It is rich in phenylalanine and threonine

Yam, like other root crops, is not a good source of essential amino acids. It is rich in phenylalanine and threonine but limiting in the sulphur amino-acids, cystine and methionine and in tryptophan. Yam consuming areas of Africa have a high incidence ofandkwashiorkor, a serious medical condition in children caused by protein deficiency. Experts emphasize the need to supplement a yam-driven diet with more protein-rich foods in order to support active and healthy growth in infants.