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Iron bioavailability studied in infants: the influence of phytic acid and ascorbic acid in infant formulas based on
L Davidsson1, P Galan, P Kastenmayer
1Nestlé Research Centre, Vers-chez-les-Blanc, Lausanne, Switzerland.
Insights
Reducing phytic acid or increasing ascorbic acid in soy formula significantly enhances iron bioavailability in infants. This improves iron absorption from soy-based infant nutrition.
Area of Science:
- Nutritional Science
- Pediatric Nutrition
- Biochemistry
Background:
- Soy-based infant formulas are a common alternative to cow's milk-based formulas.
- Phytic acid in soy can inhibit iron absorption, potentially leading to iron deficiency in infants.
- Ascorbic acid is known to enhance non-heme iron bioavailability.
Purpose of the Study:
- To investigate the impact of phytic acid and ascorbic acid content in soy formula on iron (Fe) bioavailability in infants.
- To quantify the effect of dephytinization and increased ascorbic acid levels on iron incorporation into red blood cells.
Main Methods:
- Utilized a double stable isotope technique to trace iron incorporation into infant red blood cells.
- Employed paired comparisons, with each infant serving as their own control.
- Analyzed iron bioavailability using soy formulas with varying levels of phytic acid and different iron (Fe):ascorbic acid molar ratios.
Main Results:
- Reducing phytic acid content by 83% increased fractional iron incorporation from 5.5% to 6.8% (p < 0.05).
- Complete removal of phytic acid significantly boosted iron incorporation from 3.9% to 8.7% (p < 0.001).
- Increasing the iron (Fe):ascorbic acid molar ratio from 1:2.1 to 1:4.2 enhanced iron incorporation from 5.9% to 9.6% (p < 0.01).
Conclusions:
- Both phytic acid reduction and increased ascorbic acid content effectively enhance iron bioavailability from soy-based infant formulas.
- These findings suggest practical strategies for improving the nutritional quality of soy formulas to prevent iron deficiency in infants.
- Optimizing soy formula composition is crucial for ensuring adequate iron status in vulnerable infant populations.
Abstract:
The influence of phytic acid and ascorbic acid content of soy formula on iron (Fe) bioavailability was investigated in infants by analysis of the incorporation of stable isotopes of Fe into red blood cells 14 d after administration using a double stable isotope technique. Paired comparisons were made with each infant acting as his or her own control. The geometric mean fractional Fe incorporation into red blood cells increased from 5.5 to 6.8% (p < 0.05) when soy formula with the native content of phytic acid was compared with a 83% dephytinized formula. A more pronounced effect was shown with soy formula containing no phytic acid; the mean fractional Fe incorporation increased from 3.9 (native phytic acid) to 8.7% (zero phytic acid; p < 0.001). A significant (p < 0.01) effect was also demonstrated when the Fe:ascorbic acid molar ratio in the native phytate-containing formula was increased from 1:2.1 to 1:4.2; mean fractional Fe incorporation increased from 5.9 to 9.6%. These results demonstrate that the Fe bioavailability from soy-based infant formulas can be similarly increased by either removing phytic acid or increasing the ascorbic acid content.