Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Lectures by Greg Podgorski, Utah State University Diet Advice From DNA? Current Issues in Biology, Volume 6 Scientific American

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Less than a decade after deciphering the human genome sequence, web-based genetic tests abound Nutrigenetic tests aim to provide dietary and life-style recommendations based on a person’s genetic profile There is good science behind the concept of nutrigenetics, but the current practice of nutrigenetics companies illustrates how commercialization often races ahead of science Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? We simply don’t have an adequate enough understanding of how particular genes contribute to health and disease Dietary recommendations based on MTHFR gene variants is an example of the overreach of commercial nutrigenetics The MTHFR gene encodes an enzyme that breaks down the amino acid homocysteine Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Some studies have found that elevated homocysteine levels are associated with increased risk of heart disease or stroke There are two common MTHFR gene variants; one variant produces a low activity enzyme Having the low activity form of MTHFR elevates homocysteine levels Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Increasing vitamin B intake can reduce homocysteine levels It is logical to expect that decreasing homocysteine levels in people with the low activity MTHFR variant will protect against heart disease and stroke However, five studies have failed to find this connection This scientific doubt has not stopped nutrigenetics companies from marketing tests for MTHFR and basing dietary recommendations on the results Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? The Government Accountability Office (GAO) ran a sting operation on four nutrigenetics companies Investigators ordered 14 tests on two different DNA samples Each questionnaire submitted with the DNA samples described adult men and woman of different ages, weights, and lifestyles Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? The recommendations made using the same sample of DNA were often vastly different and sometimes contradictory The personalized reports alternated between predictions that could apply to anyone and advice based entirely on the lifestyle questionnaire The GAO concluded that the results provided by these companies could not have been determined from the genetic test results Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? In at least one case, personalized profiles were used to market an expensive dietary supplement that contained the same ingredients found in over-the- counter multivitamins available at a fraction of the cost Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? A concern with bogus nutrigenetic testing is that it may dampen public faith in the validity of more legitimate genetic tests A challenge in nutrigenetics and other types of genetic testing is that for most disorders many genes are involved and these genes interact In any complex disorder, it’s unlikely that we know all the genes and even for those we do know, the effect of their interactions is notoriously difficult to predict Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Another concern with today’s web-based nutrigenetics is that obtaining a profile that predicts low risk provides a false sense of security Individuals who believe they are at low risk will be less likely to take the preventative care and screenings known to truly reduce disease risk Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? There is increasing interest in regulating at-home genetic tests Under current law, the FDA (Food and Drug Administration) can only regulate tests sold as medical device kits to clinical laboratories Most genetic tests fall outside this domain and cannot be regulated Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? If misused, nutrigenetics can undermine the faith of a public primed to expect great things from the Human Genome Project If, however, nutrigenetics can provide the impetus for effective regulation of genetic testing, it will promote the use of basic genetics research for human well-being Concept Review

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The idea of nutrigenetics is to provide dietary guidelines based on: a) family history b) a person’s particular set of genes c) genetic predispositions to lifestyle choices d) the interaction between nutrients and gene regulation

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The idea of nutrigenetics is to provide dietary guidelines based on: b) a person’s particular set of genes

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The goal of reducing homocysteine in people with low MDHFR activity is to: a) reduce the risk of heart disease and stroke b) reduce the risk of obesity c) correct vitamin B deficiency d) correct problems in protein digestion

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The goal of reducing homocysteine in people with low MDHFR activity is to: a) reduce the risk of heart disease and stroke

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension Lowering homocysteine through diet has been found to: a) decrease the risk of heart attack and stroke b) have no significant affect on the risk of heart attack and stroke c) increase the risk of heart attack and stroke d) lead to vitamin B deficiency

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension Lowering homocysteine through diet has been found to: b) have no significant affect on the risk of heart attack and stroke

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The strength of the link between homocysteine levels and health has: a) caused many nutrigenetics companies to go out of business b) caused nutrigenetics companies to stop testing for MTHFR gene variants c) caused nutrigenetics companies to provide a disclaimer on interpreting MTHFR test results d) not caused any change in the way nutrigenetics companies interpret MTHFR test results

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The strength of the link between homocysteine levels and health has: d) not caused any change in the way nutrigenetics companies interpret MTHFR test results

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The GAO concluded that the nutrigenetics companies they investigated provided diet advice: a) that was harmful to clients b) that rested on a firm scientific foundation c) that was based solely on the family history d) that could have applied to anyone and was based on lifestyle

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The GAO concluded that the nutrigenetics companies they investigated provided diet advice: d) that could have applied to anyone and was based on lifestyle

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension Current nutrigenetics recommendations do not account for the fact that: a) there are variants of genes b) dietary recommendations may change according to a person’s genetic profile c) different genes often interact in complex ways d) levels of metabolites such as homocysteine can be influenced by diet

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension Current nutrigenetics recommendations do not account for the fact that: c) different genes often interact in complex ways

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The FDA is able to regulate: a) most forms of genetic testing b) all forms of genetic testing c) human genome-related research d) medical device kits sold to clinical labs

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension The FDA is able to regulate: d) medical device kits sold to clinical labs

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension A concern about existing nutrigenetics testing is that it will: a) make people lose confidence in all forms of genetic testing b) increase the number of unnecessary medical tests c) increase health care costs d) reduce sales by pharmaceutical companies

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Testing Your Comprehension A concern about existing nutrigenetics testing is that it will: a) make people lose confidence in all forms of genetic testing

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Thinking About Science In animal studies, raising the levels of the cholesterol carrier HDL decreases the risk of heart disease. If people are found with a genetic variant that causes low HDL levels and increasing intake of vitamin K increases HDL levels, what is the most critical thing to know before recommending vitamin K supplementation in people genetically predisposed to low HDL? a) how long vitamin K supplementation can increase HDL levels b) the DNA sequences of the normal and variant gene c) whether increasing HDL in people influences heart disease risk d) the way vitamin K influences HDL levels

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA? Thinking About Science In animal studies, raising the levels of the cholesterol carrier HDL decreases the risk of heart disease. If people are found with a genetic variant that causes low HDL levels and increasing intake of vitamin K increases HDL levels, what is the most critical thing to know before recommending vitamin K supplementation in people genetically predisposed to low HDL? c) whether increasing HDL in people influences heart disease risk

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA Biology and Society Nutrigenetics testing should be under strict federal control Strongly Agree Strongly Disagree A. E. C. B. D.

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA Interpreting Charts and Graphs Which of the following statements is supported by the figure? a) the number of gene tests and number of laboratories has increased at about the same rate b) the number of gene tests performed per laboratory has decreased over time c) the number of gene tests performed per laboratory has stayed constant over time d) the number of gene tests performed per laboratory has increased over time

Copyright © 2010 Pearson Education, Inc. publishing as Benjamin Cummings Diet Advice From DNA Interpreting Charts and Graphs Which of the following statements is supported by the figure? d) the number of gene tests performed per laboratory has increased over time