Bioavailability of Iron-fortified Whey Protein Concentrate in Iron-deficient Rats

Tomoki Nakano,Tomomi Goto,Takayoshi Aoki,Tarushige Nakaji

doi:10.5713/ajas.2007.1120

Abstract

An iron-fortified whey protein concentrate (Fe-WPC) was prepared by addition of ferric chloride to concentrated whey. A large part of the iron in the Fe-WPC existed as complexes with proteins such as β-lactoglobulin. The bioavailability of iron from Fe-WPC was evaluated using iron-deficient rats, in comparison with heme iron. Rats were separated into a control group and an iron-deficiency group. Rats in the control group were given the standard diet containing ferrous sulfate as the source of iron throughout the experimental feeding period. Rats in the iron-deficiency group were made anemic by feeding on an Fe-deficient diet without any added iron for 3 wk. After the iron-deficiency period, the iron-deficiency group was separated into an Fe-WPC group and a heme iron group fed Fe-WPC and hemin as the sole source of iron, respectively. The hemoglobin content, iron content in liver, hemoglobin regeneration efficiency (HRE) and apparent iron absorption rate were examined when iron-deficient rats were fed either Fe-WPC or hemin as the sole source of iron for 20 d. Hemoglobin content was significantly higher in the rats fed the Fe-WPC diet than in rats fed the hemin diet. HRE in rats fed the Fe-WPC diet was significantly higher than in rats fed the hemin diet. The apparent iron absorption rate in rats fed the Fe-WPC diet tended to be higher than in rats fed the hemin diet (p = 0.054). The solubility of iron in the small intestine of rats at 2.5 h after ingestion of the Fe-WPC diet was approximately twice that of rats fed the hemin diet. These results indicated that the iron bioavailability of Fe-WPC was higher than that of hemin, which seemed due, in part, to the different iron solubility in the intestine.

Highlights

Iron deficiency, with and without anemia, is one of the most significant nutritional problems all over the world (Yip, 1994), affecting approximatively 20% of the world population
Seventy-one percent of iron in fortified whey protein concentrate (Fe-whey protein concentrate (WPC)) was eluted in fraction 1
These results suggest that iron in FeWPC exists as a complex with mainly protein such as βlactoglobulin

Summary

INTRODUCTION

With and without anemia, is one of the most significant nutritional problems all over the world (Yip, 1994), affecting approximatively 20% of the world population. Because iron deficiency anemia is mainly caused by the insufficient intake of iron, the strategy of iron fortification of food is used worldwide to prevent iron deficiency (Clugston et al, 2002; Demment et al, 2003). It is important to consider intake of iron and its bioavailability to prevent iron deficiency. Heme iron is used extensively as an iron supplement in the food industry. Heme iron is insoluble in neutral pH, and their absorption and bioavailability have not yet been sufficiently taken into account in its use The presence of amino acids in the intestines is reported to increase iron absorption (Allen, 2002). The use of suitable proteins in the diet may increase the absorption rate of dietary iron. The cells were used in the iron uptake experiments after 15 d of culture

Calcium Magnesium Sodium Potassium

MATERIALS AND METHODS

RESULTS AND DISCUSSION

Hemin diet