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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Dietary Prevention of Obesity-related Disease Research » Research » Publications at this Location » Publication #63301
Title: NONHEME IRON ABSORPTION, IRON STATUS, AND ENTEROCYTE ACONITASE ACTIVITY ANDIRON CONCENTRATION IN RATS: EFFECTS OF DIETARY IRON AND FAT

Author
item Droke, Elizabeth
item Lukaski, Henry

Submitted to: Nutrition Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Humans and animals respond to dietary iron restriction and blood loss by increasing iron absorption from the small intestine. Previous research has demonstrated that dietary fat can affect iron absorption. How these changes in iron absorption are brought about is not clear. Therefore, a study was conducted with rats to determine if iron absorption could be affected by different types and amounts of dietary fat, and different amounts of dietary iron. The effects on cellular factors that may be important in iron absorption also were determined. Dietary iron restriction resulted in iron deficiency and enhanced iron absorption. In iron deficient rats, stearic acid, cocoa butter and beef tallow increased iron absorption in comparison to safflower oil. Rats fed 7% safflower oil had less iron absorption than rats fed 7 or 15% cocoa butter or 15% beef tallow. An iron-containing protein and the iron concentration in intestinal cells were affected by the amount of dietary iron, but were not affected by dietary fat. This study indicates that stearic acid, cocoa butter, beef tallow and safflower oil and dietary fat levels of 7 or 15% can affect iron absorption. The results also suggest that an iron- containing protein and the iron concentration of small intestinal cells may be important in iron absorption. This study provides further information as to how changes in iron absorption occur.

Technical Abstract: The cytosolic iron regulatory protein 1 (IRP1) exhibits aconitase (c-acon) activity when it is iron (Fe) loaded and may be important in the regulation of Fe absorption. Because stearic acid (SA) can enhance Fe absorption, the relationship between Fe absorption and enterocyte c-acon activity in Fe-deficient (FeD) rats fed different types and amounts of dietary fat was determined. Male weanling rats (8/group) were fed diets varying in Fe (10 or 35 ug/g), fat type [SA, safflower oil (Saff), cocoa butter (CB), or beef tallow (BT)] and fat amount (7 or 15%). Rats killed for baseline values were FeD with low enterocyte c-acon activity. After 4 wk, change in hemoglobin and c-acon activity were less (p<0.001) and 59**Fe absorption was greater (p<0.001) in rats fed low dietary Fe (10 ug/g) than in rats fed adequate dietary Fe (35 ug/g). Absorption was greater (p<0.05) in SA-, CB- and BT- than Saff-fed rats on a low Fe diet. Enterocyte cytosolic and total cellular Fe (TCFe) were less (p<0.001) in rats fed low versus adequate dietary Fe. In rats fed adequate Fe, TCFe was dependent (p<0.01, r**2=0.59) on liver and serum Fe concentrations. Low dietary Fe (10 ug/g) resulted in Fe deficiency, higher absorption, and lower enterocyte c-acon activity and Fe concentration than adequate dietary Fe (35 ug/g). These findings suggest that enterocyte c-acon activity may be an index of IRP1 activity and important in enterocyte cellular Fe metabolism and absorption.