Celery contains both insoluble and soluble fiber, but the majority of its fiber is insoluble. In one cup of chopped raw celery (about 100 grams), you get roughly 1.7 grams of total dietary fiber, with 1.0 gram coming from insoluble fiber and 0.7 grams from soluble fiber. That’s about a 60/40 split favoring the insoluble type.
How Celery’s Fiber Breaks Down
Raw celery has 1.6 grams of total dietary fiber per 100 grams, which makes it a relatively low-fiber food compared to options like broccoli, lentils, or whole grains. Still, the fiber it does contain is predominantly insoluble. Those stringy strands you feel when you bite into a celery stalk are a good visual cue: they’re made of cellulose, hemicellulose, and lignin, the structural components of plant cell walls. Cellulose is the most abundant of these, and lignin (the compound that makes plant tissue rigid) increases as the celery matures, which is why older stalks feel tougher and more fibrous.
The soluble fiber in celery, while a smaller fraction, includes compounds like pectin. Soluble fiber dissolves in water and forms a gel-like substance during digestion, while insoluble fiber stays largely intact as it moves through your digestive tract.
What Insoluble Fiber Does in Your Body
Insoluble fiber works differently than most people assume. Large, coarse particles of insoluble fiber physically stimulate the lining of the large intestine, which triggers the gut wall to secrete water and mucus. This added fluid makes stool softer, bulkier, and easier to pass. The key requirement is that the fiber resists being broken down by gut bacteria and stays relatively intact all the way through the colon.
Celery’s insoluble fiber contributes to this process, though modestly given the small amount per serving. If regularity is your goal, celery works best as one piece of a fiber-rich diet rather than a primary source. For context, adults need between 21 and 38 grams of fiber daily depending on age and sex. A cup of chopped celery covers less than 10% of that.
Cooking Changes the Fiber Ratio
If you cook celery, the balance between its fiber types shifts. Research on vegetables shows that cooking causes a significant decrease in insoluble fiber with a corresponding increase in soluble fiber. Heat and water break down some of the rigid cell wall structures, converting portions of the insoluble fraction into soluble forms. The total fiber doesn’t disappear, but the ratio changes.
This means raw celery gives you more insoluble fiber per bite than cooked celery. If you’re eating celery specifically for its insoluble fiber content, keeping it raw preserves that advantage. Steaming or stir-frying generally retains more of the original fiber structure than boiling, which draws more compounds into the cooking water.
Celery’s Role in a High-Fiber Diet
Celery is extremely low in calories (about 14 per 100 grams), which means it has a high fiber-to-calorie ratio even though the absolute amount of fiber is small. Dietary fiber in general helps reduce energy intake and can suppress appetite, making high-fiber foods useful for weight management. However, you’d need to eat a large volume of celery to get a meaningful dose of fiber from it alone.
A pilot clinical trial using concentrated celery powder (which contains about 10.5 grams of fiber per 100 grams) found that the doses used in supplementation weren’t high enough to produce measurable changes in weight or waist circumference. Researchers noted that previous analyses suggest roughly 16 grams of daily fiber is the threshold for fiber-related weight loss benefits, a number that’s hard to reach through celery alone at typical serving sizes.
Where celery fits well is as a crunchy, hydrating vehicle that adds some insoluble fiber to meals and snacks without adding significant calories. Pairing it with higher-fiber foods like hummus, nut butters, or beans creates a more complete fiber profile. Other vegetables with higher insoluble fiber content per serving include broccoli, green beans, and cauliflower, so mixing these into your diet alongside celery will get you closer to daily recommendations.