E. Determine nutrient content of food

If the food item of interest appears in the food composition tables, determination of their potential as vitamin A sources is straightforward. However, for many indigenous and wild species, data may not be available in this form. In many cases, the species have not been studied for vitamin A content, although data may be available in scientific papers that can be located through a careful literature review. Leafy, green vegetables and fruits, flowers, juices, vegetables, and tubers that are red or yellow in color, and animal organs and fats, and some milk products have the greatest potential as sources of provitamin A and vitamin A and should be considered the most carefully. Laboratory analyses are beyond the scope of a rapid survey such as this, although foods with high potential that have not been examined for vitamin A content should be ultimately studied. If the opportunities are available for collaborating with food analysts, you are encouraged to explore with them the proper manner to collect specimens for analysis.

If you are compiling vitamin A contents of food for your data tables, it may be valuable to consult with the national food analytical laboratories for advice on the accuracy of the data from your references. Analytical methods are quite variable in their accuracy and caution is advised.

Appendix 8 gives some guidance on general levels of vitamin A in food.