NOTE: THIS IS NOT THE SPECIES OF MORINGA THAT MOST OF YOU ARE GROWING! Most cultivated moringa trees are Moringa oleifera.
In a survey reported in the East African Medical Journal, 597 school children and their parents were surveyed in areas of southern Ethiopia that have very high incidence of goiter. Measurements of iodine concentration in the urine showed that children were getting plenty of iodine (Lack of iodine can cause goiter.) One important factor in the prevalence of goiter was a familial tendency to develop goiter. Children whose parent(s) had goiter were significantly more likely to develop goiter themselves.
Also significant was the role of locally consumed foods. Survey participants were questioned about the regions’ most commonly consumed foods, including maize, yam, potato, teff, M. stenopetala (locally referred to as halleko) and sorghum. Only M. stenopetala had a significant association with the prevalence of goiter. In particular, those who ate M. stenopetala more than twice per day were 4.57 times more likely to have goiter than the other groups.
The authors of the article mentioned that isothiocyanate and hydrocyanic acid have been isolated from a related species of moringa, M. pterygosperma. Isothiocyanate is a known cause of goiter, while hydrocyanic acid metabolizes to thiocyanate in the human body. It is possible, but not proven, that M. stenopetala may also have similar substances.
The authors recommend that further studies be done on M.stenopetala to find out what links (if any) its consumption has to the occurrence of goiter. Until then, what should you do if you are growing M. stenopetala? Before you become alarmed and stop eating the leaves of this valuable tree, remember that practically any food contains both helpful compounds (e.g. carbohydrates for energy; protein; vitamins and minerals) and harmful ones (e.g. hydrocyanic acid). Our advice has been stated in EDN many times previously: “Eat like the deer.” That is to say, whenever possible, like the deer, eat a variety of different foods in moderation rather than very large quantities of one thing.
Berkelaar, D. 2004. A Caution about Eating Excessive Amounts of Moringa stenopetala: Eat Like the Deer. ECHO Development Notes no. 82