Vitamin D, Diet and Activity Study
Condition: Breast Cancer; Obesity; Hypovitaminosis D
MeSH terms: Breast Neoplasms; Rickets; Avitaminosis; Vitamin D Deficiency
Study type: Interventional

Summary: 
      Experimental and human data suggests that vitamin D could protect against breast cancer.
      Overweight/obese individuals are at increased risk of low vitamin D levels. Vitamin D may
      reduce production of fat tissue, thereby reducing weight gain, which would result in lower
      levels of adipose-derived hormones and other breast cancer risk factors.The purpose of this
      study is to test the effect of vitamin D supplementation on the response to a weight loss
      (diet + exercise) intervention and select breast cancer risk factors in overweight and obese
      postmenopausal women with low blood vitamin D levels.
    

Detailed description: 
      Objective: To test the incremental effect of vitamin D supplementation (2000 IU/day) in 228
      overweight and obese postmenopausal women with low blood vitamin D levels on response to a
      weight loss (diet + exercise) intervention in a double-blind placebo-controlled clinical
      trial.

      Primary Aim:

      • Determine the effects of 12-months vitamin D supplementation vs. placebo on weight loss in
      women following a weight loss diet and exercise program.

      Secondary Aims:

        -  Determine the effects of 12-months vitamin D vs. placebo on blood biomarkers associated
           with increased breast cancer risk (insulin, glucose, CRP).

        -  Test 12-months vitamin D effects on muscle strength as measured by 1RM leg press and
           bench press in women undergoing weight loss.

        -  Test the effect of 12-month vitamin D supplementation on effects on quality of life
           (QOL) in women undergoing weight loss.

      Additional Aims:

        -  In a 50% subset of women, test the effect of 12-month vitamin D supplementation vs.
           placebo on breast epithelial cell cytomorphology (quantified by the Masood cytology
           index) obtained through random periareolar fine needle aspiration (RPFNA).

        -  Collect subcutaneous abdominal fat aspirations in the 50% subsample of women.

      OUTLINE: This is a randomized study. Participants are stratified according to body mass index
      (< 30 vs ≥ 30) and RPFNA-consent. All participants will receive a 6-month weight loss
      intervention (prescribed weight loss goal of 10% of initial body weight) followed by 6
      months' maintenance therapy.

      Baseline, 6-, and 12-month measurements will include weight, BMI, waist and hip
      circumference, serum 25-hydroxyvitamin D, fasting blood samples, and questionnaires on
      details of diet especially items containing vitamin D, physical activity levels, sun exposure
      including clothing and sunscreen habits, dietary supplement and vitamin use, and medications.
    

Intervention name(s): Vitamin D; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): 2000 IU per day of Vitamin D; 1 Placebo per day
Other intervention name(s): calciferol; Sugar pill
Intervention MeSH terms: Vitamin D
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Keywords: Vitamin D; lifestyle intervention; postmenopausal women