It is recommended that adults consume between 25 and 30 grams of dietary fiber a day. The average American currently gets about half that amount. According to the latest Dietary Guidelines for Americans, dietary fiber is a “nutrient of public health concern,” meaning this low level of intake could actually be detrimental to our health. So, it’s potentially good news that food manufacturers are adding fiber to processed foods. But is that fiber as good for our health as fiber found naturally in fruits, vegetables, nuts, legumes, and whole grains?
Health Benefits of Fiber. According to a research review co-authored by Nicola McKeown, PhD, a scientist with Tufts’ Nutritional Epidemiology program and an associate professor at the Friedman School, there is reproducible evidence that dietary fiber found naturally in foods has a role in lowering cholesterol, improving glycemic control, and preventing constipation. And fiber may have more health benefits as well. “Research in this field is continually expanding,” says McKeown. “We’ve only begun to consider things like how the gut microbiota utilize different types of dietary fibers to potentially impact health.”
Dietaryfiber, also referred to as non-digestible carbohydrate, is the portion ofa plantfood that cannot be broken down by digestive enzymes. There are numerous substances that fit this definition, and they do not all behave the same way in the body. “Fibers have different effects because of inherent properties—solubility, viscosity, and fermentability,” says McKeown. The level of each of these properties determines what health effects a particular fiber will have in the human body. For example, both soluble fibers like those in oats and insoluble fibers like wheat bran are good for regularity (although through different mechanisms), but only viscous soluble fibers help lower cholesterol levels.
Put it into practice
-Aim for 25 to 30 grams of dietary fiber a day.
-Try to get most of that fiber by eating plenty of fruits, vegetables, legumes, nuts/seeds, and whole grains.
-Check labels of processed foods for grams of Dietary Fiber per serving.
-Be aware that some or all of the fibers in processed foods may be added, and that these fibers may not have the same health benefits as intrinsic fibers in whole foods.
-Do not choose processed foods on the basis of fiber content alone; also consider the content of refined carbohydrates, added sugars, and sodium, which have negative health effects.