| Dietary intake is generally difficult to assess. The use of tissue biomarkers may be a more objective indicator of nutrient intake that can also be used to validate dietary assessment methods. The most cost-effective technique, albeit invasive, for assessing dietary intakes of folic acid in a GP setting would be to measure serum and red blood cell folate levels from a representative sample of the practice. Selecting a reliable laboratory is essential, both to secure valid and quality data and to minimise the potential margin for error |