1. Advanced Nutrition MargiAnne Isaia, MD MPH Fiber

2. DIETARY FIBER No classic definition: various different definitions Remnant of PLANT cells after hydrolysis by digestive enzymes - Plant non-starch polysaccharides plus lignin - Indigestible cell wall proteins - Resistant starches : their properties mimic some of those of traditional fiber (may occur naturally in the diet) - It can be manufactured - It can occur as a product of the processing of foods Animal polysaccharides ? (chitosan or glycosaminoglycans) (A food manufacturer could add these animal-derived substances to food and report them as dietary fiber) DIETARY FIBER

3. STRUCTURE AND SOURCES Structure:Carbohydrates (multiple sugar units) Non-carbohydrates F I B E R Sources:Plant based food Caloric value:0 SOLUBLEINSOLUBLE Pectines Gums Mucilage Algal substancesCellulose Hemi-cellulose Lignin Intercellular (cement material) Special secretions Cell secretions Algae, sea weeds Main cell wall constituent Cell wall material Woody part of plants oatmeal, corn, legumes (beans), flaxseed, green vegetables, citrus, berries, carrots, red beet… whole grains, bran, flaxseed, cabbage family, beans, root vegetables, tomatoes…

4. DIETARY FIBER - Intact and in the food vs. extracted/synthesized Database :- the physiologic effects of high fiber foods - potential health benefits of high fiber foods Not clear: the same effects and benefits - if the fiber were extracted from food or synthesized in the laboratory. ? Possible : an isolated fiber to be more effective than its original food source. an isolated fiber may lose its efficacy - Purified fiber should demonstrate health benefits DIETARY FIBER

5. DIETARY FIBER – DEFINITIONS Dietary fiber: consists of non-digestible carbohydrate and non –CHO lignin that are intrinsic and intact in plants Functional fiber: consists of isolated, non-digestible carbohydrates that have beneficial physiological effects in humans. Total fiber : combines both DIETARY FIBER

6. Non-starch polysaccharides - Cellulose (Glucose units,  1-4 bond, cell walls) -  glucans (Glucose units,  1-4 and  1-3 bonds, oats, barley) - hemicellulose (branched, hexose and pentose) - Pectines (uronic acids, fruits) - Gums (galactomannans, plants) Non- CHO (lignin) woody part of plant - Phenyl propane polymer DIETARY FIBER

7. PHYSICAL PROPERTIES Water-holding capacity - ability to hold water in the matrix - potential to increase stool bulk - potential to slow nutrient digestion and absorption - Soluble fiber > capacity than insoluble fiber DIETARY FIBER

8. PHYSICAL PROPERTIES Cation binding: - ability to bind Iron, Calcium, Zinc, Copper - adverse effect when status is marginal - fibers with phytates and uronic acid > binding DIETARY FIBER

9. PHYSICAL PROPERTIES Binding to bile acids - lignin > pectin, gum> cellulose - can also bind glycerides, fatty acids, phospholipids - binding is most effective at acidic pH - lignin - bile (hydrophobic) - pectin – bile (hydrophilic) - interferes with micelle formation - potential to increase dietary Cholesterol excretion DIETARY FIBER

10. EFFECTS ON CHOLESTEROL (all fibers, except cellulose) in liver 75% cholesterol becomes bile bile 98% reabsorbed Fiber – binds bile acids – sweep them into the stool… To replace them – more Cholesterol converted into bile --- blood Cholesterol level lowers…

11. PHYSICAL PROPERTIES Fermentability – action by colonic bacteria products formed : methane, CO 2, H 2, SCFA (fuel for colonic cells) - isolated fiber > whole food fiber; soluble > insoluble Viscosity - pectins, gums increases viscosity - potential to influence gastric emptying DIETARY FIBER

12. EFFECTS OF FIBER ON GASTRO-INTESTINAL PHYSIOLOGY Effects of fiber on the stomach - delay the rate of emptying of ingested food from the stomach into the duodenum ( effect similar to Gastric Inhibitory Peptide) (it depends on the presence of other food components and the amount or type of fiber consumed) Effect of fiber on the small intestine - the gel-like environment produced from viscous fibers has potential to slow nutrient digestion and absorption. DIETARY FIBER

13. EFFECTS OF FIBER ON THE LARGE INTESTINE FERMENTATION Depends on physicochemical properties of the fiber and the colonic micro flora Formed: H 2, CO 2, methane and other gases, SCFA: acetate, propionate and butyrate “Butyrate paradox”: butyrate used by colonic epithelial cells as an energy source decreases tumor cell proliferation  Colon Cancer prevention IN VIVO STUDIES: providing butyrate in the diet (in drinking water, as a fiber source, as a slow-release pellet) - no protective role (“butyrate paradox”) Prebiotics vs. Probiotics( yogurt & Lactic Bacillus) - Propionate is cleared by the liver - Acetate is taken by peripheral tissues DIETARY FIBER

14. EFFECTS ON COLONIC BACTERIA (some soluble fibers) DIETARY FIBER FIBERS SUBSTRATE FOR FERMENTATION ENERGY FOR THE CELLS LINING THE COLON ( SCFA) RISK FOR COLON CANCER UN-DESIRABLE EFFECT -- GAS CAUTION: - don’t combine fresh fruit and fresh vegetables at the same meal - use special culinary herbs when cooking legumes

15. EFFECTS OF FIBER ON THE LARGE INTESTINE - Laxation by increasing the weight of the stool Increase in stool weight is based on fiber type: - wheat bran (fibers resistant to fermentation)  the most - fruit, vegetables  moderately - legumes  only slightly The greater the weight of the stool, the more rapid is the rate of passage through the colon, the better the laxative effect - Health benefits:reduced risk for diverticular disease (effect of constipation) reduced risk for colon cancer (less exposure for toxins, carcinogens, dilution of carcinogens) DIETARY FIBER

16. IMPROVING LARGE BOWEL FUNCTION Transit time ( bowel movements) / Stool volume Rural diet (high fibers) - 24 hrs Western diet (low fibers) - 72 hrs Stool volume Rural diet 500 g / day Western diet 100g /day Transit time

17. CONTRIBUTION OF FIBER TO ENERGY Fiber – negligible contribution to energy For food–labeling purposes : 0 kcal/g, if it is insoluble 4 kcal/g, if it is soluble FIBER, SATIATION, SATIETY, AND OBESITY Fiber influences meal termination ( intra meal satiety = satiation) Soluble fiber delays emptying of the gastric content and provides an extended feeling of fullness ( inter meal satiety) A consumption of an additional 14 g/d of fiber decreases the energy intake by 10% (decreases the incidence of obesity) DIETARY FIBER

18. 300 calories portion HIGH FAT FOODS STARCHY FOODS + high protein content HIGH FIBER FOODS Do not satisfy hunger Intrameal satiety gastric distension satiation Fiber & Weight Management DIETARY FIBER Fiber helps maintain ideal body weight! Gastric distension energy density caloric density Low Medium High

19. FIBER AND GLUCOSE TOLERANCE, INSULIN RESPONSE, AND DIABETES Soluble fiber – beneficial effect on plasma Glucose and Insulin response in patients with Type 2 Diabetes Mellitus (intervention studies) Glycemic response = the measure of the food ability to elevate blood Glucose influenced by: amount of food, fiber content, fat content, preparation method Low Glycemic CHO foods – Glucose enters the blood stream slowly and helps maintain stable blood Glucose level Effect based on: - delayed gastric emptying - slowed rate of digestion and absorption DIETARY FIBER

20. EFFECTS ON GLUCOSE (soluble fiber) 30 55 60 65 70 75 80 85 90 6090120150180 M i n u t e s a f t e r m e a l P l a s m a g l u c o s e l e v e l Apple Apple Juice Stabilizes blood G curve - Keep G from entering into blood stream too rapidly - Help avoid the sudden fall (from a mountain pick of high G to a valley of low G…) Legumes: The greatest Glucose stabilizing effect!

21. GOD’S NATURAL COLON CLEANSER DIETARY FIBER Targets different toxins Decreases the contact time Dilutes the toxins DRUGS, CHEMICALS, ADDITIVES, PESTICIDES THE CARCINOGEN SUBSTANCES HAVE DECREASED TIME IN CONTACT WITH THE INTESTINAL WALL The most effective …“BROOM” ! Dietary fiber needs……………. 35g / day Western diet 11-18g / day

22. FIBER AND HEART DISEASE Epidemiologic studies : Fiber- protective role against Coronary Heart Disease by: - lowering blood Cholesterol - attenuating blood triglyceride levels - normalizing postprandial Glucose level (hyprerglycemia in pts with diabetes and in general population. Hyperglycemia is a risk factor for CVD) DIETARY FIBER

23. POTENTIAL CONCERN Overconsumption of fiber: - gastro-intestinal distress (flatulence) - lowering nutrient availability (mineral bio-availability, when phytate present, decreased absorption of cations) - high lignin in the diet may inhibit digestion of some lipid components - pancreatic lipase inhibitor present in wheat bran - amylase inhibitors in legumes (heating inactivates many of these inhibitors) DIETARY FIBER

24. RECOMMENDATIONS 5 servings of fruits, and vegetables daily 6 servings of whole grains, and legumes daily 20 - 35 g/d fiber DRI: 14g/ 1000 kcal/d DIETARY FIBER

26.  FBG levels (fasting blood G)  Glicosuria  Insulin resistance  Insulin sensitivity - Inhibit postprandial hyperglycemia  Satiety rate  Energy density  Transit time - Alter hormonal response - Inhibit recirculation of bile acids  Cholesterol  TG  Body weight  Constipation  Diverticular disease  Colon cancer Body cleaner (toxins, metals) ObesityCHDGIDDM F A B U L O U S F I B E R

27. REFERENCE Shils M. et al, Modern Nutrition in Health and Disease, 10 th ed. www.pubmed.org http://cme.medscape.com 5 th International Congress of Vegetarian Nutrition, Loma Linda, California March 2008 www.pcrm.org

28. QUESTIONS?