Soluble vs insoluble fiber: What’s the difference and why you need both
When we think of fiber, we often lump it all into one category: good for digestion. But there are two main types of fiber—soluble and insoluble—and they work very differently in your body. Understanding how these two types of fibers work and where to get them in your daily diet means better digestion and elimination, improved heart health, balanced blood sugar control, increased metabolism and protection from countless chronic diseases.
The basics: What is fiber?
Fiber is a type of carbohydrate found in plant-based foods that your body can’t digest. Instead of being broken down and absorbed like other carbs for energy, fiber passes through your digestive system, largely intact.
Soluble fiber: The gel-former
What it does
Soluble fiber dissolves in water to form a gel-like substance. This slows digestion and can help:
- Lower cholesterol levels by binding to bile acids in the gut
- Excrete excess estrogens by binding estrogen via bile in the gut
- Stabilize blood sugar by slowing glucose absorption
- Feed beneficial gut bacteria (it acts as a prebiotic)
Where to find it
- Legumes (lentils, beans, peas)
- Oats
- Chia seeds
- Flax seeds
- Avocado
- Cooked carrots, turnips and Brussels sprouts
- Barley
- Apples
- Florasophy
Insoluble fiber: The gut mover
What it does
Insoluble fiber does not dissolve in water. Instead, it adds bulk to your stool and helps food move more quickly through the digestive tract. This is key to:
- Prevent constipation
- Promote regularity
- Reduce risk of diverticulosis and hemorrhoids
Where to find it
- Grains
- Nuts and seeds
- Legumes
- All vegetables and fruits
Why you need both
A balanced fiber intake—roughly 40 grams per day for adults—should ideally include both types:
- Soluble fiber supports metabolic health, detox, heart health and the microbiome
- Insoluble fiber supports regular digestion and prevents constipation
Most fiber-rich foods contain both types, but in different proportions. We suggest aiming for 20 grams of each, daily.
A word of caution
If you’re not used to eating much fiber, increase your intake gradually and drink plenty of water. Sudden changes can cause bloating or discomfort as your gut microbiome adjusts.
Bottom line
Most Americans, even those eating primarily whole foods, are often lacking in total fiber intake. However, with a little more attention to this crucial “non-nutrient,” the research is clear: You will have better health today and in the future. Soluble and insoluble fiber play unique and essential roles in your health.
Eating a variety of whole plant foods ensures you get a good mix of both—keeping your digestion on track, your blood sugar stable, and your gut bacteria happy. Adding just 3 teaspoons of Florasophy to your daily routine will get you about 25% of the way towards your soluble fiber goals and can make a world of difference in your well-being. To jump start your fiber boost, check out our delicious high-fiber recipes here.
About Megan Barnett, MS, CNS
Megan Barnett, MS, CNS is a clinical nutritionist, research writer, public speaker and educator with over ten years in the field of nutrition science and functional medicine. She co-owns BioLounge, a functional medicine clinic in Portland, Oregon, and she is the co-founder and product developer of Florasophy organic soluble fiber blends. She sits on the board of directors for the American Nutrition Association where she supports the credentialing and professional development of her colleagues while providing leadership in the treatment and prevention of disease using evidence-based nutrition science.