Concepcion Mendoza

Zinc Absorption from low phytic acid Genotypes of Maize (Zea mays L.), Barley (Hordeum vulgare L.), and Rice (Oryza sativa L.) Assessed in a Suckling Rat Pup Model

Dietary phytic acid is a major causative factor for low Zn bioavailability in many cereal- and legume-based diets. The bioavailability of Zn in seed of low phytic acid (lpa) variants of maize ( Zea mays L.), rice ( Oryza sativa L.), and barley ( Hordeum vulgare L.) was evaluated using a suckling rat pup model. Suckling rat pups (14 days old, n = 6-8/treatment) were fasted for 6 h and intubated with (65)Zn-radiolabeled suspensions prepared using seed produced by either wild-type (normal phytic acid) or lpa genotypes of each cereal. Test solutions were radiolabeled overnight (all genotypes) or immediately prior to intubation (barley genotypes). Pups were killed 6 h postintubation and tissues removed and counted in a gamma counter. Zn absorption was low from wild-type genotypes of maize (21, 33%) and rice (26%), and phytic acid reduction resulted in significantly higher Zn absorption, 47-52 and 35-52%, respectively. Zn absorption from wild-type barley incubated overnight was high (86-91%), and phytate reduction did not improve Zn absorption (84-90%), which is likely due to endogenous phytase activity. When the wild-type barley solutions were prepared immediately before intubation, Zn absorption was significantly lower (63, 78%) than from the lpa cultivars (92, 96%). Variation in seed or flour phenolic acid levels did not affect Zn absorption. Differences in seed Zn levels did not substantially affect Zn absorption. Thus, when phytic acid is abundant in a diet, it has a larger effect on Zn absorption than the level of Zn. Therefore, reducing the phytic acid content of staple cereal grains may contribute to enhancing Zn nutrition of populations consuming these staple foods.

Development and Use of an Evaluation Tool for Taste-Testing Activities by School-Aged Children

We describe the development and application of a teacher-administered tool for routine program evaluation of food-tasting activities among low-income children and adolescents in a classroom or afterschool setting. This six-item evaluation tool is intended to capture student willingness to try new foods and ask for them at home. Phase 1 involved one-on-one interviews to determine the feasibility of the taste test tool among nine elementary school teachers in 2009 (168 students) and a validation pilot study in 2010 among 114 school-aged students participating in a University of California Supplemental Nutrition Assistance Program Nutrition Education (UC SNAP-Ed) summer program. Phase 2 determined instrument reliability and compared student response by grade level and food category in a convenience sample of 514 UC SNAP-Ed classrooms in 2010-2011. The mean proportion of the classroom ever having tried the foods before was 0.62 ± 0.33, and 0.77 ± 0.27 were willing to ask for the foods at home (P<0.0001). Compared with younger students (preschool through sixth grade), older students (seventh through 12th grade) were less likely to try the foods in class and less willing to try them again or ask for them at home (P<0.05). Students reported significantly greater previous exposure and willingness to try the food again for fruits than for vegetables (P<0.0001). A teacher-administered taste test tool is feasible to use in a group setting and capable of yielding valid, reliable information to evaluate student response and to guide SNAP-Ed program delivery.