Nutrition: Highs and lows of fiber in your diet

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Must be time to talk about dietary fiber. Last week I received this message: “Hello dear, can you send us some information about a low-fiber diet? (My husband) is going in for a colonoscopy and was told to avoid fiber for 3 days before his test.”

Then reader G.M. writes: “Hello Barbara, I had a CAT scan done and they said I have colonic diverticulosis and now mild diverticulitis. I’ve been using a Nutribullet (blender) for four or five months using berries, 1/2 a banana, purified water or coconut milk and unsweetened coconut yogurt. There’s always a thing about nuts and seeds. Is it OK to keep using (this blender) with this disease because of the tiny seeds which they say break up? I know a juicer takes all the pulp and fiber out but we’re always told to get fiber with diverticular disease and I thought this would be a great way to get natural fiber rather than just Metamucil. Help!”

So let’s start with this: Dietary fiber is a type of carbohydrate in plant foods that our human bodies do not digest. Therefore fiber moves through our intestines relatively unchanged, except for some that is fermented by bacteria in the large intestine (colon). Although not officially a nutrient, dietary fiber benefits our health and may offer some some protection against heart disease, type 2 diabetes and certain types of cancer.

Because fiber is good for us, a low fiber diet is usually only recommended for limited amounts of time for specific medical reasons. Low fiber generally means less than 10 to 15 grams a day while the usual recommendation for fiber intake is 25 or more grams a day. High fiber foods such as beans, peas, lentils, whole grains or any fruit or vegetable with more than 1 or 2 grams of dietary fiber per serving need to be avoided on a low fiber diet.


I’d say it’s OK for you to use your blender, G.M. The bigger question is whether you are treating diverticulosis or diverticulitis. Diverticulosis describes the presence of small pouches in your colon called “diverticula.” A diet high in fiber is usually advised for people with this condition.

Diverticulitis (notice the “itis” in the last syllable) is an inflammation of the diverticula — a more serious condition often treated with antibiotics and a low fiber diet. More severe cases may require hospitalization or surgery. When diverticulitis subsides, a person is usually told to gradually add more fiber back into their diet.

What about nuts and seeds? Recent research has found little, if any, association of nuts or seeds with diverticulitis. Therefore, most experts do not consider these foods off-base for people with diverticular disease…unless they need to follow a low fiber diet.

Want to be more confused? While we used to think that diverticular disease was mostly about dietary fiber, current evidence shows it more strongly related to our genetics and our age. The quality of our gut bacteria may also play a role. Stay tuned…

Barbara Quinn is a registered dietitian nutritionist affiliated with the Community Hospital of the Monterey Peninsula. Email her at to ©2020 The Monterey County Herald. Visit The Monterey County Herald at . Distributed by Tribune Content Agency, LLC.

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