Cheat meal? Blood test can squeal on you

Washington, June 20: A simple blood test can help determine whether a person is following a prescribed diet, say scientists suggesting that the method can help improve the accuracy of clinical trials.

Clinical trials of diets and their health impacts are often plagued by participants' poor adherence to assigned diets, which can make it difficult or even impossible to detect the true effects of those diets.

The approach, described in the American Journal of Clinical Nutrition, could provide an objective and relatively easy-to-obtain measure of dietary adherence, potentially greatly reducing the uncertainty of dietary intake estimates.

Scientists from Johns Hopkins Bloomberg School of Public Health in the US demonstrated their approach by showing that the levels of dozens of metabolites in the blood differed significantly between treatment and control groups enrolled in a clinical trial of the blood pressure- lowering DASH ( Dietary Approaches to Stop Hypertension) diet.

The DASH diet emphasises fruits and vegetables and restricts red meat, sodium and sweets.

“We can now consider these metabolites as candidate biomarkers for assessing adherence to the DASH diet in future nutrition research studies, and one day clinicians might use these markers to monitor what their patients eat,” said Casey M Rebholz, an assistant professor at Johns Hopkins.

Dietary adherence in clinical trials and even in ordinary clinical practice traditionally has been assessed by asking participants to keep track of what they eat. Human nature being what it is, such self- reports are not always accurate.

Researchers have sought an objective measure of dietary adherence by testing urine samples, but the requirement for each participant to collect samples for testing is burdensome.