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Biomedical subjects

G Block

Publications and source records attributed to G Block.

At least 37 records · Page 2Linked to original sources
PubMed1993

Vitamin and mineral status of women of childbearing potential.

Increasing data suggest a role for micronutrients in pregnancy outcome, and in some cases nutritional status must be adequate in the first weeks of pregnancy. We examined nationally representative survey data on women of childbearing age: the NHANES II data for serum measures of iron status and the CSFII four-day data for dietary measures of intake of protein, iron, zinc, folic acid, and vitamins A, C, and B6. For those nutrients, women below or near poverty had consistently lower levels, with median intakes below the RDA for all but protein (e.g., folic acid, 150 micrograms in contrast with the RDA of 180 for nonpregnant and 400 for pregnant women; for B6, 0.96 mg instead of 1.6 or 2.2). Even among women with incomes as high as three times the poverty level or more, large segments of the population had very low intakes. For example, the 25th percentile in that group was only 142 micrograms/day of folic acid, 4.6 alpha-tocopherol equivalents of vitamin E, 6.7 mg zinc, and 433 mg of calcium. Approximately 15% of women had low transferrin saturation.

Adolescent↗
PubMed1993

Dietary diversity and subsequent mortality in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study.

We examined the relation of dietary diversity to subsequent all-cause mortality by using data from the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, 1982-1987. The analytic cohort consisted of 4160 men and 6264 women (including 2556 deaths), 25-74 y at baseline (1971-1975). Twenty-four-hour dietary recalls were evaluated for variety among the five major food groups: dairy, meat, grain, fruit, and vegetable, with a dietary diversity score (DDS); consumption of each food group contributed 1 point to a maximum possible DDS of 5. Age-adjusted risk of mortality was inversely related to DDS (P < or = 0.0009) in men and women. The inverse diversity-mortality association was adjusted for potential confounders: education, race, smoking status, and dietary fiber intake; the relative risk of mortality in men and women consuming two or fewer food groups was 1.5 (95% CI 1.2-1.8) and 1.4 (95% CI 1.1-1.9), respectively. In conclusion, diets that omitted several food groups were associated with an increased risk of mortality.

Adult↗
PubMed1993

Problems with estimating vitamin C intakes.

The vitamin C content of foods was examined from two national databases and new values were obtained by HPLC. HPLC values were lower in four of the five highest vitamin C contributors to the US diet (orange juice, grapefruit, tomatoes and tomato juice, and potatoes), as well as in broccoli, red peppers, and cooked collard and mustard greens, compared with values from the other databases. When HPLC values were substituted in the Health Habits and History Questionnaire, the resulting estimates of dietary intake of vitamin C in two studies were lower. Despite these lower estimates of absolute intake, in one study the correlation between dietary vitamin C and plasma ascorbic acid was similar. In conclusion, the accuracy of the vitamin C content of foods is important for estimating the absolute amount of vitamin C intake in the population but may not change the ranking of people in epidemiological studies.

Ascorbic Acid↗
PubMed1993

The bioavailability to humans of ascorbic acid from oranges, orange juice and cooked broccoli is similar to that of synthetic ascorbic acid.

The relative bioavailability of ascorbic acid from several sources was compared in 68 male non-smokers. Subjects underwent two 8-wk ascorbic acid depletion-repletion cycles. In repletion, subjects were randomized to receive 108 mg/d ascorbic acid as tablets with or without iron, as orange segments or juice, or as raw or cooked broccoli with a crossover within each major treatment group (e.g., cooked to raw broccoli) for the second repletion. Relative ascorbic acid bioavailability was estimated based on the slope obtained from linear regression of plasma ascorbic acid on time during each repletion. In the first repletion, slopes for all groups were similar except for the group consuming raw broccoli (20% lower response, P < 0.01). Second repletion responses were attenuated, but were similar to the first repletion. Ascorbic acid ingested as cooked broccoli, orange juice or fruit, or in synthetic form seems to be equally bioavailable. The lower relative bioavailability of ascorbic acid from raw broccoli is unlikely to be of practical importance in mixed diets.

Adult↗
PubMed1993

Estrogen receptor status and dietary intakes in breast cancer patients.

We used data from a study of racial differences in cancer patient survival to examine the association between estrogen receptor status and the intake of nutrients and food groups among 689 black and white women, ages 20-79, with breast cancer newly diagnosed in 1985 and 1986. We reviewed medical records and collected interview data, including a 34-item food frequency questionnaire. Consistent with published reports, we found positive estrogen receptor status to be positively associated with age and inversely associated with parity and oral contraceptive use. Whites were more likely than blacks to have estrogen receptor-positive tumors. We examined eight nutrients and six food groups in multivariate analyses for association with estrogen receptor status. After adjusting for age, race, usual body mass index, and parity, a high percentage of calories from fat was associated with estrogen receptor-positive cancer, and a high percentage of calories from carbohydrates was associated with estrogen receptor-negative breast cancer. These findings indicate that women with breast cancer who are on diets with a high percentage of calories from fat may be more likely to develop estrogen receptor-positive cancers.

Adult↗
PubMed1992

Vitamin supplement use and reduced risk of oral and pharyngeal cancer.

Use of vitamin and mineral supplements was assessed in a population-based case-control study of oral and pharyngeal cancer, conducted during 1984-1985 in four areas of the United States. There was no association with intake of multivitamin products, but users of supplements of individual vitamins, including vitamins A, B, C, and E, were at lower risk after controlling for the effects of tobacco, alcohol, and other risk factors for these cancers. After further adjustment for use of other supplements, vitamin E was the only supplement that remained associated with a significantly reduced cancer risk. The adjusted odds ratio of oral and pharyngeal cancer for "ever regularly used" vitamin E was 0.5 (95% confidence interval 0.4-0.6). To the authors' knowledge, this is the first epidemiologic study to show a reduced oral cancer risk with vitamin E use. Although it is not clear that the lower risk among consumers of vitamin E supplements is due to the vitamin per se, the findings are consistent with experimental evidence and should prompt further research on the role of vitamin E and other micronutrients as inhibitors of oral and pharyngeal cancer.

Age Factors↗
PubMed1992

Glutathione in foods listed in the National Cancer Institute's Health Habits and History Food Frequency Questionnaire.

Glutathione (GSH) is an antioxidant and anticarcinogen that is present in plant and animal tissues that form the bulk of the human diet. Recent studies show that GSH is absorbed intact in rat small intestine and that oral GSH increases plasma GSH concentration in humans. To provide a database for epidemiological studies of dietary intake of GSH and risk of diseases in humans, we have measured the content of GSH in the foods listed in the National Cancer Institute's Health Habits and History Questionnaire. Foods were purchased in the Atlanta area and prepared as most commonly consumed in the United States. GSH analyses were performed using a high-performance liquid chromatography technique with a method of additions to correct for losses during sample preparation. A separate set of samples was run after treatment with dithiothreitol to measure the total of GSH and its disulfide forms (GSH). The results show that dairy products, cereals, and breads are generally low in GSH; fruits and vegetables have moderate to high amounts of GSH; and freshly prepared meats are relatively high in GSH. Frozen foods generally had GSH contents similar to fresh foods, whereas other forms of processing and preservation generally resulted in extensive loss of GSH. Thus this database will allow researchers to examine the relationship between dietary GSH and risk of cancers and other diseases.

Beverages↗
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↗