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Isoflavone content of infant foods and formulas
D C Knight1, J A Eden, J L Huang
1School of Obstetrics and Gynaecology, Royal Hospital for Women, Randwick, New South Wales, Australia.
Insights
Infants are ubiquitously exposed to dietary isoflavones from various foods and formulas. Soy-based infant formulas show higher isoflavone levels, but exposure remains within normal physiological limits.
Area of Science:
- Food Science
- Nutritional Biochemistry
- Pediatric Nutrition
Background:
- Phytoestrogens, like isoflavones, are plant-derived compounds with estrogenic activity.
- Infant diets are diversifying, necessitating an understanding of phytoestrogen exposure.
- Assessing phytoestrogen intake is crucial for infant health and development.
Purpose of the Study:
- To quantify phytoestrogen content in infant foods, formulas, and drinks.
- To determine infant exposure levels to isoflavones based on feeding regimens.
- To evaluate the impact of different dietary choices on isoflavone intake in the first year of life.
Main Methods:
- High-performance liquid chromatography (HPLC) was employed for precise quantification.
- Analysis included key isoflavones: genistein, daidzein, biochanin A, formononetin, and equol.
- Samples of soy beverages, cow's milk, infant formulas, and yogurts were procured from Australian supermarkets.
Main Results:
- Isoflavones were detected in all tested food samples, indicating widespread dietary exposure.
- Soy-based infant formulas contained significantly higher isoflavone levels (17.2–21.9 mg L⁻¹) compared to casein-based formulas (0.001–0.03 mg L⁻¹).
- Soy beverages, not recommended for infants under 12 months, exhibited the highest isoflavone concentrations (22.9–71.5 mg L⁻¹).
Conclusions:
- Dietary exposure to isoflavones is virtually ubiquitous for infants in their first year.
- Consumption of soy infant formulas may lead to higher isoflavone exposure.
- Attained isoflavone levels appear to be within normal physiological boundaries for infants.
Objective:
The purpose of this study was to investigate the phytoestrogen content of different foods, formulas and drinks that may be consumed by infants during their first year of life in an attempt to define levels of exposure on different feeding regimens.
Methodology:
High performance liquid chromatography (HPLC) was used to determine the levels of genistein, daidzein, biochanin A, formononetin and equol in samples purchased from Australian supermarkets. Single lots of duplicate or triplicate samples of soy beverages, cow's milks, infant formulas and infant yoghurts were analysed.
Results:
All foods tested contained isoflavones, at varying levels, suggesting that exposure to these compounds is almost ubiquitous. Casein-based infant formulas contained between 0.001 and 0.03 mg L(-1). Soy-based infant formulas ranged from 17.2 to 21.9 mg L(-1) with the values detected in yoghurt at similar levels to that of cow's milk. For comparison, the soy-based beverages (which are not recommended for use under 12 months of age) contained levels of isoflavones from 22.9 to 71.5 mg L(-1).
Conclusions:
Given the relatively broad choice of infant foods becoming available, exposure to dietary isoflavones during the first year of life is virtually ubiquitous. The exposure may be higher if soy infant formulas are consumed, however, the levels attained appear to fall within normal physiological boundaries.