Nutrigenomics is an emerging science that studies the molecular relationships between nutrition and the response of our genes, to determine how even subtle genetic changes can affect human and animal health. The basic concept is that chemical nutrients affect gene expressions in a specifi c mode by switching from health to a pathophysiological condition, or vice versa. Nutrigenomics designs optimal nutrition based on an individual’s unique genotype. Simply stated, nutrigenomics defi nes functional foods based on an individual’s genes.
THE BACK STORY
The role of diet and nutrition continues to be a major focus of study when addressing the increasing incidence and recognition of diet-related diseases in humans and animals. Nutrition research is studying how dietary constituents at the molecular level can optimize and maintain cellular, tissue and organ balance to help prevent disease.
The development of nutrigenomics has been aided by powerful advances in genetic research. Genetic variability, the inter-individual differences in genetics, can affect metabolism as well as an individual’s phenotype. Genetic disorders of nutritional metabolism can cause abnormal physiological effects that are exhibited as population diversity. Simple examples would be the genes associated with obesity or diabetes in various canine species, and vitamin B12 deficiency in giant Schnauzers.
RATIONALE AND AIMS
Nutrients relay signals that tell a specific cell in the body about the diet. Basically, a sensory system in the cell interprets information from nutrients about the dietary environment. Once the nutrient interacts with this system, it changes gene (genomics) and protein (proteomics) expression and metabolite production (metabolomics) accordingly. So different diets elicit different patterns of gene and protein expression and metabolite production. Nutrigenomics describes the patterns of these effects, which are called molecular dietary signatures.
An important aim of nutrigenomics involves identifying the markers of early phases of diet-related diseases, so that nutritional intervention can return the patient to a healthy state. Another aim is to demonstrate the effects of biologically active food components on health, leading to the design of functional foods that will keep individuals healthy according to their own specific needs.
APPLYING NUTRIGENOMICS TO DOGS
Recently, veterinary and nutrition scientists have begun applying animal genomics to the field of nutrition. Nutritional genomics and proteomics will play a vital role in the future of pet foods. Functional genomics will emerge as important areas of study, now that the genome “maps” for the dog are available.
Studying and monitoring the health of dogs parallels that of humans. Close to 500 canine genetic diseases have been described to date. Molecular biological techniques have been used for several decades to identify the cause of single gene disorders in animals, allowing for prevention and treatment strategies. Currently, at least 30 canine disease genes have been cloned and characterized. This has led to the development of genetic mutation-based tests for diagnosis and carrier detection. These tests permit the elimination of carriers from the breeding population, ultimately decreasing or eliminating the incidence of disease.
However, while determining the DNA sequences of single gene mutations is now feasible, identifying the genetic loci (locations on the genome) responsible for complex genetic diseases is a much more difficult task. Nevertheless, dogs serve as excellent models for the nutritional diseases in other animal species and humans. Although a genetic component exists for these conditions, nutrition plays a major role in the development and/ or treatment of many. Changing lifestyles in urban populations have led to a significant increase in obesity and diabetes in people and dogs. The negative health outcomes of obesity and diabetes observed in humans are also seen in canines. These are just two common examples of animal diseases having both a nutritional cause and a therapeutic component.
Certain dietary constituents such as vitamins A and D, zinc and fatty acids can directly influence gene expression, whereas others such as dietary fiber can have an indirect effect through changes in hormonal signaling, mechanical stimuli, or metabolites produced from the microbial flora in the bowel.
So-called “functional” food ingredients and herbal supplements are now being incorporated into animal as well as human foods. Examples of nutrients currently added to pet foods include those intended to improve joint health such as glucosamine, chondroitin sulfate, and green lipped mussel. Others protect the body from cellular free radical damage, and include vitamin E, beta carotene and selenium. Omega-3 fatty acids improve the skin, while oligosaccharides (carbohydrates) and probiotics are good for gut health.
It’s also important to keep in mind that the benefits provided by pet foods designed for a dog’s life stages, body type or lifestyle may be well suited for one dog, but not another. With our growing knowledge of genes and gene expression, it should be possible to formulate diets not only for preventing structural abnormalities, but also for more complex diseases such as diabetes, cancer, aging, behavioral changes and heart disease.
In summary, animal nutrition professionals need to be able to prescribe or recommend nutrients and diet formulations based on a more precise knowledge of how nutrients or food components interact at the level of the genome. Diets for dogs should be designed and tailored to the genome or genomic profile of the individual in order to optimize physiological balance, disease prevention and treatment, and performance. Our advancing knowledge about human and animal genomes, along with the breadth of biotechnology, offer us the opportunity to individualize dietary intervention to help prevent, mitigate or cure chronic diseases.