Fiber 101 – Types, Benefits, and Label-Reading Tips
Fiber – it’s good for everything from your heart to your gut, and chances are, you’re not getting enough of it. Before I lose you, it’s not just found in cloudy Metamucil powder or boring bran muffins. There are a ton of fiber sources and they each come with their own unique benefits. Even if you already look for total fiber on nutrition labels, you might be surprised to know that not all sources are created equally. Luckily, if you know what to look for, you can meet your needs like a pro.
What is fiber?
Fiber is part of the carbohydrate family that the human body can’t digest or absorb.
What are the benefits?
- Speeds up digestion by adding bulk to the contents of your GI tract (yay, poop!)
- Slows down digestion – Wait, what? Yep. Fiber can both speed up and slow down digestion. (More on this later.)
- Stabilizes blood sugar levels – Slower digestion means that nutrients like carbs get a longer time to absorb, meaning more stable blood sugar levels after a meal.
- Lowers cholesterol – But how? Let’s start with this first – cholesterol in the body is converted into bile acids (part of that yellow-green yucky stuff called bile that’s stored in our gallbladder). Usually, bile is reabsorbed in our intestines as it passes through the GI tract with digested food. Certain types of fibers interfere with this absorption, which causes more of the bile to be taken out of the body instead. Still with me? More bile going out means more bile needs to be made for digestion, which requires more cholesterol to build it. (Here’s a helpful video that explains this topic!)
- Increases fullness after a meal. This can help you feel more satisfied and eat fewer calories.
- Feeds good bacteria in your gut – Prebiotic fiber can be broken down by bacteria in your intestine, keeping them happy and well-fed. Happy gut bacteria = happy body.
How much do I need?
I’ll give it to you straight – you’re probably not getting enough. The average American gets about 15 grams per day, which is about half of the amount that most of us need. The exact amount you need depends on your gender and age (1).
Men
- Under 50: 38 grams
- 51+: 30 grams
Women
- Under 50: 25 grams
- 51+: 21 grams
Are all types of fiber created equally?
I’ll spare you the boring stuff. What you need to know is that fiber can be categorized in a few ways – two of which are:
- How it acts (important for figuring out their benefits)
Fiber can be classified by how it acts – soluble or insoluble. Basically, the soluble type is, well… soluble in water, causing it to form a gel in the GI tract, which causes the contents of the GI tract to move more slowly. Soluble fiber also helps reduce cholesterol. Insoluble fiber doesn’t dissolve in water, and passes through the GI tract more quickly, helping speed up digestion and keep ya regular.
- Where it comes from (important for when we’re label reading)
Fiber can be classified by where it comes from – dietary or functional. Dietary fiber is made of intact parts of plants. The functional stuff is made of isolated parts of plants produced by extraction or manufacturing. Total fiber on the nutrition facts label is the sum of both dietary and functional. Within each of those categories, there are a variety of subclasses, each with their own unique sources and benefits (2,3).
Reading Labels for Fiber
Prior to 2016, any type of fiber could be included on the nutrition label, regardless of how strong the evidence was on its benefits. In 2016, the FDA tightened the definition of fibers to include only those with a proven benefit, which limited the types of fibers that could be listed on the label (4).
In 2018, the FDA began taking citizen petitions (a lot of which came from the food industry) and re-examining these rules, widening the umbrella over fibers that could be listed on the label (5). These new rules have received some backlash, as not all of these new fibers are associated with the health benefits you’d typically expect from a fibrous food. This could leave food buyers confused (6).
In short, reading nutrition labels can actually be really confusing. How do you know that the fiber in a product (like a snack bar) is going to benefit your health in the way that you’d expect? I got you, boo. Check out the chart below for a handy summary about fibers found in whole foods and packaged products, plus what you’re getting from them.
(Viewing this on mobile? Turn your phone to landscape mode to view the entire table.)
Dietary Fiber
| Fiber type | Other names | Sources | Benefits | |
|---|---|---|---|---|
| Soluble | Pectins | fruit pectin | apples, carrots, citrus fruits, jams/jellies, peaches, peas, strawberries | Reduces cholesterol |
| Gums | guar gum, locust bean gum, carob bean gum, carob seed gum, xanthan gum | barley, legumes, oats, also added to ice creams, beverages, dressings, condiments | Slows digestion and keeps blood sugar more stable after a meal | |
| Insoluble | Cellulose | cellulose gel, microcrystsalline cellulose | whole wheat, bran, vegetables | Adds bulk to stool, increases feelings of fullness, speeds up digestion |
| Hemicellulose | bran, whole grains | || | ||
| Lignin | fruits, seeds, vegetables | Gives gut bacteria the fuel to produce beneficial short-chain fatty acids |
Functional Fiber
| Fiber type | Other names | Sources | Benefits | |
|---|---|---|---|---|
| Isolated from plants, non-digestible | Inulin | chicory root extract, chicory root fiber, fructooligosaccharide, oligofructose, prebiotic fiber | bars (lookin’ at you, Fiber One), cereals, “better for you” ice creams like Halo Top | Acts as a prebiotic – aka food for your gut bacteria, beneficial for bone health and osteoporosis prevention. Some evidence that it reduces cholesterol levels in people with existing high cholesterol (7) |
| Psyllium | psyllium husk, psyllium seed husk | Metamucil, fortified cereals | Reduces coronary heart disease risk | |
| Beta glucans | barley beta fiber or beta-glucan, oat bran | barley, oats, rye, wheat | Reduces coronary heart disease risk, reduces cholesterol | |
| Arabinoxylan | cereal grains (wheat, etc.) | Slows digestion and keeps blood sugar more stable | ||
| Synthetic, non-digestible | Galactooligosaccharaides | GOS | naturally found in chickpeas, artichokes. Added to milk/juice beverages, infant formula and foods. | Prebiotic fiber, improves texture and bulk of foods, increases calcium absorption in the gut |
| Resistant maltodextrin/dextrin | wheat dextrin, soluble corn fiber, resistant dextrin, soluble wheat fiber | corn, wheat | Increases calcium absorption in the gut |
As you can see, all of the fibers listed on the label have at least some health benefits, but they aren’t exactly the ones you’d expect. For example, if you’re trying to speed up your digestion, you might be trying to boost your fiber intake. You won’t be getting that exact benefit from inulin, even though it may be listed as fiber on the label. Kinda’ misleading…
The food industry is great at picking up on what consumers want. People generally understand that fiber is important, so more packaged foods with added fiber are popping up at the supermarket lately. Before assuming that more total fiber on the label = health benefits, it’s important to ask where it is coming from.
Are you still wondering about your favorite fibrous snack bar? (Mine is made by NuGo!) Check that ingredient list and compare it to the chart to find out what benefits you’re really getting.
Take-Home Points:
- Fiber is awesome for you, and chances are, you need to eat more of it.
- Different types of fiber do different jobs in the body.
- Check the label! Fiber goes by many names so you may not be getting the type you need for your goals.
- Eat a mix of foods that contain fiber to get the full spectrum of benefits, and eat for your goals if you have a specific one in mind (lowering cholesterol, speeding up or slowing down digestion, etc.)
References:
- https://health.gov/dietaryguidelines/2015/resources/2015-2020_Dietary_Guidelines.pdf
- https://jandonline.org/article/S2212-2672(15)01743-8/abstract
- https://academic.oup.com/fqs/article/1/1/47/4791730
- https://www.esha.com/dietary-fiber-nutrition-facts-label/
- https://www.fda.gov/downloads/Food/LabelingNutrition/UCM610139.pdf
- https://www.politico.com/story/2018/06/14/fda-clarifies-what-counts-as-fiber-in-nutrition-facts-labels-646084
- https://www.medscape.com/viewarticle/762858
