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Lecture Presentation Outline
I.
Diet-Gene Interactions
 Instructor Resources: Unit 26 Nutrition Scoreboard transparency master; Unit 26 PowerPoint
presentation on Multimedia Manager
A. Effects of gene types on response to nutritional factors:
1. Whole oats lower blood cholesterol levels
2. High folate intake decreases the risk of heart disease
3. High polyunsaturated fat, low dietary cholesterol, or low saturated fat diets lower blood
cholesterol level
4. High carbohydrate diets increase the risk of type 2 diabetes
5. High alcohol intake during pregnancy produces physical and behavioral abnormalities in the
fetus
6. Consumption of green tea reduces risk of prostate cancer
B. Research into genetics of disease risk finds relationships between health characteristics and
genetic traits
C. Genetic Secrets Unfolded
 Instructor Resources: transparency #71: Chromosomes and DNA
1.
2.
3.
Genetic traits do not cause increases or decreases in incidence of disease
a. Genes not cause of obesity and diabetes, nor declines in heart disease and strokes
Genes contribute to disease resistance, disease development and drug response
We know most about single gene defects
II. Single Gene Defects
 Instructor Resources: Activity 26-1: Genetic Disorders
A. Many diseases from defects in a single gene have been identified that affect nutrient needs
1. Defects alter absorption or utilization of nutrients such as amino acids, iron, zinc, and the
vitamins B12, B6, or folate
2. PKU and lactose intolerance caused by defective codes for enzymes
3. Celiac disease and hemochromatosis result from genetic abnormalities in formation of other
proteins
4. PKU, celiac disease, and lactose intolerance treated by limiting phenylalanine, gluten, or
lactose
5. Hemochromatosis treated by a low-iron diet
B. Not all single gene abnormalities produce ill effects
C. Most diseases related to genetic traits are not as straightforward as single gene defects
1. They more likely represent a complex of genetic and environmental risk factors
III. Chronic Disease
 Heart disease, cancer, hypertension, obesity, diabetes, and aging disorders result from interactions
among multiple genetic and environmental factors

Nutrients can turn genes on or off and compensate for the ill effects certain genotypes have on body
processes
 Instructor Resources: transparency #11: Top 10 Causes of Death in the U.S. (2001); Activity 1 in
Instructor’s Activity Book: Putting Together a Family Tree Health History
A. Heart Disease
 Instructor Resources: transparency #53: Diets that Lower Heart-Disease Risk
1.
2.
Heart disease from plaque in arteries near heart
Plaque “hardens the arteries,” narrows artery openings, and increases artery blockage and
heart attack
3. Some who eat high-saturated-fat diets build up plaque, others don’t
4. For some, low folate and low vegetables increase risk that plaque will accumulate
5. Differences due to variations in genotypes
6. Heart disease influenced by blood pressure, body weight, and levels of triglycerides and
clotting factors in the blood
a. Each influenced by environmental factors in people with specific genetic traits
7. Risk for heart disease is sum of all pro and con influences of environmental and genetic
factors
B. Cancer
 Instructor Resources: transparency #61: Cancer Development; Activity 26-2: Cancer and Heredity
1.
Many cancers related to high fat and alcohol intakes, low vegetable and fruit diets, high
levels of body fat, smoking, and toxins
2. Some cancers have genetic components that interact with environmental exposures
a. Endometrial (uterine wall) – 100% environmental factors, 0% genetic factors
b. Ovary – 78% environmental, 22% genetic
c. Lung – 74% environmental, 26% genetic
d. Breast - 73–95% environmental, 5–27% genetic
e. Stomach – 72% environmental, 28% genetic
f. Colon – 65% environmental, 35% genetic
g. Pancreas – 64% environmental, 36% genetic
h. Prostate – 58% environmental, 42% genetic
3. Hope for cancer prevention lies in modifying environmental exposures
C. Hypertension
1. Causative roles in hypertension may include
a. High body fat
b. High alcohol intake
c. Physical inactivity
d. Genetic traits
2. High salt intakes seem related in some people
 Instructor Resources: transparency #68: Sodium in Processed Foods
a.
Some people, salt sensitive, genetically predisposed to salt effects on blood pressure
b.
c.
D. Obesity
1. Blood pressure increases with high salt
½ of people with hypertension salt sensitive
¼ of normal people are salt sensitive
 Instructor Resources: ABC video clip on Multimedia Manager: Obesity and Genetics (5:58)
1.
2.
3.
Obesity caused by excessive calorie diets and inadequate physical activity
Over 200 genetic traits have been associated with obesity
a. High-carbohydrate diets influence gene expression and obesity development in some,
genetic predisposition toward inactivity may enhance obesity in others
When people switch from low calorie diets to high calorie intakes, rates of obesity increase
dramatically
a. Genetic traits expressed from high food intakes, have adapted to survive on low caloric
intakes, promote development of obesity
b. Diabetes and heart disease rates in population groups also rise with increasing rates of
obesity
 Instructor Resources: transparency #12: Diabetes in Japanese Immigrants
E. Diseases Related to Aging
1. Diabetes, cancer, heart disease, memory impairment, hypertension, and stroke increase with
age
2. Health declines not inevitable nor genetic
3. Influenced by diet, exercise, and other components of lifestyle
IV. Food Selection
A. Food preferences are learned, but likes may be influenced by genetic traits
1. Over 80 genes help people taste bitter foods
2. Some genes make them very sensitive to bitter foods
a. People with high sensitivity to bitter tastes dislike cooked cabbage, collard greens,
spinach, brussel sprouts, or other bitter vegetables
b. People who like these vegetables don’t perceive them to be bitter-tasting
3. Genetic tendency to reject these will limit intake, maybe linked to diseases associated with
low vegetable intake
V. Looking Ahead
A. Advances in genetic bases of disease will yield longer, healthier lives
B. Attempts to fix abnormal genes by gene therapy will broaden
C. Disease prevention and treatment through nutritional changes is a very hot topic
1. Personalized modifications of dietary intake based on genotype will become standard
practice in clinical dietetics and medicine
2. Gene-Based Designer Diets
a. In future, people might reduce cancer risk by consuming cruciferous vegetables, reduce
diabetes risk by high protein diet, or heart disease by limiting dietary cholesterol or
saturated fat intake
b.
Such advances will not end disease or guarantee health, but will improve life