Download Bio 28: Nutrition Instructor: Paul Nagami Laney College

Carbohydrates, pt. 2
Jan. 30, 2014
Bio 28: Nutrition
Instructor: Paul Nagami
Laney College
Today’s Agenda
• Reminders + Administrative Details
• Review
• More on chemistry, to help prepare you for
next chapter.
• Benefits of Carbohydrates
• Blood Glucose
• Diabetes
• Tooth Decay
• Pick up work
(Review and Chemistry Chalk Talk
here)
If you missed this class, you may want to pay close attention to
the opening parts of chapter 4 and ask me to clarify any
confusing details at office hours!
You should know how atoms make molecules (what a
chemical bond is) and what the difference is between a single
and a double bond.
Why Carbohydrates?
Many diets (Atkins, etc) emphasize reducing non-fiber
carbohydrates. What useful roles do carbohydrates serve in
our body?
Energy source: How many kcal of energy are there in a
gram of carbs?
Protein sparing: The body needs glucose to run its cells!
Without carbohydrates, it will get glucose from other sources,
such as proteins, via gluconeogenesis.
Preventing ketosis: Without carbs, the body turns fats into
acidic ketone bodies, which can potentially lower blood pH,
hurt the kidneys, and have other ill effects. (Though it may
help epileptics.)
Glycemic Index
Food (50
grams
taken on an
empty
stomach)
Glycemic
index
(relative to
glucose)
Glucose
100
Boiled potato
85
Soda
72
Table sugar
64
Baked beans
44
Apple
38
Carbohydrates raise your blood
sugar, but not all of them raise it
equally quickly. For diabetics, it’s
important to avoid sudden spikes
in blood sugar!
Glycemic index is a measure of
how quickly food causes blood
sugar to rise – in theory, anyway.
Use as a weight-loss tool remains
controversial. A low glycemic
index food can still have plenty of
calories!
Mobilizing Blood Sugar
Balancing Blood Sugar
Diabetes mellitus occurs
when the body can’t control
blood sugar levels.
Fat is incompletely
broken down, creating
acidic ketones.
The loss of water
through the urine (to get
rid of excess sugar)
causes dehydration.
Blood vessels can get
narrow, leading to the
death of tissue.
Diabetic Retinopathy
Types of Diabetes
Type I Diabetes (Juvenile-onset, usually): Pancreas doesn’t
make insulin. Beta cell damage. 10% of all diabetes patients.
Type II Diabetes (adult-onset, usually): Body makes insulin
but doesn’t respond to it! (Insulin resistance)
U. S. Diabetes cases per
year, in thousands, from
1980 to 2011. Source:
Centers for Disease
Control
Gestational
diabetes:
Pregnant
women are at
higher risk of
insulin
resistance.
Untreated,
this can harm
the fetus.
Risk Factors for Diabetes
Estimated 24 million Americans with diabetes.
Obesity: A huge risk factor for Type 2 Diabetes. In one study
of nurses aged 30-55, severe obesity raised the risk of diabetes
49 times over!
Age: As people approach middle
age, the risk of diabetes rises.
Genetics: Inherited
differences in metabolism can
play a role.
Race/Ethnicity: AfricanAmerican, Native American, and
Hispanic patients, especially
women, are more likely to
develop diabetes than men.
Managing Diabetes
Considering the differences between Type I and Type II
diabetes…
How much would you expect insulin
shots to help someone with Type I
diabetes?
How much would you expect insulin
shots to help someone with Type II
diabetes?
How could Type II diabetes be
managed?
Tooth Decay
Sugary foods increase
the risk of tooth decay,
since they stick to the
teeth, forming a film
that bacteria can
consume and live in.
The bacteria convert
the sugar into lactic
acid, which eats away
at the enamel of teeth!