Phytate and Zince in Local Taro

Letter to the Editor, Kaselehlie Press
by Dr. Lois Englberger

Dear Editor,

I would like to share with you and the public that a further analysis on local giant swamp taro cultivars (fanal and simihden) has been carried out (see Kaselehlie Press article March 6-19, 2003). This confirms that these cultivars can contribute significantly to zinc status.

Zinc is needed in small amounts in the body for growth and for protection against infection. In the previous KP article, data were presented on the high content of zinc in local giant swamp taro. However, the absorption of zinc is inhibited by a common substance in the food called phytate. Cereals, such as rice and wheat, and other foods are high in phytate content. To really know whether foods can contribute important amounts of zinc, they needs to be analyzed for phytate as well, and a phytate zinc molar ratio is calculated to indicate the bioavailability of the zinc.

No data on phytate content in giant swamp taro from Micronesia were previously available. The laboratory, the Atlanta Center of Nutrient Analysis, Food and Drug Administration, Atlanta, Georgia, which analyzed the taro first, does not do phytate analyses. Now a second laboratory (Howard University, Washington, DC) was identified and it analyzed the taro for phytate and zinc.

Professor Harland, who carried out the analysis, wrote: " We were surprised at the high zinc values, particularly for the Simihden. Thus with this food you need not be concerned with the phytate:zinc molar ratio."

The Fanal contained 14.5 mg zinc per 100 g sample and the Simihden contained 46.1 mg zinc per 100 g sample. The phytate:zinc molar ratio was 1.8 and 0.4 respectively (other studies show that this ratio is often over 20 for cereals). The zinc results were this time even higher than those of the FDA lab, which found Fanal to contain 5.4 mg zinc/100 g and Simihden to contain 23 mg zinc per 100 g.

This further confirms that some giant swamp taro cultivars are important sources of zinc and may provide important health benefits.