Potential Nutritional and Health Benefits of Tree Spinach - Chaya
The tree spinach (Cnidoscolus chayamansa McVaughn, Euphorbiaceae), called "chaya" in south Texas, is popular in Mexico and Central America and has been introduced into the United States (mainly South Texas and Florida) for potential uses as a leafy vegetable and/or as a medicinal plant. The plant is an attractive shrub, 3 to 5 m tall (Breckon 1979). The leaves are broad and may consist of 3 or more lobes with fleshy petioles (Fig. 1). The white-colored flowers, which are usually borne on cyme-branched inflorescences, may contain 3-forked arrangements in which the pistillate flowers are located on the basal fork. The staminate flowers are expanded distally from the base of the lobes. Mature seeds and fruit are rare and unknown (McVaugh 1944).
The young shoots and tender leaves of chaya are cooked and eaten like spinach. They comprise part of the staple diet and are the main dietary source of leafy vegetable for the indigenous people of Yucatan peninsula of Mexico and Kekchi people of Alta Verapaz in Guatemala (Harris and Munsell 1950; Booth et al. 1992). There are many underexploited native leafy plants with potential as a traditional food source (NAS 1975). With current renewal of interest in household gardens, attention is being focused on promoting some of these plants as leafy green vegetables among populations in the developing countries (FAO 1987). The edible parts of chaya plant, which taste like spinach when cooked, provide important nutritional sources for protein, vitamins (A and C), minerals (calcium, iron, phosphorus), niacin, riboflavin, and thiamine among populations that cannot afford expensive foods rich in these nutrients (Yang 1979). The plant may also constitute a potentially valuable leafy green vegetable here in the United States and elsewhere.
Chaya traditionally has been recommended for a number of ailments including diabetes, obesity, kidney stones, hemorrhoids, acne, and eye problems (Diaz-Bolio 1975). Chaya shoots and leaves have been taken as a laxative, diuretic, circulation stimulant, to improve digestion, to stimulate lactation, and to harden the fingernails (Rowe 1994). Like most food plants such as lima beans, cassava, and many leafy vegetables, the leaves contain hydrocyanic glycosides, a toxic compound easily destroyed by cooking. Even though some people tend to eat raw chaya leaves, it is unwise to do so.
While the nutritional value of chaya has been demonstrated (Martin and Ruberte 1978; Booth et al. 1992), none of the purported therapeutic values of chaya leaves has been substantiated with scientific experimentation. Therefore, the present study reports on nutritional composition of raw and cooked chaya leaves and the results compared with the nutritional composition of spinach leaves. Also a possible antidiabetic effect of the aqueous leaf extracts or chaya tea, administered through drinking water to streptozotocin-induced diabetic rabbits, was evaluated.