Phenotypic NutritionDecember 2005
By Steven V. Joyal, MD
Can you control your genetic destiny? Are you doomed to suffer debilitating diseases because of “bad genes”?
The answer is that a powerful strategy called phenotypic nutrition can help modulate the expression of your unique genetic code, thus dramatically reducing your risk of developing disease. Phenotypic nutrition uses specific nutrients with targeted biochemical and genetic effects to help protect you from disease.
One of the most important threats to your health and longevity is metabolic syndrome, a disorder little known to the public but fast becoming an extremely important public health issue. This deadly, common condition affects approximately one of every five people overall, with even higher rates among certain ethnic groups.1
By applying a phenotypic nutrition strategy, we can help to guard against the deadly dangers of cardiovascular disease associated with metabolic syndrome.
Metabolic Syndrome Defined
Over 20 years ago, Stanford University professor Gerald Reaven, MD, coined the term “Syndrome X” to describe a constellation of metabolic abnormalities in serum cholesterol, blood pressure, blood-clotting tendencies, and cardiovascular disease risk.2
Now known as metabolic syndrome, this constellation of abnormalities is recognized as placing individuals at dramatically in-creased risk for cardiovascular disease.3 For example, a study published in 2004 in the Journal of the American Medical Association followed more than 1,200 men for 11 years. The investigators found that men with metabolic syndrome were 160-320% more likely to die from coronary heart disease than those without metabolic syndrome.4
The diagnostic criteria for metabolic syndrome proposed by the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) include:
Despite the grave cardiovascular risk posed by metabolic syndrome, there is currently no standard, accepted interventional treatment regimen to prevent the disorder. However, for those at greatest risk for metabolic syndrome, phenotypic nutrition allows us to tailor a nutrient and supplement strategy to amplify beneficial biochemical pathways as well as gene expression.
Orthomolecular Medicine: Visionary Science
In 1968, the Nobel Prize-winning scientist Linus Pauling, PhD, published an article in the journal Science describing the “orthomolecular” approach to illness. This was the first time that such an approach was presented to the public—specifically, that “varying the concentrations of substances normally present in the human body may control mental disease.”6 Dr. Pauling later extended this strategy beyond mental illness to include the discipline of orthomolecular medicine.
Orthomolecular medicine is a paradigm that attempts to prevent and treat disease by integrating conventional medical therapies with vitamins, phytonutrients, and other dietary micronutrients. Dr. Pauling’s fascination with vitamin C and its role in helping to prevent and treat disease is an example of orthomolecular medicine. Dr. Pauling published pioneering reviews on the use of vitamin C and the orthomolecular approach to cancer over 30 years ago.7,8
Biochemical Variations and Nutrient Needs
From our physical and psychological traits to our enzyme systems that process nutrients and help guard against disease, each of us is unique.
Roger Williams, PhD, discoverer of pantothenic acid (vitamin B5) and founder and director of the Clayton Foundation Biochemical Institute at the University of Texas, was a visionary in the understanding of biochemical uniqueness. Dr. Williams’ timeless classic Biochemical Individuality, originally published in 1956, acknowledges the unique biochemical variations among individuals and how these differences relate to their distinct nutritional needs for optimal health and disease prevention.
Nutrigenomics: Guiding Genetic Destiny
Driven by recent technological breakthroughs associated with the mapping of the human genome, the science of nutrigenomics holds great potential for predicting how specific nutrients and dietary ingredients can directly affect health and disease by specific genetic interactions. Nutrigenomics holds promise in advancing the goal of preventing disease with individualized, targeted nutrient-gene interactions.9,10 Nutrigenomics suggests that genetic testing will allow for “individualized nutrition” based on unique genetic needs.
Currently, however, nutrigenomics remains a very young and developing science that has not yet developed to the point of being able to offer broad-based nutrient-gene testing of this sort. Furthermore, ethical questions surround genetic testing. For example, if you were to undergo a genetic test predicting you were at fourfold greater risk of having a heart attack unless you consumed specific nutrients, would you want that information shared with your health insurance company or employer? Who would control the confidentiality of this type of information?
There is, however, another approach that we can use for specific, individualized nutrient recommendations that incorporates Dr. Pauling’s visionary approach to orthomolecular medicine, Dr. Williams’ brilliant insight into biochemical individuality, and the futurist promise of nutrigenomics—without having to worry about the ethical and confidentiality issues related to genetic testing.
This alternative approach is called phenotypic nutrition.
Genes, Genotype, and Phenotype
Your unique genetic code defines your genotype. The expression of your individual genetic code is your phenotype. Both your genes and your environment influence your phenotype.
While it is not known exactly which genes are responsible for the constellation of abnormalities associated with metabolic syndrome, a number of genes so far identified play a role in the malfunction associated with abnormally elevated plasma glucose.11
Metabolic syndrome is a phenotypic expression of the genetic code as it interacts with the environment. Specifically, if you have a genetic tendency to develop the metabolic syndrome phenotype, you will be far more likely to develop this phenotype if you are overweight, do not exercise, consume a diet high in simple sugars and saturated fats, and do not consume enough specific nutrients with beneficial nutrient-gene interactions.
In 2004, an innovative approach to weight management and obesity was published in the peer-reviewed journal Current Drug Targets. This approach, called “nutriphenotypic,” is selective nutrition based on an individual’s phenotypic metabolic characteristics.12
This past year, researchers described the concept of a “nutritional phenotype” that characterizes the relationship of biochemical measures, metabolic parameters, and functional characteristics (for example, exercise, body weight, exposure to environmental pollutants and toxins, emotional stress) on health. The nutrient phenotype is a function of genes, diet, environment, and behavior.13
The nutriphenotypic/nutrient phenotype approach represents an integrative strategy to help prevent and treat disease.
Just as specific inputs to a computer will cause specific outputs, phenotypic nutrition uses specific nutrients for specific effects.
Phenotypic nutrition affects the expression of your genes and unique biochemistry so that you can influence your genetic destiny. Instead of dooming individuals to disease and an early demise due to “bad genes,” phenotypic nutrition uses nutrients that act on specific genes as well as biochemical and molecular pathways to help prevent disease and achieve optimal health and longevity.
With phenotypic nutrition, once high-risk individuals have been identified, strategies that include dietary modifications and specific nutraceuticals can be implemented to help decrease disease risk.
Identifying Those Most at Risk
Metabolic syndrome is characterized by insulin resistance. Identifying individuals with evidence of insulin resistance before the development of full-blown metabolic syndrome allows us to intervene with a nutrient and lifestyle strategy to prevent the progression of this condition.
Thankfully, simple metabolic markers are very useful in helping to identify individuals with insulin resistance who are at high risk of cardiovascular disease.
Moreover, research has demonstrated that a condition of low-grade systemic inflammation is associated with insulin resistance. For example, a recent clinical study showed that insulin and insulin resistance remained significantly and independently related to C-reactive protein (CRP) levels, a marker of inflammation, after adjustments for age, sex, body mass index, waist size, alcohol consumption, level of physical activity, and smoking habits.15 Another clinical study found that CRP was significantly correlated to insulin resistance.16
DHEA. Scientists have associated suboptimal levels of dehydroepiandrosterone (DHEA) with risk for metabolic syndrome. For example, a cross-sectional study of 400 independently living men aged 40-80 reported a statistically significant relationship between DHEA levels and risk of metabolic syndrome—specifically, the higher the level of DHEA, the lower the risk of metabolic syndrome.17
A number of randomized, placebo-controlled clinical studies have shown that supplemental DHEA excels in improving many metabolic derangements associated with metabolic syndrome. For example, in a study of elderly men and women, 50 mg per day of DHEA for six months was associated with significant improvements in visceral fat, subcutaneous fat, and insulin sensitivity.18 Another study evaluated DHEA’s effects on markers of insulin resistance and cardiovascular risk in 28 hypoadrenal (demonstrating diminished adrenal gland function) women. In this randomized, double-blind, placebo-controlled crossover study, women supplementing with DHEA significantly improved their insulin sensitivity and reduced their levels of triglycerides and low-density lipoprotein (LDL).19
These simple, surrogate screening assessments for insulin resistance and cardiovascular disease risk—that is, of triglycerides, insulin, HDL, CRP, and DHEA—can identify those at high risk of developing metabolic syndrome.
DHA and EPA
Peroxisome proliferator-activated receptors (PPARs) are genetic transcription factors that act on DNA response elements. Carbohydrate responsive element binding protein (ChREBP) and sterol regulatory element binding protein-1c (SREBP-1c) are two other critical regulators of glucose metabolism in the liver. Fatty acids such as DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) are nutrients that directly affect these genetic transcription factors.
PPARs are present in high-energy-demand tissues, including the liver, heart, and, to a lesser extent, skeletal muscle. PPARs are critical to a phenotypic nutrition approach to preventing metabolic syndrome, as PPARs promote fatty acid oxidation and fat cell differentiation while promoting glucose utilization.20
Studies have shown that EPA and DHA decrease the expression of genes involved in fatty acid storage. Through a depleting effect on SREBP-1c, EPA and DHA reduce insulin response to oral glucose and protect against the effect of insulin resistance induced by a high-fat diet. At the molecular level, this is accomplished by preventing the decreased expression of the gene encoding the glucose transporter GLUT4 in fat cells.21
Research has also shown that EPA and DHA down-regulate genes involved in inflammation, an important protective attribute for our prevention program, given inflammation’s association with metabolic syndrome. For example, pre-clinical studies have shown that these fatty acids down-regulate pro-inflammatory nuclear factor-kappa beta (NfkB) through a PPAR-gamma-dependent pathway.22 Human studies have shown a relationship between increased DHA consumption and diminished CRP levels,23 and other in-vivo studies have shown that markers of oxidative stress such as urinary F2-isoprostanes decrease significantly with EPA and DHA intake.24
A naturally occurring nutrient, lipoic acid is known to improve glucose metabolism by influencing genetic transcriptional factors in fat cells through the mitogen-activated protein kinase (MAPK) pathway.25 For example, in a multicenter, placebo-controlled trial, type II diabetes patients treated with lipoic acid demonstrated a significant increase in insulin-stimulated glucose disposal.26 Furthermore, lipoic acid’s molecular attributes include increasing glucose uptake through recruitment of the glucose transporter-4 (GLUT-4) to plasma membranes, a mechanism that is shared with insulin-stimulated glucose uptake.27
Research also shows that lipoic acid decreases markers of vascular inflammation in metabolic syndrome. A recent randomized, double-blind clinical trial showed that after four weeks of therapy, endothelium-dependent vasodilation of the brachial artery was increased by 67%, 44%, and 75% in groups receiving irbesartan (an angiotensin-blocking drug), lipoic acid, and irbesartan plus lipoic acid, respectively, compared to placebo. Furthermore, treatment with irbesartan and lipoic acid was associated with statistically significant reductions in plasma levels of pro-inflammatory mediators such as interleukin-6.28