Location: Human Nutrition Research Center on Aging
2006 Annual Report
Because the response of the individual to nutrients contains a strong genetic component, our approach aims to uncover sets of genes involved in the dietary response and to describe specific gene-diet interactions. This will be tested, using high throughput genotyping techniques, both in ongoing studies of free-living populations and in intervention studies. Our primary focus is to describe gene-diet interactions affecting/influencing progression of the metabolic syndrome, in particular obesity, often a precursor to CVD and diabetes. Cardiovascular candidate genes, both those previously described in the literature, as well as those we identify through bioinformatics analysis, will be used to examine associations and interactions on various scales. These include genetic variations, disease-related phenotypes and specific nutrients [fatty acids, cholesterol, plant sterols) and behavioral habits (alcohol consumption, smoking, physical (in)activity]. Rigorous statistical analysis will uncover the associations between phenotypes indicative of increased risk of metabolic syndrome and the genes responsible for such. Because CVD and diabetes are traditionally considered diseases of the aged, we will also continue with our investigations to identify genes responsible for healthy aging. The principal approach taken for these studies involves gene expression microarray analysis of fruit fly D. melanogaster populations with a propensity for increased longevity. Candidate aging genes will then be studied in mammalian models as well in human populations.
The seriousness of the problem at hand is evident. Cardiovascular diseases (mainly coronary heart disease and stroke) are the leading causes of death in the US, accounting for more than 40 percent of all deaths. About 1 million Americans die of CVD each year, which amounts to approximately two deaths every minute. More than half of all these deaths occur among women. However, the burden of this disease is not fully represented by the mortality figures. About one-fourth of the US population suffers from these diseases and account for 6 million hospitalizations each year. As the population ages the cost of these diseases to health care systems in the US increases. The estimated cost in 2001 - including health care expenditures and lost productivity, was nearly $300 billion.
This research program relates to the ARS National Program 107 - Human Nutrition (107), specifically to component 6: Prevention of Obesity and Disease: Relationship Between Diet, Genetics and Lifestyle. Cardiovascular diseases affect all minorities - some of which, i.e., African Americans and Hispanics, may suffer an even greater burden. Therefore, it is important to understand the specific nutritional needs to prevent disease in general and CVD in particular for all the subgroups represented in the US population. This research impacts on other components of the 107 Program. By addressing the individuality of the nutritional needs based on genetics, this research contributes to the component 4: Nutrient Requirements. By examining the impact of genetic knowledge of the behavioral aspects of the individuals, this work impacts components 3: Nutrition Monitoring, and 7: Health Promoting Intervention Strategies for Targeted Populations. By understanding the molecular mechanisms of nutrients and their interaction with different gene variants, we can contribute to the understanding of component 2: Bioavailability of Nutrients and Food Components.
Objective 2 To investigate the interactions between genetics and nutrients in the development of cardiovascular disease (CVD), the major age-related disorder affecting life expectancy and quality of life in the United States (US). Emphasis is placed on elucidating mechanisms by which genetic variation interacts with dietary and behavioral factors to regulate the homeostasis of the cardiovascular system.
Objective 3 To identify genes newly associated with cardiovascular health and overall longevity and determine their expression response to dietary intervention using animal models of aging.
1. Determine whether obesity modulates the relation between APOE genotype, insulin and glucose. Objective 1.
2. Determine the association of APOE genotype with carotid atherosclerosis in men and women: the Framingham Heart Study. Objective 1.
3. Determine the association of genetic variation at the perilipin (PLIN) locus with obesity-related phenotypes in women. Objective 1.
4. Identify novel genomic regions implicated in HDL levels using Genome-wide linkage analyses and candidate gene fine mapping in the Framingham Study. Objective 1.
5. Determine the effect of polyunsaturated fatty acids and the PPARA-L162V polymorphism on plasma triglyceride and apolipoprotein C-III concentrations in the Framingham Heart Study. Objective 2.
6. Genotype 20 candidate genes for CVD in a large postprandial study (GOLDN). Objective 2.
7. Genotype the PLIN gene to investigate the relation between variants at this gene and response to weight loss diets. Objective 2
8. To carry out bioinformatic analyses of the human genome to identify novel targets to analyze gene-gene and gene-diet interactions by. Objective 1.
9. To develop a high throughput genotyping method to map quantitative trait loci affecting lifespan and fat content in Drosophila using microarrays. Objective 3
10. To complete starvation experiments using long and short-lived drosophila lines aimed to confirm candidate genes identified from gene expression analysis. Objective 3.
11. To identify 13 mutants in Drosophila for 31 candidate genes identified from gene expression analyses, and characterization of the mutants for lifespan with the identification of one mutant with an extension of lifespan of about 20 days (50% increase). Objective 3.
1. To analyze the interaction of the APOE and CETP genes as determinants of plasma lipid levels and CVD risk. Objective 1.
2. To determine genotype variants at the Adiponectin and Visfatin genes to establish their association with obesity risk and plasma glucose and lipid levels. Objective 1.
3. Finely map the chromosome 6 region implicated in lipid metabolism to identify the specific genes determining the observed phenotypes. Objective 1.
4. Begin further bioinformatic analyses of the human genome to identify novel targets to analyze novel genes for CVD risk. Objective 1.
5. To determine genetic variants at the adiponectin, visfatin and perilipin genes in association with variability of plasma lipids in response to diet both in the fasting and the fed states. Objective 2.
6. To perform the statistical analyses of 10 of the genes genotyped within the GOLDN study to examine variability in postprandial response. Objective 2.
7. To genotype variants at the TR2 family of genes to determine their influence of dietary preferences and CVD risk markers. Objective 2.
8. Identify, confirm, and characterize genes affecting lifespan in Drosophila by creating transgenic flies. Objective 3.
9. Complete the mapping of quantitative trait loci affecting lifespan and fat content in Drosophila using microarray methods. Objective 3
1. Genotype novel genes in chromosome 6 associated with plasma lipids levels. Objective 1.
2. Identify novel targets to analyze novel genes for CVD risk by conducting bioinformatic analyses of the human genome. Objective 1.
3. To perform the statistical analyses of 10 of the genes genotyped within the GOLDN study to examine variability in postprandial response. Objective 2.
4. Use metabonomic variables to determine further insights on genotype-phenotype associations in relation with CVD risk. Objective 1.
1. To identify new genes involved with plasma lipid profiles and obesity by analyzing the data from a 500K SNP gene chip analyses within the Framingham population. Objective 1
2. Bioinformatic work to identify appropriate and informative single nucleotide polymorphisms (SNPs) within genes of interest as identified in milestone 1. Objective 1
3. To determine the potential use of genetic markers at multiple loci and environmental variables to predict CVD risk with greater precision than the traditional biochemical-based approaches by using Bayesian models. Objective 1.
4. To determine new genes found to be associated with CVD risk from milestone 2007-3 for potential interaction with dietary factors modulating plasma lipid phenotypes in the fasting state. Objective 2.
5. Complete experiments involving dietary factors and extension of life expectancy in drosophila. Objective 3
6. Initiate dietary intervention studies in humans aimed to improve quality of life in the elderly by enhancing expression of longevity related genes. Objective 3
1. Genotype new single nucleotide polymorphisms (SNPs) at loci derived from milestones 2008-1 and 2008-2 to search for associations with CVD risk factors. Objective 1
2. To determine gene-diet interactions for novel SNPs associated with CVD resulting from Milestone 2009-1. Objective 2.
3. To determine more complex gene-gene-diet interactions using genes involved in specific metabolic pathways (i.e., PPARA, LPL, APOC3 and PUFA intake). Objective 2.
4. To identify genes affecting lifespan and the rate of aging in mammals and understand how the affected metabolic processes can be regulated by dietary factors. Objective 3.
These studies focused on several polymorphisms present in one of the genes, apolipoprotein A-V (APOA5), which appears to participate in the metabolism of blood triglycerides, thus regulating the levels of atherogenic lipoproteins known as triglyceride rich lipoproteins (TRL). The polymorphisms examined are common in Caucasians and even more common in Asian populations. Our previous data show that subjects carrying the mutant forms for any of the polymorphisms examined have higher levels of fasting plasma triglycerides both in the fasting and the postprandial states. Moreover, some of the polymorphisms are also associated with an even more atherogenic lipid profile involving, in addition to high TRL, low levels of the protecting HDL fraction and increased levels of the most atherogenic form of LDL, which is known as small dense LDL. However, our most recent findings demonstrate that the risk associated with the presence of these mutations is modulated by dietary habits as well as obesity. We have demonstrated that these mutations may be especially detrimental in those subjects consuming a high proportion of polyunsaturated fatty acids of the n-6 family. Conversely, polyunsaturated fatty acids of the n-3 family were especially protective in those subjects carrying the polymorphism at the APOA5 gene. Moreover, a most interesting finding has been that these polymorphisms are predictors of disease only in those subjects with elevated body mass index.
In summary, our group has defined a series of genetic markers that are associated with an increased risk of atherosclerosis, but this risk may manifest only in those subjects consuming a high n-6 polyunsaturated fatty acid rich diet and/or have overweight or obesity. These data contribute to the identification of a segment of the population especially susceptible to diet-induced atherosclerosis and especially targeted for more aggressive weight reduction programs. These findings underscore the importance of dietary recommendations tailored to specific population groups or to individuals based on their genetic makeup and provides strength to the future feasibility of Nutrigenetics. This work is aligned with National Program 107 - Human Nutrition program component 6: Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle.
A Genetic Marker That Identifies a Subgroup of Women More Sensitive to Changes in Dietary Saturated Fat and Carbohydrates. We conducted this study on a nationally representative sample (Chinese, Malays, and Indians) selected in the Singapore National Health Survey following the World Health Organization-recommended model for field surveys of diabetes. A total of 1,909 men and 2,198 women (aged 18-69 years) were studied. Perilipin gene polymorphisms, lifestyle, clinical, and biochemical data were obtained. Homeostasis model assessment of insulin resistance (HOMA-IR) was used to evaluate insulin resistance. Diet was measured by a validated food frequency questionnaire in one of every two subjects. We found in women significant gene-diet interactions between perilipin polymorphisms and saturated fatty acids and carbohydrate in determining HOMA-IR. These interactions were in opposite directions for saturated fat and carbohydrates. Thus, women in the highest saturated fatty acid (SFA) tertile (11.8-19%) had higher HOMA-IR (48% increase) than women in the lowest tertile (3.1-9.4%) only if they were homozygotes for specific PLIN alleles. Conversely, HOMA-IR decreased (-24%) as carbohydrate intake increased. These effects were even stronger when SFAs and carbohydrate were combined as an SFA-to-carbohydrate ratio. This gene-diet interaction was homogeneously found across the three ethnic groups. Therefore, perilipin polymorphisms modulate the association between SFAs/carbohydrate in diet and insulin resistance in Asian women. This work is aligned with National Program 107 - Human Nutrition program component 6: Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle.
The current recommendations to lower cardiovascular risk are based on therapeutic life style changes, including diet modification, smoking and physical activity. However, the benefits of these universal recommendations fall short of the expectations for a significant proportion of the US population. Scientists on this project in collaboration with colleagues at the Framingham Heart Study conducted several studies to determine whether levels of the protective lipoprotein circulating in blood, namely, HDL-C are determined by the interaction between genes and diet.
One of the major goals is to achieve reductions in blood low-density lipoproteins cholesterol (LDL-C) levels. However, in addition to LDL-C, the levels of HDL-C are a major risk factor for CVDs in the U.S. and all over the world. The circulating levels of this lipoprotein are regulated by sex hormones, genetics and other behavioral factors including dietary habits and physical activity. Although we know that the use of polyunsaturated fatty acids (PUFA) decreases LDL-C, some scientists have warned about the use of those fats present in vegetable oils such as corn and soybean oils because they also decrease the levels of the protective HDL. However, many intervention studies have shown a dramatic range in HDL-C response to the PUFA consumption. Consistent with the major aim of this CRIS, which is to provide the most appropriate dietary recommendation for the prevention of disease at the individual level, scientists in this CRIS, in collaboration with the Framingham Heart Study clearly demonstrated that the levels of HDL-C are determined by the interaction between genes and diet. We found that subjects from the Framingham Heart Study with a particular mutation in the gene for apolipoprotein A-I (about 20% of the US population who consumed more polyunsaturated forms of fat had higher HDL-C levels - which are protective against heart disease - than subjects who also had the same gene but ate fewer polyunsaturated fats. On the contrary, those subjects who did not have this gene mutation had lower HDL-C levels as their intake of polyunsaturated fat went up. This work is aligned with National Program 107 - Human Nutrition program component 6: Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle.
A related study focused on a polymorphism present in one of the genes, (LIPC) involved on the removal of excess cholesterol from the body by regulating the protective HDL fraction. The polymorphism examined is common in Caucasians and even more common in African Americans, Hispanics and other minorities. Our data shows that subjects carrying the CC form of the gene "react" to higher contents of fat in their diets by increasing the concentrations of HDL-C, which could be interpreted as a "defense mechanism" against atherosclerosis and subsequently CVD. Conversely, subjects carrying the TT form of the gene are not able to "compensate" for the nutritional stress and they experience decreases on the HDL-C levels. These data contribute to the identification of a segment of the population especially susceptible to diet-induced atherosclerosis. Considering the higher frequency of the TT form of the gene among African Americans and Hispanics, our results provide crucial information about the impaired ability of these minorities to adapt to new dietary environments. These findings underscore the importance of dietary recommendations tailored to specific population groups or to individuals based on their genetic makeup and provides strength to the future feasibility of Nutrigenetics. This work is aligned with National Program 107 - Human Nutrition program components 6: Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle; and 7. Health Promoting Intervention Strategies for Targeted Populations.
There is an increased interest to understand the factors that regulate the expression of our genes. Some of them are known nuclear transcription factors and are involved in the expression of genes following their activation by external factors such as nutrients. One of them is known as peroxisome proliferator-activated receptor alpha (PPARA). The gene coding for this transcription factor (PPARA) contains several mutations that have been associated with different cardiovascular risk factors including plasma lipids, obesity and diabetes status. We investigated one of these mutations to ascertain the potential interaction between this gene, plasma lipids and dietary factors in the population enrolled in the Framingham study (1003 men and 1103 women). Our data clearly demonstrate that the effect of a common variant at the PPARA gene known as the L162V polymorphism is associated with plasma triglyceride concentrations in a manner that is modulated but the intake of polyunsaturated fatty acids, with high intake of these fatty acids triggering lower triglycerides only in carriers of the 162V form of this gene. Our results support the relevance of knowing the genetic make up in order to provide more precise and successful dietary recommendations for disease prevention. This work is aligned with National Program 107 - Human Nutrition program components 6: Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle; and 7. Health Promoting Intervention Strategies for Targeted Populations.
As previously indicated, one of the major lipid-related risk factors is determined by the levels of HDL. The levels of these macromolecules in plasma are determined by a host of environmental and genetic factors. Among the first, the most relevant are diet, smoking, alcohol and physical activity. Among the latter, several genes have been already identified associated with HDL-C levels, but all together still explain a very small percent of the total genetic contribution. Therefore, it is paramount to identify more gene targets that could help to understand the metabolism of HDL and define new therapeutic approaches to increase HDL and to decrease CVD risk. In this research, we have searched for new genes for HDL in the whole human genome of participants in the Framingham Heart Study and narrowed down our search to a region of chromosome 6 that may hold additional clues to the metabolism of HDL. In addition, we have preliminary data suggesting that several genes within that region could be responsible for the observed variation in plasma HDL levels in the population. These findings could open new therapeutic avenues to our fight against CVD. Moreover, it could be used to differentiate among individuals according to their genetic cardiovascular risk and to target those subjects at higher risk for more aggressive dietary therapy. This work is aligned with National Program 107 - Human Nutrition program components 6: Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle; and 7. Health Promoting Intervention Strategies for Targeted Populations.
The new accomplishments of this project described in sections 4A and 4B have the potential to advance the field of personalized dietary recommendations to ameliorate plasma lipoprotein levels and to reduce cardiovascular risk (4a). In addition, our findings related to the genetics of weight loss can provide valuable tools towards more effective behavioral approaches to reduce the epidemic of obesity (4b) and the consequences of the metabolic syndrome. These totally new findings produced by this project are already having an impact in the scientific and commercial worlds.
Nature Medicine, July 2005 Designer Diets By Gunjan Sinha
Discover (magazine), October 2005 We RNA what we eat: Nutritional genomics promises to make diets truly person By Jennifer Kahn
Associated Press , October 13, 2005 Scientists look to DNA for personalized nutrition By Malcolm Ritter
NewsTrack - United Press International , December 7, 2006 Study: Gene variation affects weight loss
Nutra Ingredients.com, December 8, 2005 Calorie control weight-loss may depend on genes By Staff Reporter
The Common Voice, December 9, 2005 When Calorie Restriction Fails for Weight Loss By Regina Wilshire
National Post, January 3, 2006 This just in: Eat your vegetables: A reporter's personal genome project By National Post
ABCnews.com, January 11, 2006 Can Geneticists Cure Obesity? By Amanda Onion
News-Medical-Net, February 16, 2006 Advancing knowledge of diet-gene interactions
MedIndia, February 10, 2006 Nutrigenomics here comes a team to better your future!
ARS News Service, March 2, 2006 Genetic variations affect obesity-related risks By Rosalie Marion Bliss
News @ Nature.com, March 7, 2006 Coffee mixes badly with certain genes By Helen Pearson
Best Syndication, March 17, 2006 Sciona DNA Diet Based On Genetic Analysis - May Be Better than Atkins South Beach or Zone Diets - Nutrigenomics May Prevent Disease By Dan Wilson
PR_The Krupa Companies, March 16, 2006 Interaction Between Nutrition and Genetics May Lead to Dietary Interventions for Heart Disease
ARS News Service, March 20, 2006 Genetic Variants Shown to Hoard Body Fat By Rosalie Marion Bliss
El Pais (leading newspaper in Spain), April 5, 2006 Los genes guiaran la dieta By Angela Boto
Sunday Times (London, UK), April 9, 2006 Fishy tales By Amanda Ursell
Prevention, May 2006 News & Trends: Do these genes make me look fat?
AARP, The Magazine, May & June 2006 Eat More, Stay Thin: 10 fat-fighting tricks of the naturally lean By Brian Good Boston Globe, May 11, 2006 A quick study in 2 venues: In volleyball, biology, Ordovas is a player By Mike Reiss
Boston Globe, May 22, 2006 'Gut bugs' studied as a cause of obesity By Bijal P. Trivedi
Time Magazine, Jun 4, 2006 Does My Diet Fit My Genes? By Christine Gorman
Dr. Ordovas has been invited as keynote speaker to talk about the work carried out in relation to this CRIS to many International and National conferences sponsored by international and national scientific societies, universities and the Food and Pharmaceutical industries. A selection of those events are listed below:
German Institute of Human Nutrition Potsdam-Rehbrucke (DIfE), Potsdam (Germany), October, 2005.
Spanish Society of Diabetes, Segovia (Spain), October, 2005.
NHLBI New Technologies Workshop, Washington DC, October, 2005
International Workshop on Diet and Cancer Prevention. Palermo (Italy) November 2005
ILSI, Asian Nutrigenomics Conference. Singapore. December 2005.
International Forum on n-3 PUFA. Rome. January 2006
California Avocado Commission. San Diego, CA. February 2006
NUTRACON. Los Angeles, CA. March 2006
LIPGENE, Marseille (France). March 2006
Asian Pacific Society of Atherosclerosis and Vascular Diseases. Korea. April 2006
International Nutrigenomics Conference. Auckland. New Zealand. April 2006
DSM Nutrition Division, Switzerland. May 2006
Spanish Society of Atherosclerosis, Santander (Spain), June 2006
International Atherosclerosis Society, Rome (Italy), June 2006