| Nutritional genomics and metabolomics
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| Figure 21.1 Factors which determine the state of nutrition. |
| Figure 21.2 Dietary Reference Intakes (RDA): the component values. While the Estimated Average Requirement (EAR) reflects the intake adequate for half of a population, the RNI (or RDA) are values representing intake adequate for the great majority of individuals. |
| DEFINITIONS IN NUTRITION SCIENCE |
| These are the definitions used by the Food and Nutrition Board, Institute of Medicine (IOM) of the National Academies in the United States: |
| Estimated Average Requirement (EAR): The average daily nutrient intake level estimated to meet the requirement of half of the healthy individuals in a particular life stage and gender group. |
The EAR is bracketed by two other values:
- (1) Recommended Daily Allowance (RDA), (in the United Kingdom the Reference Nutrient Intake, RNI). It describes the average daily nutrient intake level sufficient to meet the nutrient requirement of nearly all (97 to 98%) healthy individuals in a particular life stage and gender group.
- (2) The lower Reference Nutrient Intake (LNRI) used in the UK: the daily intake observed at the low end of intake distribution in a population (about 2%). Below this intake a deficiency may occur.
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| Adequate Intake (AI): a recommended average daily nutrient intake level based on observed or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of healthy people that are assumed to be adequate - used when an RDA cannot be determined. |
| Tolerable Upper Intake Level (UL): The highest average daily intake level likely to pose no risk of adverse health effects to almost all individuals in a particular life stage and gender group. As intake increases above the UL the potential risk of adverse health effects increases. |
| Note that the currently used Dietary Reference Intakes have replaced the Dietary Reference Values (DRVs) used previously in the UK, and the Recommended Dietary Allowances (RDAs) used in the USA. Refer to Further Reading for details. |
| The ongoing development of nutritional genomics has huge potential implications for future nutritional interventions.
Nutritional genomics is analogous to pharmacogenomics: it aims to exploit the knowledge accumulated by the Human Genome Project, and the ability to monitor the expression of a large number of genes, to devise individual dietary treatments customized to a genetic background. There is more - the monitoring of the patterns of metabolic response (metabolomics) offers further opportunities to determine
individual responses to nutrients and to develop personalized nutrition profiles.
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