Walter C. Willett

A population-based case-control study of carotenoid and vitamin A intake and ovarian cancer (United States)

AbstractObjective: To evaluate the association between dietary intake of carotenoids and vitamin A and the incidence of ovarian cancer. Methods: We conducted a population-based case–control study of ovarian cancer in Massachusetts and Wisconsin. Incident cases diagnosed between 1991 and 1994 were identified through statewide tumor registries. We selected community controls at random from lists of licensed drivers and Medicare recipients; 327 cases and 3129 controls were included in the analysis. Data were collected by telephone interview, which included an abbreviated food and supplement list to quantify typical consumption of carotenoids (lutein/zeaxanthin, alpha-carotene, beta-carotene), retinol and total vitamin A at 5 years prior to diagnosis in cases, or to a comparable reference date in controls. Results were adjusted for age, state, and other risk factors. Results: Participants with the highest dietary intake of lutein/zeaxanthin (≥24,000 μg/week) experienced a 40% lower risk of ovarian cancer (95% CI = 0.36–0.99) compared to those with the lowest intake. Intake of alpha-carotene, beta-carotene, retinol and total vitamin A was unrelated to risk. Among foods, we observed non-significantly lower risks with high consumption of spinach, carrots, skim/lowfat milk and liver. Conclusion: These results support previous findings suggesting an inverse relationship between carotenoid intake and ovarian cancer risk.

Prospective assessment of exclusive breastfeeding in relation to weight change in women

OBJECTIVE: To study prospectively the relation of parity, prepregnancy body mass index (BMI), and exclusive breastfeeding to weight gain.DESIGN: The cohort of the Nurses Health Study II, with analysis restricted to women who were aged 24 to 40 y at baseline (1989), who had a history of no more than one past full-term pregnancy at baseline, gave birth to one child between 1990 and 1991, but had no other pregnancies during the follow-up.SUBJECTS: 1538 of the 33 082 nulliparous women and 2810 of the 20 261 primiparous, in 1989.MEASUREMENTS: Introduction of daily formula/milk was assumed to represent the end of exclusive breastfeeding period. Duration of exclusive breastfeeding was categorized into 0, 1–3, 4–7, 8–11, and 12 months or more.RESULTS: After adjusting for age, physical activity, and BMI in 1989, lactation was associated with a weight gain from 1989 to 1993 of approximately 1 kg (statistically significant only for women nulliparous in 1989 with a BMI <25 kg/m2 (P=0.02) and for those women primiparous in 1989, with a BMI ≥25 kg/m2 (P=0.04)) comparing women who breastfed with women who did not, and duration of lactation was unrelated to the magnitude of weight change (P>0.40 for all comparisons).CONCLUSIONS: Although promotion of breastfeeding has high priority because of its enormous advantages for a newborn child, the associated maternal weight reduction is minimal. Dietary guidelines for pregnant and breastfeeding women should include ways to prevent weight retention after parity.

Overall and abdominal adiposity and hypertriglyceridemia among Korean adults: the Korea National Health and Nutrition Examination Survey 2007–2008

Background/Objectives:Obesity is associated with increased triglyceride levels. We examined whether overall obesity (body mass index (BMI)) and abdominal obesity (waist circumference (WC)) are independently associated with hypertriglyceridemia among the Korean population.Subjects/Methods:A national sample of 5036 Koreans aged 19–64 was examined with cross-sectional surveys, the Korea National Health and Nutrition Examination Survey, in 2007 and 2008. BMI, WC and other lifestyle information were assessed.Results:We documented 1344 cases (26.7%) of hypertriglyceridemia (fasting triglycerides of >150 mg/dl). Both BMI and WC were each independently associated with hypertriglyceridemia. Multivariate odds ratios (ORs) of increasing categories of BMI (<18.5, 18.5⩽–<23, 23⩽–<25, 25⩽–<28, ⩾28 kg/m2), were 0.49, 1.00 (reference), 1.26, 1.63 and 1.84, respectively (P=0.0007) adjusting for WC. There was a positive association between WC and hypertriglyceridemia across increasing quintiles of WC (multivariate-adjusted ORs: 1.00 (reference), 1.54, 2.54, 2.21 and 2.36; P<0.0001), adjusting for BMI. WC was positively related to hypertriglyceridemia in both gender. However, only women’s BMI was independently associated with hypertriglyceridemia after adjusting for WC. The joint relation between BMI and WC and hypertriglyceridemia showed that within each BMI category, higher WC predicted a greater prevalence of hypertriglyceridemia and vice versa. The receiver operating characteristic curves indicated that BMI (0.69) and WC (0.72) were similar in predicting hypertriglyceridemia.Conclusions:Both BMI and WC were strongly independently associated with hypertriglyceridemia among the population. Both measurements should be considered for use in assessing health risk at clinical settings and epidemiologic research among Asian population.

Lactation in relation to postmenopausal breast cancer

A modest inverse association between lactation and breast cancer risk has most consistently been observed in premenopausal women, and certain breastfeeding patterns, such as prolonged duration and early age at first lactation, may be important determinants of risk. However, these associations have not generally been observed in relation to postmenopausal breast cancer. As part of a multicenter population-based case-control study, the authors examined postmenopausal breast cancer risk according to breastfeeding characteristics. Breast cancer patients aged 50-79 years were identified from statewide tumor registries in Massachusetts, New Hampshire, and Wisconsin from July 1992 through July 1995. Similarly aged control women were randomly selected from population lists. Information regarding lactation history and breast cancer risk factors was obtained through telephone interviews. This analysis included only data on parous postmenopausal women (3,633 cases and 3,790 controls). After adjustment for age, parity, age at first birth, and other breast cancer risk factors, breastfeeding for at least 2 weeks was associated with a slightly reduced risk of breast cancer in comparison with women who had never lactated (relative risk = 0.87, 95% confidence interval 0.78-0.96). There was only a modest suggestion that increasing cumulative duration of lactation was inversely associated with breast cancer risk; the relative risk for women who had breastfed for > or =24 months was 0.73 (95% confidence interval 0.56-0.94) (p-trend for duration = 0.10). Age at first lactation was not consistently associated with risk. Modest inverse associations appeared to persist even up to 50 years since first lactation. Use of hormones to suppress lactation was not associated with postmenopausal breast cancer, nor was inability to breastfeed related to risk. These results suggest that lactation may have a slight and perhaps long-lasting protective effect on postmenopausal breast cancer risk.