Regional Data Centres

International study finds discrepancies in food folate analysis

Thailand --- During the last decade, the importance of adequate folate levels in the diet, and therefore the importance of accurate assessments of folate intake among the general population, has become well recognized. However, due to the notoriously inaccurate food folate data available such assessments are extremely difficult to execute. Even when executed, the analyses of results are problematic.

In the last several years, trienzyme extraction has replaced the more limited conjugase treatment as the preferred method of food folate treatment. Nonetheless, the results are not always satisfactory.

Recently, an international, inter-laboratory performance of food folate assays was undertaken at the Institute of Nutrition at Mahidol University in Thailand, as a follow-up to the recommendations of the working group on folate bioavailability, which met during the 3rd International Food Data Conference held at FAO, Rome in 1999. Soybean flour, fish powder and breakfast cereal were used as test materials. Once prepared, these materials were sent to 34 laboratories, which were asked to use their routine methods of food folate analysis. Twenty-six of these laboratories (76%) returned their results.

The inter-laboratory coefficients of variation for these test materials were 24%, 35% and 24% for soybean flour, fish powder and breakfast cereal, respectively. laboratories may be difficult. The wide variation was mainly due to the different methods used for folate extraction and detection. Based on these findings, the study’s principal author, Dr Prapasri Puwastien, expressed the urgency for standardizing methods of folate extraction and the development and routine use of validated reference materials, among laboratories. Once a consensus is obtained for analytical steps, an inter-collaborative study to develop reliable reference materials would be possible.

Reference: Prapasri Puwastien, Naruemol Pinprapai, Kunchit Judprasong and Tsunenobu Tamura (2005). International inter-laboratory analyses of food folate. Journal of Food Composition and Analysis. Volume 18, Issue 5, Pages 387-397.