Cognitive function, iron status, and hemoglobin concentration in obese dieting women

Abstract

Objective: To determine the relationships between cognitive function and iron status in dieting obese women. Design: Longitudinal weight loss study (repeated measures within-subject design) with 3 weeks of baseline, 15 weeks of 50% caloric restriction, and 3 weeks of weight stabilization. Dietary iron was fed at twice the US Recommended Dietary Allowance with half of the iron from food sources and half from an oral supplement. Setting: This was a free-living study with the exception that subjects came to the research center for one meal per day and were provided all other meals and snacks to take home. Subjects: Healthy, premenopausal, obese women (mean BMI 31.5) were recruited through local newspaper, poster and radio advertising. Twenty-four women volunteers were recruited and 14 completed the study. Measurements: Cognitive function, iron and hematological status, height, body weights and body composition were measured at baseline; at weeks 5, 10, and 15 of the energy restriction period; and at the end of weight stabilization. Computerized cognitive tests included: Bakan vigilance task, two ®nger tapping, simple reaction time, immediate word recall, and a focused attention task. Iron status and hematological measures included: serum iron, total iron binding capacity (TIBC), transferrin saturation, serum ferritin, hemoglobin (Hb), hematocrit, red cell count, MCV, MCH, MCHC, and RDW. Results: A signi®cant reduction in Hb, hematocrit, and red blood cell count occurred across the study. Hb at the end of the study was positively correlated (r = 0.72, P < 0.01) with mean performance on a measure of sustained attention. Transferrin saturation also correlated positively to sustained attention task performance for those subjects whose Hb declined across the study (r = 0.86, P < 0.01). Conclusions: These ®ndings suggest that dieting diminishes iron status in obese women, even when suf®cient dietary iron is available, and that the inability to sustain attention may be an early sign of developing iron de®ciency in dieting women.

Modification of Iron Status in Young Overweight/Mildly Obese Women by Two Dietary Interventions Designed to Achieve Weight Loss

“…A further 5.4% suffered from iron deficiency with anemia, which is also below the mean for industrialized societies (10.3% in women aged 15-59 years) [1] . Thus, the present study provides no evidence that overweight/mildly obese women are more likely to have a poorer iron status due to poorly controlled diets or sporadic fasting, as mentioned by some authors [4] .…”

“…However, dieting can impair iron status in obese women, even when sufficient dietary iron is available [4] .…”

Iron treatment normalizes cognitive functioning in young women

“…Nevertheless, most of the findings are in agreement and provide us with data with which we can compare our results. With respect to observational studies, Kretsch et al (27) reported a correlation of both hemoglobin and transferrin saturation with sustained attention in obese dieting women, whereas Foley et al (28) found a correlation between iron concentrations (ie, zinc protoporphyrin) and spatial performance in male and female undergraduate students. Our observation of a significant difference in the attention domain between ironsufficient and iron-deficient women is in agreement with these observations.…”

Impact of iron levels on cognitive functioning among dental students of Udaipur, Rajasthan (India)

“…(2012) Studies related to the impact of hemoglobin levels on mental functioning in adult populations are few and the outcomes are inconclusive 12,13 . Keeping this in view, the present study was designed to assess the possible impact of iron nutritional status on cognitive functioning among dental students between the ages of 18-25 years as the profession of dentistry requires keen recognizing abilities, decision making skills as well as ample physical stamina, which may be impaired by low iron/hemoglobin levels thereby influencing one's ability to be a successful dentist.…”