monitor compliance to ensure that devices are worn properly and regularly.

Adolescent↗
PubMed2004

Intervention-related bias in reporting of food intake by fifth-grade children participating in an obesity prevention study.

Data collected as part of Pathways, a school-based trial for the primary prevention of obesity in American Indian children conducted between 1997 and 2000, were analyzed to examine possible intervention-related bias in food reporting. The authors hypothesized that children in the intervention schools may have systematically underreported their dietary intake relative to children in the control schools. Nutrient intake estimates for lunch derived from record-assisted 24-hour dietary recalls were compared with intake estimates from observed lunch intakes. Reported nutrient intakes were included in regression analyses as the dependent variables; observed intake, intervention condition, and age were included as independent variables. Results indicated that, among females, intervention condition was a significant predictor of reported energy, fat, and saturated fatty acid intakes. Independently of observed intake, reported lunch energy intake among females in the intervention schools was 66.8 calories lower than reported intake among females in the control schools (p = 0.03). These findings suggest that investigators should consider bias in reporting of dietary intake by intervention condition when conducting diet-focused intervention studies. Specifically, enhancing measures that rely on self-reports with objective measures of dietary intake would help investigators to evaluate whether differential reporting by treatment group has occurred.

Bias↗
PubMed2004

Association of folate and alcohol with risk of ovarian cancer in a prospective study of postmenopausal women.

Studies evaluating the association of ovarian cancer with alcohol intake are inconsistent, and few have evaluated this association in the context of folate consumption. Dietary folate and alcohol intakes and lifestyle and medical information were collected with self-administered questionnaires in 1986 from postmenopausal women aged 55-69 followed prospectively for 15 years for risk of epithelial ovarian cancer in the Iowa Women's Health Study. Among 27,205 eligible women free of baseline cancer, 147 incident epithelial ovarian cancer cases were identified by linkage to a cancer registry. Compared to the lowest quartile of total folate (food plus supplement) intake, the multivariable risk ratios (RR) for increasing quartiles were 1.0 (referent), 1.59, 1.24, 1.73 (95% confidence interval [CI], 0.90-3.33; p for trend, 0.20). Compared to non-drinkers, the RRs for increasing alcohol intake were 1.0 (referent), 0.78 for 0.01-3.9 g/d, 0.75 for 4.0-9.9 g/d and 0.58 for > or =10 g/d (95% CI, 0.30-1.11; p for trend, 0.08). Among women with alcohol intake > or =4 g/d compared to < 4 g/d, the apparent risk reduction was limited to those with total folate intake > or =331 microg/d (RR, 0.52; 95% CI, 0.22-1.19; p for interaction, 0.04) although this estimate was based on only seven cases. The association did not change appreciably when we excluded tumors of mucinous histology. These findings suggest that alcohol consumption is inversely related to postmenopausal ovarian cancer, and that the association of folate with ovarian cancer may vary by the amount of alcohol consumed.

Aged↗
PubMed2004

Accuracy of estimation of large food portions.

To examine accuracy of reporting of large food portions, 50 adults were invited to eat a restaurant meal that included a hamburger patty, french fries, and ice cream. After eating, participants were asked to estimate the amount of food consumed using commonly used and larger-sized food models as a guide. With the use of commonly used models, underreporting was evident for all three foods. For example, the amount of hamburger patty consumed was on average 4.01 oz, although the average amount reported was 3.04 oz (P<.05). When larger-sized models were used, the amount reported more closely matched the amount consumed, although underreporting persisted for the hamburger patty and french fries. In summary, significant underreporting of large food portions may result when commonly used food models are used to assist individuals in reporting food portions.

Adult↗
PubMed2004

Factors associated with soft drink consumption in school-aged children.

OBJECTIVE: To identify factors associated with nonalcoholic carbonated beverage (soft drink) consumption in children. DESIGN: Mail-in surveys collected by Dragonfly, a children's educational magazine distributed nationally to elementary and middle schools, were analyzed. The survey included questions about frequency of soft drink consumption and factors related to soft drink consumption. SUBJECTS AND PARTICIPANTS: The sample consisted of 560 children, 8 to 13 years old, who completed and mailed in the survey. There was an equal distribution of boys and girls (51% and 49%, respectively). STATISTICAL ANALYSES: Frequency distributions were calculated and chi(2) tests were conducted to determine whether soft drink consumption and related factors varied by sex and age. Multivariate logistic regression analyses were conducted to examine the association of soft drink consumption with each factor after adjustment for potential confounders. RESULTS: Preference for the taste of soft drinks was the strongest predictor in the analysis, with those who reported the strongest taste preference 4.50 times more likely (95% confidence interval=2.89-7.04) to consume soft drinks five or more times per week than those with a lower taste preference. Youth whose parents regularly drank soft drinks were 2.88 times more likely (95% confidence interval=1.76-4.72) to consume soft drinks five or more times per week compared with those whose parents did not regularly drink soft drinks. CONCLUSIONS: Results suggest that several factors may be associated with soft drink intake in school-aged children, most notably taste preferences, soft drink consumption habits of parents and friends, soft drink availability in the home and school, and television viewing. Additional research is needed to verify these findings in a representative sample of children.

Adolescent↗
PubMed2004

Does folate intake decrease risk of postmenopausal breast cancer among women with a family history?

BACKGROUND: Several recent studies suggest that adequate dietary folate may attenuate the risk of breast cancer associated with intake of alcohol. We examined whether the putative benefit extends to women with a family history (FH) of breast cancer using a cohort of 33,552 postmenopausal women aged 55-69 years in 1986. METHOD: Folate and alcohol intake was estimated from a food frequency questionnaire completed at baseline. Folate was categorized as upper 50th, 31st-50th, 11th-30th, and <10th percentiles. Alcohol use was initially classified into three levels; never drinkers, less than the median and greater than the median. Subsequent models collapsed levels of intake to any versus none. Occurrence of breast cancer was determined through linkage to the Iowa SEER registry. Multivariate-adjusted relative risks (RR) and 95% confidence intervals (CI) were estimated through Cox proportional hazards regression, stratified on FH using non-drinkers with high folate and no FH as the referent group. RESULTS: Through 14 years, 1823 incident cases were identified, 308 among FH+ women. Among FH- women, low folate was not a risk factor among non-drinkers (RR = 0.96, CI = 0.73-1.26), but was among drinkers (RR = 1.40, CI = 1.05-1.86). Drinkers with high folate were not at elevated risk (RR = 1.03, CI = 0.89-1.19). Among FH+ women, low folate was a risk factor among drinkers (RR = 2.21, CI = 1.43-3.41) and non-drinkers (RR = 2.39, CI = 1.36-4.20). Further, drinkers with high folate remained at increased risk (RR = 1.67, CI= 1.30-2.14). However, FH+ women with high folate who did not drink alcohol had no elevated risk. CONCLUSION: These results suggest that folate may attenuate the risks of postmenopausal breast cancer associated with family history, but only if alcohol use is avoided or minimized.

Aged↗
PubMed2004

Does supplemental vitamin C increase cardiovascular disease risk in women with diabetes?

BACKGROUND: Vitamin C acts as a potent antioxidant; however, it can also be a prooxidant and glycate protein under certain circumstances in vitro. These observations led us to hypothesize that a high intake of vitamin C in diabetic persons might promote atherosclerosis. OBJECTIVE: The objective was to examine the relation between vitamin C intake and mortality from cardiovascular disease. DESIGN: We studied the relation between vitamin C intake and mortality from total cardiovascular disease (n = 281), coronary artery disease (n = 175), and stroke (n = 57) in 1923 postmenopausal women who reported being diabetic at baseline. Diet was assessed with a food-frequency questionnaire at baseline, and subjects initially free of coronary artery disease were prospectively followed for 15 y. RESULTS: After adjustment for cardiovascular disease risk factors, type of diabetes medication used, duration of diabetes, and intakes of folate, vitamin E, and beta-carotene, the adjusted relative risks of total cardiovascular disease mortality were 1.0, 0.97, 1.11, 1.47, and 1.84 (P for trend < 0.01) across quintiles of total vitamin C intake from food and supplements. Adjusted relative risks of coronary artery disease were 1.0, 0.81, 0.99, 1.26, and 1.91 (P for trend = 0.01) and of stroke were 1.0, 0.52, 1.23, 2.22, and 2.57 (P for trend < 0.01). When dietary and supplemental vitamin C were analyzed separately, only supplemental vitamin C showed a positive association with mortality endpoints. Vitamin C intake was unrelated to mortality from cardiovascular disease in the nondiabetic subjects at baseline. CONCLUSION: A high vitamin C intake from supplements is associated with an increased risk of cardiovascular disease mortality in postmenopausal women with diabetes.

Aged↗
PubMed2004

Reliability and validity of a brief questionnaire to assess television viewing and computer use by middle school children.

Sedentary behaviors, like television viewing, are positively associated with overweight among young people. To monitor national health objectives for sedentary behaviors in young adolescents, this project developed and assessed the reliability and validity of a brief questionnaire to measure weekly television viewing, usual television viewing, and computer use by middle school children. Reliability and validity of the Youth Risk Behavior Survey (YRBS) question on weekday television viewing also were examined. A brief, five-item television and computer use questionnaire was completed twice by 245 middle school children with one week apart. To concurrently assess validity, students also completed television and computer use logs for seven days. Among all students, Spearman correlations for test-retest reliability for television viewing and computer use ranged from 0.55 to 0.68. Spearman correlations between the first questionnaire and the seven-day log produced the following results: YRBS question for weekday television viewing (0.46), weekend television viewing (0.37), average television viewing over the week (0.47), and computer use (0.39). Methods comparison analysis showed a mean difference (hours/week) between answers to questionnaire items and the log of -0.04 (1.70 standard deviation [SD]) hours for weekday television, -0.21 (2.54 SD) for weekend television, -0.09 (1.75 SD) for average television over the week, and 0.68 (1.26 SD) for computer use. The YRBS weekday television viewing question, and the newly developed questions to assess weekend television viewing, average television viewing, and computer use, produced adequate reliability and validity for surveillance of middle school students.

Adolescent↗