Anemia in Postmenopausal Women Linked With Poor Nutrition

Emma Hitt, PhD
Anemia is linked to poor nutrition in postmenopausal women, according to a recent observational study of the Women's Health Initiative (WHI).
Cynthia A. Thomson, PhD, RD, with the University of Arizona, in Tucson, and colleagues reported their findings in the April issue of the Journal of the American Dietetic Association.
According to the researchers, nutritional anemia includes those types associated with prolonged inadequate intake of folate, vitamin B₁₂, iron, protein, and vitamin C.
Dr. Thomson and colleagues hypothesized that a greater number of dietary inadequacies of these nutrients would be associated with a greater risk for incident and persistent anemia.
To evaluate their hypothesis, the researchers used data from the WHI observational cohort study (WHI-OS), which contained a longitudinal sample of postmenopausal women. A total of 93,676 postmenopausal women between the ages of 50 and 79 years were recruited at 40 clinical sites across the United States. Women were enrolled from 1993 until 1998, and data collection was completed in 2000.
Diet was assessed by a food frequency questionnaire for iron, vitamin B₁₂, folate, red meat, and cold breakfast cereal. Dietary intake for women older than 50 years was used as a reference to measure inadequacies. Anemia was defined as a blood hemoglobin concentration of less than 120 g/L in women. Persistent anemia was defined as anemia present at each measurement.
Anemia was identified in 3979 (5.5%) of the participants. Inadequate intake of anemia-associated nutrients was less frequent in non-Hispanic whites (7.4%) vs other racial or ethnic groups (14.6% - 16.3%).
Smoking, age, and body mass index were associated with anemia. Women with anemia reported a lower dietary intake of red meat, folate, vitamin B₁₂, vitamin C, and iron. In addition, deficiencies in dietary intake of 1 nutrient were associated with a 21% greater risk for persistent anemia (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.05 - 1.41), whereas 3 deficiencies in dietary intake resulted in a 44% increase in the risk for persistent anemia (OR, 1.44; 95% CI, 1.20 - 1.73).
Deficiencies in total intake of 1 nutrient were associated with a 34% increased risk for persistent anemia (OR, 1.34; 95% CI, 1.14 - 1.56). Regarding deficiencies in total intake of 3 nutrients, the risk increased to 56% (OR, 1.56; 95% CI, 1.25 - 1.95).
Editorial: Nutrient Measurements Costly
According to editorialists Lisa Tussing-Humphreys, PhD, RD, with the US Department of Agriculture–Agriculture Research Service, in Los Angeles, California, and Carol Braunschweig, PhD, RD, with the University of Illinois, in Chicago, this study provides "one of the largest prospective assessments of diet and anemia in US postmenopausal women."
They add that the findings "lend credibility to the use of an FFQ [food frequency questionnaire] for large epidemiological studies investigating the relationship between diet and anemia risk."
However, according to the editorialists, the mean nutrient intakes reported indicate that "a portion of the anemia observed in the WHI-OS cohort was not diet-related," they write. "For example, it is well known that decreases in hemoglobin occur from nutrient deficiencies only when stores are nearly exhausted."
In addition, although the accurate assessment of anemia allows clinicians to classify the type of anemia and recommend suitable treatment options, inclusion of these measurements in large epidemiologic studies is "cost-prohibitive and unlikely."