Definition of dietary fiber, History, Classification, Functions, Health benefits, Clinical studies, Products, Meta-analysis,

1. FOOD AS MEDICINE:
DIETARY FIBER
By
Kevin KF Ng, MD, PhD
Former Associate Professor of Medicine
Division of Clinical Pharmacology
University of Miami, Miami, FL., USA
Email: kevinng68@gmail.com
A slide presentation for HealthCare Provider Seminar Mar 2019

2. Lecture outline
▪ What is dietary fiber
▪ History
▪ Classification
▪ Functions
▪ Clinical studies
▪ Products
▪ Summary

3. What is Dietary Fiber?
Dietary fiber is a complex
carbohydrate that is neither
digested nor absorbed in the
small intestine.

4. Milestones in history of Dietary Fiber

5. Denis Burkitt and the origins of the dietary fibre hypothesis
▪ For more than 200 years the fibre in plant foods has been known by animal
nutritionists to have significant effects on digestion.
▪ Its role in human nutrition began to be investigated towards the end of the 19th
century.
▪ Between 1966 and 1972, Denis Burkitt used ideas from a range of disciplines
together with personal observations proposed a radical view of the role of fibre in
human health.
▪ Burkitt built on the work of three physicians (Peter Cleave, G. D. Campbell and Hugh
Trowell), a surgeon (Neil Painter) and a biochemist (Alec Walker) proposed that diets
low in fibre increased the risk of CHD, obesity, diabetes, dental caries, various
vascular disorders and large bowel conditions such as cancer, appendicitis and
diverticulosis.
https://www.cambridge.org/core/journals/nutrition-research-reviews/article/denis-burkitt-and-
the-origins-of-the-dietary-fibre-hypothesis/1DA569CF06DB93A4FF2DA54629A5D566

6. Dietary Fiber is now recognized as an essential nutrient
Macronutrients
1.Carbohydrate
2.Protein
3.Fat
4.Water
Micronutrients
1.Carbohydrate
2.Protein
3.Fat
4.Water
5.Vitamins
6.Minerals
7.Essential fatty
acids
Newly added
macronutrient
• Dietary fiber

7. Emergence of Dietary Fiber as an Essential Nutrient
24,701 articles in PubMed
From 1970-2018

8. Classification of Dietary Fiber
https://www.megazyme.com/technical-support/dietary-fiber/what-is-dietary-fiber

9. Classification of Dietary Fiber based on bulk properties
Dietary Fiber
Solubility Fermentation Viscosity

10. Classification and Examples of Dietary Fiber based on bulk properties
Dietary Fiber
Solubility Fermentation Viscosity

11. Structure and constituents in a plant cell
https://www.sciencedirect.com/science/article/abs/pii/S0958166914000275

12. Structure of a plant cell wall
plant cell wall is 95% of dietary fiber
https://wallyplant.wordpress.com/cellwall/

13. Structure of the Fungal Cell Structure
https://www.youtube.com/watch?v=QcuPKy_Slnghttps://mykosan.com/health-benefits-of-medicinal-mushrooms/

14. Microstructure of Soluble and Insoluble Common
Bean Dietary Fiber
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1186&context=foodmicrostructure
uncooked insoluble fiber uncooked soluble fiber
uncooked soluble fiber cooked soluble fiber
cooked soluble fiber soluble fiber at greater magnification
25 µm 50 µm
25 µm 25 µm
10 µm

15. Soluble fiber at 10 µm magnification
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1186&context=foodmicrostructure
10 µm
pore

16. Main constituents in the dietary fiber polysaccharides
https://www.scribd.com/read/282557311/Dietary-Fibers-Chemistry-and-Nutrition

17. Chemical structures of amylose, cellulose and Ᏸ-glucans
https://lpi.oregonstate.edu/mic/other-nutrients/fiber

18. Examples of some polymers of glucose
https://link.springer.com/article/10.1007/s00223-017-0339-3
3–10 units > 10 units1-2 units

19. Polysaccharides of glucose
https://www.creative-proteomics.com/services/polysaccharide-analysis.htm

20. What happens to the dietary fiber in the gastrointestinal tract?

21. Population of bacteria in the gastrointestinal tract
http://www.anti-agingfirewalls.com/2012/02/20/gut-microbiota-probiotics-prebiotics-
and-synbiotics-%E2%80%93-keys-to-health-and-longevity/
2
12

22. Fate of dietary fiber in the gastrointestinal tract

23. Fate of dietary fiber in the gastrointestinal tract
20-48%
2-5%
35-55%

24. Biological actions of lactic and succinic acids and the predominant
short chain fatty acids produced by bacteria in the GIT (2017)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5666883/

25. Benefits of dietary soluble and insoluble fiber
▪ Normalize bowel movements
▪ Maintain bowel health
▪ Anti-microbial
▪ Anti-inflammatory
▪ Immuno-modulatory
▪ Anti-hyperglycemia
▪ Anti-hyperlipidemia
▪ Anti-hypertension
▪ Anti-obesity
▪ Anti-cancer

26. Meta-analysis: Hierarchy of evidence in clinical studies
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049418/

27. Meta-analysis: Hierarchy of evidence in clinical studies
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049418/

28. Dietary fiber intake related to relative risk for disease based on
estimates from prospective cohort studies. (2009)
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1753-4887.2009.00189.x

29. Dietary Fiber Intake and Total Mortality:
A Meta-Analysis of Prospective Cohort Studies (2014)
https://academic.oup.com/aje/article/180/6/565/2739168
Favors dietary fiber

30. Effect of fiber supplement on weight loss. (2009)
Values are means ± SEM. Data in 15 studies obtained at 4 and 8 weeks and additional data in 9 of those studies
obtained at 12 weeks. Significant differences were seen at 4 weeks (P = 0.0063) and 8 weeks (P = 0.0088).
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1753-4887.2009.00189.x

31. Effects of fruit and vegetable consumption on
inflammatory biomarkers and immune cell populations:
a systematic literature review and meta-analysis (2018)
https://academic.oup.com/ajcn/article-abstract/108/1/136/5042153?redirectedFrom=fulltext
Favors fruit & vegetable

32. Association between dietary fiber and markers of systemic inflammation
in the Women’s Heath Initiative Observational Study 2008
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2603616/

33. Dietary fiber intake and risk of metabolic syndrome:
A meta-analysis of observational studies (2018)
Favors dietary fiber
https://www.clinicalnutritionjournal.com/article/S0261-5614(17)31392-4/ppt

34. Beneficial effects of high fiber intake in patients with type 2
diabetes mellitus (2000)
https://medium.com/personal-growth/fibre-the-anti-nutrient-612603de4cec

35. Long-term effects of soluble fibers on LDL-cholesterol values.
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1753-4887.2009.00189.x

36. The net effect of consumption of oat products on
total cholesterol concentrations (1999)
Am J Clin Nutr 1999;69:30–42
Favors oat dietary fiber

37. Effect of Dietary Fiber on Blood Pressure
A Meta-analysis of Randomized Placebo-Controlled Trials (2005)
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/486375
Systolic BP Diastolic BP
Favors dietary fiber

38. Dietary fiber intake and risk of cardiovascular disease:
systematic review and meta-analysis (2013)
https://www.bmj.com/content/347/bmj.f6879
Favors dietary fiber

39. Risk of CHD across increasing levels of total fiber intake.
RR=risk ratio (2013)
https://www.bmj.com/content/347/bmj.f6879
Recommended daily intake

40. Dietary Fiber Intake and Risk of First Stroke
A systemic review and meta-analysis
Greater dietary fiber intake is significantly associated with lower risk of first stroke
https://www.ahajournals.org/doi/full/10.1161/STROKEAHA.111.000151

41. Dietary Fiber Intake Reduces Risk for Colorectal Adenoma:
A Meta-analysis (2013)
https://www.gastrojournal.org/action/showFullTextImages?pii=S0016-5085%2813%2901586-2
Favors dietary fiber

42. Dietary fiber, whole grains, and risk of colorectal cancer:
meta-analysis of prospective studies (2011)
https://www.bmj.com/content/343/bmj.d6617

43. Dietary fiber intake and reduced risk of ovarian cancer:
a meta-analysis (2018)
https://www.semanticscholar.org/paper/Dietary-fiber-intake-and-
reduced-risk-of-ovarian-a-Zheng-Shen/39324523d64a5a863557d7643ae9a50f0f529575
Favors dietary fiber

44. Recommended Daily Serving of Dietary Fiber
▪ The recommended daily serving of fiber
is 25-35 grams.
▪ Most Americans consume 15 grams of
fiber.
▪ The difference in the intake is called
Fiber Gap

45. A New Daily Reference Value (DRV)
for Dietary Fiber
▪ In the 2016 ruling, the FDA increased the daily reference
value (DRV) for dietary fiber from 25 grams per day to 28
grams per day.
▪ This increase will require all food manufacturers to update the
percent daily value (%DV) for dietary fiber on all nutrition
labels
https://www.esha.com/dietary-fiber-nutrition-facts-label/

46. Daily intake of dietary fiber in selected countries
Fiber gap
Adapted from Tuohy et al. Current Pharmaceutical Design, 2009
DRV
DRV=Daily recommended value

47. Effects of deficient intake of dietary fiber
▪ Constipation
▪ Less than three bowel movements a week
▪ Weight gain
▪ Irritable bowel syndrome
▪ Hemorrhoids
▪ Colon cancer
▪ Medical illness

48. Effects of excess intake of dietary fiber (> 70 g a day)
▪ Dehydration
▪ Nausea
▪ Bloating
▪ Gas
▪ Stomach cramps
▪ Constipation or diarrhea

49. Side effects of dietary fiber and supplements
▪ Bloating
▪ Cramping
▪ Flatulence
▪ Diarrhea
▪ May interact with some medications
▪ No evidence that daily use of natural fiber or supplements caused serious side
effects.
▪ It is best to obtain fiber from whole food which contains vitamins and minerals
that are not found in supplements.

50. Potential interaction of fiber supplements with medications

51. Which of the following does your stool resemble?
Consider color and consistency
https://www.otsuka.co.jp/en/health-and-illness/fiber/for-body/stool/
color
consistency

52. Natural Fiber and FDA approved Fiber Supplement
Naturally occurring fiber
• Vegetables
• Fruits
• Whole grains
• Cereal bran
• Flaked cereal
• flours
FDA approved Isolated or
synthetic fiber
• Beta-glucan soluble fiber
• Psyllium
• cellulose
• Guar gum
• Pectin
• Locust bean gum
• Hydroxypropylmethylcellulos
Non-digestible carbohydrate
pending review by FDA
• Mixed plant cell fibers
• Arabinoxylan
• Alginate
• Inulin and inulin-type frutans
• High amylose starch (resistant
starch 2)
• Galatooligosaccharide
• Polydextrose
• Resistant maltodextrin/dextrin
https://www.fda.gov/food/labelingnutrition/ucm528582.htm#beneficial_physiological_effects

53. High contents (% weight) of dietary fiber in some foods
http://pubs.sciepub.com/jfnr/1/3/1/

54. How to calculate fiber requirements per day based on
Dietary Guidelines for Americans 2015-2020
https://health.gov/dietaryguidelines/2015/resources/2015-2020_dietary_guidelines.pdf

55. High Fiber Food
https://www.pinterest.com/pin/215469163394519578/
Food Serving ServingGrams GramsFood

56. Fiber supplements in the Internet Market:
Confused?
https://www.google.com/search?q=internet+fiber+supplements

57. Summary
▪ Dietary fiber is defined as a complex polysaccharide that resists the digestion in the small
intestine.
▪ It is classified as soluble, insoluble , fermentable or non-fermentable, viscous or non-viscous
fibers.
▪ The soluble fiber entraps and delays the absorption of water, bile acids, sugar and fat in the small
intestine passing the contents to the large intestine for further action.
▪ The health benefits of soluble fiber include weight loss, reduction of blood sugar, cholesterol, blood
pressure and prevention of cancer.
▪ Fermentation of soluble and insoluble fibers in the large intestine produce short chain fatty acids,
gas and biomass.
▪ The short chain fatty acids (acetate, propionic acid, butyrate) provide energy metabolism, balance
between beneficial and harmful bacteria, satiety, immuno-modulation and anti-cancer effect.
▪ A number of dietary fibers had been isolated and sold as fiber supplements.
▪ It is better to consume naturally occurring dietary fiber than supplements since dietary fibers
contains other nutrients that are not found in supplements.

58. ANY QUESTION?
Please contact
Kevin KF Ng, MD, PhD
Email: kevinng68@gmail.com