Nutritive value of brown and black beans for infants and small children

A precooked, instantized mixture of brown and black beans, with and without 0.3% DL-methione added, served as the only source of protein in the diets of 10 recovered malnourished infants and children 10 to 42 months of age. At 6.4 to 5.7% dietary protein calories stool wet weights were twice as high, apparent N absorption significantly lower (65.6 +/- 5.9 versus 87.5 +/- 2.3% of intake), and apparent N retention much lower (9.8 +/- 6.1 versus 34.5 +/- 10.2% of intake) than during preceding and following isocaloric and isonitrogenous casein-based diets. The addition of methionine resulted in minimal improvement in N retention and a highly suggestive increase in fasting plasma free methionine. Prolonged feeding of the methionine-enriched beans at 8.0 to 10.9% protein calories supported satisfactory growth and serum albumin levels in two of three children, not so in the smallest one, in whom repeated balance studies demonstrated no decrease over time in stool wet weight and on marginal improvement in N absorption and retention. The poor digestibility of the protein in these beans is the first-limiting factor in its utilization by infants and small children.