More Reasons to Include Fiber in Your Diet?
JAMAnetwork.com, April 17, 2019.
The numerous and popular low-carb diets (think Atkins and keto) have driven home the notion that carbs are bad for us, primarily because they are highly refined and linked in many ways to concurrent high sugar ingestion. But like fats, there are good and bad species of carbs, with some high in fiber content.
A good deal of recent and solid research finds that intake of fiber and whole grains—probably due to their high fiber content—but not foods with a low glycemic index, was associated with significant reductions in mortality and chronic illnesses.
The use of fiber in these studies, which are observational and not randomized controls, found an associated 15% to 30% decrease in all-cause and cardiovascular-related mortality and incidence of coronary heart disease, stroke, Type 2 diabetes, and colorectal cancer in those who consumed the most dietary fiber relative to those who consumed the least. What was also shown was that compared with low intake, high dietary fiber intake was associated with lower body weight, blood pressure, and serum cholesterol. The studies also found a general dose-responsive phenomenon operative, that is the more fiber ingested, the greater the associated positive effect. Again cause-and-effect was not demonstrated, but the association seems pretty strong.
In most westernized countries, not enough of us consume the recommended amounts of dietary fiber; for example in the US the average dietary fiber intake by men and women is 18 g and 15 g, respectively, yet, the 2015-2020 Dietary Guidelines for Americans recommends a daily minimum intake of 33.6 g per day for men and 28 g for women 19 to 30 years of age.
If you buy into these studies, and traction among healthcare providers appears to be growing, then it seems that any of us wanting to lower the risk of a variety of cardiovascular disease and many different cancers, might want to consume more, not fewer, carbs, as long as they’re good carbs such as fiber-rich whole grains, legumes, fruits, and vegetables.
The rationale behind fiber’s purported health benefits suggest a mechanical effect (fiber accelerates the transit time of stool) but this is not the only benefit. Changes in gut microbiota and metabiome are observed, and in the case of cereal fiber, improved insulin sensitivity, lipid profile, endothelial function, and reduced inflammation is observed.
In other words, the explanation for why a high-fiber diet appears to be protective goes beyond the obvious and awaits further delineation.
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