Photosynthesis
and Fiber
By Jennifer Turley and Joan
Thompson
© 2016 Cengage
Presentation Overview
• Photosynthesis
• Carbohydrate structures: sugar,
starch, fiber
• Fiber categories & recommends
• Fiber benefits & actions
• Negative effects of too much
fiber
• Food sources
Photosynthesis
• The process by which
plants make
carbohydrate
structures.
• Photosynthesis requires
chlorophyll.
• CO2 + H20 + sunlight =
carbohydrate in plants.
• sugars
• starch
• fiber
Fiber Content in Foods, Part 1
• Dietary Fiber: The residue after “in vivo”
treatment. Animal tested.
Fiber Content in Foods, Part 2
• Functional Fiber: Indigestible carbohydrate
isolated from natural sources or synthetic
indigestible carbohydrate.
• Has beneficial physiological effects in humans.
• An example of indigestible carbohydrate isolated
from a natural source is cellulose gel added to a
processed food.
Fiber Content in Foods, Part 3
• Total Fiber:
• Is the combination of dietary &
functional fiber in food.
• Is reflected as the fiber content value
on food package labels in the Nutrition
Facts panel.
Categories of Fiber:
Soluble
Solubility
Fiber Sources Food Sources
Softens & Gels in Pectins
water. Does
Gums
attract water
Mucilages
Fruits (like apple
pectin),
vegetable,
legumes, and
oats
Categories of Fiber:
Insoluble
Solubility
Fiber Sources
Does not soften or Cellulose
gel in water.
Hemi-cellulose
Does attract water Lignins
Food Sources
Whole grain foods,
Celery strings
Apple peels
Fiber Recommendations
• The DRI for total fiber intake:
• Adult male is 38 grams. Adult female is 25
grams.
• Personalized DRI is 1.4 grams total fiber
per 100 Calories consumed.
• Example: A person eating 4200 Calories in
1 day should consume 59 grams of fiber.
High Fiber Intake & Foods
• High fiber intake is well over 2 grams/100 Calories
consumed.
• High fiber foods provide > 2 gm fiber/serving.
• High fiber foods are easy to assess on the food
package label by comparing the grams of fiber
with reference to the Calories provided/serving.
Fiber Food Sources
Grains
Cereals
Legumes
Fruits
Vegetables
Most Americans under consume these types
of foods and thus fiber. The average
American’s fiber intake is 11-13 gm/day.
Fiber in Foods
Food Sources & Amounts of Fiber,
Part 1
Food
Very High
High
Good
Low
Group
>4gm
2-4gm
1-2gm
≤1gm
Grains
½ C Bran Flakes
1 Slice Rye Bread
1 C Cornflakes
½ C Brown or Wild
Rice
½ C White Rice
1 C Oatmeal or
puffed brown rice
1 C Shredded whole wheat
cereal
or whole multigrain cereal
1 Slice Whole Wheat
Bread
1 Corn Tortilla
½ C Pasta
Food Sources & Amounts of
Fiber, Part 2
Food
Very High
High
Good
Low
Group
>4gm
2-4gm
1-2gm
<1gm
Vegetable
½ C Legumes
(dried beans)
½ C Broccoli,
Cauliflower, Corn,
Beans, Cabbage
½ C Carrots,
Green pepper,
Celery, Onion,
Lettuce
1 C Some
Vegetable Juices
1oz Nuts & Seeds
Food Sources & Amounts of Fiber,
Part 3
Food
Very High
High
Good
Group
>4gm
2-4gm
1-2gm
Fruit
N/A
1 Apple, Banana
½ C Watermelon,
Orange, Peach,
Honeydew melon,
1 C Berries
Cantaloupe
2 Prunes
Benefits-Actions of Fiber:
Bulk
• Increases the volume of food
in the diet without adding
Calories, thus it decreases the
caloric density of the food.
• Bulks the stool volume.
• Both soluble & insoluble fiber
provide these benefits.
Benefits-Actions of Fiber:
Stool Softener
• Complex carbohydrate chemical
structures are hydrophillic (binds
water or attracts water) creating a
softer stool that is easier to move
along the G.I. tract.
• Relieves constipation,
hemorrhoids, & diverticulosis.
• Both soluble & insoluble fiber
provide these benefits.
Benefits-Actions of Fiber:
Decreases transit time
• Food, the bolus, chyme and feces
move through the GI tract faster,
thus the transit time is reduced.
• Decreases time in the colon.
• Reduces exposure time to
potential carcinogens thus
reduces colon cancer.
• Both soluble & insoluble fiber
provide these benefits.
Benefits-Actions of Fiber:
Improves GI tract muscle tone
• The larger volume of bulk and
the softer mass moving
through the “tube” allows the
GI tract muscles to exercise
efficiently.
• Both soluble & insoluble fiber
provide this benefit.
Benefits-Actions of Fiber:
Heart-Health, Part 1
• Reduces heart disease risk by
binding cholesterol-rich bile in the
GI tract.
• Normally, bile is reabsorbed.
• Bile binds tightly to soluble fiber &
cannot be reabsorb.
• Thus, a large source of
cholesterol can be excreted in the
feces.
• Soluble fiber provides this benefit.
Benefits-Actions of Fiber:
Heart-Health, Part 2
Benefits-Actions of Fiber:
Increases gastric emptying time.
• It takes a longer time for the
chyme to leave the stomach.
• The rate of glucose absorption is
slowed.
• This is beneficial with diabetes &
reactive hypoglycemia.
• Soluble fiber provides this
benefit.
Negative Effects of too Much
Fiber
• Causes gas & bloating (due to decomposition of
fiber by gastrointestinal microbes)
•
•
•
•
•
Too large & frequent bowel movements
Binds positively charged minerals
Binds beta-carotene
Decreases caloric value
Can cause GI tract blockages without
adequate water intake
• Too much soluble or insoluble fiber can
cause negative effects
Whole Grain Processing,
Part 1
• Wheat kernels are refined by removing the
husk, bran, & germ.
• The endosperm (containing mostly starch &
protein) remains.
• Iron, thiamin, riboflavin, niacin, folate,
vitamin B6, magnesium, zinc, & fiber are lost.
Whole Grain Processing,
Part 2
• Some nutrients are added back into refined
grain products as a result of the Enrichment
act of 1942.
• Added: iron, thiamin, riboflavin, niacin, folate
• Not Added: vitamin B6, magnesium, zinc, fiber
Processing a
Wheat
Kernel
Husk,
Bran &
Germ are
removed
% Nutrients in whole grain, enriched white & unenriched white breads
Some Summary Points
• Plants make carbohydrates via
photosynthesis.
• Fiber is non-caloric.
• Categories are soluble & insoluble.
• Total fiber = functional & dietary fiber.
• The DRI is 1.4 gm/100 Calories eaten.
• There are health benefits for adequate
fiber intake.
• There are negative effects from too
much fiber.
• Whole foods provide the best source of
fiber and nutrients.
References for this presentation are the
same as those for this topic found in
module 3 of the textbook