Date of Award:

2006

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Advisor/Chair:

Ronald G. Munger

Abstract

The relationship between milk intake and risk of osteoporotic fractures is uncertain. Associations between milk intake and milk avoidance in relation to osteoporotic hip fracture were examined in the Utah Study of Nutrition and Bone Health (USNBH), a statewide case-control study. Cases were ascertained at Utah hospitals treating 98 percent of hip fractures during 1997-2001 and included 1188 men and women aged 50-89 years. Age- and gender-matched controls were randomly selected from Utah driver's license and Medicare databases (N= 1324). In-person interviews were conducted and participants reported frequency of milk intake per week at age 18 and during pregnancy among women who reported being pregnant. Milk avoidance for a period of more than one year and duration of milk avoidance were also reported. Diet and supplement intake in the one-year period before fracture (cases) or the interview (controls) was assessed using a picture-sort food frequency questionnaire. Milk consumption frequency was categorized into four levels of intake at each life stage. Total calcium intake was categorized into quintiles of distribution of intake. Logistic regression models were used to examine associations between milk intake and milk avoidance and risk of hip fracture while controlling for the potential confounding effects of gender, age, body mass index, alcohol use, smoking, physical activity, estrogen use, and total calorie, protein, calcium, and vitamin D intake. Recent milk intake, milk intake during pregnancy, and milk avoidance duration were not associated with risk of hip fracture. A borderline association was found at age 18 showing a decreased risk of hip fracture among those in the highest quartile (2: 15 cups of milk per week) of milk intake (odds ratio (OR): 0.86, 95 percent confidence interval (Cl): 0.75, 1.00; P = 0.046). Milk avoidance for a year or more was associated with an increased risk of hip fracture compared to those who did not avoid milk (OR: 1.38, 95 percent CI: 1.07, 1.78). A significant interaction was found between milk avoidance and quintile of total calcium intake (P = 0.02). Milk avoidance was associated with a significantly higher risk of hip fracture at the lowest two quintiles of calcium intake (OR: 1.72, 95 percent CI: 1.26, 2.17; P = 0.02 and OR: 1.58, 95 percent CI: 1.01, 2.15; P = 0.01, respectively) but was not associated with elevated risk among those with higher calcium intakes. In conclusion, milk intake during pregnancy for women, and in the year before hip fracture (for cases) or before interview (for controls), was not associated with hip fracture risk. The highest level of milk intake at age 18 was associated with decreased risk of hip fracture. Avoidance of milk for one year or more was associated with hip fracture risk, but only among those with low calcium intake (Q1 and Q2).

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