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Observations and Predictions for the Coming Years
Expect this: Within the next 3-5 years, schooled nutritionists will be capable of far better serving their clients’ health-related goals, given the unique genetic encryption of every individual. Novel questions arising during consultations such as: “What is the subset of breast cancer that runs in your family?”
or “Have you been tested for a diabetic transcription profile?” will be the norm. I also predict that nutrition Rx will naturally evolve from “code” interpretation, with diminishing reliance on probable, yet variable, population norms. And, the quickly emerging discipline of “nutrigenomics” (the science of gene expression as affected by food) will become the darling of the diet industry, establishing itself as the most efficacious lifestyle science yet known. Nutrigenomics is actually a young science, still in its infancy and less than 10 years old. The first reported account linking dietary components to gene expression appeared in 1996 when researchers demonstrated that flavonoids found in citrus peel enhanced expression of a gene involved in the body’s natural defense against cancer. In another early-on study, folic acid exhibited its extraordinary talent for methylating DNA – a good thing. Undermethylated DNA – a prerequisite for cancer cell proliferation – has been detected in humans consuming a folate-deficient diet. The concept that food chemicals can affect gene expression – once regarded as questionnable – got a well-deserved credibility boost compliments of these impressive initial investigations.
The Human Genome Project – Getting to Know You
Initiated in 1990 under the wings of the National Institutes of Health and the Department of Energy, the Human Genome Project was slated for completion in 2005. Plaudits, however, are rightfully due to the thousands of participating researchers as the project objectives were fulfilled in 2003, two years ahead of schedule. Some key findings included: Human DNA contains a total of approximately 3 billion nucleotide bases. (Notes: In the human genome, there are four different base types, i.e. adenine, thymine, guanine, and cytosine that can be linked together in any possible sequence forming a single strand of DNA. However, entwining this strand is a second strand, which together form a double helix – thank you Drs. Watson and Crick. The second strand is an exact complement of the first in that adenine on the first strand is always paired with thymine on the second – or vice versa. Similarly, guanine always pairs with cytosine. In evolutionary development, certain sequences of base pairs serve as genes – genetic templates used for the synthesis of gene-specific enzymes and hormones.) The human genome contains approximately 30,000 genes – each serving as a template for the synthesis of a protein (enzyme, hormone, or co-factor). The average gene contains 3000 nucleotide bases. 99.9% of the nucleotide bases are exactly the same in all people. 50% of all discovered genes have unknown functions. The 0.1% of the nucleotide bases that vary within the human race are referred to as SNP’s, single nucleotide polymorphisms (and simply called “snips”). Snips serve as markers for characteristics that make us unique: heredity, physiology, etc. Not surprising, snips are currently utilized by the phamaceutical industry to develop customized individual-specific drugs (pharmacogenomics), anthropologists to track ancestry, and the medical community to determine or confirm disease risk.
Some Impressive Nutrigenomic Contributions: Inflammation
The potential for nutrigenomics is obvious, particularly in the future development of designer diets and supplements. However, it is currently (and affectively) being used to assess the role of food components in the promotion of inflammation – a condition associated with several chronic diseases (cardiovascular disease, cancer, diabetes, arthritis, immune dysfunction, joint pain). Genes directly involved in inflammation include COX-2 and lipoxygenase (LOX) – both of which expression is amplified by omega-6 fat (vegetable oils). On the other hand, omega-3 fatty acids (from fish oil and flax seed oil) are competitive inhibitors of COX and LOX, thereby promoting an anti-inflammatory effect. The age-old advice of consuming more fish, or taking a fish oil supplement for inflammation has been corroborated, compliments of nutrigenomics. In addition to the lipid work, several hundred herbs have been tested for their ability to modulate expression of the COX-2 and other inflammatory genes. To date, the best performers have been curcumin (from turmeric), resveratrol (from grapes), catechins (from green tea), theaflavins (from black tea), and vitamin E. Being that there are thousands of reported global folk remedies for inflammation, verification of efficacy through nutrigenomics should quickly add to our arsenal of evidence-based alternative therapies.
How the Pyramid(s) Were Built
The USDA Pyramid and its ethnic variations (Chinese, Mexican, Italian, Native American, etc.) were developed from studies that assume all of us will respond positively (and near-equally) to the same dietary guidelines. However, the concept of one size fits all, nutrition-wise, is holding less and less water as we continue to define genetic diversity among the U.S. populace. According to the University of California (Davis) nutrigenomics website (http://nutrigenomics.ucdavis.edu/), minority populations have disproportionately high incidences of all chronic diseases. Surveys such as the Secretary's Task Force Report on Black and Minority Health (1985) document higher risks of diabetes, obesity, asthma, cardiovascular disease, and some cancers among certain U.S. minority groups. Mortality from prostate cancer, for example, is 60% higher in African American men than men of European decent. A reasonable assumption (in my opinion) is that human genetic diversity is composed of subsets, some of which are linked to amplified gene expression associated with increased disease risk. And, in lieu of the rapidly unfolding human genome, it is difficult to imagine a future of food pyramids, heart diets, diabetic diets, weight loss programs, etc. that are not accommodating to genetically-defined population subsets. With optimum health as the goal for every U.S. citizen, we cannot assume we’re essentially the same –culturally, socio-economically, physiologically, or genetically. Knowing what makes us tick (and tick well) – literally – is within our grasp. The analogy I use in class to describe lifestyle practices in support of health (prior to genome technology) is a comparison to postponing deterioration of an automobile through responsible usage (no speeding or lugging, no fast braking, using the right octane fuel, etc.) but never servicing the engine. Now, two years after mapping the entire human genome, we’re beginning to look under our hoods, corroborating what we’ve always suspected, i.e. no two engines (genomes) are exactly alike. Every individual requires customized tuning (therapy) for maximum health and long life. Welcome to the big-bang of individualized healthcare.
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