Reader B.D. posed this challenge to me this week: “I would appreciate your opinion as a dietitian on this article on dietary fiber.”
The article, “Does a high fibre diet prevent disease?” written by Dr. Sebastian Rushworth — a junior physician in Stockholm who graduated from medical school in 2020 — challenges what he says is “the now widespread belief that dietary fiber is an important part of a healthy diet.”
Rushworth points out that observational data (studies on the reported habits of people) “find a correlation between a low fiber diet and pretty much any chronic disease you care to look at. The randomized trials that have been done have however for the most part failed to show evidence of a benefit of increasing intake of dietary fiber.”
Here are my thoughts.
Nutrition knowledge is constantly evolving. And while the evidence this physician presented from 2016 and 2017 seems to question the health benefits of dietary fiber, there are now even more reasons to seriously keep this component in our diets.
One vital issue that has recently emerged in the field of nutrition is this: Studies on the effects of individual nutrients (such as dietary fiber) often don’t tell the whole story. That’s why nutrition professionals — including those who wrote the current Dietary Guidelines for Americans, 2020-2025 — now focus on dietary patterns rather than isolated nutrients.
What does that mean?
The health benefits I might get from taking a supplement of pure fiber might not be the same as what I reap from eating a combination of high fiber foods such as vegetables, fruit and whole grains. That’s why current recommendations advise us to eat nutrient-dense foods. In other words, dietary fiber is one nutrient that appears to work in tandem with other components of a health-promoting diet.
Also before we push our high fiber foods aside, let’s remember there are numerous types of dietary fiber in various foods. Studies that look at just one type or the other may miss the big picture.
And remember that each type of fiber plays a unique role to nourish health beneficial microbes in our intestines. These good gut bugs help bolster our immunity, improve our ability to absorb certain nutrients and even play a role in controlling our weight. A low intake of dietary fiber reduces the healthy diversity of these good guys, according to molecular scientists.
Rushworth’s statement that “there simply isn’t enough data to draw any firm conclusions about what effect dietary fiber has on cardiovascular disease risk” may well be true. However, there is strong evidence that dietary patterns such as the Mediterranean or the DASH (Dietary Approaches to Stop Hypertension) diets can improve blood pressure and other symptoms of heart disease. These diets are rich in high fiber foods.
I rest my case.
Barbara Quinn-Intermill is a registered dietitian, certified diabetes educator and the author of “Quinn-Essential Nutrition.” Email her at email@example.com.