Vitamin D thread -Please use this for your Vit D info.

[R.B.]

Cancer Epidemiol Biomarkers Prev. 2010 Dec 2. [Epub ahead of print]
Joint effects of dietary vitamin D and sun exposure on breast cancer risk: results from the French E3N cohort.

Engel P, Fagherazzi G, Mesrine S, Boutron-Ruault MC, Clavel-Chapelon F.

1Nutrition, Hormones and Cancer, Inserm (Institut National de la Santé et de la Recherche Médicale) ERI 20, EA 4045, and Institut Gustave Roussy.
Abstract

BACKGROUND: Ecological studies have suggested that vitamin D production through UV solar irradiance could reduce breast cancer (BC) risk. Although studies restricted to dietary vitamin D intake have provided inconsistent results, little is known about the relationship between pre and postmenopausal BC and combined intakes from diet, supplements and sun exposure.

METHODS: Cox proportional hazards regression mvaluated the association between vitamin D intakes, mean daily Ultraviolet Radiation dose (UVRd) at the place of residence and risk of BC among 67,721 women of the French E3N cohort. All analyses were stratified on menopausal status taking into account important confounders including calcium consumption.

RESULTS: During 10 years of follow-up, a total of 2,871 BC cases were diagnosed. Dietary and supplemental vitamin D intakes were not associated with BC risk; however, in regions with the highest UVRd, postmenopausal women with high dietary or supplemental vitamin D intake had a significantly lower BC risk as compared to women with the lowest vitamin D intake (HR = 0.68, 95% CI: 0.54 - 0.85, and HR = 0.55, 95% CI: 0.36 - 0.90 respectively).

CONCLUSIONS: Our results suggest that a threshold of vitamin D exposure from both sun and diet is required to prevent BC and this threshold is particularly difficult to reach in postmenopausal women at northern latitudes where quality of sunlight is too poor for adequate vitamin D production.Impact:Prospective studies should further investigate associations between BC risk, vitamin D status and sunlight exposure.

[R.B.]

J Epidemiol. 2010 Dec 11. [Epub ahead of print]
Vitamin D Decreases Risk of Breast Cancer in Premenopausal Women of Normal Weight in Subtropical Taiwan.

Lee MS, Huang YC, Wahlqvist ML, Wu TY, Chou YC, Wu MH, Yu JC, Sun CA.

School of Public Health, National Defense Medical Center.
Abstract

Background: Evidence for an association between vitamin D status and breast cancer is now more convincing, but is uncertain in subtropical areas like Taiwan. This hospital-based case-control study examined the relationship of breast cancer with vitamin D intake and sunlight exposure.Methods: A total of 200 incident breast cancer cases in a Taipei hospital were matched with 200 controls by date of interview and menopausal status. Information on risk factors for breast cancer was collected in face-to-face interviews and assessed with reference to vitamin D intake (foods and nutrients) and sunlight exposure. Vitamin D intake was divided into quartiles, and threshold effect was evaluated by comparing Q2-Q4 with Q1.Results: After controlling for age, education, parity, hormone replacement therapy, body mass index (BMI), energy intake, menopausal status, and daily sunlight exposure, the risk of breast cancer in participants with a dietary vitamin D intake greater than 5 µg per day was significantly lower (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.24-0.97) than that of participants with an intake less than 2 µg per day. In analysis stratified by menopausal status and BMI, both dietary vitamin D and total vitamin D intakes were associated with a protective effect among premenopausal women. There was a significant linear trend for breast cancer risk and dietary vitamin D intake in premenopausal women (P = 0.02). In participants with a BMI lower than 24 kg/m(2) (ie, normal weight), dietary vitamin D intake was inversely related to breast cancer risk (P for trend = 0.002), and a threshold effect was apparent (Q2-Q4 vs Q1: OR, 0.46; 95% CI, 0.23-0.90).Conclusions: Vitamin D had a protective effect against breast cancer in premenopausal women of normal weight in subtropical Taiwan, especially an intake greater than 5 µg per day.