Premenopausal breast cancer risk and intake of vegetables, fruits, and related nutrients.

BACKGROUND: Given the international variations in breast cancer incidence rates and the changes in breast cancer incidence among migrant populations, it has been hypothesized that diet is a factor influencing risk of this disease. Many studies indicate that a diet high in vegetables and fruits may protect against breast cancer. PURPOSE: We conducted a case-control study of diet, including the intake of non-food supplements, and premenopausal breast cancer risk. We evaluated in detail usual intake of vegetables and fruits (each measured as the total reported grams consumed for all queried vegetables and fruit), vitamins C and E, folic acid, individual carotenoids, and dietary fiber with its components. METHODS: Case patients (n=297) were identified through pathology records from hospitals in Erie and Niagara counties in western New York. They consisted of premenopausal women 40 years of age or oder who were diagnosed with breast cancer from November 1986 through April 1991. Control subjects (n=311), frequency-matched to case patients on the basis of age and county of residence, were randomly selected from New York State Department of Motor Vehicles records. In-person interviews included detailed reports of usual diet in the period 2 years before the interview. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: There was a reduction in risk associated with high intake of several nutrients. With the lowest quartile of intake as the referent, adjusted ORs for the highest quartile of intake for specific nutrients were as follows: vitamin C (OR=0.53; 95% CI=0.33-0.86), alpha-tocopheral (OR=0.55; 95% CI=0.34-0.88), folic acid (OR=0.50; 95% CI=0.31-0.82), alpha-carotene (OR=0.67; 95% CI=0.42-1.08) and beta-carotene (OR=0.46; 95% CI=0.28-0.74), lutein + zeaxanthin (OR=0.47; 95% CI=0.28.0-77), and dietary fiber from vegetables and fruits (OR=0.48; 95% CI=0.30-0.78). No association with risk was found for beta-cryptoxanthin, lycopene, or grain fiber. Fruits were weakly associated with a reduction in risk (fourth quartile OR=0.67; 95% CI=0.42-1.09). No association was found between breast cancer risk and intake of vitamins C and E and folic acid taken as supplements. A strong inverse association between total vegetable intake and risk was observed (fourth quartile OR=0.46; 95% CI=0.28-0.74). This inverse association was found to be independent of vitamin C,alpha-tocopherol, folic acid, dietary fiber, and alpha-carotene. Adjusting for beta-carotene or lutein + zeaxanthin somewhat attenuated the inverse association with vegetable intake. CONCLUSIONS: In this population, intake of vegetables appears to decrease premenopausal breast cancer risk. This effect may be related, in part, to beta-carotene and lutein + zeaxanthin in vegetables. It appears, however, that, of the nutrients and food components examined, no single dietary factor explains the effect. Evaluated components found together in vegetables may have a synergistic effect on breast cancer risk; alternatively, other unmeasured factors in these foods may also influence risk.

A diet history questionnaire ranks nutrient intakes in middle-aged and older men and women similarly to multiple food records.

We evaluated the reproducibility of a modified version of the National Cancer Institute diet history questionnaire and also studied comparability of nutrient estimates from this questionnaire to those from four 2-d food records. Subjects (n = 211) were from a population-based sample of middle-aged and older adults participating in the Beaver Dam Eye Study in south-central Wisconsin. Median age-specific correlation coefficients between the questionnaire, administered twice at a 3-mo interval, were 0.8 in men and 0.7 in women (range = 0.5 to 0.9). Questionnaire estimates of protein, cholesterol, thiamin, niacin, iron and zinc were consistently lower than food record estimates whereas estimates of fat were higher. Correlation coefficients between estimates from the questionnaire and records were generally > 0.5, indicating overall good agreement in ranking. However, the range in correlation coefficients was wide [ranging from 0.06 for iron (without supplements) in middle-aged women to 0.8 for alcohol in middle-aged men and women]. Questionnaire estimates similarly classified persons into the lowest two food record quintiles of intake 50 to 93% of the time depending on nutrient. These results suggest that the questionnaire produces nutrient estimates that rank individuals on the basis of intake of most nutrients similarly to estimates from multiple food records.

Nutrient supplements contribute to the dietary intake of middle- and older-aged adult residents of Beaver Dam, Wisconsin.

Intake of macronutrients and micronutrients was estimated from a diet history questionnaire in a population-based sample of persons (n = 2152), 43-86 y of age. Men and women 65 y of age or older consumed less protein, fat, cholesterol, niacin, riboflavin, calcium, iron, zinc and lycopene than their middle-aged counterparts. After including nutrient intake from supplements, age differences in intake were no longer significant for zinc in women or for niacin and iron in men. After further adjusting for energy intake, only protein, cholesterol, and lycopene mean intakes were lower in older compared with middle-aged men and women. Regular use of supplements was most prevalent among older men and women (40 and 48%, respectively). Supplement use was greater in the current time period compared with retrospective reports of supplement use 10 y before interview. The impact of supplement intake on median values of intake was greatest in women, particularly for vitamins A, C and E, riboflavin and calcium. The high prevalence of supplement use emphasizes the importance of considering this source of nutrients in future investigations in which dietary intake is measured.

Calcium intake and blood pressure in blacks and whites.

This study focuses on 1790 residents of Erie County, New York, over age 19, who participated in a study of blood pressure in 1986. Subjects were selected using a highly stratified sampling procedure to obtain a sample that included approximately equal numbers of blacks and whites in three educational strata (less than 12 years, 12 years, and more than 12 years of education). Calcium intake was estimated using questions regarding usual frequency of intake of foods high in calcium and of calcium-containing supplements and antacids. Calcium intake by normotensives tended to be higher than intake by hypertensives; differences were significant for females but not for males. Calcium intake was significantly inversely associated with systolic blood pressure for black females and diastolic blood pressure in black and white females after control for age, education, body mass index, smoking, and alcohol. For other sex-race groups, there was generally a trend (although not significant) toward decreased blood pressure with increased calcium intake. Diastolic blood pressure was inversely associated with calcium from milk and yogurt (but not cheese) for white females. A similar association (although not significant) was found for black females; no association was found for males. No differences were found between blacks and whites in response to calcium. This cross-sectional study provides some additional evidence of a protective effect of calcium intake on blood pressure in both black and white females.

Misclassification of nutrient intake of individuals and groups using one-, two-, three-, and seven-day food records.

In this study, 6,844 food records were collected during three years (1979-1982) from 106 volunteer Wisconsin women, aged 35-65 years. Subjects recorded all intake of food, and vitamin/mineral supplements on a structured, precoded form. One-, two-, three-, and seven-day records were compared with usual intake of calcium, kilocalories, vitamin A, and vitamin C. Usual intake was calculated using 37-72 food records per subject. Estimates of group means from a small number of records were not significantly different from mean usual intake (p greater than 0.05). Correlations with usual intake ranged from 0.43-0.64 and from 0.71-0.90 for the one day and the seven-day estimates, respectively. For the one-day record, 43-67% of subjects were correctly classified to the extreme quintiles of intake, 52-76% for the seven-day record. Classification was least good for vitamin A, better for other nutrients with lower intraindividual variance. However, overall agreement with usual classification of assignment to quintiles even with the seven-day record was less than 55% for all four nutrients. Effects at extremes of intake might be more easily analyzed than dose-response relations.

Relationships between usual nutrient intake and bone-mineral content of women 35-65 years of age: longitudinal and cross-sectional analysis.

In a 4-yr clinical trial, effect on single-photon absorptiometric measurements of arm bones of usual intakes of energy and 14 nutrients plus vitamin-mineral supplements was studied in 99 women, aged 35-65, randomly assigned to placebo (NS) or calcium-supplemented (1.5 g)(S) groups. Cross-sectional analysis of initial bone measurements showed vitamin C (r = 0.313, p less than 0.05) and niacin (r = 0.353, p less than 0.01) correlated with ulna in postmenopausal subjects (n = 67). Longitudinal analysis of bone-change rates of postmenopausal subjects (NS + S) showed higher calcium intakes associated with lower loss rates of humerus bone-mineral content (BMC) (r = 0.360, p less than 0.01). In postmenopausal NS but not S subjects, energy, protein, calcium, phosphorus, zinc, and folate correlate significantly with change in radius BMC; high levels of intake correlated with slower loss (p less than 0.05). Several nutrients besides calcium are related to bone loss in women.

Effects on blood pressure of calcium supplementation of women.

The relationship between dietary and supplemental (1.5 g/d) calcium intake and blood pressure was examined in 81 normotensive and 34 medicated hypertensive women between the ages of 35 and 65 years who completed a 4-yr clinical trial to assess age-associated bone loss in women. Calcium intakes were monitored during the entire study. Resting blood pressures and systolic blood pressure response (SBPR) to a stress test were recorded three times during the study. At the end of the study there was no relationship between systolic or diastolic blood pressure or SBPR and total calcium intake in normotensive women (n = 81). In the medicated hypertensive group (n = 34) there was a 13 mm Hg decrease in systolic pressure of supplemented women (n = 18) and a 7 mm Hg increase in unsupplemented women (n = 16) over the 4 yr (p less than .02).