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