A study funded through the European Nutrigenomics Organisation (NuGO) found that it is possible to characterize individual responses to fasting, and to take a ‘snapshot’ of small metabolic changes after 36 hours of fasting.
The study’s findings, published in the journal Metabolomics, identified a number of metabolites and hormones not previously associated with fasting. The researchers, led by Hannelore Daniel from the ZIEL Research Centre for Nutrition and Food Sciences in Germany, also found high variability between individuals for certain markers, including leptin, the satiety hormone.
“This study shows how it is possible to use metabolomics to characterize the different responses of individuals to nutritional or physiological stress,” said Professor Ian Johnson from the Institute of Food Research in the UK.
“By using the same approach applied to a large number of volunteers, we hope in the future to be able to divide the population into metabolic “types”, an important step towards personalized nutrition,” said co-researcher Professor Ian Johnson from the Institute of Food Research in the UK.
The rise of ‘omics’
Many food companies – both ingredient suppliers and food manufacturers are taking the potential of nutrigenomics very seriously. Companies such as Nestle, DSM, and Chr Hansen are all investing heavily in the area. However, actual products are as yet, scarce.
Nutrigenomics is seen by many as the future of nutrition. Nutrigenomics is defined as how food and ingested nutrients influence the genome (personalized nutrition). Nutrigenetics is defined as how a person's genetic make-up affects a response to diet (individual nutrition). The difference between the two is important.
Ten participants were recruited for the study at the Rowett Institute of Nutrition and Health, University of Aberdeen in Scotland. Following four overnight fast the participants provided blood, saliva and urine samples. The fasting period was extended to 36 hours for the last sampling day.
Results showed that, of the 377 products analyzed, 44 per cent of them were shown to change after prolonged fasting of 36 hours compared with overnight fasting (12 hours). Some of these markers were already known to be ‘fasting markers’ but many metabolites and hormones that were altered associated with fasting for the first time in this study.
“We now have a clear fasting signature,” said Dr Daniel.
The researchers noted a complete change in the body’s fuel management system: Specifically, the researchers noted a significant decrease in leptin, the satiety hormone, but this extent of this varied between individuals. Furthermore, ketone levels increased in the urine, again with inter-individual difference, while blood ketone levels rose by a similar amount in all volunteers, added the researchers: The presence of plasma ketone bodies is indicative of tissue fat being broken down.
“This is the first study to our knowledge that has applied metabolomics to comprehensively assess the response to prolonged fasting in human volunteers,” wrote the researchers.
“In addition to well-known markers that characterize this catabolic state (such as NEFA, glycerol and ketone bodies in plasma) we have identified some 100 new metabolites in blood and urine that change in the fasting state. In this respect we provide a snapshot of the ‘catabolic metabolome’ that may be taken as a mirror image of the ‘anabolic metabolome’ reported in three recent metabolomics studies in human volunteers that used the oral glucose tolerance test (OGTT) as a challenge.”
Published online ahead of print, doi: 10.1007/s11306-010-0255-2
“Metabolomics of prolonged fasting in humans reveals new catabolic markers”
Authors: I. Rubio-Aliaga, B. de Roos, S.J. Duthie, L.K. Crosley, C. Mayer, G. Horgan, I.J. Colquhoun, G Le Gall, F. Huber, W. Kremer, et al.