Food Choices: Nutrients and
Nourishment
BIOL 103
Chapter 1
What is Nutrition?
• The science of foods (e.g. nutrients and other
substances), including the relationships to
health and disease; processes within the body
(ingestion, digestion, absorption, transport,
storage, functions, and disposal of end
products); and the social, economic, cultural
and their components, and psychological
implications of eating.
Factors that Influence Food Choices
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Sensory
Cognitive
Genetics
Environmental
Health status
Why do we eat the way we do?
• Sensory (taste, texture,
smell)
– Flavor
• Flavors: sour, bitter, salty,
sweet, umami
– Texture/Appearance
Why do we eat the way we do?
• Cognitive
– Learned food
habits/food reward
– Social factors
– Comfort/discomfort
foods
• Behavioral motives
– Advertising
– Nutrition and health
beliefs
Why do we eat the way we do?
• Environment
– Economics
– Lifestyle
– Availability
– Cultural Influences
– Religion
The American Diet
• “Meats and potatoes”
• Americans age 2 and older
consume, on average,
2157 calories (based on
2000 calories diet)
• How healthful is the
“American” diet?
– Too little: ______________
________________________
– Too much:_____________
________________________
Nutrients
• Definition: Any substance that provides
nourishment essential for growth and the
maintenance of life.
• Essential vs. Non-essential nutrient
– Essential nutrient:
– Non-essential:
• How to determine if it is an nutrient?
The six classes of nutrients
1. Carbohydrates
2. Proteins
3. Lipids (fat)
4. Vitamins
5. Minerals
6. Water
• Macronutrients vs. Micronutrients
General Functions of Nutrients (what
do they do in our body)
1. Provide ________
2. Regulate ______________________
(ingestion, digestion, absorption, transport,
storage, functions, and disposal of end
products)
3. ________________________body structures
How nutrients can be categorized…
• Organic or Inorganic?
• What is their function?
Carbohydrates
• Carbohydrates: “hydrate
of carbon”
– Made of:
• Function:
– energy source for cells and
tissues
• Dietary sources: starches
and sugars found in
grains, vegetables,
legumes (dry beans and
peas), fruits, dairy
products
Lipids
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Lipids (fats, oils, cholesterol,
phospholipids)
– Made of:
Functions:
– energy storage as triglycerides
– Cholesterol is a starting
material for many hormones
– carries fat-soluble vitamins (K,
A, D, E)
– provides structure for body
cells
Food sources: fats, oils, meat, dairy,
some plants (avocado, coconut)
Proteins
• Made of:
• Functions:
– energy source
– structure for
cells/tissues/body
structures
– Regulation of body
processes
• Food sources: meats,
dairy products, grains,
legumes, vegetables.
Vitamins
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Made of:
Function:
– helps regulate body
processes
– help extract energy from
carbs, fat, and proteins
Food sources: meats, vegetables,
grains, dairy, fats
•
Fat Soluble Vitamins
– Vitamins K, A, D, E
– Stored in larger quantities
•
Water Soluble Vitamins
– Vitamin C/ascorbic acid
– B Vitamins: thiamin (B1),
riboflavin (B2), niacin (B3),
pantothenic acid (B5),
pyridoxine (B6), biotin (B7),
folate (B9) cobalamin (B12)
– Function: helpers in energy
metabolism
Minerals
• Inorganic substances
• Macrominerals vs.
Microminerals or “trace
minerals”
• Functions:
– Structure
– Regulation
• Food sources: all food
groups
Water
• Most important
nutrient 
• Functions:
– temperature control
– lubrication of joints
– transportation of
nutrients and wastes
• Food sources:
beverages, foods like
fruits and vegetables.
Energy in Food
• We eat nutrients so that we can gain energy
– Q: Which nutrients contain sources of potential
energy?
• Energy: capacity to do work
• How do we measure energy in Nutrition?
– Kilocalories (kcal)
• 1000 calories = 1 kilocalorie
• 1 kcal: the amount of energy needed to raise the
temperature of 1 kilogram (kg) of water by 1 degree
Celsius.
Energy in Food
Use calorie as a general term for energy and kilocalorie as a specific
measurement or unit of that energy.
Problem Set #1
• A) Jeff is eating a snack with 20g of
carbohydrates, 5 grams of proteins, and 3
grams of fat. What is the total amount of
available energy (in kcal) in his snack? (Note:
you will need to show your work for full credit
in an exam).
Problem Set #1
B) Determine the percentages of kilocalories of
carbohydrate, protein, and fat in Jeff’s snack.
Many of the leading causes of death can be avoided by
good diet and exercise
More than 2/3 of U.S. Adults are
overweight/obese
Diet and Health
• Healthy: “a state of complete physical,
mental, and social well-being AND not
merely the absence of disease or infirmity.”
(WHO)
• Disease
– Acute
– Chronic
• Factors that influence Obesity:
– Behavior
– Environment
– Genetics
Diet and Health
• Physical Activity
– Role in long-term weight
management
• At least ___ mins/day of
moderate activity
– Weight-management
• At least ___ mins/day of
moderate activity
– What is moderate
activity?
USDA – ChooseMyPlate.Gov
Common Study Designs used in
Nutrition Research
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Cell culture studies
Animal Studies
Epidemiological studies
Case Control Studies
Clinical Trials
– Randomized
– Double-blind
– Placebo-controlled
Evaluating Information on the Internet
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There are no rules for posting on the internet
Consider the source
Keep in mind the scientific method
Be on the lookout for “junk science”
– May distort facts through omission of details