1. Photosynthesis & Fiber
Module 3.3
Photosynthesis & Fiber
By Jennifer Turley and Joan Thompson
© 2013 Cengage

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

3. Photosynthesis Process by which plants make carbohydrate structures
Photosynthesis requires chlorophyll
CO2 + H20 + sunlight 
carbohydrate in plants
sugars
starch
fiber

4. Fiber Content in Food
Dietary fiber- The residue after “in vivo” treatment. Animal tested
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

5. Fiber Content in Food Total Fiber-
The combination of dietary & functional fiber
Is reflected as the fiber content value on food package labels in the Nutrient Facts Panel

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

7. Categories of Fiber Solubility Fiber Sources Food Sources
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

8. Fiber Recommendations
DRI for total fiber intake:
Adult males= 38g
Adult females= 25g
Personalized DRI is 1.4g total fiber per 100 Calories consumed
Example: a person eating 4200 Calories/ day should consume 59g of fiber

9. High Fiber Intake & Food Sources
High fiber intake is well above
2g/ 100 Calories consumed
High fiber foods provide >2g fiber
per serving
How you assess high fiber:
Compare total grams of fiber to total
Calories per serving

11. Fiber Food Sources Grains Cereals Legumes Fruits & Vegetables
Most American’s under consume these types of foods, and thus fiber.
Average American intake is 11-13g fiber/ day

12. Fiber in Foods

13. Food Sources Food Group Very High >4gm High 2-4gm Good 1-2gm Low
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 Food Group Very High >4gm High 2-4gm Good 1-2gm Low
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 Food Group Very High >4gm High 2-4gm Good 1-2gm Low
Fruit
N/A
1 Apple, Banana
Orange, Peach,
1 C Berries
2 Prunes
½ C WatermelonHoneydew melon,
Cantaloupe
1 C Fruit Juice

16. Benefits/ Actions of Fiber:
Bulk
Increases the volume of food in the diet without adding calories… decreases caloric density of food
Bulks the volume of stool
BOTH soluble & insoluble fiber provide bulk

17. Benefits/ Actions of Fiber:
Stool Softener
Complex carbohydrate chemical structures are hydrophillic (i.e. water-loving)  binds/attracts water  creating a softer stool that is easier to move along the G.I. tract.
Relieves constipation, hemorrhoids & diverticulosis

18. Benefits/ Actions of Fiber:
Stool Softener
Complex carbohydrate chemical structures are hydrophillic (i.e. water-loving)  binds/attracts water  creating a softer stool that is easier to move along the G.I. tract.
Relieves constipation, hemorrhoids & diverticulosis
BOTH soluble & insoluble fiber act as a softener

19. 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

20. 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

21. 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 reabsorbed
Thus, a large source of cholesterol can be excreted in the feces
ONLY Soluble fiber provides this benefit

22. Benefits/ Actions of Fiber:
Bile binds tightly to soluble fiber & cannot be reabsorbed

23. Benefits/ Actions of Fiber:
Slows 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
ONLY soluble fiber provides this benefit

24. Benefits/ Actions of Fiber:
This is beneficial with diabetes & reactive hypoglycemia

25. Too Much Fiber: Negative Effects
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

26. Whole Grain Processing
Refined wheat kernels  removes the husk, bran & germ
The endosperm (containing mostly starch & protein) remains
Iron, thiamin, riboflavin, niacin, folate, vitamin B6, magnesium, zinc, & fiber are lost

27. Whole Grain Processing
Some nutrients are added back into refined grain products as a result of the Enrichment Act of 1942
Enriched-nutrients that were lost are added back in
Fortified-nutrients that are not
naturally occurring in that food are
added in

28. % Nutrients in whole grain, enriched white & un-enriched white breads

29. 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