At The Functional Kitchen, we like to think of fiber as nature's broom for our digestive system. Before we dive into the benefits of fiber and how much you should be getting in a day, we will do a quick review of what fiber is-if have not noticed by now, we love to help you be informed eaters!
What is fiber?
Fiber is a specific type of carbohydrate. Now, do not let that scare you. Carbohydrates are absolutely an important part of a well-balanced diet (that is a whole other blog for another day). Bottom line, fiber is important for overall health and fiber is a carb!
There are two types of fiber: insoluble and soluble. We are not able to digest either type of fiber but the bacteria in our guts can (more on this in a minute.) Insoluble fiber is more "broom-like" than soluble fiber. It pretty much stays as is from the time we eat it to the time we excrete it. It helps push things through our intestines. On the other hand, soluble fiber forms a gel with water. This helps push things through by bulking up the content of our intestines. Soluble fiber also can be fermented by our gut bacteria! (1)
What are some of the benefits of fiber?
Fiber's function as an intestinal broom may be its most well-known function. Its ability to keep things moving at a healthy rate can help reduce the risk of constipation. It also helps regulate bowel movements, meaning what is ultimately waste does not stay in our intestines longer than necessary (3).
Fiber can help us feel full and satiated after meals and can slow down how quickly sugar is absorbed into our blood. This means fiber can help us keep portion sizes reasonable while still feeling satisfied. The fact that it slows the absorption of sugar can help us maintain better blood sugar balance over time.
Fiber also binds cholesterol, creating the opportunity to possibly lower overall cholesterol levels (2,3).
Remember how we said soluble fiber is fermentable by gut bacteria? The beneficial bacteria in our large intestine break down soluble fiber to get the energy they need to grow and thrive. This ultimately means they have a better chance at out-competing any undesirable bacteria that attempt to colonize the gut. This helps keep our gut, and ultimately immune system, functioning optimally. (3)
Higher fiber diets are correlated with better life expectancy and reduced risk for multiple diseases. A series of systematic reviews and meta-analyses published in 2019 suggest that higher fiber diets are associated with a 15-30% decrease in (2):
all-cause deaths
cardiovascular-related deaths
coronary heart disease
strokes and deaths from strokes
type 2 diabetes
colorectal cancer
How much fiber should I be getting in a day?
According to the 2020-2025 Dietary Guidelines for Americans, women 19 years and older should be getting between 25 and 28 grams a day. Men 19 years and older should aim for about 31-34 grams a day (4). These are just ranges though: our fiber needs depend on our life stage and a variety of other factors so if you are interested in better understanding your specific needs, reach out to our registered dietitians at The Functional Kitchen!
Most Americans are not meeting their fiber needs though. In fact, 90% of women and 97% of men do not meet the recommended intakes for dietary fiber, based on the 2020-2025 Dietary Guidelines for Americans. This ultimately shows that we, as a nation, are not consuming enough fruits, vegetables, and whole grains (4). So how can you up your fiber intake? Keep on reading to find out!
How can I add fiber to my diet?
Remember to put food first. There are numerous fiber supplements on the market but nature has provided us with so many wonderful sources of fiber to choose from!
When you think fiber, think plants! That means vegetables, fruit, whole grains, nuts, seeds, and beans! Here are some foods that pack a fiber-punch:
(note: this list is not exhaustive, but is a great place to start on your next grocery run)
Almonds
Asparagus
Avocado
Bananas
Beets
Brown rice
Black beans
Cabbage
Chickpeas
Edamame
Garlic
Lentils
Mung beans
Oats
Onions
Pumpkin seeds
Quinoa
Raspberries
Sweet potatoes
Tomatoes
You can also check out this list to get an idea of how much fiber is in a typical serving of several foods. That way, you can see which foods you may already be getting fiber from and how you can easily add more to your diet!
References:
1. The Institute for Functional Medicine. Probiotic Foods for Postbiotic Abundance. https://www.ifm.org/news-insights/prebiotic-foods-postbiotic-abundance/. Accessed 10/10, 2021.
2. Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses [published correction appears in Lancet. 2019 Feb 2;393(10170):406]. Lancet. 2019;393(10170):434-445. doi:10.1016/S0140-6736(18)31809-9
3. Newman T, Kubala, J. Why do we need dietary fiber? https://www.medicalnewstoday.com/articles/146935. Published 2020. Accessed 10/10, 2021.
4. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020.