What Do The Different Kinds Of Fiber Do? 30 Foods That Rank Highest
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We’ve talked before about how important fiber is:
Why You’re Probably Not Getting Enough Fiber (And How To Fix It)
And even how it’s arguably the most important dietary factor when it comes to avoiding heart disease:
What Matters Most For Your Heart? Eat More (Of This) For Lower Blood Pressure ← Spoiler: it’s fiber
And yes, that’s even when considered alongside other (also laudable) dietary interventions such as lowering intake of sodium, various kinds of saturated fat, and red meat.
So, what should we know about fiber, aside from “aim to get nearer 40g/day instead of the US average 16g/day”?
Soluble vs Insoluble
The first main way that dietary fibers can be categorized is soluble vs insoluble. Part of the difference is obvious, but bear with us, because there’s more to know about each:
- Soluble fiber dissolves (what a surprise) in water and, which part is important, forms a gel. This slows down things going through your intestines, which is important for proper digestion and absorption of nutrients (as well as avoiding diarrhea). Yes, you heard right: getting enough of the right kind of fiber helps you avoid diarrhea.
- Insoluble fiber does not dissolve (how shocking) in water and thus mostly passes through undigested by us (some will actually be digested by gut microbes who subsist on this, and in return for us feeding them daily, they make useful chemicals for us). This kind of fiber is also critical for healthy bowel movements, because without it, constipation can ensue.
Both kinds of fiber improve just about every metric related to blood, including improving triglycerides and improving insulin sensitivity and blood glucose levels. Thus, they help guard against various kinds of cardiovascular disease, diabetes, and metabolic disease in general. Do note that because whatever’s good for your heart/blood is good for your brain (which requires a healthy heart and bloodstream to nourish it and take away waste), likely this also has a knock-on effect against cognitive decline, but we don’t have hard science for that claim so we’re going to leave that last item as a “likely”.
However, one thing’s for sure: if you want a healthy gut, heart, and brain, you need a good balance of soluble and insoluble fibers.
10 of the best for soluble fiber
| Food | Soluble Fiber Type(s) | Soluble Fiber (g per serving) | Insoluble Fiber Type(s) | Insoluble Fiber (g per serving) | Total Fiber (g per serving) |
|---|---|---|---|---|---|
| Kidney beans (1 cup cooked) | Pectin, Resistant Starch | 1.5–2 | Hemicellulose, Cellulose | 6 | 8 |
| Lentils (1 cup cooked) | Pectin, Resistant Starch | 1.5–2 | Cellulose | 6 | 7.5 |
| Barley (1 cup cooked) | Beta-glucan | 3–4 | Hemicellulose | 2 | 6 |
| Brussels sprouts (1 cup cooked) | Pectin | 1–1.5 | Cellulose, Hemicellulose | 2 | 3.5 |
| Oats (1 cup cooked) | Beta-glucan | 2–3 | Cellulose | 1 | 3 |
| Apples (1 medium) | Pectin | 1–2 | Cellulose, Hemicellulose | 2 | 3 |
| Carrots (1 cup raw) | Pectin | 1–1.5 | Cellulose, Hemicellulose | 2 | 3 |
| Citrus fruits (orange, 1 medium) | Pectin | 1–1.5 | Cellulose | 1 | 2.5 |
| Flaxseeds (2 tbsp) | Mucilage, Lignin | 1–1.5 | Cellulose | 1 | 2.5 |
| Psyllium husk (1 tbsp) | Mucilage | 3–4 | Trace amounts | 0 | 3–4 |
10 of the best for insoluble fiber
| Food | Soluble Fiber Type(s) | Soluble Fiber (g per serving) | Insoluble Fiber Type(s) | Insoluble Fiber (g per serving) | Total Fiber (g per serving) |
|---|---|---|---|---|---|
| Wheat bran (1 cup) | Trace amounts | 0 | Cellulose, Lignin | 6–8 | 6–8 |
| Black beans (1 cup cooked) | Pectin, Resistant Starch | 1.5 | Cellulose | 6 | 7.5 |
| Brown rice (1 cup cooked) | Trace amounts | 0.5 | Hemicellulose, Lignin | 2–3 | 2.5–3.5 |
| Popcorn (3 cups popped) | Trace amounts | 0.5 | Hemicellulose | 3 | 3.5 |
| Broccoli (1 cup cooked) | Pectin | 1 | Cellulose, Hemicellulose | 4 | 5 |
| Green beans (1 cup cooked) | Trace amounts | 0.5 | Cellulose, Hemicellulose | 3 | 3.5 |
| Sweet potatoes (1 cup cooked) | Pectin | 1–1.5 | Cellulose | 3 | 4.5 |
| Whole wheat bread (1 slice) | Trace amounts | 0.5 | Cellulose, Hemicellulose | 1 | 1.5 |
| Pears (1 medium) | Pectin | 1 | Cellulose, Hemicellulose | 4 | 5 |
| Almonds (1 oz) | Trace amounts | 0.5 | Cellulose, Hemicellulose | 2 | 2.5 |
10 of the best for a balance of both
| Food | Soluble Fiber Type(s) | Soluble Fiber (g per serving) | Insoluble Fiber Type(s) | Insoluble Fiber (g per serving) | Total Fiber (g per serving) |
|---|---|---|---|---|---|
| Raspberries (1 cup) | Pectin | 1 | Cellulose | 5 | 6 |
| Edamame (1 cup cooked) | Pectin | 1 | Cellulose | 5 | 6 |
| Chia seeds (2 tbsp) | Mucilage, Pectin | 2–3 | Lignin, Cellulose | 3 | 5.5 |
| Artichokes (1 medium) | Inulin | 1 | Cellulose, Hemicellulose | 5 | 6 |
| Avocado (1 medium) | Pectin | ~2 | Cellulose | 4 | 6 |
| Black beans (1 cup cooked) | Pectin, Resistant Starch | 1.5 | Cellulose | 6 | 7.5 |
| Quinoa (1 cup cooked) | Pectin, Saponins | 1 | Cellulose, Hemicellulose | 3 | 4 |
| Spinach (1 cup cooked) | Pectin | 0.5 | Cellulose, Lignin | 3 | 3.5 |
| Prunes (1/2 cup) | Pectin, Sorbitol | 2 | Cellulose | 4 | 6 |
| Figs (3 medium) | Pectin | 1 | Cellulose | 2 | 3 |
You’ll notice that the above “balance” is not equal; that’s ok; we need greater quantities of insoluble than soluble anyway, so it is as well that nature provides such.
This is the same kind of balance when we talk about “balanced hormones” (does not mean all hormones are in equal amounts; means they are in the right proportions) or “balanced microbiome” (does not mean that pathogens and friendly bacteria are in equal numbers), etc.
Some notes on the above:
About those fiber types, some of the most important soluble ones to aim for are:
- Beta-glucan: found in oats and barley, it supports heart health.
- Pectin: found in fruits like apples, citrus, and pears, it helps with cholesterol control.
- Inulin: a type of prebiotic fiber found in artichokes.
- Lignin: found in seeds and wheat bran, it has antioxidant properties.
- Resistant starch: found in beans and lentils, it acts as a prebiotic for gut health.
See also: When Is A Fiber Not A Fiber? The Food Additive You Do Want
One fiber to rule them all
Well, not entirely (we still need the others) but there is a best all-rounder:
The Best Kind Of Fiber For Overall Health?
Enjoy!
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