Assessment of iron and zinc bioavailability in biofortified pearl millet varieties

Abstract:

Nearly 2 billion people worldwide suffer from iron and zinc deficiencies, with sub-Saharan Africa bearing a disproportionate share of this burden. Biofortified pearl millet (Pennisetum glaucum L.) has been promoted as a food-based strategy to address micronutrient malnutrition, yet total mineral content alone does not predict how much iron or zinc the human body can absorb. This research evaluated five biofortified pearl millet varieties—ICTP-8203Fe, Dhanashakti, AHB-1200Fe, HHB-299, and a local check—for total iron and zinc content and their in vitro bioavailability using the pepsin-pancreatin dialysis method. Grain samples were collected from research plots at the Central Kenya College of Agriculture, Nyeri, during the 2023 growing season. Total iron ranged from 4.18 mg/100 g (local check) to 8.64 mg/100 g (ICTP-8203Fe), while zinc varied between 2.97 and 5.41 mg/100 g. Dialyzable iron fractions were 7.3 to 14.8 percent of total iron, and dialyzable zinc ranged from 18.6 to 29.4 percent. ICTP-8203Fe showed the highest bioavailable iron (1.28 mg/100 g), and Dhanashakti provided the greatest bioavailable zinc (1.59 mg/100 g). Anti-nutritional factors—phytate and tannin—were inversely correlated with mineral bioavailability (r = −0.81 for phytate-iron and r = −0.74 for tannin-zinc). These findings indicate that breeding for high total mineral content must be paired with screening for low anti-nutrient levels to maximize nutritional benefit.