We evaluated whether the adipose tissue content of 2 fatty acids of exogenous origin specific for ruminant fat, 15:0 and 17:0, reflect average long-term dairy fat consumption in free-living subjects. In 81 healthy women aged 30-77 y, we compared the relative content of these 2 fatty acids in subcutaneous adipose tissue with relative intake (% of total fat) based on four 1-wk weighed diet records made 3-4 mo apart and on a food-frequency questionnaire reflecting average past year consumption. The mean (+/-SD) daily milk fat intake was 20.0 +/- 9.1 g and fat from ruminant meat was 3.0 +/- 1.5 g according to food records, representing 29.2 +/- 8.9% and 4.6 +/- 2.2% of total fat, respectively. The intake of 15:0 and 17:0, which are 1.05% and 0.61% of milk fat and 0.43% and 0.83% of ruminant meat fat, was 0.22 +/- 0.10 and 0.15 +/- 0.06 g, respectively. Content of 15:0 and 17:0 in adipose tissue was 0.35% and 0.24% and relative dietary intake was 0.33% and 0.22% according to the food records and 0.32% and 0.21%, respectively, according to the food-frequency questionnaire. Correlation coefficients between 15:0 content in adipose tissue and intake from dairy foods only, according to food records, were 0.63 (Pearson) and 0.59 (Spearman); corresponding values for 17:0 were 0.42 and 0.45, respectively. Content of 15:0 and 17:0 in subcutaneous adipose tissue might be a valid biological marker of long-term milk fat intake in free-living individuals in populations with high consumption of dairy products.

Our results indicate that various types of fat may have specific opposite effects on the risk of breast cancer that closely resemble the corresponding effects in experimental animals. Research investigations and health policy considerations should take into account the emerging evidence that monounsaturated fat might be protective for risk of breast cancer.

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Dietary antioxidant vitamins and retinol have been proposed to be protective against breast cancer on the basis of their ability to reduce oxidative DNA damage and their role in cell differentiation. Epidemiologic studies have not been convincing in supporting this hypothesis, but women with high exposure to free radicals and oxidative processes have not been specifically considered. We explored these issues in the Swedish Mammography Screening Cohort, a large population‐based prospective cohort study in Sweden that comprised 59,036 women, 40–76 years of age, who were free of cancer at baseline and who had answered a validated 67‐item food frequency questionnaire. During 508,267 person‐years of follow‐up, 1,271 cases of invasive breast cancer were diagnosed. Cox proportional hazards models were used to obtain hazard ratios (HRs) and 95% confidence intervals (CIs). There was no overall association between intake of ascorbic acid, beta‐carotene, retinol or vitamin E and breast cancer incidence. High intake of ascorbic acid was inversely related to breast cancer incidence among overweight women (HR=0.61; 95% CI 0.45–0.82, for highest quintile of intake among women with body mass index>25 kg/m2) and women with high consumption of linoleic acid (HR=0.72; 95% CI 0.52–1.02, for highest quintile of ascorbic acid intake and average consumption of more than 6 grams of linoleic acid per day). Among women with a body mass index of 25 or below, the hazard ratio for breast cancer incidence was 1.27 (95% CI 0.99–1.63), comparing the highest to the lowest quintile of ascorbic acid intake. Consumption of foods high in ascorbic acid may convey protection from breast cancer among women who are overweight and/or have a high intake of linoleic acid. © 2001 Wiley‐Liss, Inc.

Objective: We studied whether the validity of fat estimates from food frequency questionnaires (FFQ) can be increased by using in nutrient calculation an additional qualitative information about the type of fat and reduced consumption of visible fat and skin. Design: A random sample of women answered an 88-item self-administered FFQ and performed 461-week weighed dietary records (DR). Setting: Uppsala County in central Sweden. Subjects: One hundred and eighty-four women aged 30±77 y, with FFQ and complete DR; 73 women with subcutaneous adipose tissue (AT) samples. Methods: Fat intake from the FFQ was calculated with/without use of qualitative information and compared to DR and fat composition of AT. Main outcome measures: Estimates of long-time intake of total fat, saturated, monounsaturated, polyunsaturated fat and ten speci®c fatty acids based on FFQ, DR and composition of AT. Conclusions:The increase in the validity of fat estimates due to use of qualitative information about fat was negligible; energy adjustment had greater impact than asking additional questions. Sponsorship: The study was supported by grants from the Swedish Cancer Society.