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Diet and Metabolomics

The composition of biological samples such as urine and plasma is often reflective of dietary intake. Nutrients have numerous influences on endogenous metabolism. For example, the intake of folate is integral in the course of both nucleic acid and amino acid metabolism and therefore folate can indirectly effect the concentrations of other metabolites in these pathways. When the equilibrium of any metabolic pathway is disturbed by dietary components or indeed by drugs or disease, a consequent shift in the metabolome will result. However, the effect of diet will not always cause a sizeable or lasting change in metabolism. Many individuals have inconsistent dietary patterns and this also contributes to minor daily fluctuations in metabolic profiles. Food of course, is not solely a source of nutrients. It also provides a huge source of non-nutrients such as, additives, pesticide residues, packaging or cooking residues, toxicants and natural non toxicant phytochemicals. Although non-nutrients have a lesser role in metabolic functioning, they may become engaged in exogenous metabolism and exert an additional effect on the metabolome composition. Urinary metabolic profiles may be particularly susceptible to influence from non-nutrients as urine is the route of excretion for many metabolic waste products. Therefore, urinary metabolic profiles (and possibly post-prandial plasma profiles) may be the most reflective of acute dietary intake and exogenous metabolism. Fasting plasma metabolic profiles may provide a better insight to exogenous metabolism and habitual dietary intake.