Peanut butter increases the bioavailability and bioconversion of kale β-carotene to vitamin A.

BACKGROUND AND OBJECTIVES: Kale is a rich source of provitamin A- β-carotene. This study used intrinsically labeled kale [2H9] β-carotene to determine the effect of peanut butter on the bioconversion of kale β-carotene to vitamin A in preschool children.

METHODS AND STUDY DESIGN: Preschool children (n=37; age 12-36 mo) were randomly assigned to 50 g cooked kale (1.5 mg β-carotene content) with either 33 g peanut butter (PBG) or with 16 g lard (LG) and a reference dose of 1 mg [13C10] retinyl acetate capsule. Blood samples were processed to serum and analyzed by Negative Chemical Ionization-Gas Chromatography Mass Spectrometry (NCI-GCMS) for the enrichments of [2H] retinol from kale [2H9] β-carotene and [13C10] retinol from reference dose.

RESULTS: The area under curves (AUCs) of molar enrichment at days 1, 2, 3, 6, 15, and 21 after the labeled doses was 56.3±10.5 and 84.8±16.2 (nmole) for [2H] retinol from LG and PBG kale [2H9] β-carotene, respectively. The AUC of [13C10] retinol from reference dose was 432.6±54.9 (LG) and 560.3±156.7 (nmole) (PBG), respectively. The calculated β-carotene conversion factors were 13.4±3.1 and 11.0±3.9 to 1 (p>0.05) by weight for LG and PBG, respectively.

CONCLUSIONS: This study showed that peanut butter enhances the vitamin A value of kale.