Iron Absorption From Iron-fortified Fonio Porridge: a Stable Isotope Study

Objective: To compare the bioavailability of iron in fonio porridge fortified with isotopically enriched [57Fe] or [58Fe]-ferrous sulfate with and without reducing phytic acid by native phytase in wheat flour.

Study population: Sixteen apparently healthy young women aged 18-30 years recruited at the University based on their willingness to participate and according to inclusion criteria.

Study design: Fonio porridges fortified with isotopically labelled [57Fe] or [58Fe] ferrous sulfate, with (test meal) and without wheat flour (control meal) are administered to fasting subjects on two consecutive days using a randomised crossover design. Half the subjects received the test meal on the first day and the control on the second day and vice versa. No food or drink was allowed within the 3 hours after consumption. All meals were administered under close supervision. Venous blood sample were collected (day 1 and day 16) for iron status and iron absorption measurement. Iron absorption measurement is calculated based on iron isotope-dilution in erythrocyte 14 days after intake of the labelled meals.

Study parameters: Fourteen days before the test, height and weight were measured for nutritional status and subjects were screened for pregnancy and malaria. They were also treated with antihelminth (albendazole tablet). The day before meals test (day 0), whole blood sample was collected for hemoglobin (Hb), serum ferritin (SF), serum Transferrin Receptor (sTfR) and C-reactive protein (CRP). Anemia and iron deficiency was defined as Hb < 120 g/L, and SF < 12 µg/L respectively. Pregnancy test and malaria tests were repeated on that day. On day 1 and day 2, the fonio porridges were randomly given to the subjects on a cross-over designed. Fourteen days after the meal test (day 16) whole blood sample was collected for iron absorption measurement.

Inclusion criteria

• age 18 - 30 y-old
• apparently healthy
• body weight < 65 kg (confirmed by anthropometric measurement at recruitment)
• not pregnant (confirmed by pregnancy test)
• not lactating (confirmed by age of last child if any)
• no reported chronic medical illnesses (diabetes, rheumatism, high blood pressure, etc)
• no reported symptoms of malaria in the last 2 months (fever, headache, stomachache, diarrhoea, nausea, vomiting) (confirmed by malaria test)
• No severe anemia (Hb<90 g/l)
• no intake of vitamin and mineral supplements in the last 2 weeks
• no iron medication or supplementation during the study
• no blood donation in the last 6 months
• no reported allergy to gluten

Exclusion criteria

• body weight (> 65 kg)
• pregnant
• recent fever malaria
• abnormal CRP level (>10 mg/l)
• severe anemia (Hb < 90g/l) and iron deficiency (serum ferritin concentration < 12 µg/l)