Understanding the Interaction of Food and Genes
The insight gained from genetic research provides opportunities to prevent disease and improve quality of life through functional foods and tailored diets. Discoveries in genetics make it possible to understand the effects of nutrients in processes at the molecular level in the body and also the variable effects of dietary components on each individual.
Nutrigenomics, proteomics, and metabolomics are three new disciplines that will contribute to the rapid development of functional foods.
Nutrigenomics is defined as the interaction of dietary components with genes. The dietary components of interest can be essential nutrients (e.g., vitamins, minerals, fatty acids), other bioactive substances (e.g., phytochemicals), or metabolites of food components (e.g., retinoic acid, eicosanoids).
Proteomics is the study of the full set of proteins encoded and expressed by a genome. Proteomics identifies the large number of proteins in the organism, maps their interactions, and analyzes the proteins’ biologic activities.
Metabolomics (or metabonomics) is metabolite profiling, measuring the real outcome of the potential changes suggested by genomics and proteomics. Metabolomics investigates regulation and metabolic fluxes in individual cells or cell types.
At a simplistic level, nutrigenomics describes how dietary components affect the protein profile of an individual; proteomics describes how that altered protein profile affects the biological systems of the individual; and metabolomics describes the cellular response to the changes.
Bioinformatics is a new tool that uses computer database technology to integrate data from multiple, and sometimes disparate, disciplines.
Already, these disciplines and tools have improved our understanding of food science and human nutrition.
Diet represents one of the key environmental factors to which our genes are exposed, from conception throughout life. Gene expression results in production of proteins that function in myriad ways within the human body, serving as enzymes, oxygen transporters, hormones, and building blocks for cells throughout the body. Simply put, gene expression governs our existence.
Nutrients, in turn, govern the concentration of different proteins in different organs by functioning as regulators of gene transcription and translation, nuclear RNA (ribonucleic acid) processing, messenger RNA (mRNA) stability, and mRNA degradation. The intensity of a dietary signal and the subsequent response can vary with the amount of a food component consumed and the frequency with which it is ingested. The developmental age of the individual also may determine which genes are influenced.
Now that the human genome has been catalogued, the race is on to determine the functional significance of each gene, understand the complex functional networks and control mechanisms, and figure out the role that genotype and environment play in determining the physical characteristics of an individual.
Functional studies to date have largely evaluated one gene at a time. However, to truly understand the biology of processes directed by genes, researchers need to simultaneously study functional interactions, networks, and pathways. With enough data and proper bioinformatics, scientists will be able to model the genetic circuitry to identify interventions that can optimize biological outcomes through health and wellness lifestyle choices, such as diet.
Research has shown that nutrients affect gene expression and formation of various proteins at discrete points in the processes that lead to enzymes, structural proteins, and other chemicals on which life depends. Thus, the amount, and even the form, of nutrients present during gene expression can affect the manufacture of protein, resulting in less of a protein being produced, production of a less than optimally functional form, or no protein at all. Each of those possibilities exists as a result of the hereditary form of genes present and whether the genes are normal or contain polymorphisms that affect gene expression.
The challenges facing nutrigenomics are similar to those encountered in drug development. Many common diseases are not caused by a genetic variation within a single gene. Instead, diseases are caused by complex interactions among multiple genes, in conjunction with environmental and lifestyle factors. Although both environmental and lifestyle factors contribute tremendously to disease risk, their effect is currently difficult to measure and evaluate.
Genetic factors may confer susceptibility or resistance to a disease and may determine the severity or progression of disease. Since we do not yet know all of the factors involved in these intricate pathways, researchers have found it difficult to develop screening tests for most diseases and disorders. By studying stretches of DNA that have been found to harbor a genetic variation associated with a disease trait, researchers may begin to find relevant genes associated with a disease and variable response to dietary components. Defining and understanding the role of genetic factors in disease also will allow researchers to better evaluate the role that non-genetic factors—such as behavior, diet, lifestyle, and physical activity—have on disease.
Recognizing the tremendous health benefits offered by functional foods, the Institute of Food Technologists commissioned an expert panel to review the available scientific literature related to functional food development. The panel’s report is divided into nine sections: Definitions, Introduction, Food and Genes, Current Legal Standards, Scientific Standards, Policy Limitations, Bringing Functional Foods to Market, Role of Research, and Conclusions. Copies of the report are available at www.ift.org. Founded in 1939, the Institute of Food Technologists is an international not-for-profit scientific society for food science and technology.