Prebiotic Fiber Sources

Edition: 2017-08-13
(This topic has now has 3 pages of comments. Here’s quick link to recent traffic on page 3.)

Undoctored^®, Wheat Belly^® and Cureality presently recommend 20 grams of prebiotic fiber in the daily diet, mixed and varied, worked up to gradually if starting from a diet previously deficient in such fiber. Because we are apt to get 5 grams or so from foods (esp. on a diet with ample unprocessed vegetables), it is often not necessary to supplement the entire 20 grams.

The following tables (food sources, other sources) summarize various prebiotic dietary fiber sources suggested in Undoctored, Wheat Belly and Cureality publications. It also includes four foods which are program-safe in serving sizes intended principally to provide prebiotic fiber (Jerusalem artichoke, dandelion greens, garlic and leeks). Many other foods contain prebiotic fiber, but are not listed, usually because they provide well less than 5 grams at typical serving sizes.

About Prebiotic Fiber

Prebiotic fibers, aka fermentable fibers, which includes resistant starches and some soluble fibers, are necessary for the gut’s contribution to overall health. Prebiotic fibers are the substrate on which gut flora (microbial life forms) feed, producing a variety of beneficial by-products, principally short-chain fatty acids.

Note that the Fiber figure shown on Nutrition Facts panels is not the same as prebiotic fiber. NF Fiber is the sum of prebiotic and non-fermentable fibers. The prebiotic fiber content of a labelled food won’t exceed the NF Fiber figure, but there’s no way to tell what fraction is fermentable, and how much is just “roughage”. So NF panels are of limited use in planning prebiotic fiber intake; hence, this page (and others similar to it around the web).

Used alone, the word “fiber” may be a warning label. Most “fiber” products on the market are merely junk foods high in non-fermentable roughage fibers. If they make a health claim on the package, they are almost assured to be junk, due to the current FDA standards for such. The FDA has no recognition of, or standards for, prebiotics. Independent testing firm ConsumerLab.com has not yet tested any products intended for use as prebiotics. They currently think that 6 grams/day suffices, so you can see that it’s going to be a while before there are any useful official postures on this topic.

Probiotics and Admonishments

Probiotics are actual gut microbes (most often just bacteria), and are not the topic of this article. The current program recommendation is to start any course of probiotics 3-to-5 days prior to adding prebiotic fibers to the diet.

Where the gut microbe population is thought to be unbalanced (e.g. over-growths), or even have extinctions, a course of a quality high-potency probiotic might be useful.

With or without probiotics, any adverse reaction to adding prebiotics to the diet is suggestive of a dysbiosis. If symptoms are severe, prebiotic fiber may need to be reduced or discontinued until further diagnosis can be completed. Some situations, such as stubborn C.diff, Candida or SIBO may require independent interventions, possibly including antibiotics.

About the Data

The fiber sources are presented as two tables, one natural foods or extracts thereof, and the second commercial mixes or synthetic products. These tables are limited to sources that have been discussed in Undoctored, Wheat Belly or Cureality publications. There are many other fiber sources, but these would require investigation by the user. Keep the glucose meter handy for some of them.

There may be errors in these tables. If so, that just points out how necessary it is to provide this sort of reference information. Most ordinary consumers are not going to undertake anything like the level of investigation and calculation that was required to generate this page. Web sources are incomplete, confusing and materially inconsistent.

The numeric values largely rely on statements made by Dr. Davis in various books, blog posts and forum comments. Other sources will differ, and entirely satisfactory industry standardized testing procedures don’t really exist yet. Determining the prebiotic fiber (or resistant starch) fraction of some foods is fraught with pitfalls. A common method is to freeze-dry and grind prior to analysis. This can easily alter the composition.

Once it is established that the information on the present page is useful, presented in an actionable form, not to mention correct (insofar as anyone can tell), future editions of this table may have in-line scripting added to provide sortable headings.

Legend

Data For 5 Grams Net…	5 grams was selected both as a “starter” dose, and as ¼ of a home-made mix. If using the fiber as ½ of a mix, multiply these numbers by 2. Although not recommended (except for Virtue), if using the fiber as the entire daily 20 grams, multiply by 4.
Fiber Name	This is the food, food ingredient or product name that is, or contains, the prebiotic fiber. Listed alphabetically.
Prebiotic Fraction	The percentage, by weight, of the item that is prebiotic fiber.
Gross Reqd.	How much of the item, in grams, is needed to provide 5 grams of prebiotic fiber. This is merely 5÷Resistance, but aids in quickly building a 20 gram net daily portion. An advisory ∇ is provided if this fiber has emulsifying properties, or would provide excess net carbohydrate exposure at 5 grams net prebiotic fiber. A caution is provided if there is an actual food safety hazard.
Typ. Cost	Typical U.S. internet price for an organic, non-GMO product (bulk/loose where offered), with otherwise safe ingredients where present. Price is per 5 grams of net prebiotic fiber, in U.S. cents(¢). This provides a comparative measure of economy.
Net. Carb.	The amount of net carbohydrate that would result from Gross portion providing 5 grams net prebiotic fiber. This amount needs to be factored into the meal or interval net carbohydrate budget. An advisory ∇ is provided if this fiber would provide excess net carbohydrate exposure at 5 grams net prebiotic fiber. A caution is provided if there is an actual food safety hazard.
Cook	Yes: item may be used in cooked dishes, with no particular temperature limit 212°F: Yes, but with a temperature limit No: item may not be used in cooked dishes (due to starch conversion, do not heat above 135°C/57°C or so) n/a: Not Applicable (food consumed as-is).
Remarks	Important notes about the fiber, such as “Limited:”, which usually means that the item would provide excess net carbs if used to provide 20 grams net prebiotic fiber. See also the link to any further discussion below the table.

Food-Sourced Fibers Table

		Data For 5 Grams Net Prebiotic Fiber Serving
Fiber Name(s)	Prebiotic Fraction	Gross Reqd.	Typ. Cost	Net Carb.	Can  Cook	Remarks
Acacia Fiber	91%	5.5 g∇	17¢	0.5 g (10%)	Yes	∇ Due to emulsifying properties, use acacia powder only as a minority ingredient of a prebiotic mix. 5.5 grams is just under one level tablespoon. More detail
Banana, Unripe	23%	22 g	3¢	0% (?%)	No	One medium Cavendish is about 118 grams gross, so 22 grams would be 1⁄5th of a banana. A whole banana would slightly over the daily 20 grams. Most people don’t seem to have a problem with it. More detail
Chickpeas (garbanzo beans, ceci beans)	16%	31 g	21¢	8.4 g (27%)	Yes	Limited: 20 grams prebiotic fiber from chickpeas would be 33 grams net carb. 5 grams prebiotic fiber (31 grams gross) is about 1⁄3 cup. More detail
Dandelion Greens	24%	8 g	6¢	nil (5%)	Yes	Blanching suggested to reduce bitter taste. More detail
Garlic	18%	29 g	50¢	9 (31%)	Yes	The permeating odor is apt to place a limit on serving size that’s lower than 29 grams. What effect canning, bottling and processing (e.g. Garlique) has on the prebiotic fiber content is an open issue. More detail
Glucomannan as Konjac Root, aka Elephant Root	100% 40%	5.0 g 12.5 g	28¢ 23¢	0 g <1g	Yes Yes	Caution: Pure glucomannan is so highly hygroscopic and expansive that it can be a choking hazard if consumed as dry powder. Root product data is for typical shiritake noodles. More detail
Green Peas	7%	75 g∇	42¢	38 g∇ (50%)	Yes	Limited: primarily due to net carbs. 15 grams net carb would be around 1⁄8 cup of peas (claimed carb & fiber content varies considerably between products). More detail
Hummus	6%	79 g	$2	8 g (10%)	n/a	Watch for adverse ingredients in commercial hummus products. More detail
Inulin as Chicory root	100% 72%	5 g 7 g	20¢ 34¢	0% <1g (18%)	212°F 212°F	Inulin is a mild (safe) sweetener, so adjust any other safe sweeteners amounts in the recipes. Avoid using in highly acidic recipes. More detail
Jerusalem Artichoke	32%	16 g	7¢	2 g (15%)	Yes	Helianthus tuberosus, also called sunchokes. This is a native North American root crop unrelated to the common artichoke. Use fresh, as the fructose polymer converts to simple fructose over time. More detail
Kidney Beans, Black Beans, White Beans	6.3%	79 g∇	70¢	17 g∇ (21%)	Yes	Limited: primarily due to net carbs. 79 grams is just over 1⁄3 cup. However, claims for net carbs vary considerably with these beans. White beans are twice as high in prebiotic fiber vs. kidney beans.  Do not consume raw. More detail
Leeks (Raw)	12%	43 g	27¢	5 g (21%)	No	Cooking reduces the prebiotic fiber value. More detail
Lentils	7%	63 g∇	76¢	19 g∇ (31%)	Yes	Limited: WB recommends no more than ¼ to ½ cup cooked lentils per meal, due to elevated net carbs. More detail
Lima Beans	7%	71 g	78¢	11 g (15%)	Yes	WB recommends no more than ¼ to ½ cup cooked lima beans per meal, due to elevated net carbs. More detail
Unripe Plantains	15%	33 g	10¢	0%	No	A medium plantain is about 179 grams. Some sources claim the prebiotic fiber content is as high as 50%. More detail
Potato (Whole, Raw)	9%	53 g	13¢	0%	No	Use peeled white uncooked potato. Cooking potatos drops the prebiotic fiber content to 3% or less.  Remove green skin. More detail
Potato (Starch, Raw, Unmodified)	50%	15 g	14¢	5 g (67%)	No	Use unmodified raw potato starch, organic non-GMO. More detail

Commercial Fibers & Mixes Table

Discussion

Acacia Fiber

This is made from the gum of any of a number of species of plants and trees from the Mimosoideae subfamily. Products vary in effective net prebiotic fiber content claims. Claims are made that Acacia senegal is superior to Acacia seyal. [ Return to Table(Acacia) ]

Bananas, Unripe

The table data is for green unripe bananas. Ripe banana might as well be candy. A green banana tastes chalky and lacks the distinctive banana flavor. If it tastes like banana, it’s probably at least partially ripe. This also implies that they work best in recipes, like smoothies, that provide ample flavoring and safe sweetness. Do not use green banana in cooked foods - the heating converts resistant starch to available net carb.

A tip for getting bananas green is to seek organic bananas. This inventory turns over slower, so stores seem to be OK with setting it out greener. If you see only ripe/yellow bananas out, ask a store employee if they have any green in back; they often do.

Because we don’t want them to ripen, violate normal banana stewardship and refrigerate them whole, or peel and freeze them. Organic bananas are worth seeking, particularly if you are also experimenting with banana tea, which uses the peels. Non-GMO may not be worth seeking, as all Cavendish bananas are clones to begin with.

Note: do NOT use raw or green banana flour. Products tested to date have been too high in net carbs. The suspicion is that either the drying or milling process (or both) is converting the starch. [ Return to Table(Banana) ]

Chickpea (Garbanzo, Cico Bean)

Due to the net carb content of chickpeas being higher than the prebiotic content, use this bean as only a fraction of the day’s substrate mix.[ Return to Table(Chickpea) ]

Dandelion Greens

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Fructooligosaccharide

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Garlic

{placeholder}[ Return to Table(Garlic) ]

Glucomannan (Konjac)

Some (but not all) “shiritake” noodles and rice mimics are made from konjac (with the others being made from something else, typically soy, for which the information here does not apply).[ Return to Table(Glucomannan/Konjac) ]

Galacto-oligosaccharides

Food sources (such as green peas) tend to be too high in net carbs, making extracted GOS attractive. Other brands considered had adverse additional ingredients (sugars, emulsifiers).[ Return to Table(GOS) ]

Green Peas

The prebiotic fiber is predominantly GOS, for which Wheat Belly recommends a maximum of 5 grams/day, but you’ll hit the meal/interval net carb limit before reaching that. Soaking to reduce phytates, alas, also reduces GOS.[ Return to Table(GreenPea) ]

Hummus

For products that contain no added sugars, both the prebiotic fiber content and the net carb content will be reduced to the fraction of the recipe that is chickpeas. Chickpea content is typically around 40%.[ Return to Table(Hummus) ]

Isomalto-oligosaccharide

Considerations for product selection include the original plant sourcing (typically cassava/tapioca or corn), and geographic sourcing of the raw materials (which can easily be China, confirmed by vague answers to pointed inquiries on this matter).[ Return to Table(IMO) ]

Inulin and Chicory Root

Avoid using inulin in highly acidic recipes, as it can convert the fiber to sugars.

Granulated/roasted chicory used as a coffee substitute or tea may not provide full prebiotic fiber benefit. Depending on the roasting temperature, the net carbohydrate fraction may also be raised (which may not be a big problem in the amount used for beverages).[ Return to Table(Inulin/Chicory) ]

Jerusalem Artichoke

{placeholder}[ Return to Table(Inulin/Chicory) ]

Kidney Beans, Black Beans, White Beans

The prebiotic fiber is predominantly GOS, for which Dr. Davis recommends a maximum of 5 grams/day, but you’ll hit the meal/interval net carb limit before reaching that. Soaking to reduce phytates, alas, also reduces GOS.  Do not consume raw due to Phytohaemagglutinin in uncooked beans.[ Return to Table(Kidney Bean) ]

Leeks (Raw)

{placeholder}[ Return to Table(Kidney Bean) ]

Lentils

The prebiotic fiber is predominantly GOS, for which Wheat Belly recommends a maximum of 5 grams/day, but you’ll hit the meal/interval net carb limit before reaching that. Soaking to reduce phytates, alas, also reduces GOS.[ Return to Table(Lentils) ]

Lima Beans

The prebiotic fiber is predominantly GOS, for which Dr. Davis recommends a maximum of 5 grams/day, but you’ll hit the meal/interval net carb limit before reaching that. Soaking to reduce phytates, alas, also reduces GOS.[ Return to Table(Lima Bean) ]

PGX^®

PolyGlycopleX^® (a-D-glucurono-a-D-manno-β-D-manno-β-D-gluco, a-L-gulurono-β-D mannurono, β-D-gluco-β-D-mannan) is a proprietary blend of natural polysaccharides. But keep looking, they apparently sell the stuff in bulk, so someone wiser may formulate a product lacking disqualifiers.[ Return to Table(PGX) ]

Plantains, Unripe

The table data is for green unripe plantains. Ripe plantains are 30% net carb. Unripe plantains work best in no-cook recipes, like smoothies, that provide ample flavoring and safe sweetness. Do not use green plantain in cooked foods - the heating converts resistant starch to available net carb.

Plantains tend to be easier to get green, but the tips above for bananas apply.

Because we don’t want them to ripen, violate normal plantain stewardship and refrigerate them whole, or peel and freeze them.

Note: do NOT use raw or green plantain flour. It may have the same problem as raw banana flour.[ Return to Table(Plantain) ]

Raw Potato

Some estimates place the prebiotic fiber content as high as 45%, but these may be based on “dry matter”, which is only 20% of the potato mass.

Do not consume raw potato skin, or green potato flesh due to solanine. Do not cook raw potato, as this converts all but 3% or less of the prebiotic fiber to available carbohydrate.

Re-cooling cooked potato (e.g. potato salad) only repolymerizes 1-2% of the starch.[ Return to Table(Potato) ]

Raw Potato Starch

Do not cook raw potato starch, as this converts the prebiotic fiber to available carbohydrate. The program recommends using no more than 1-2 tbsp. (12-24g total, 8-16g prebiotic fiber) at a time due to net carbs.[ Return to Table(RPS) ]

Prebiotin™

{placeholder}[ Return to Table(Prebiotin) ]

Virtue Prebiotic Mixes

The value proposition of these mixes appears to be:
• variety: 3 prebiotic fibers pre-mixed
• net carbs; formulated to be a non-issue
• quality: non-GMO Wheat Belly-compliant ingredients
• dosing unit: ideal 5 gram starter dose
• convenience and flavor
They can be added to a home-made mix of other fibers at higher doses.[ Return to Table(Virtue) ]

Fibers Under Investigation

Apple pectin, Larch AG, Mung bean starch, XOS

Intentionally Omitted Fibers

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Bob Niland [disclosures] [topics]