Genetics and Genomics - How They Relate to Dietary Patterns

With today's guest Nicola Pirastu we learn the difference between several common genetic terms, how your diet choices may or may not be good for your personal health and how your diet can impact your genes and their expressions.

Genetics Vs Genomics

The terms genetics and genomics sound alike, and they are often used interchangeably. But there are some important distinctions and similarities between genetics and genomics and how they affect our dietary patterns. But firstly, what do they mean?

Genetics is the study of heredity, or how the characteristics of living organisms are transmitted from one generation to the next via DNA, and it comprises genes, the basic unit of heredity.

Genetics dates back to Darwin and scientist Lamarck, whose studies of pea plants in the mid-1800s established many of the rules of heredity. Genetics involves the study of specific and limited numbers of genes, or parts of genes, that have a known function.

In biomedical research, scientists try to understand how genes guide the body's development, cause disease or affect our eating or dietary patterns.

Genomics, in contrast, is the study of the entirety of an organism's genes – called the genome.

Genomics is the branch of molecular biology concerned with the structure, function, evolution, and mapping of genomes.

Genomics is a much newer field than genetics and became possible only in the last couple of decades due to technical advances in DNA sequencing and computational biology. (It is notable that the term genomics was first coined in 1986 by a Jackson Laboratory scientist, Tom Roderick, Ph.D.)

Genomics play huge roles in our dietary patterns as they help us know why our body relates to different foods and why our food preferences may or may not affect our overall health. For example two men of the same age were placed on a diet and eat fruits and vegetables high in sodium and saturated fat.

One develops hypertension, hypercholesterolemia, and eventually atherosclerosis, while the other lives a long life without such chronic disease. In another case, two postmenopausal women consume similar diets low in choline.

One develops liver dysfunction due to the choline deficiency, but the other does not. Why individuals experience different health outcomes even though they eat similar diets and practice comparable lifestyles is an important question that's been on the minds of nutrition and other healthcare experts in the medical community for decades.

While it's long been suspected that genetics plays a critical role in determining how a person responds to dietary intake, only recently has research in the field of nutrigenetics demonstrated this.

Learn the difference between nutrigenetics and nutrigenomics?

• Nutrigenetics: This is the study of the relationship among genes, diet, and health.
• Nutrigenomics: This involves the study of the interaction between nutrients and genes at the molecular level.

Nutrition scientists have looked at whether genetic testing ends up improving eating behaviors. The evidence is mixed. A recent large randomized controlled study found there was little apparent benefit.

The two weeks study comprised of 200 people. Three groups of participants were given personalized dietary advice, with variations based on their regular diet, including blood biomarkers such as cholesterol; and genetic variants. A control group was given conventional dietary advice.

At the end of the study, the three groups that received personalized nutrition advice had all improved their eating habits, compared with the control group.

But the improvements in each of the three groups were about the same. "It didn't seem to matter whether they were personalized based on current diet.

Nutrigenetics and Personalized Nutrition

The field of nutrigenetics is relatively new. In 2003, the Human Genome Project, which identified all the genes in human DNA and determined the sequence of the 3 billion chemical base pairs that make up human DNA, was completed.

Knowing the sequences of the human genome opened the doors to examine the relationship among an individual's genetic makeup, dietary intake, and health outcomes. The excitement surrounding nutrigenetics stems from the notion that it's the foundation of personalized nutrition.

Clearly, population-based dietary recommendations are helpful, but they aren't adequate for all individuals since people respond differently to diets. Personalized nutrition bases dietary recommendations on genetic predisposition to disease.

The idea is that once personalized nutrition is integrated into routine care, patients can be genotyped for specific genetic variations, made aware of their nutrient deficiencies, and given strategies to dramatically reduce their risk.

Effects of Genomic Research

Genome-based research is already enabling medical researchers to develop improved diagnostics, more effective therapeutic strategies, evidence-based approaches for demonstrating clinical efficacy, and better decision-making tools for patients and providers.

Ultimately, it appears inevitable that treatments will be tailored to a patient's particular genomic makeup.

Thus, the role of genetics in health care is starting to change profoundly and the first examples of the era of genomic medicine are upon us.

You can have a healthy diet not because it's good but because it's healthy.

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