How good is fiber for you? THIS GOOD.

I think I’ve driven home the point that fiber makes the world go round, or at least your bowel movements happen, so it is of utmost importance that you understand it and eat it! After studying the dietary and stool patterns of rural Africans in the early 1970s, Dr. Denis Burkitt speculated that a deficiency in dietary fiber was contributing to constipation and other colonic diseases in Western countries. Many diseases common in and characteristic of modern western civilization have been shown to be related to the amount of time necessary for the passage of intestinal content through the alimentary tract, and to the bulk and consistency of stools. These factors have in turn been shown to be greatly influenced by the fiber content of the diet. Calorie intake, speed of passage through the intestine, levels of intracolonic pressures, number and type of fecal bacteria, as well as levels of serum cholesterol and changes in bile-salt metabolism have all been shown to be related to the amount of dietary fiber consumed.

Here’s the scoop on fiber:

What is fiber? Fiber is a type of carbohydrate in plants or grains that the body can’t digest.  Most carbohydrates are broken down into sugar molecules but fiber cannot be broken down and instead passes through the gut undigested. 

What does fiber do? Dietary fiber increases stool bulk and weight which increases causes colonic distention and promotes stool propulsion, decreasing colonic transit time.  It helps regulate the body’s use of sugars, helping to keep hunger and blood sugar in check. It also appears to reduce the risk of developing various health conditions, including heart disease, diabetes, metabolic syndrome, diverticular disease, and constipation.

  • Cardiovascular disease - High fiber intake is associated with a 40-50% reduction in cardiovascular disease compared with low fiber, especially after heart attack. Each 10 g increase in fiber per day associated with a 14% relative reduction in the risk for all coronary events and a 27% reduction in heart disease death. Protect against heart disease by controlling cardiovascular risk factors (lowering insulin levels, lowering cholesterol and triglyceride levels, and lowering blood pressure).
  • Diabetes mellitus – Fiber consumption from grains has a protective effect against diabetes mellitus. Increased fiber intake may also be beneficial in controlling blood glucose in patients with established diabetes as it delays glucose absorption
  • Cancer – A number of laboratory, nutritional, and epidemiologic studies have identified low levels of dietary fiber in the pathogenesis of colorectal cancer
  • Low fiber diets may lead to cholesterol gallstones
  • Esophageal cancer- Dietary fiber, specifically cereal fiber, may protect against esophageal cancer (adenocarcinoma). Wheat fiber may neutralize mutagen formation from the conversion of salivary nitrites (carcinogenic) to nitrosamines.
  • Mortality –Increased dietary fiber intake is associated with decreased all-cause mortality. High fiber intake was associated with decreased mortality with a dose-response relationship (each 10 g/day increment associated with RR 0.89. Fiber intake also inversely associated with mortality from circulatory, respiratory, digestive, and non-cardiovascular, noncancer inflammatory diseases- especially in smokers and heavy drinkers (>18 g alcohol/day). Fiber from vegetables and cereals had higher impact than fiber from fruit.

How much do I need? At LEAST 25-30 grams of fiber per day, but most Americans get only about 15 grams a day.


  • Soluble fiber
    • Dissolves in water, form a “gel
    • Fermented by colonic bacterial flora to hydrogen, methane, CO2, sulfides, and short chain fatty acids, including acetate, butyrate, and propionate (which have been shown to stimulate water and sodium absorption in the colon and to promote mucosal healing)
    • Ex. oats, barley, legumes (peas & beans ex. Lentils, chickpeas), nuts, fruits (apples, blueberries), psyllium, pectin, wheat dextrin. Fiber in citrus fruits and legumes stimulates growth of colonic flora, thereby increasing fecal mass!
    • DIABETES: Can help control glucose levels,  reduce the risk of developing type 2 diabetes
    • HIGH CHOLESTEROL: Help lower blood cholesterol. Soluble fibers (psyllium, pectin, wheat dextrin, oat products) reduce LDL (bad cholesterol!). In a meta-analysis, every gram increase in soluble fiber reduced LDL-C by an average of 2.2 mg/dL . A meta-analysis of randomized trials found that whole grain diets reduce LDL and total cholesterol, and that whole grain oats were particularly effective. Psyllium may result in small further reductions in LDL in patients receiving low dose statin therapy
    • CARDIOVASCULAR DISEASE: Can reduce the risk of coronary artery disease and stroke by 40-50% (compared to a low fiber diet)
    • HIGH BLOOD PRESSURE:: A study in diabetics found that daily consumption of the ancient grain Salba (chia!) reduced systolic blood pressure and levels of C-reactive protein (inflammatory marker)
    • IBS: Help improve IBS symptoms with a number needed to treat of 6 (insoluble fiber is not better than placebo)
  • Insoluble fiber
    • From plant cell wall- does not dissolve in water
    • Bulks the stool, making it softer and easier for stool to pass on a regular basis (NOT a laxative!)
    •  Good for: Diverticulitis, hemorrhoids, chronic diarrhea, fecal incontinence, colon cancer prevention
    • Example: Grains! Wheat/whole wheat/wheat bran, rye products like bread, brown rice, carrots, cucumbers and tomatoes.

Side effects

Abdominal bloating or gas can be minimized by starting with a small amount (1/2 the suggested dose) and slowly increasing until stools become softer and more frequent. Ex. increased by 3g every 1-2ws. 

So what should I do?

- Increase both soluble & insoluble dietary fiber containing-foods discussed above

- Consider raw bran (start with 2 tablespoons with each meal) followed by a glass of water

- And if you can't fit enough dietary fiber in, don't worry! There's always....

Fiber supplements

- They work exactly the same as dietary fiber, absorbing water and increasing fecal mass, thereby increasing stool frequency and softening consistency of stool.

- Always take with 6-12oz water, tea, or coffee 

- And remember-- Do not administer WITHIN 1 HOUR of other medications and AVOID calclium supplements as fiber can bind iron, calcium, and zinc and interfere with its absorption

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