There are many benefits of using genomics to help determine your diet. One of these is preventing future complex diseases. This future is here.
Nothing in life is to be feared, it is only to be understood.
Maria Skłodowska-Curie (1867 – 1934)
The supermarket of today will be the pharmacy of tomorrow.
Let the medicine be your food, and the food be your medicine.
Hippocrates (460-370 B.C.)
Nutritional Genomics is divided into two different -but collaborating- sister areas. These areas are, in fact, two sides of the same coin:
Nutrigenetics and Nutrigenomics.
Both focus on the interaction between nutrition, genes, and health outcomes. However, there are important conceptual differences in the information, and we can obtain information from each of them.
Starting from 2001, after the human genome was first fully sequenced, valuable new bodies of data were made available to scientists of all disciplines to explore the interactions between our genetic and genomic information with environmental factors such as diet.
In this new Nutrigenomics era, the importance of genes in human nutrition has been in the spotlight. The focus of the nutritional field has shifted towards detailed molecular studies of nutrition that focus more on preventing complex and chronic diseases, rather than solely nutritional deficiencies.
Prevention is always better than treatment
Nutrigenetics studies how our genes determine the effects that our food has on us. This genetic “make-up” is what makes us unique. It includes individual pigments and character traits.
Our genetic predisposition and sensitivity is ¨measured¨ by specific genetic markers: SNPs (Single Nucleotide Polymorphisms)
Nutrigenetics is the scientific area that identifies what parts of our inherited traits can be modified by what we eat, how we act, and how to make these changes. Our genetic make-up consists of numerous genetic markers, mainly SNPs which do not change throughout our lives. We are born with this “genetic fingerprint”. Changes to our SNPs mean changes to one of the four letters of our DNA sequence. What does a change to a single letter mean? Think about letters, words, and sentences.
For example, think of the difference between FAT and FIT. If we replace the A with an I, the meaning of the word changes entirely.
Conversely, think of a woman named ANNA. She will always respond to us, whether we spell her name with one N (ANA) or two (ANNA). Here, a one-letter difference, a spelling mistake, does not change the meaning of the word.
Nutrigenetics identifies the letters in the “words” of our DNA “book” and compensates them through dietary and lifestyle changes.
Nutrigenetics identifies what parts of our inherited traits can be modified by what we eat, how we act, and how to make these changes. Nutrigenetics determine the genetic “make-up” that makes us unique and does not change throughout our lives. We are born with this “genetic fingerprint”.
Nutrigenomics studies how nutrition and concrete dietary patterns modulate the expression of our genes as a whole. Gene expression can change throughout life and environmental or external factors can have a huge impact on this change, whether it is a positive or a negative one.
NOT another magic diet or miracle.
NOT a short-term solution, but rather long-term prevention.
NOT the same as those from pharmacogenomic studies. There are fundamental differences between nutrition and pharmacological therapy such as
Nutrigenetics and nutrigenomics deal with the complexity and variability of dietary patterns and lifestyle habits, not pure synthetic compounds and molecules, like drugs.
Nutrients and new dietary patterns, in contrast to prescription drugs, can be given in higher concentrations without becoming toxic.
The nutrient effect is always synergistic and is produced gradually, accumulating throughout one’s life.
Starting after the human genome was first fully sequenced in 2001, valuable new bodies of data were made available to scientists of all disciplines to explore the interactions between our genetic and genomic information with environmental factors such as a diet.
The human genome contains approximately 2.9 billion nucleotides or 30,000 genes, some of which are involved in metabolic pathways. Most of the genes that have been identified do not directly cause complex diseases, but rather enhance our susceptibility and predisposition. A wide range of biochemical and molecular pathways are involved in this predisposition. A wide range of biochemical and molecular pathways are involved in this predisposition. The genomic revolution of the 21st century facilitated the study of the genes in the connection of nutrition and soon, nutritional genomics was born as a scientific discipline.
The interaction between genes and one’s diet has always been fundamental to human health. Their interaction has been an integral component of human evolution. The continuous cross-talk between genes and diet has helped humanity survive and evolve. Examples of how a food or a component of food can affect a person’s health status have been known for some time.
For example, the hemolysis that may occurs after fava beans consumption in people with glucose-6 dehydrogenase deficiency, or the dietary problems people with genetically determined lactose intolerance or gluten-sensitive enteropathies are some of the most well-known cases.
Nutrition aims to find a fine-tuned balance between the processes and metabolic pathways in order to maintain homeostasis and promote health. Diet plays an essential role in preventing and developing many complex and chronic diseases. Although we might have a genetic predisposition to either suffer or immunity from a certain illness or condition, it is our lifestyle that determines whether or not we develop it. We can reduce our inherited risk of diabetes, heart disease, or obesity by making healthy choices from a very early age.
There are numerous nutrigenetics and nutrigenomics tools. Depending on how and where we will use them, we choose and combine different ones. Only the experienced, specialized health professional, nutritionist-dietitian can make this choice. Here we mention the most commonly used tools in nutrigenetics.
The outcome of nutritional genomics studies should always be analyzed in parallel with the phenotype. That is all the mechanistic, clinical, and/or epidemiological data that is available for the person and the compound and/or dietary pattern under study. Using bioinformatics tools to link information between the genome, transcriptome, proteome, and metabolome is a major challenge.
Bioinformatics tools are necessary for the interpretation of changes in genes related to specific nutrients or dietary patterns whose function is still unknown. Special bioinformatic software packages are required for the challenging analysis of these outputs. Grouping genes based on functional similarity can help to enhance the biological interpretation of large lists of genes. It has also been shown that disease-related genes tend to interact and display significant functional clustering.
Genes can be clustered together according to their functional similarities. Such clusters can help us understand their biological role and functions. It has also been shown that genes that predispose to certain diseases tend to interact with each other (gene-gene interactions) and present similar functions. Moreover, “negative” genes may equilibrate “positive” genes and vice-versa. Knowing and understanding these interactions and functions is a tool that the specialized health professional will use before interpreting and recommending actions.
Genes associated with similar disorders show both a higher likelihood of physical interactions between their products and a higher expression profiling similarity. That supports the existence of distinct disease-specific function modules. Subtle changes in our DNA can now be measured by quantitative techniques such as high-density microarrays, real-time poly-chain reaction (PCR), and of course, sophisticated sequencing methods.
The high potential and novelty of nutrigenetic results have rapidly attracted the attention of the market. Consumers must look and pay careful attention to whether the concrete criteria of nutrigenetic tests are filled before considering a test valid and based on scientific evidence.
Which genes are tested is crucial. Why and how are selected should be baased on the pillars of Evidence-Based Medicine, a high level (I or II) of scientific evidence. This is required before nutritional recommendations can be made for the general public. Controlled random double-blind clinical intervention trials can provide the scientific evidence that is required. Also, to some extent, large cohort studies (level II) can also fulfill these requirements. Each and every one of the genetic markers included in the test should be supported by scientific evidence. This evidence could be interventions, replications, and verification studies published in first-class scientific peer-reviewed journals.
Genotyping is the main laboratory analysis performed in actual nutrigenetic tests. Certified and validated procedures should be used to perform genotyping analysis. This laboratory should also be accredited by official bodies and periodically audited to confirm compliance.
A simple presentation of genotyping results is not enough for understanding and interpreting the deep meaning of nutrigenetics. Close assistance and coaching is essential to correctly and accurately comprehend and incorporate all necessary changes into one’s lifestyle and everyday dietary habits. This can only be performed by specially trained and experienced professionals in the nutritional genomics field.
The correct application of nutrigenetic knowledge requires collaboration between experts and synergy among different specialties. Each nutrigenetic analysis needs to be treated as a whole service and not as a product. It requires interpretation because it is the only way it can be incorporated into everyday habits.
If I have seen further, it is only by standing on the shoulders of Giants.
Isaac Newton (1642-1727)
Nutrition is the only environmental factor we are exposed to on a daily basis. It is also the only environmental factor that we have total control over throughout our lives. Nutrition is involved in the pathogenesis and progression of polygenetic and complex diseases.
From a nutritional genomics point of view, nutrients act as dietary signals. Cells detect their signal and they transmit it, thus influencing gene and protein expression, and subsequently, metabolite production. The molecular structure of each nutrient determines the concrete signal emitting and the concrete pathways that this signal will affect. Even a small structural change (e.g. SFA vs MUFA or cholesterol vs plant sterols) have a deep impact on the activation of the affected pathways.
Nutrigenomics and nutrigenetics aim at identifying genes that influence the risk of diet-related, complex diseases on a genome-wide scale. It is of high importance to highlight that nutrigenomics and nutrigenetics examine the whole complexity and variability of nutrition. The molecular structure of each nutrient determines the concrete signal emitting and the concrete pathways that this signal will affect. Even a small structural change (e.g. SFA vs MUFA or cholesterol vs plant sterols) have a deep impact on the activation of the affected pathways.
The vast majority of the complex diseases are mainly chronic ones. They are characterized by complex phenotypes without the “one gene-one disease” approach. Numerous genes are responsible for the appearance and progression of these diseases, and we cannot “blame” only one of them. They are what we nominated as polygenic diseases.
Complex diseases, such as cardiovascular disease (CVD), Type II Diabetes Mellitus (T2DM), and obesity are also multifactorial. CVD is the leading cause of death in industrialized countries. Currently, CVD accounts for more than 12×10 annual deaths worldwide, and it is one paradigm of multifactorial disorders where multiple genetic and modifiable risk factors are combined to modulate the disease outcome. Multifactorial diseases need numerous factors and/or conditions to cluster together in the same person, before their appearance.
Genetic and environmental factors are the key factors for the appearance of complex diseases.
These complex and multifactorial diseases require an improved overview (holistic) picture of their early phases to achieve prevention. The complex nature of these diseases includes the interaction of several mechanisms, at the molecular level, which, up to now, we’re only partly known. Nutrigenetics and nutrigenomics exploit the multiple, minor, and synergistic changes in genomic and genetic responses related to nutrition and health, instead of focusing on the single “target” response which is common in drug therapy.
How “much” genetic and how “much” environmental factors contribute to each disease and for each person, is not clear and it is a totally personalized issue. Each one of us deserves, not only a personalized but also a precision treatment when it comes to complex diseases.
Each one of us deserves a personalized and precise treatment when it comes to multifactorial, diet-depended diseases.
Large national and international research organizations in the Nutritional Genomics field are being formed to jointly address the great scientific challenges (Figure). Their success is based on a collaborative effort among scientists from different disciplines such as nutrition, molecular biology, biomedicine, genomics, bioinformatics among others.