M.S. (Master of Science)
Department of Human and Family Resources
Women--United States--Nutrition||Iron in the body||Tea--Physiological effect||Health surveys--United States||Nutrition surveys--United States||Coffee--Physiological effect
Acute laboratory studies have demonstrated that the concentration and volume of coffee and tea consumed with or after a meal inhibits nonheme iron absorption which may eventually lead to iron deficiency. However, no epidemiological studies have focused on the relationship between habitual coffee and tea consumption and iron deficiency among adult populations. Premenopausal women above the age of 19 years were selected from the NHANES II population of 20,322 subjects for this study since they are most prone to iron deficiency. Of the 2,960 premenopausal women, 664 met the study criteria of not having any condition that would affect iron status other than dietary factors which included having a pregnancy within 12 months prior to the survey, taking medications or iron supplements, or suffering from blood loss or inflammatory or infectious disease. Subjects were classified as iron-deficient if two of the three indicators of iron status according to the MCV model were abnormal: mean corpuscular volume, transferrin saturation, and erythrocyte protoporphyrin. Using this model, 595 subjects were found to be normal and 69 subjects were iron-deficient. Coffee consumption of the premenopausal women ranged from 0 to 20 cups per day and tea consumption ranged from 0 to 10 cups per day. The mean beverage consumption of the women was 2.25 cups per day and did not differ significantly between normal and iron-deficient groups. Chi square analysis showed no difference in the frequency of iron deficiency among 3 levels of coffee and/or tea consumption: 1) 0-1 cup per day (no. = 263); 2) 2-5 (no. = 294); 3) 6 or more (no. = 107). No significant difference in the mean consumption of dietary variables important to iron nutrition which included meat, fish, poultry, organmeats, fruits and vegetables rich in vitamin C, all fruits and vegetables, legumes, grains and cereals, eggs, iron, or Vitamin C was found between normal and deficient subjects. Income level of the iron-deficient women was significantly lower, and irondeficient women had twice as many children. Even when subjects who reported habitually drinking 8 or more cups of coffee and/or tea per day were compared to subjects who never consumed these beverages, only serum iron, which was within the normal range for both groups, was significantly lower in the heavy beverage-consuming group. No other iron status indexes were found to be different. Women drinking 8 or more cups per day of coffee and/or tea were significantly older, had twice as many children, and had a mean Vitamin C intake of 97% of the RDA which was significantly lower than the Vitamin C intake of the women who never drank coffee and/or tea. Although laboratory studies have shown inhibition of nonheme iron absorption by coffee and tea, which would eventually lead to depletion of iron stores, habitual consumption of heavy amounts of coffee and tea was not found to affect the iron status of this vulnerable group of the NHANES II subpopulation.
Mating, Mary J., "The relationship of coffee and tea consumption with iron status among premenopausal women in the second national health and nutrition examination survey" (1987). Graduate Research Theses & Dissertations. 6191.
Northern Illinois University
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