Iron bioavailability from fresh cheese fortified with iron-enriched yeast

An iron-enriched yeast able to lyse at body temperature was developed for iron fortification of chilled dairy products. The aim was to evaluate iron (Fe) absorption from iron-enriched yeast or ferrous sulfate added to fresh cheese.

Two stable isotope studies with a crossover design were conducted in 32 young women. Fe absorption from fresh cheese fortified with iron-enriched yeast (2.5 mg ⁵⁸Fe) was compared to that from ferrous sulfate (2.5 mg ⁵⁷Fe) when ingested with fresh cheese alone or with fresh cheese consumed with bread and butter. Iron absorption was determined based on erythrocyte incorporation of isotopic labels 14 days after consumption of the last test meal.

Geometric mean fractional iron absorption from fresh cheese fortified with iron-enriched yeast consumed alone was significantly lower than from the cheese fortified with FeSO₄ (20.5 vs. 28.7 %; p = 0.0007). When the fresh cheese was consumed with bread and butter, iron absorption from both fortificants decreased to 6.9 % from the iron-enriched yeast compared to 8.4 % from ferrous sulfate. The relative bioavailability of the iron-enriched yeast compared to ferrous sulfate was 0.72 for the cheese consumed alone and 0.82 for cheese consumed with bread and butter (p = 0.157).

Iron from iron-enriched yeast was 72-82 % as well absorbed as ferrous sulfate indicating that the yeast lysed during digestion and released its iron.