Julie B. Hirsch, PhD09.01.05
It has been 52 years since Watson and Crick described DNA as a double helix. In the intervening years our knowledge of the importance of DNA has only slowly been revealed, culminating in 2001 by publication of the sequence of the human genome. We understand that genes are responsible for traits in humans such as blue eyes and brown hair. We also know that our genes are partially responsible for our susceptibility to human disease.
We are now beginning to understand that DNA is not only responsible for the transfer of traits from parents to offspring, but that DNA plays a dynamic, active role in our daily lives. When we exercise, genes in our muscles are suddenly awakened and make proteins that permit us to more effectively metabolize energy sources. When we are hungry, genes in our body are turned on that impact insulin levels. Certain food substances have been identified that turn on or turn off genes. Retinoic acid, zinc and other food substances are known to bind to DNA, thereby altering gene expression. Food substances can have a dramatic effect on susceptibility or onset of human diseases by interacting with DNA. For example, dietary fatty acids, which can regulate cellular function through direct modification of gene transcription, are known to impact blood pressure, impact vasoconstriction, modify risks of atherosclerosis and alter the risk of cancer.
In the broadest sense of the term, nutrigenomics is the effect of dietary components on gene expression. Every time you eat, food is converted to nutrition through the physical and biochemical breakdown. This is true for nutrients like carbohydrates or vitamins and minerals, or non-nutrients, like bioactives such as phytochemicals or metabolites. Bioactives from foods such as carrots and fish can be transported to destination cells, get into the nucleus, and bind to the promoter region of our mRNA (most often with the help of a transcription factor). This, in turn, affects the multitude of proteins that our DNA churns out, such as enzymes and others responsible for cellular and biological functions.
While the genome has been sequenced, we still do not know much about what the proteins produced by these genes actually do. To complicate matters more, the major disease states associated with morbidity, like cancer and heart disease, as well as the additional common diseases that are responsible for the bulk of healthcare dollars, such as diabetes, obesity, and arthritis, are all very complex and have many, many genes responsible for the progression and complications associated with these health states. For example, a gene chip is commercially available that has identified over 300 genes associated with arthritis.
While we know much about the biochemistry and metabolism of many nutraceuticals, we don't know how they affect specific genes. In order for nutrigenomics to be applicable, it is essential to know what genes to effect and then figure out if a bioactive or extract/ingredient can regulate the expression of such genes central to the health condition of concern.
As with our understanding of the very nature of DNA, nutrigenomics will find its way into our life by evolution, not revolution. We envision two key phases of products that could be separated by as much as 10 years: the "biomarker phase" and the "genetics phase."
The biomarker phase is upon us and will be based on genetic tools that are presently available. It must be based on the impact of bioactives on biomarkers (such as cholesterol or blood pressure) and endpoints (such as pain or mobility). With an estimated 20,000-25,000 genes in the human body, it will be many years before we understand the function of each gene and the involvement of each gene in chronic human diseases. However, with our present state of knowledge it is still possible to use gene expression screening to identify bioactives that can impact genes involved in human disease. For example, it has been demonstrated by researchers at Rutgers University, New Brunswick, NJ, that theaflavins from tea impact expression of multiple genes involved in arthritis. When mice are fed a theaflavin-enriched tea plant extract, inflammatory cytokines are greatly reduced. Also, these mice have greatly reduced symptoms of induced arthritis. Hence, genetic screening technology can be used to identify bioactives that have a direct impact on treatment or prevention of a disease through regulation of associated genes. Ultimately there needs to be a quantifiable, measurable human outcome, or biomarker. To determine if the product works in people is rather simple. If mobility is improved and swelling is reduced after taking the product, its benefit, especially in those who suffer daily from arthritis, will be obvious. With reliable biomarkers, positive in vitro and in vivo results should be validated in people.
All natural, plant-based extracts appear to be ideal for the development of products in the biomarker phase. Natural products are often composed of mixtures of related compounds that could have an impact on several genes in associated biochemical pathways. For example, research has demonstrated that consumption of cocoa could prevent obesity in rats fed a high fat diet. These rats had altered gene expression of several genes involved in fatty acid synthesis and fatty acid transport. As target genes are identified, gene expression screening will be a valuable tool to identify whether foods and extracts have an effect on such genes and will enable the discovery of bioactives that alter biomarkers associated with human disease.
The genetics phase will be based on genetic testing. One day in the not-to-distant future, you will go to the doctor's office and have your DNA analyzed. The result of a test will be a personalized road map for disease prevention. If you know what diseases you are likely to contract, you can supplement your diet with personalized preventive products. Such DNA tests exist today, but only for a woefully small number of genes. These present day tests provide only a glimpse of the future. The MTHFR gene is one example of how such tests would work. Individuals with a mutated MTHFR gene, with a T instead of a C at a specific position in the DNA, make an enzyme with an altered amino acid (valine instead of alanine) that has altered enzyme activity. It has been estimated that 10% of Europeans have two copies of the mutated MTHFR. When present in two copies, this mutation results in higher plasma levels of homocysteine. High plasma homocysteine level is correlated with increased risk of cardiovascular disease. Present day tests for the MTHFR gene recommend increased consumption of folic acid for those with the mutated MTHFR gene. Because it has been shown to reduce homocysteine levels.
The genetics phase will entail nutrigenetics, a subset of nutrigenomics, which will enable dietary recommendations for individuals with specific, chronic disease genotypes. Nutrigenetics refers to how a person's genetic makeup predisposes them to dietary components. We now know that genetic variation (genotype) dictates the response of individuals to medicines (pharmacogenomics), as well as to food and supplements that interact with genes. While nutrigenomics explores how food chemicals alter the expression of genetic material, genetic differences called polymorphisms (or SNPs) affect an individual's biological response. Because not everyone is genetically identical, ultimately through nutrigenetics, recommendations of dietary supplements and whole foods can be made based on the specific genes of these individuals. For example, it is possible that a single allelic variation can alter whether polyunsaturated fatty acids or soluble oat can help reduce cholesterol.
It is important to realize that this two-dimensional strategy of scanning sequences of candidates of genes for presence of genetic variants to correlate with a potential therapeutic effect may not be enough. Even being able to identify a functional effect of a gene can be further complicated with allelic mutations. Recently unveiled is a three dimensional approach, which incorporates gene copy-number changes with information on single-nucleotide variation and clinical outcomes, especially for complicated diseases such as cancer or obesity. This further validates the need for biomarkers to be able to perform the clinical testing on those populations who are potentially predisposed.
Man evolved as a hunter-gatherer. Most of human history was marked by periods of intense physical activity alternating with periods of famine, and a relatively short lifespan. The 21st century lifestyle is at odds with our genes-we are sedentary, sated and we all want to live to be 100. The consequence of this disconnect with our genes is the epidemic of disease states associated with inactivity and aging (obesity, cardiovascular disease, cancer, arthritis, and type II diabetes). Opportunities exist to discover bioactives that can enhance the benefits of exercise, reduce our tendency to store fat and delay the effects of aging.
Two areas that are ripe for development of nutrigenomic products are exercise and obesity. The act of exercising, like nutrition, turns genes on in the human body. This phenomenon has been characterized extensively in human skeletal muscle. In contracting muscle, messenger RNA production of the IL-6 gene (interleukin-6, a gene involved in inflammation) increases 100-fold. The IL-6 protein is transported to the plasma (with IL-6 levels increasing 30-fold) and appears to have potent anti-inflammatory activity as measured by reduced levels of another inflammatory protein TNF_ (tumor necrosis factor- alpha). Hence, regular exercise induces a strong anti-inflammatory effect in the human body, which may account for the benefit of regular exercise against insulin resistance and cardiovascular disease, as low-grade inflammation is associated with both of these conditions.
In addition, other genes are turned on only during the recovery phase following exercise. This interplay of nutrition, genes and exercise presents multiple opportunities to develop specifically designed food and beverage products that interact with our genes for exercise performance and recovery. As we know, antioxidants may help prevent various diseases associated with oxidative stress, such as cancer, cardiovascular disease and inflammation. Perhaps, this is a good place to start.
Interesting work has also shown that gene expression during exercise differs between older and younger subjects. The potential exists to develop age-specific products that target expression of genes needed for optimal anti-inflammatory activity
Obesity, of course, is an incredibly complex arena. Nearly 100 genes have been implicated in effecting obesity, through causing obesity or increasing the likelihood of becoming obese. Genes range from central nervous system on/off switches, which tell you when you are hungry to hormone (insulin and leptin) regulators to adipocyte/fat initiators. One example in recent findings suggests that several variants of the ENPP1 gene play a primary role in the development of both obesity (in children and adults) and type 2 diabetes through mediation of insulin resistance. Other research has shown that exercise training increases lipid metabolism gene expression in skeletal muscle. What if weight loss is not all about energy in/energy out in the form of calories? If exercise can induce our bodies to mobilize fat transport or prevent generation of excess fat through gene regulation, perhaps it is possible to mimic the effect of exercise with the right biologically active food component.
The truth is, what we do and who we are (i.e., our diet or whether we exercise, as well as environmental factors and our genes) all intertwine to control our susceptibility to disease, and therefore, our quality of life. It is clear from epidemiological and clinical evidence that we can take measures to prevent or delay onset of disease through consumption of healthful foods, as those prescribed in the U.S. Dietary Guidelines for Americans. The field of nutrigenomics seeks to understand which of the thousands of different compounds, contained as part of a food matrix, play particular roles in specific health benefits.
Nutrigenomics uncovers the mechanism of action for onset and progression of diseases and the associated side effects from bioactives from foods. Nutrigenomics is a technologically advanced method to help justify a cause and effect relationship for the positive benefit between food and a disease-in a sense to answer a piece of the puzzle as to how bioactives work. Nutrigenomics is especially powerful as a biological mechanism of action. However, clinical studies must be performed to confirm that the in vitro/cellular, animal, or epidemiological data for targeting disease prevention, for example, can be validated in humans.
The objective in gene expression-based discovery is not to create a single compound (or drug), which is developed to act on a single molecular target for the benefit of acting on a single disease. We understand that our bodies work through coordinated regulation with an intricate feedback system of checks and balances. Food-based compounds work on numerous genes affecting multiple pathways. Because we are constantly exposing our bodies to different foods, environments and activities, the molecular mechanisms and amount of gene up and down-regulation is highly complex. However, once there is cause, such as in vitro and in vivo gene expression evidence, substantiation can be achieved through clinical trials, which measure the human outcome and quantify the benefit. Nutrigenomics is useful for identifying and confirming natural compounds, which play important roles in benefiting targeted health conditions. To put it simply, nutrigenomic discovery of natural bioactives can lead to the development of extracts rich in bioactive compounds that are proven to improve one's health.NW
About the authors: Julie Hirsch, PhD, is director of product development for WellGen, New Brunswick, NJ, and David Evans, PhD, is president and CEO. Dr. Hirsch has more than 10 years of experience in product development, market research and business development within the food industry and she is currently an adjunct faculty member of the department of Food Science at Rutgers University. Dr. Evans joined WellGen in 1999 as CEO and president. Prior to joining WellGen, Dr. Evans spent 18 years with DNAP Holding Corp and its predecessor company, DNA Plant Technology (DNAP), in various capacities. Dr. Evans is an inventor on 12 U.S. patents and has published over 100 scientific papers. The authors can be reached at 732-932-9611; Website: www.wellgen.com.
We are now beginning to understand that DNA is not only responsible for the transfer of traits from parents to offspring, but that DNA plays a dynamic, active role in our daily lives. When we exercise, genes in our muscles are suddenly awakened and make proteins that permit us to more effectively metabolize energy sources. When we are hungry, genes in our body are turned on that impact insulin levels. Certain food substances have been identified that turn on or turn off genes. Retinoic acid, zinc and other food substances are known to bind to DNA, thereby altering gene expression. Food substances can have a dramatic effect on susceptibility or onset of human diseases by interacting with DNA. For example, dietary fatty acids, which can regulate cellular function through direct modification of gene transcription, are known to impact blood pressure, impact vasoconstriction, modify risks of atherosclerosis and alter the risk of cancer.
In the broadest sense of the term, nutrigenomics is the effect of dietary components on gene expression. Every time you eat, food is converted to nutrition through the physical and biochemical breakdown. This is true for nutrients like carbohydrates or vitamins and minerals, or non-nutrients, like bioactives such as phytochemicals or metabolites. Bioactives from foods such as carrots and fish can be transported to destination cells, get into the nucleus, and bind to the promoter region of our mRNA (most often with the help of a transcription factor). This, in turn, affects the multitude of proteins that our DNA churns out, such as enzymes and others responsible for cellular and biological functions.
While the genome has been sequenced, we still do not know much about what the proteins produced by these genes actually do. To complicate matters more, the major disease states associated with morbidity, like cancer and heart disease, as well as the additional common diseases that are responsible for the bulk of healthcare dollars, such as diabetes, obesity, and arthritis, are all very complex and have many, many genes responsible for the progression and complications associated with these health states. For example, a gene chip is commercially available that has identified over 300 genes associated with arthritis.
While we know much about the biochemistry and metabolism of many nutraceuticals, we don't know how they affect specific genes. In order for nutrigenomics to be applicable, it is essential to know what genes to effect and then figure out if a bioactive or extract/ingredient can regulate the expression of such genes central to the health condition of concern.
Commercial Implications
As with our understanding of the very nature of DNA, nutrigenomics will find its way into our life by evolution, not revolution. We envision two key phases of products that could be separated by as much as 10 years: the "biomarker phase" and the "genetics phase."
The biomarker phase is upon us and will be based on genetic tools that are presently available. It must be based on the impact of bioactives on biomarkers (such as cholesterol or blood pressure) and endpoints (such as pain or mobility). With an estimated 20,000-25,000 genes in the human body, it will be many years before we understand the function of each gene and the involvement of each gene in chronic human diseases. However, with our present state of knowledge it is still possible to use gene expression screening to identify bioactives that can impact genes involved in human disease. For example, it has been demonstrated by researchers at Rutgers University, New Brunswick, NJ, that theaflavins from tea impact expression of multiple genes involved in arthritis. When mice are fed a theaflavin-enriched tea plant extract, inflammatory cytokines are greatly reduced. Also, these mice have greatly reduced symptoms of induced arthritis. Hence, genetic screening technology can be used to identify bioactives that have a direct impact on treatment or prevention of a disease through regulation of associated genes. Ultimately there needs to be a quantifiable, measurable human outcome, or biomarker. To determine if the product works in people is rather simple. If mobility is improved and swelling is reduced after taking the product, its benefit, especially in those who suffer daily from arthritis, will be obvious. With reliable biomarkers, positive in vitro and in vivo results should be validated in people.
All natural, plant-based extracts appear to be ideal for the development of products in the biomarker phase. Natural products are often composed of mixtures of related compounds that could have an impact on several genes in associated biochemical pathways. For example, research has demonstrated that consumption of cocoa could prevent obesity in rats fed a high fat diet. These rats had altered gene expression of several genes involved in fatty acid synthesis and fatty acid transport. As target genes are identified, gene expression screening will be a valuable tool to identify whether foods and extracts have an effect on such genes and will enable the discovery of bioactives that alter biomarkers associated with human disease.
The genetics phase will be based on genetic testing. One day in the not-to-distant future, you will go to the doctor's office and have your DNA analyzed. The result of a test will be a personalized road map for disease prevention. If you know what diseases you are likely to contract, you can supplement your diet with personalized preventive products. Such DNA tests exist today, but only for a woefully small number of genes. These present day tests provide only a glimpse of the future. The MTHFR gene is one example of how such tests would work. Individuals with a mutated MTHFR gene, with a T instead of a C at a specific position in the DNA, make an enzyme with an altered amino acid (valine instead of alanine) that has altered enzyme activity. It has been estimated that 10% of Europeans have two copies of the mutated MTHFR. When present in two copies, this mutation results in higher plasma levels of homocysteine. High plasma homocysteine level is correlated with increased risk of cardiovascular disease. Present day tests for the MTHFR gene recommend increased consumption of folic acid for those with the mutated MTHFR gene. Because it has been shown to reduce homocysteine levels.
The genetics phase will entail nutrigenetics, a subset of nutrigenomics, which will enable dietary recommendations for individuals with specific, chronic disease genotypes. Nutrigenetics refers to how a person's genetic makeup predisposes them to dietary components. We now know that genetic variation (genotype) dictates the response of individuals to medicines (pharmacogenomics), as well as to food and supplements that interact with genes. While nutrigenomics explores how food chemicals alter the expression of genetic material, genetic differences called polymorphisms (or SNPs) affect an individual's biological response. Because not everyone is genetically identical, ultimately through nutrigenetics, recommendations of dietary supplements and whole foods can be made based on the specific genes of these individuals. For example, it is possible that a single allelic variation can alter whether polyunsaturated fatty acids or soluble oat can help reduce cholesterol.
It is important to realize that this two-dimensional strategy of scanning sequences of candidates of genes for presence of genetic variants to correlate with a potential therapeutic effect may not be enough. Even being able to identify a functional effect of a gene can be further complicated with allelic mutations. Recently unveiled is a three dimensional approach, which incorporates gene copy-number changes with information on single-nucleotide variation and clinical outcomes, especially for complicated diseases such as cancer or obesity. This further validates the need for biomarkers to be able to perform the clinical testing on those populations who are potentially predisposed.
Genes Out of Sync
Man evolved as a hunter-gatherer. Most of human history was marked by periods of intense physical activity alternating with periods of famine, and a relatively short lifespan. The 21st century lifestyle is at odds with our genes-we are sedentary, sated and we all want to live to be 100. The consequence of this disconnect with our genes is the epidemic of disease states associated with inactivity and aging (obesity, cardiovascular disease, cancer, arthritis, and type II diabetes). Opportunities exist to discover bioactives that can enhance the benefits of exercise, reduce our tendency to store fat and delay the effects of aging.
Two areas that are ripe for development of nutrigenomic products are exercise and obesity. The act of exercising, like nutrition, turns genes on in the human body. This phenomenon has been characterized extensively in human skeletal muscle. In contracting muscle, messenger RNA production of the IL-6 gene (interleukin-6, a gene involved in inflammation) increases 100-fold. The IL-6 protein is transported to the plasma (with IL-6 levels increasing 30-fold) and appears to have potent anti-inflammatory activity as measured by reduced levels of another inflammatory protein TNF_ (tumor necrosis factor- alpha). Hence, regular exercise induces a strong anti-inflammatory effect in the human body, which may account for the benefit of regular exercise against insulin resistance and cardiovascular disease, as low-grade inflammation is associated with both of these conditions.
In addition, other genes are turned on only during the recovery phase following exercise. This interplay of nutrition, genes and exercise presents multiple opportunities to develop specifically designed food and beverage products that interact with our genes for exercise performance and recovery. As we know, antioxidants may help prevent various diseases associated with oxidative stress, such as cancer, cardiovascular disease and inflammation. Perhaps, this is a good place to start.
Interesting work has also shown that gene expression during exercise differs between older and younger subjects. The potential exists to develop age-specific products that target expression of genes needed for optimal anti-inflammatory activity
Obesity, of course, is an incredibly complex arena. Nearly 100 genes have been implicated in effecting obesity, through causing obesity or increasing the likelihood of becoming obese. Genes range from central nervous system on/off switches, which tell you when you are hungry to hormone (insulin and leptin) regulators to adipocyte/fat initiators. One example in recent findings suggests that several variants of the ENPP1 gene play a primary role in the development of both obesity (in children and adults) and type 2 diabetes through mediation of insulin resistance. Other research has shown that exercise training increases lipid metabolism gene expression in skeletal muscle. What if weight loss is not all about energy in/energy out in the form of calories? If exercise can induce our bodies to mobilize fat transport or prevent generation of excess fat through gene regulation, perhaps it is possible to mimic the effect of exercise with the right biologically active food component.
Utilizing Nutrigenomics
The truth is, what we do and who we are (i.e., our diet or whether we exercise, as well as environmental factors and our genes) all intertwine to control our susceptibility to disease, and therefore, our quality of life. It is clear from epidemiological and clinical evidence that we can take measures to prevent or delay onset of disease through consumption of healthful foods, as those prescribed in the U.S. Dietary Guidelines for Americans. The field of nutrigenomics seeks to understand which of the thousands of different compounds, contained as part of a food matrix, play particular roles in specific health benefits.
Nutrigenomics uncovers the mechanism of action for onset and progression of diseases and the associated side effects from bioactives from foods. Nutrigenomics is a technologically advanced method to help justify a cause and effect relationship for the positive benefit between food and a disease-in a sense to answer a piece of the puzzle as to how bioactives work. Nutrigenomics is especially powerful as a biological mechanism of action. However, clinical studies must be performed to confirm that the in vitro/cellular, animal, or epidemiological data for targeting disease prevention, for example, can be validated in humans.
The objective in gene expression-based discovery is not to create a single compound (or drug), which is developed to act on a single molecular target for the benefit of acting on a single disease. We understand that our bodies work through coordinated regulation with an intricate feedback system of checks and balances. Food-based compounds work on numerous genes affecting multiple pathways. Because we are constantly exposing our bodies to different foods, environments and activities, the molecular mechanisms and amount of gene up and down-regulation is highly complex. However, once there is cause, such as in vitro and in vivo gene expression evidence, substantiation can be achieved through clinical trials, which measure the human outcome and quantify the benefit. Nutrigenomics is useful for identifying and confirming natural compounds, which play important roles in benefiting targeted health conditions. To put it simply, nutrigenomic discovery of natural bioactives can lead to the development of extracts rich in bioactive compounds that are proven to improve one's health.NW
About the authors: Julie Hirsch, PhD, is director of product development for WellGen, New Brunswick, NJ, and David Evans, PhD, is president and CEO. Dr. Hirsch has more than 10 years of experience in product development, market research and business development within the food industry and she is currently an adjunct faculty member of the department of Food Science at Rutgers University. Dr. Evans joined WellGen in 1999 as CEO and president. Prior to joining WellGen, Dr. Evans spent 18 years with DNAP Holding Corp and its predecessor company, DNA Plant Technology (DNAP), in various capacities. Dr. Evans is an inventor on 12 U.S. patents and has published over 100 scientific papers. The authors can be reached at 732-932-9611; Website: www.wellgen.com.
