What is so great about fiber?
No doubt you have heard about fiber. There are probably foods in your pantry right now that advertise their fiber richness. So many people giving advice about a healthy diet emphasize the importance of fiber to the point that it almost seems like a buzzword. But if you are like most of my clients, you may not know much about why we are “supposed” to eat fiber. So let’s start with the basics and build on that.
What is Fiber?
Fiber is a type of carbohydrate. Like all carbohydrates, it is comprised of multiple sugar molecules linked together.
In the carbohydrates we have previously discussed, like sucrose, enzymes in your gut can break the bonds between the sugar molecules. This allows the individual sugar molecules to travel to your bloodstream during digestion, releasing simple sugars for energy.
But fiber is different. Fiber is indigestible. We humans don’t have the enzymes to break down the bonds between the sugar molecules. This means that the sugars in fiber aren’t pulled apart and sent to the bloodstream. Instead, they travel to the large intestine mostly intact.
Fiber and the Gut Microbiome
Since fiber is not broken down, it gets to the large intestine intact, making it a food source for your gut bacteria. It feeds the healthy bacteria that you want to feed. There is still so much that is unknown and actively being studied about the gut microbiome. What we do know is that the microbiome plays a key role in training our immune system and keeping us healthy. And gut dysbiosis (the scientific word for when things get out of whack) is associated with type 2 diabetes and cardiovascular disease. (1) Keeping your gut healthy and well fed, is key to your overall health!
When gut bacteria feed on fiber, the process is called fermentation. Yep, similar to the way that beer ferments. There are naturally some gases released in this process. This fermentation is what gives things high-fiber foods like beans and Brussel sprouts their smelly reputation.
This fermentation of fibers by gut bacteria also produces short-chain fatty acids (SCFAs).(2) SCFAs improve your gut health by maintaining the integrity of the intestinal barrier (i.e. protecting against leaky gut), keeping inflammation in check, and reducing the risk of colon cancer. (3) These SCFAs also act on metabolic processes like glucose and fat metabolism and even in regulating satiety. (4)
Other Health Benefits of Fiber
Now is the part of the blog where I should tell you that there are two types of fiber: soluble (dissolves in water) and insoluble (does not dissolve in water). They are structurally different, come from different sources, and do different things in the body. I think there’s a little too much focus on all that by a lot of nutrition people. You need both. If you are eating mostly whole foods and paying just a little attention to your fiber intake, you will get enough of both. But if you are curious, I’ll tell you where to get each type after I tell you a little bit about the benefits of each.
1. Lowers cholesterol and reduces risk of cardiovascular disease
Soluble fiber can help prevent the absorption of dietary cholesterol, meaning that it prevents cholesterol from entering your bloodstream. It can also increase the rate that you get rid of cholesterol in your bile (by the way, that is how cholesterol leaves your body, in bile that is dumped into the gut to be “eliminated” i.e. pooped out). This lowers your levels of LDL cholesterol (the “bad” cholesterol). (5) By improving cholesterol, fiber reduces the risk of cardiovascular disease. (5)
2. Helps control blood sugar
Because your body is unable to break down fiber and absorb the sugars, it does not spike your blood sugar like other carbohydrates can. (6) Fiber may also protect someone with prediabetes from advancing to type 2 diabetes. (7,8) For those who have diabetes, sufficient fiber intake may improve glycemic control, reducing fasting plasma glucose levels. (7,9)
3. Makes your bowel movements easy
Insoluble fiber gets all the credit for fiber’s role in keeping you regular. Insoluble fiber helps bulk up your stool, and bulky stool is easier to pass.
4. Keeps you feeling full longer
Because your body does not digest, it moves slowly through your stomach and intestines. This keeps you full longer. (6) Think about the difference between how full you feel after eating an apple versus drinking apple juice. That difference is largely fiber. (7) If you are constantly feeling hungry shortly after eating, fiber may be the answer.
How Much Fiber Do You Need?
Current recommendations encourage women to get 25 grams a day and men 38 grams per day. Women and men over age 50 should shoot for 21 and 30 grams per day, respectively.10 On average, Americans fall way short. We average 10-15 grams a day.
That means the chances are good that you could be eating more fiber. I love nutrition recommendations that focus on more! More berries, more oatmeal, more avocado, more edamame. More of the good stuff!
(Caveat: Not everyone handles high amounts of fiber well. If you are one of those who feels kind of gross after eating lots of fiber or avoids it for other medical reasons, then you do what your body needs. For most people it is great, but you may not be most people. And that’s cool. Do you.)
Where Can You Get Fiber?
Fiber is in virtually every non-animal whole food. Plants are full of fiber. Fiber is in all of these:
Vegetables
Whole fruits
Beans
Nuts
Legumes
Great sources of soluble fiber include oatmeal, chia seeds, lentils, beans, blueberries, and apples. And that insoluble fiber that helps keep you regular is abundant in quinoa, brown rice, kale, walnuts, almonds, legumes, apples, and pears.
You can also find fiber-rich breakfast foods and snacks. Though I am always going to promote the whole food options, sometimes that may not work for what you have going on. Foods that advertise their fiber benefits will include their fiber content on the nutrition label. Be sure to look at the nutrition label to check that it has the fiber it is advertising.
Want Some More Info About Fiber?
If you are interested in figuring out how to eat more fiber or want to figure out to incorporate more of all kinds of nourishing foods into your dietary routine, the basecamp Program may be perfect for you. You get customized nutrition consulting and coaching from me, where we work to incorporate more nourishing foods—like fiber—into your current lifestyle to reach your unique goals.
References:
1. Myhrstad MCW, Tunsjø H, Charnock C, Telle-Hansen VH. Dietary Fiber, Gut Microbiota, and Metabolic Regulation—Current Status in Human Randomized Trials. Nutrients. 2020;12(3):859. doi:10.3390/nu12030859
2. Cronin P, Joyce SA, O’Toole PW, O’Connor EM. Dietary Fibre Modulates the Gut Microbiota. Nutrients. 2021;13(5):1655. doi:10.3390/nu13051655
3. Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Frontiers in Endocrinology. 2020;11.
4. He J, Zhang P, Shen L, et al. Short-Chain Fatty Acids and Their Association with Signalling Pathways in Inflammation, Glucose and Lipid Metabolism. Int J Mol Sci. 2020;21(17):6356. doi:10.3390/ijms21176356
5. McRae MP. Dietary Fiber Is Beneficial for the Prevention of Cardiovascular Disease: An Umbrella Review of Meta-analyses. J Chiropr Med. 2017;16(4):289-299. doi:10.1016/j.jcm.2017.05.005
6. CDC. Fiber Foods. Centers for Disease Control and Prevention. Published February 4, 2022.
7. Anderson JW, Baird P, Davis RH Jr, et al. Health benefits of dietary fiber. Nutrition Reviews. 2009;67(4):188-205. doi:10.1111/j.1753-4887.2009.00189.x
8. Lindström J, Peltonen M, Eriksson JG, et al. High-fibre, low-fat diet predicts long-term weight loss and decreased type 2 diabetes risk: the Finnish Diabetes Prevention Study. Diabetologia. 2006;49(5):912-920. doi:10.1007/s00125-006-0198-3
9. McRae MP. Dietary Fiber Intake and Type 2 Diabetes Mellitus: An Umbrella Review of Meta-analyses. J Chiropr Med. 2018;17(1):44-53. doi:10.1016/j.jcm.2017.11.002
10. LDN KDM MS, RD. Should I be eating more fiber? Harvard Health. Published February 21, 2019.
