Optimization of a phytase-containing micronutrient powder with low amounts of highly bioavailable iron for in-home fortification of complementary foods.
BACKGROUND
In-home fortification of complementary foods with micronutrient powders containing low amounts of iron may be potentially safer than powders containing high amounts of iron. However, low iron doses have little nutritional effect, unless iron absorption is high.


OBJECTIVE
The objective was to maximize iron absorption from a low-iron micronutrient powder for in-home fortification by testing combinations of iron as NaFeEDTA, ascorbic acid, and a microbial phytase active at gut pH. In addition, a recently proposed enhancer of iron absorption, L-alpha-glycerophosphocholine (GPC), was tested.


METHODS
In 6 separate iron-absorption studies using a crossover design, women (n = 101) consumed whole-maize porridge fortified with 3 mg stable isotope-labeled FeSO4 or NaFeEDTA with different combinations of enhancers added to the meals at the time of consumption. Incorporation of iron isotopes into erythrocytes 14 d later was measured.


RESULTS
The addition of phytase when iron was present as either NaFeEDTA or FeSO4, with or without ascorbic acid, significantly increased iron absorption. The combined addition of phytase, ascorbic acid, and NaFeEDTA resulted in an absorption of 7.4%, compared with an absorption of 1.5% from FeSO4 without enhancers in the same meal (P < 0.001). The addition of ascorbic acid did not significantly increase iron absorption from NaFeEDTA, and the addition of calcium did not significantly inhibit iron absorption from NaFeEDTA in the presence of ascorbic acid. The addition of L-alpha-glycerophosphocholine did not significantly increase iron absorption.


CONCLUSIONS
Optimization of the micronutrient powder increased iron absorption from a highly inhibitory meal approximately 5-fold. This approach may allow for effective, untargeted in-home fortification of complementary foods with low amounts of highly bioavailable iron.
Troesch
Barbara
B
Laboratory for Human Nutrition, Institute of Food Science and Nutrition, ETH, Zurich, Switzerland. barbara.troesch@ilw.agrl.ethz.ch
Egli
Ines
I
Zeder
Christophe
C
Hurrell
Richard F
RF
de Pee
Saskia
S
Zimmermann
Michael B
MB
D010832:6-Phytase / Q000494:pharmacology*; D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000517:prevention & control; D001205:Ascorbic Acid / Q000494:pharmacology; D001682:Biological Availability; D018592:Cross-Over Studies; D004357:Drug Synergism; D004492:Edetic Acid; D004912:Erythrocytes / Q000737:chemistry* / Q000378:metabolism; D005260:Female; D005290:Ferric Compounds; D005293:Ferritins / Q000097:blood; D005527:Food, Fortified; D005997:Glycerylphosphorylcholine / Q000494:pharmacology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D007503:Iron Isotopes; D019266:Iron, Dietary / Q000493:pharmacokinetics*
D005290:Ferric Compounds; D006454:Hemoglobins; D007503:Iron Isotopes; D019266:Iron, Dietary; D005997:Glycerylphosphorylcholine; D005293:Ferritins; D004492:Edetic Acid; D010832:6-Phytase; C019179:Fe(III)-EDTA; D001205:Ascorbic Acid