Obesity-Related Hypoferremia Is Not Explained by Differences in Reported Intake of Heme and Nonheme Iron or Intake of Dietary Factors that Can Affect Iron Absorption

Abstract

Hypoferremia is more prevalent in obese than nonobese adults, but the reason for this phenomenon is unknown. To elucidate the role dietary factors play in obesity-related hypoferremia, the intake of heme and nonheme iron and the intake of other dietary factors known to affect iron absorption were compared cross-sectionally from April 2002 to December 2003 in a convenience sample of 207 obese and 177 nonobese adults. Subjects completed 7-day food records, underwent phlebotomy for serum iron measurement, and had body composition assessed by dual-energy x-ray absorptiometry, during a 21-month period. Data were analyzed by analysis of covariance and multiple linear regression. Serum iron (mean±standard deviation) was significantly lower in obese than nonobese individuals (72.0±61.7 vs 85.3±58.1 µg/dL [12.888±11.0443 vs 15.2687±10.3999 µmol/L]; P<0.001). The obese cohort reported consuming more animal protein (63.6±34.5 vs 55.7±32.5 g/day; P<0.001) and more heme iron (3.6±2.8 vs 2.7±2.6 mg/day; P<0.001). Groups did not differ, however, in total daily iron consumption, including supplements. Obese subjects reported consuming less vitamin C (77.2±94.9 vs 91.8±89.5 mg/day; P=0.01), which may increase absorption of nonheme iron, and less calcium (766.2±665.0 vs 849.0±627.2 mg/day; P=0.038), which may decrease nonheme iron absorption, than nonobese subjects. Groups did not significantly differ in intake of other dietary factors that can impact absorption of iron, including phytic acid, oxalic acid, eggs, coffee, tea, zinc, vegetable protein, or copper. After accounting for demographic covariates and dietary factors expected to affect iron absorption, fat mass (P=0.007) remained a statistically significant negative predictor of serum iron. This cross-sectional, exploratory study suggests that obesity-related hypoferremia is not associated with differences in reported intake of heme and nonheme iron or intake of dietary factors that can affect iron absorption.Several studies in children and adults have shown that obesity is associated with low serum iron concentrations (1-3) and a greater prevalence of iron deficiency (4). However, the pathophysiological mechanisms leading to hypoferremia among obese individuals are unknown. One proposed mechanism is an iron-poor diet (5). However, a difference in iron intake between obese and nonobese subjects has not been shown among US adults.

Iron status in obese women

“…It is stated that increased body fat, especially visceral fat, predisposes towards worse iron homeostasis due to an increased rate of pro-inflammatory cytokines produced by visceral adipose tissue [20][21][22][23][24][25]. A large-scale study conducted on obese patients revealed also a positive correlation between TIBC and the percentage content of fat tissue.…”

“…A study conducted by Menzie et al revealed that dietary iron intake and its estimated bioavailability are similar in obese and normal weight subjects [22,24]. On the other hand, an increased level of proinflammatory cytokines, adipokines and hepcidin, may impair iron absorption [22].…”

Overweight children have higher circulating hepcidin concentrations and lower iron status but have dietary iron intakes and bioavailability comparable with normal weight children

“…9,[14][15][16] It has also been suggested that reduced iron intake due to poor dietary choices by overweight individuals may contribute to poor iron status, but there is little data to support this. 1,9,15,16 In adults, dietary iron intake and its estimated bioavailability are similar in overweight and normal weight adults, 17 but no data are available for children. Even if iron intakes and estimated dietary bioavailability are similar, absorption of dietary iron could be reduced in overweight individuals if the circulating hepcidin level is increased.…”

Iron in Obesity: A Victim or Suspect

“…Учитывая наличие явных про-тиворечий по поводу связи гипоферремии при ожирении и алиментарного дефицита железа (Hassapidou et al, 2006;Menzie et al, 2008), вклад данной причины в генез гипоферремии остается дискуссионным. Что касается увеличения объема циркулирующей крови у индивидуумов с ожире-нием, данное предположение было подтверждено в эксперименте (Bertinato et al, 2013).…”