Photosynthesis and Fiber By Jennifer Turley and Joan Thompson © 2013 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 Dietary Fiber: The residue after “in vivo” treatment. Animal tested.

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.

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.

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

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

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

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 American under consume these types of foods and thus fiber. The average American fiber intake is 11-13 gm/day.

Fiber in Foods

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

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

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

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 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 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

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 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 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

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

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