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Biomedical subjects

E Riboli

Publications and source records attributed to E Riboli.

At least 91 records · Page 5Linked to original sources
PubMed2000

Risk of iron overload among middle-aged women.

Iron overload, expressed as increased body iron stores, has been recognized as a potential hazard because it promotes the generation of oxygen radicals. We analyzed factors associated with serum ferritin levels (an indicator of body iron stores) among middle-aged women with a high prevalence of nutrient supplement use. Serum ferritin concentrations were determined on automated immunoassay for 487 healthy women with the mean age of 57 years who participated in the New York University Women's Health Study. The mean serum ferritin concentration in postmenopausal women was more than twice that in premenopausal women. Serum ferritin concentrations progressively increased with advancing age, but adjustment for menopausal status considerably weakened this association. Among non-dietary factors, nonwhite ethnicity, obesity and cigarette smoking were positively associated with serum ferritin concentrations. After adjustment for these factors and for menopausal status, serum ferritin levels were positively associated with meat intake and multivitamin use and inversely associated with breakfast cereal consumption. However, none of these lifestyle factors positively associated with serum ferritin levels had a significant impact on serum ferritin levels above 100 ng/ml (approximately equal to median concentration). Our results suggest that iron overload seems unlikely among middle aged women through their diet and nutritional supplements.

Adult↗
PubMed2000

Reliability of fatty acid composition in human serum phospholipids.

OBJECTIVE: We examined the reliability of the fatty acid composition of serum phospholipids in the New York University Women's Health Study, a prospective study of sex hormones, diet and breast cancer. DESIGN: Non-fasting serum samples collected at three yearly visits, in 46 healthy women, and stored at -80 degrees C for 7-12 y, were included in the study. Serum phospholipid fatty acid composition was measured by capillary gas chromatography. RESULTS: For the 20 individual fatty acids measured, the reliability coefficients were less than 0.50 for four, between 0.50 and 0.70 for nine, and greater than 0.70 for seven. Among the major fatty acids, arachidonic and alpha-linolenic acids had high reliability coefficients (0.71 and 0. 72, respectively), palmitic, oleic, linoleic, eicosapentaenoic and docosahexaenoic acids had intermediate coefficients (0.57, 0.69, 0. 62, 0.64 and 0.66, respectively), whereas stearic acid had the lowest coefficient (0.15). The reliability coefficients for total monounsaturated fats, omega-6 and omega-3 fatty acids were moderately high (0.66, 0.53 and 0.66, respectively), whereas the coefficients for total saturated fats and total polyunsaturated fats were low (0.31 and 0.43, respectively). CONCLUSIONS: These results indicate that the fatty acid composition of serum phospholipids can be a useful tool in epidemiologic studies, although for most fatty acids a single determination is associated with some error in measurement that should be taken into account at the design and analysis stages. Storage for up to 12 y at -80 degrees C preserved polyunsaturated fatty acids from oxidation very well.

Adult↗
PubMed2000

Standardization of the 24-hour diet recall calibration method used in the european prospective investigation into cancer and nutrition (EPIC): general concepts and preliminary results.

OBJECTIVES: Despite increasing interest in the concept of calibration in dietary surveys, there is still little experience in the use and standardization of a common reference dietary method, especially in international studies. In this paper, we present the general theoretical framework and the approaches developed to standardize the computer-assisted 24 h diet recall method (EPIC-SOFT) used to collect about 37 000 24-h dietary recall measurements (24-HDR) from the 10 countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC). In addition, an analysis of variance was performed to examine the level of standardization of EPIC-SOFT across the 90 interviewers involved in the study. METHODS: The analysis of variance used a random effects model in which mean energy intake per interviewer was used as the dependent variable, while age, body mass index (BMI), energy requirement, week day, season, special diet, special day, physical activity and the EPIC-SOFT version were used as independent variables. The analysis was performed separately for men and women. RESULTS: The results show no statistical difference between interviewers in all countries for men and five out of eight countries for women, after adjustment for physical activity and the EPIC-SOFT program version used, and the exclusion of one interviewer in Germany (for men), and one in Denmark (for women). These results showed an interviewer effect in certain countries and a significant difference between gender, suggesting an underlying respondent's effect due to the higher under-reporting among women that was consistently observed in EPIC. However, the actual difference between interviewer and country mean energy intakes is about 10%. Furthermore, no statistical differences in mean energy intakes were observed across centres from the same country, except in Italy and Germany for men, and France and Spain for women, where the populations were recruited from areas scattered throughout the countries. CONCLUSION: Despite these encouraging results and the efforts to standardize the 24-HDR interview method, conscious or unconscious behaviour of respondents and/or interviewer bias cannot be prevented entirely. Further evaluation of the reliability of EPIC-SOFT measurements will be conducted through validation against independent biological markers (nitrogen, potassium).

Analysis of Variance↗
PubMed2000

Oxidative DNA damage in human lymphocytes: correlations with plasma levels of alpha-tocopherol and carotenoids.

In order to investigate whether oxidative damage is associated with differences in antioxidant intake, we measured the levels of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodGuo) in lymphocytes and alpha-tocopherol and several carotenoids in plasma of women with different dietary habits. We found that women from Granada (Spain), a region with a typically Mediterranean diet, had significantly higher levels of 8-oxodGuo compared with Malmö (Sweden), a region with a Northern European dietary intake pattern (2.30 +/- 0.78 versus 1.59 +/- 1.01 8-oxodGuo/10(-6) deoxyguanosine). Levels of plasma alpha-tocopherol and carotenoids were higher in Granada and these values were significantly positively correlated with levels of 8-oxodGuo. Our results do not support the hypothesis that a Mediterranean diet rich in alpha-tocopherol and carotenoids protects cells against oxidative DNA damage. It is possible, however, that consumption of foods other than fruits and vegetables, including fats, are responsible for the higher levels of 8-oxodGuo in Granada. Further studies are warranted to better elucidate the role of antioxidants in the modulation of oxidative stress in vivo.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Diet, smoking and anthropometric indices and postmenopausal bone fractures: a prospective study.

OBJECTIVE: Bone fractures are an important cause of morbidity and mortality among the elderly in the US. The present study assesses the possible role of a number of risk factors for postmenopausal bone fractures. METHODS: We analysed the relationships of anthropometric, demographic and lifestyle factors with the risk of bone fracture among 6250 postmenopausal women in a prospective cohort study, the New York University Women's Health Study. RESULTS: After an average of 7.6 years of follow-up, 1025 new incident bone fractures were reported, including 34 hip and 159 wrist fractures (incidence rates; 71.6 and 334.7 per 105 woman-years, respectively). The risk of fracture increased with increasing age, body height and total fat intake, while it was significantly lower among obese and African American women. The relative risk among African Americans was 0.45 (95% CI: 0.32-0.63) compared with non-African Americans. Women taller than 170 cm had a 64% increase in risk of fractures, as compared with those under 155 cm. These associations were generally more pronounced when fractures were limited to those at the hip and wrist. CONCLUSIONS: The present study provides an indication for a potential role of dietary fat in the development of postmenopausal fractures and further evidence to support protective effects of obesity, short stature and African American ethnicity.

Adult↗
PubMed2000

Variance and confidence limits in validation studies based on comparison between three different types of measurements.

BACKGROUND: The methods used in epidemiological studies to assess exposure are often affected by a conspicuous amount of measurement error. Exposure-measurement error is recognised to cause attenuation in the association between exposure and disease. Among different possible approaches, the validity coefficient of a measurement can be estimated by a comparison of three types of measurements, using either structural equation models or factor analysis (the triads method). These approaches assume that the measurements are linearly related to true intake and have independent random errors. METHODS: In this paper we present an estimator of the variance of the estimated validity coefficient to compute the associated confidence intervals. Standard error for the validity coefficient allows the efficiency of validation studies to be evaluated. Our work was motivated by the fact that existing software does not provide correct standard errors for the estimated validity coefficient. The approach is illustrated using selected examples from dietary validation studies. RESULTS: The accuracy of our formula is evaluated by comparison with the results of a simulation study, which shows that our variance estimator provides good results for sample sizes of at least n = 100 and when the expected value of the validity coefficient is not too close to 1.0, independent of the sample size. Our estimator formula performs better than either a naïve approach, that computes the standard error for a validity coefficient as if it is a straightforward correlation coefficient, or the SAS-CALIS procedure, which uses a maximum likelihood method. CONCLUSIONS: In evaluating the validity of the type of measurement chosen to assess exposure in an epidemiological study, it is important to provide an estimate of the precision of the validity coefficient of the measurement. Our variance estimator may help calculate sample size requirements for validation studies.

Analysis of Variance↗
PubMed1999

Fatty-acid composition in serum phospholipids and risk of breast cancer: an incident case-control study in Sweden.

The study of the relationship between dietary intake of fatty acids and the risk of breast cancer has not yielded definite conclusions with respect to causality, possibly because of methodological issues inherent to nutritional epidemiology. To evaluate the hypothesis of possible protection of n-3 polyunsaturated fatty acids (PUFA) against breast cancer in women, we examined the fatty-acid composition of phospholipids in pre-diagnostic sera of 196 women who developed breast cancer, and of 388 controls matched for age at recruitment and duration of follow-up, in a prospective cohort study in Umeâ, northern Sweden. Individual fatty acids were measured as a percentage of total fatty acids, using capillary gas chromatography. Conditional logistic-regression models showed no significant association between n-3 PUFA and breast-cancer risk. In contrast, women in the highest quartile of stearic acid had a relative risk of 0.49 (95% confidence interval, 0.22-1.08) compared with women in the lowest quartile (trend p = 0.047), suggesting a protective role of stearic acid in breast-cancer risk. Besides stearic acid, women in the highest quartile of the 18:0/18:1 n-9c ratio had a relative risk of 0.50 (95% confidence interval, 0.23-1.10) compared with women in the lowest quartile (trend p = 0.064), suggesting a decrease in breast-cancer risk in women with low activity of the enzyme delta 9-desaturase (stearoyl CoA desaturase), which may reflect an underlying metabolic profile characterized by insulin resistance and chronic hyper-insulinemia.

Breast Neoplasms↗
PubMed1999

Iron intake, body iron stores and colorectal cancer risk in women: a nested case-control study.

Accumulated evidence suggests that increased body iron stores may increase the risk of colorectal cancer, possibly via catalyzing oxidation reactions. We examined the relationship between iron status and colorectal cancer in a case-control study nested within the New York University Women's Health Study cohort. For 105 incident cases of colorectal cancer with an average follow-up of 4.7 years and 523 individually matched controls, baseline levels of serum iron, ferritin, total iron binding capacity (TIBC) and transferrin saturation were determined as indicators of body iron stores, and total iron intake was assessed based on their diet and supplement intake. Overall, there were no associations between the risk of colorectal cancer and any of these indices except for serum ferritin, which showed a significant inverse association. When analyzed by subsite, there was an increasing trend in risk of cancer of the proximal colon with increasing total iron intake (p-value for trend = 0.04). In addition, a significantly increased risk of colorectal cancer associated with higher total iron intake [odds ratio (OR) = 2.50; 95% confidence interval (CI): 1.06-5.87] was observed among subjects with higher intake of total fat. Our results do not support a role of increased body iron stores in the development of colorectal cancer, but suggest that luminal exposure to excessive iron may possibly increase the risk in combination with a high fat diet.

Adult↗
PubMed1999

Structure of the standardized computerized 24-h diet recall interview used as reference method in the 22 centers participating in the EPIC project. European Prospective Investigation into Cancer and Nutrition.

A computerized 24-h diet recall interview program (EPIC-SOFT) was developed for use in a large European multi-center study, namely the European Prospective Investigation into Cancer and Nutrition (EPIC). This program, which was adapted for each participating country and translated into nine languages, was developed to standardize interviews between the 22 EPIC centers. Common rules were pre-entered into the system to describe, quantify and probe approximately 1500-2200 foods and 150-350 recipes. Common methods used to classify and export the EPIC-SOFT dietary data facilitate their exchange, comparison and analysis. So far, EPIC-SOFT is the only available computerized 24-h diet recall system developed to provide comparable food consumption data between several European countries.

Databases, Factual↗
PubMed1999

Epidemiologic correlates with menstrual cycle length in middle aged women.

While irregular menstruations have been associated with lower cumulative exposure to the ovarian steroids, shorter regular cycles have been postulated to increase the cumulative exposure. Epidemiological correlates with menstrual patterns were analyzed among 4900 premenopausal women aged 45 or younger from the New York University Women's Health Study. The length of regular menstrual cycles increased with increasing age at menarche, body mass index and parity, but decreased with age, nonwhite racial background and current smoking. The likelihood of irregular cycles increased with increasing age, body mass index and number of cigarettes smoked per day. With adjustment for age, body mass index and number of cigarettes smoked per day, the risk of irregular cycles was marginally positively associated with total fat intake.

Adult↗
PubMed1999

Intake of specific carotenoids and flavonoids and the risk of gastric cancer in Spain.

OBJECTIVES: To investigate the relationship between gastric cancer and the intake of specific carotenoids (alpha-carotene, beta-carotene, lutein, and lycopene) and flavonoids (quercetin, kaempferol, myricetin, and luteolin) using new data on their concentration in foods. METHODS: Case-control study carried out in Spain that included 354 cases of gastric cancer and 354 controls, matched by age, gender, area of residence and hospital. Usual food intake was assessed using a dietary history questionnaire. RESULTS: In a multivariate model adjusted for several dietary factors, no association was found between intake of any of the studied carotenoids and the risk of gastric cancer. The adjusted OR of gastric cancer for the highest quartile of total flavonoid intake versus the lowest quartile was 0.44 (95 percent confidence interval [CI] = 0.25-0.78; P for trend = 0.003). Kaempferol intake was found to be protective (OR = 0.48; CI = 0.26-0.88; P for trend = 0.04) comparing the highest versus the lowest quartile of intake. A trend toward lower risk of stomach cancer with higher intake of quercetin was also found. CONCLUSIONS: The results of this study support the hypothesis that the well-established protective effect of fruit and vegetables against gastric cancer could, in part, be due to the presence of flavonoids.

Adult↗
PubMed1999

Epidemiologic correlates of serum folate and homocysteine levels among users and non-users of vitamin supplement.

Lower serum folate and higher serum homocysteine levels are known risk factors for various conditions. Thus, epidemiologic correlates with these measurements were studied for 256 multivitamin users and 230 non-users who were middle-aged women. Both serum folate and homocysteine levels increased with advancing age in both multivitamin users (P < 0.01 and P < 0.01) and non-users (P = 0.08 and P < 0.01). Among non-users, higher intake of vegetables, fruits, cold cereals and total protein were associated positively with serum folate and inversely with homocysteine levels. There were 25-74% increases in serum folate and 10-15% decreases in serum homocysteine between 1st and 4th quartiles of intake of these food/nutrients. In addition, 26% lower serum folate and 18% higher serum homocysteine were observed for those smoking 20 or more cigarettes per day compared with non-smokers. Among multivitamin users, body weight was correlated inversely with serum folate (P < 0.01) and positively with serum homocysteine levels (P = 0.04), while no correlates were found among lifestyle factors. Regular use of multivitamins increased serum folate about fourfold and decreased homocysteine twofold. These results suggest that multivitamin use can offset the effects of an unhealthy lifestyle on these serum markers, and that levels of serum folate and homocysteine can also be favorably influenced by healthier diet and abstinence from smoking.

Adult↗
PubMed1999

Serum folate, homocysteine and colorectal cancer risk in women: a nested case-control study.

Accumulating evidence suggests that folate, which is plentiful in vegetables and fruits, may be protective against colorectal cancer. The authors have studied the relationship of baseline levels of serum folate and homocysteine to the subsequent risk of colorectal cancer in a nested case-control study including 105 cases and 523 matched controls from the New York University Women's Health Study cohort. In univariate analyses, the cases had lower serum folate and higher serum homocysteine levels than controls. The difference was more significant for folate (P < 0.001) than for homocysteine (P = 0.04). After adjusting for potential confounders, the risk of colorectal cancer in the subjects in the highest quartile of serum folate was half that of those in the lowest quartile (odds ratio, OR = 0.52, 95% confidence interval, CI = 0.27-0.97, P-value for trend = 0.04). The OR for the highest quartile of homocysteine, relative to the lowest quartile, was 1.72 (95% CI = 0.83-3.65, P-value for trend = 0.09). In addition, the risk of colorectal cancer was almost twice as high in subjects with below-median serum folate and above-median total alcohol intake compared with those with above-median serum folate and below-median alcohol consumption (OR = 1.99, 95% CI = 0.92-4.29). The potentially protective effects of folate need to be confirmed in clinical trials.

Aged↗
PubMed1999

Comparison of nutrients in the food composition tables available in the nine European countries participating in EPIC. European Prospective Investigation into Cancer and Nutrition.

Food composition tables were studied from nine European countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC): Denmark, France, Germany, Greece, Great Britain, Italy, The Netherlands, Spain and Sweden. They were compared from the point view of availability, definition, analytical methods, and mode of expression of the nutrients of interest for EPIC, and it was seen that most of the nutrients in the tables are analysed and expressed in a compatible way. For some nutrients, however, common methods and definitions (folate, dietary fibre), or modes of expression (energy, protein, carbohydrates, carotenes, vitamin A and E) have not yet been agreed upon, so values are not comparable. For vitamin C a wide range of values are found due to the high natural variation in foods. For compiled tables, an additional problem is the use of several sources which may mean that the nutritional values are not comparable within the same table; and these values cannot be converted if the source is not stated. In addition, some tables were compiled using food composition values produced over 20 years ago with outdated analytical methods. In view of the inconsistent values for some nutrients and due to the large amount of foods reported within EPIC, it was concluded that standardised food composition tables have to be developed for the nine European countries involved in EPIC in order to provide comparable nutrient intake data.

Databases, Factual↗