1. Photosynthesis and Fiber
By Jennifer Turley and Joan Thompson
© 2013 Cengage

2. Presentation Overview
Photosynthesis
Carbohydrate structures: sugar, starch, fiber
Fiber categories & recommends
Fiber benefits & actions
Negative effects of too much fiber
Food sources

3. Photosynthesis
The process by which plants make carbohydrate structures.
Photosynthesis requires chlorophyll.
CO2 + H20 + sunlight = carbohydrate in plants.
sugars
starch
fiber

4. Fiber Content in Foods
Dietary Fiber: The residue after “in vivo” treatment. Animal tested.

5. Fiber Content in Foods
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.

6. Fiber Content in Foods 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.

7. Categories of Fiber: Soluble
Solubility
Fiber Sources
Food Sources
Softens & Gels in water. Does attract water
Pectins
Gums
Mucilages
Fruits (like apple pectin), vegetable, legumes, and oats

8. Categories of Fiber: Insoluble
Solubility
Fiber Sources
Food Sources
Does not soften or gel in water. Does attract water
Cellulose Hemi-cellulose
Lignins
Whole grain foods,
Celery strings
Apple peels

9. Fiber Recommendations
The DRI for total fiber intake:
Adult ♂ is 38 grams. Adult ♀ 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.
4200 Calories ÷ 100 x 1.4 = 58.8 grams

10. 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.

11. Fiber Food Sources Grains Cereals Legumes Fruits Vegetables
Most American under consume these types of foods and thus fiber. The average American fiber intake is gm/day.

12. Fiber in Foods

13. Food Sources & Amounts of Fiber
Group
Very High
>4gm
High
2-4gm
Good
1-2gm
Low
≤1gm
Grains
½ C Bran Flakes
1 C Shredded whole wheat or whole multigrain cereal
1 C Oatmeal or puffed brown rice cereal
1 Slice Whole Wheat Bread
1 Slice Rye Bread
½ C Brown or Wild Rice
1 Corn Tortilla
1 C Cornflakes
½ C White Rice
½ C Pasta

14. Food Sources & Amounts of Fiber
Group
Very High
>4gm
High
2-4gm
Good
1-2gm
Low
<1gm
Vegetable
½ C Legumes (dried beans)
½ C Broccoli, Cauliflower, Corn, Beans, Cabbage
1oz Nuts & Seeds
½ C Carrots, Green pepper, Celery, Onion, Lettuce
1 C Some Vegetable Juices

15. Food Sources & Amounts of Fiber
Group
Very High
>4gm
High
2-4gm
Good
1-2gm
Low
<1gm
Fruit
N/A
1 Apple, Banana
Orange, Peach,
1 C Berries
2 Prunes
½ C Watermelon,Honeydew melon,
Cantaloupe
1 C Fruit Juice

16. 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.

17. 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.

18. 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.

19. 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.

20. Benefits-Actions of Fiber: Heart-Health
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.

21. Benefits-Actions of Fiber: Heart-Health
Liver Makes Bile from Cholesterol
Gallbladder stores Bile
Released Bile emulsifies fat in G.I. tract
In absence of soluble fiber
Bile is reabsorbed, little is excreted
Bile is reabsorbed
In presence of soluble fiber is excreted

22. 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.

23. 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

24. Whole Grain Processing
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.

25. Whole Grain Processing
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

26. Processing a Wheat Kernel

27. % Nutrients in whole grain, enriched white & unenriched white breads
whole grain is best

28. Fiber Summary 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