PubMed Health⌕ Search

Biomedical subjects

G Block

Publications and source records attributed to G Block.

At least 55 records · Page 3Linked to original sources
PubMed1992

Fruit, vegetables, and cancer prevention: a review of the epidemiological evidence.

Approximately 200 studies that examined the relationship between fruit and vegetable intake and cancers of the lung, colon, breast, cervix, esophagus, oral cavity, stomach, bladder, pancreas, and ovary are reviewed. A statistically significant protective effect of fruit and vegetable consumption was found in 128 of 156 dietary studies in which results were expressed in terms of relative risk. For most cancer sites, persons with low fruit and vegetable intake (at least the lower one-fourth of the population) experience about twice the risk of cancer compared with those with high intake, even after control for potentially confounding factors. For lung cancer, significant protection was found in 24 of 25 studies after control for smoking in most instances. Fruits, in particular, were significantly protective in cancers of the esophagus, oral cavity, and larynx, for which 28 of 29 studies were significant. Strong evidence of a protective effect of fruit and vegetable consumption was seen in cancers of the pancreas and stomach (26 of 30 studies), as well as in colorectal and bladder cancers (23 of 38 studies). For cancers of the cervix, ovary, and endometrium, a significant protective effect was shown in 11 of 13 studies, and for breast cancer a protective effect was found to be strong and consistent in a meta analysis. It would appear that major public health benefits could be achieved by substantially increasing consumption of these foods.

Diet Surveys↗
PubMed1992

Comparison of two dietary questionnaires validated against multiple dietary records collected during a 1-year period.

The validity of two dietary history questionnaires was examined, one the Health Habits and History Questionnaire (HHHQ) developed by Block et al and the other a questionnaire developed by investigators at the University of Michigan (UM). The reference data consisted of the mean of four 4-day dietary records and recalls collected for 1 year before administration of the questionnaires. The sample of 85 persons included black and white men and women aged 25 to 50 years. The HHHQ was entirely self-administered; the UM questionnaire had both self- and interviewer-administered components. The HHHQ group means were similar to food record estimates for energy and most nutrients, whereas the UM questionnaire produced overestimates for energy and all nutrients examined. Correlations ranged from .31 to .60 (median = .48) for the UM questionnaire and from .42 to .68 (median = .57) for the HHHQ. Use of respondent-reported portion sizes with the HHHQ produced higher correlations than use of investigator-determined "standard" portion sizes (median r = .43 vs .57). Food frequency questionnaires can provide useful nutrient data for individuals as well as groups.

Adult↗
PubMed1992

Telephone surveys as a method for obtaining dietary information: a review.

The use of telephone surveys has increased significantly in the past decade. One advantage of telephone surveys is the ability to reach a large number of individuals: 97% of the US population owns telephones. Another advantage is cost savings: telephone surveys cost as little as one quarter to one half the amount of face-to-face surveys. Computer-assisted telephone interviewing has improved data collection, coding, and analysis. Random-digit dialing and a number of statistical advances such as weighting and stratification have significantly enhanced sample selection and research design of telephone surveys. The increasing need to collect dietary information from populations in an affordable fashion has expanded the use of telephone dietary surveys. To date, telephone dietary surveys have been used for follow-up after initial face-to-face contact has been made. The most common dietary instruments used are the 24-hour recall and the food frequency questionnaire. This review indicates that well-designed and well-administered telephone surveys are as good as, and may be better than, other methods for obtaining dietary information.

Bias↗
PubMed1992

Estimates of nutrient intake from a food frequency questionnaire: the 1987 National Health Interview Survey.

Nutrient intake data are reported from a 60-item food frequency questionnaire administered in the 1987 National Health Interview Survey to a representative sample of US adults 18 to 99 years of age (n = 22,080). These data provide for the first time an estimate of the distribution of usual nutrient intakes in a national probability sample. For several nutrients, 10% to 25% of respondents may habitually consume substantially less than the Recommended Dietary Allowance, despite apparently adequate group means. Hispanics reported higher energy and carbohydrate intakes and a lower percentage of energy from fat than blacks or whites (35.6%, 38.4%, and 38.7% of energy from fat for Hispanics, blacks, and whites, respectively.) Whites had lower cholesterol intake than the other two groups, and blacks had a higher intake of sweets. Alcohol intake was lower among women and persons older than 65 years, but no other differences in alcohol intake emerged. Use of adjustment factors improved nutrient intake estimates from this shortened questionnaire to levels similar to those obtained from other national dietary surveys. The nutrient intake data from this research can be used to compare demographic subgroups and to describe the mean and distribution of nutrient intake. Furthermore, this research provides national reference data to investigators who use this or related questionnaires in nutrition research.

Adolescent↗
PubMed1991

An evaluation of a food frequency questionnaire for assessing dietary intake of specific carotenoids and vitamin E among low-income black women.

The National Cancer Institute diet questionnaire was evaluated for use in a low-income black population. Data were collected from 91 women aged 30-69 years who were hospital outpatients in Atlanta, Georgia, June through August, 1988. Six ethnic and regional foods added to the questionnaire were found to be important contributors to intakes of several nutrients. Although 17 records were identified as containing probable recording or reporting errors, intakes of carotenes, alpha-carotene, beta-carotene, cryptoxanthin, and vitamin E were significantly and positively associated with serum levels of their referent nutrients. Among nonsmokers, correlation coefficients ranged from 0.32 to 0.45, adjusted for age, body mass index, alcohol and calorie intakes, medications and vitamin supplement use, and serum cholesterol and triglycerides. When questionnaires containing identified errors were omitted, correlations ranged from 0.30 to 0.54. There were no correlations between dietary intakes of lycopene and lutein and blood levels (-0.06 to 0.09). Among smokers, diet-serum correlations were reduced (0.00 to 0.32). These correlations are similar to those reported in research on vitamin E and carotenoids in other populations. These results suggest that the questionnaire is as valid for use in this population as it is in other populations.

Adult↗
PubMed1991

Vitamin C and cancer prevention: the epidemiologic evidence.

Epidemiologic evidence of a protective effect of vitamin C for non-hormone-dependent cancers is strong. Of the 46 such studies in which a dietary vitamin C index was calculated, 33 found statistically significant protection, with high intake conferring approximately a twofold protective effect compared with low intake. Of 29 additional studies that assessed fruit intake, 21 found significant protection. For cancers of the esophagus, larynx, oral cavity, and pancreas, evidence for a protective effect of vitamin C or some component in fruit is strong and consistent. For cancers of the stomach, rectum, breast, and cervix there is also strong evidence. Several recent lung cancer studies found significant protective effects of vitamin C or of foods that are better sources of vitamin C than of beta-carotene. It is likely that ascorbic acid, carotenoids, and other factors in fruits and vegetables act jointly. Increased consumption of fruits and vegetables in general should be encouraged.

Ascorbic Acid↗
PubMed1991

Dietary guidelines and the results of food consumption surveys.

This review focuses on dietary guidelines regarding fruit and vegetable consumption; sources of the antioxidant micronutrients, beta-carotene and vitamin C; and survey data on the US population's actual consumption of these foods. The Dietary Guidelines for Americans recommended consumption of five or more servings of vegetables and fruits daily, as did the 1989 Diet and Health report, which also emphasized fruits and vegetables rich in vitamin C and carotenoids. In contrast with these recommendations and strong evidence for a beneficial effect, very few individuals in the United States even approach the recommended levels of intake. In the US NHANES II data, 41% of the population had no fruit on the survey day; only one fourth had a fruit or vegetable rich in vitamin A or in vitamin C. Only 10% consumed the recommended five servings. Efforts to increase consumption of these foods are needed to improve the diet and health of the population.

Diet Surveys↗
PubMed1991

Epidemiologic evidence regarding vitamin C and cancer.

Approximately 90 epidemiologic studies have examined the role of vitamin C or vitamin-C-rich foods in cancer prevention, and the vast majority have found statistically significant protective effects. Evidence is strong for cancers of the esophagus, oral cavity, stomach, and pancreas. There is also substantial evidence of a protective effect in cancers of the cervix, rectum, and breast. Even in lung cancer, for which carotenoids show a consistent protective effect, there is recent evidence of a role for vitamin C. Vitamin C is an important antioxidant and free radical scavenger in plasma and acts to regenerate active vitamin E in lipid membranes. Although several different factors in fruits and vegetables probably act jointly, the epidemiologic and biochemical evidence indicate an important role for vitamin C.

Ascorbic Acid↗
PubMed1991

An open multicenter trial of Sinemet CR in levodopa-naive Parkinson's disease patients.

It has been proposed that initiation of anti-Parkinson therapy with continuous release formulations of Sinemet might prevent or delay the development of adverse effects associated with chronic levodopa therapy employed in standard formulations. In anticipation of a prospective study comparing Sinemet to Sinemet CR in previously untreated Parkinson's disease patients, we evaluated Sinemet CR as primary therapy in 45 levodopa-naive Parkinson's disease patients in a 12 week, open-label, multi-center study. At the conclusion of the study, optimal results were obtained with levodopa administered as Sinemet CR in a total daily dose of 497 mg divided into 2.4 doses per day. Statistically significant improvement compared to baseline was observed for total Parkinson's score as well as each of rigidity, tremor, bradykinesia, gait and postural stability. Statistically significant improvement was also noted in total disability as well as in each of its components. Adverse experiences were mild and transient and no significant laboratory abnormalities were encountered. We conclude that a daily dose of 1 to 1.5 tablets b.i.d. of Sinemet CR as primary therapy for patients with Parkinson's disease is well tolerated and provides effective therapy.

Aged↗
PubMed1991

Dietary diversity in the US population, NHANES II, 1976-1980.

The extent of diversity in the diets of black and white adults (n = 11,658) aged 19 to 74 years was evaluated from 24-hour dietary recalls obtained in the second National Health and Nutrition Examination Survey. Each 24-hour recall was evaluated for the consumption of items from the dairy, meat, grain, fruit, and vegetable groups (Food Group Score). A second scoring method (Serving Score) evaluated every recall for consumption of at least two servings each from dairy, meat, fruit, and vegetable groups and four servings from the grain group. Only a third of the population surveyed reported consuming foods from all the food groups on the survey day; less than 3% reported consuming foods from all food groups in at least the recommended amount. Blacks scored lower on both types of diet diversity scores than whites. Both types of diversity scores showed a significant trend to increase with increasing income and level of education. Failure to consume any foods from the dairy, meat, grain, fruit, and vegetable groups was reported by 24%, 6%, 5%, 46%, and 18%, respectively, of the population on the survey day. The proportion of the population consuming at least the desired number of servings from each of these food groups was 51%, 71%, 29%, 29%, 61%, respectively. The results emphasize the need for major public campaigns directed at increasing the diversity of US diets. Special target groups include minorities and those with limited income and formal education.

Adult↗