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It’s in Your Genes

By Lavender March 12, 2009

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Nutrition: The provision of necessities (e.g., nutrients) to cells and organisms to support life.

Genetics/Genomics: The science of genes, heredity, and variation in living organisms.

Nutritional Genomics
: The science of interrelations among the genome, nutrition, and health.

Imagine the following scenario:

You are 40 years old, and a month ago, you had a routine checkup at your doctor’s office. They collected blood samples to measure your cholesterol levels. You have a recent family history of cardiovascular disease (CVD). Both your parents have high LDL (“bad”) cholesterol levels, and low (“good”) HDL cholesterol levels. So, your doctor really wanted to make sure that your cholesterol levels were in the normal ranges.

Test results showed that you also have high LDL cholesterol levels, a significant risk factor for CVD. The doctor is stumped. He sees that you eat a well-balanced, healthful diet, and exercise regularly. You do not smoke, and rarely consume more than a few drinks of alcohol in a week’s time. Your lifestyle habits are essentially perfect—or are they?

Your doctor has an idea. He tells you to pull out your electronic genome profile card, which informs him what genes you have. He notices you have a specific variation in the apolipoprotein E (APOE) gene, corresponding to the APOE protein—which helps hold together lipoproteins such as LDL and HDL—predisposing you to a greater risk of high LDL cholesterol levels.

You see, genes are the starting point for the synthesis of all body proteins, and variations in these genes lead to variations in protein structures and functions. Without going into detail, this means that the APOE protein you express from your APOE gene results in significantly higher LDL cholesterol levels from similar amounts of dietary fat intake than someone who does not have the specific APOE gene variant you have.

In other words, you need to eat less dietary fat than other individuals to maintain your cholesterol levels within the normal ranges, even if your dietary fat intake is not currently outside the population-based recommendations.

Your doctor informs you of this situation, and suggests that you try lowering your dietary fat intake for a little while. You follow this recommendation, and your next blood test three months later reveals LDL cholesterol levels on the lower end of the normal range!

The above scenario may seem unrealistic, and it may be a long way off. However, let me assure you, a time will come in the relatively near future when that scenario is reality. Once that happens, you will be able to receive personalized nutrition advice based on your genes and lifestyle habits, rather than the overgeneralized, broad nutritional recommendations currently used.

For example, instead of the “normal” recommended intake for folate of 400 micrograms, your genes may disagree, and say that you need 800 micrograms for optimal health and body functioning. In fact, modern research already has shown that specific variants of the methyltetrahydrofolate reductase (MTHFR) gene require higher dietary intakes of B-vitamins such as folate, vitamin B6, and vitamin B12 to maintain healthy homocysteine levels. High homocysteine levels increase the risk of CVD. Without knowledge about your genes, you would have no way of knowing whether higher B-vitamin intakes could be of any benefit.

The emerging scientific field described above is called nutritional genomics. It basically represents the study of interrelations among the genome (what specific variants of each gene a person has), nutrition/diet, and overall health.

We already are able to determine which gene variants a person has, but knowing if, when, how, and why specific gene variants differentially interact with diet to influence health is a much more complicated story. This knowledge will require much more scientific research and worldwide collaboration efforts.

Believe me, I am a realist, and all this sounds like hocus-pocus at this time, but hard-earned scientific knowledge and scientists’ determination will see it through to reality in the coming years.

I believe dieticians will be needed to fill a vital role in the nutritional genomics field to have full effect.

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