How do you get enough fiber on AIP diet?

December 17, 2025 •

4 min read

According to the USDA Dietary Guidelines, a high percentage of adults fail to meet their daily fiber intake, a challenge amplified for those following the restrictive Autoimmune Protocol (AIP). On an AIP diet, eliminating common sources like grains, legumes, nuts, and seeds makes it crucial to find alternative sources to support digestive health.

Quick Summary

This guide provides practical strategies for sourcing sufficient fiber on the AIP diet, focusing on incorporating a diverse array of compliant vegetables, fruits, and resistant starches to maintain healthy gut function.

Key Points

Prioritize High-Fiber Vegetables: Focus on non-nightshade options like leafy greens, cruciferous vegetables, root vegetables, and various squashes to build a fiber-rich foundation.
Embrace Compliant Fruits: Incorporate berries, apples, pears, and avocados in moderation for both soluble and insoluble fiber, while being mindful of natural sugar content.
Utilize Resistant Starch: Leverage resistant starches from green-tipped bananas and cooked-and-cooled sweet potatoes or plantains to feed beneficial gut bacteria.
Ensure Adequate Hydration: Drink plenty of water throughout the day to help fiber function effectively and prevent constipation.
Consider Supplements Carefully: If needed, introduce AIP-compliant fiber supplements like psyllium husk slowly and under professional medical guidance.
Focus on Diversity: A wide variety of plant foods provides different fiber types, promoting a more diverse and healthier gut microbiome.
Incorporate Fermented Foods: Include foods like sauerkraut and kimchi (made with compliant ingredients) to support gut diversity with probiotics.

The Fiber Challenge on AIP

The Autoimmune Protocol (AIP) diet is a targeted elimination diet designed to help manage autoimmune symptoms by reducing inflammation and supporting gut healing. While highly effective, its restrictive nature removes several common high-fiber food groups, including grains, legumes, and nuts. This can lead to decreased fiber intake, resulting in digestive issues like constipation and reduced gut microbial diversity.

Fiber is crucial for a healthy digestive system and overall wellness. It comes in two primary forms:

Soluble fiber: Dissolves in water to form a gel-like material, which helps to lower blood sugar and cholesterol, and makes you feel full longer.
Insoluble fiber: Does not dissolve in water and adds bulk to the stool, promoting regular bowel movements and preventing constipation.

On the AIP diet, the focus shifts to sourcing both types of fiber from a wide variety of compliant plant foods to feed beneficial gut bacteria and maintain proper digestive function.

AIP-Compliant High-Fiber Vegetables

Vegetables form the backbone of a high-fiber AIP diet. They are rich in both soluble and insoluble fiber, along with essential vitamins and minerals. The key is to consume a wide variety of these vegetables, both cooked and raw, to get a diverse range of nutrients and fiber types.

Leafy Greens: Spinach, kale, Swiss chard, bok choy, and arugula are excellent sources of insoluble fiber.
Cruciferous Vegetables: Broccoli, cauliflower, and Brussels sprouts offer a significant amount of dietary fiber.
Root Vegetables and Tubers: Sweet potatoes, carrots, parsnips, rutabaga, and beets are great sources of fiber and complex carbohydrates. Sweet potatoes are particularly notable for their fiber content.
Squashes: Winter and summer squashes, including acorn, butternut, and zucchini, provide both soluble and insoluble fiber.
Other Fiber-Rich Veggies: Artichokes, asparagus, okra, and green beans are also compliant and add important bulk.

AIP-Friendly High-Fiber Fruits

While fruits should be consumed in moderation on AIP due to their sugar content, they are a valuable source of fiber. Berries are especially good as they contain less fructose compared to other fruits.

Berries: Raspberries and blackberries are particularly high in fiber. Blueberries and strawberries are also good options.
Avocado: This unique fruit is not only a source of healthy fats but also a great source of fiber.
Apples and Pears: These fruits, especially with the skin on, offer both soluble and insoluble fiber.
Figs and Dates: Dried figs are a potent fiber source. Dates can also be used as a sweetener and fiber boost in moderation.
Plantains: Both green and ripe plantains can contribute fiber and resistant starch.

Harnessing Resistant Starch

Resistant starch is a type of carbohydrate that resists digestion in the small intestine, instead fermenting in the large intestine to feed beneficial gut bacteria. This process produces short-chain fatty acids like butyrate, which are crucial for maintaining the health and integrity of the gut lining.

Green-Tipped Bananas: Unripe bananas contain high levels of resistant starch. They can be blended into smoothies or used to make flour.
Cooked and Cooled Sweet Potatoes/Plantains: Cooking and then cooling starchy foods like sweet potatoes or plantains increases their resistant starch content.
Cassava: This root vegetable is a staple for many on AIP and provides resistant starch.

Strategic Fiber Supplements (If Needed)

In some cases, and under the guidance of a healthcare professional, a fiber supplement might be considered to bridge the gap. It is crucial to choose a compliant supplement and introduce it slowly with plenty of water to prevent digestive upset. Psyllium husk is a common choice, but products with minimal additives are required. Always consult with a doctor or dietitian before adding supplements to your routine.

Fiber Comparison: Common vs. AIP Sources

To highlight the necessary dietary shifts, this table compares typical high-fiber foods with their AIP-compliant alternatives.


Typical High-Fiber Food (Avoid on AIP)	AIP-Compliant Alternative	Fiber Type
Whole Grains (Oats, Brown Rice)	Cassava, Riced Cauliflower, Sweet Potato	Soluble & Insoluble
Legumes (Beans, Lentils, Peas)	Cooked & Cooled Plantains, Artichokes, Broccoli	Soluble & Insoluble
Nuts and Seeds (Almonds, Chia, Flax)	Avocado, Raspberries, Coconut, Olives	Soluble & Insoluble
Corn	Sweet Potato, Butternut Squash, Jicama	Soluble & Insoluble
White Potatoes	Sweet Potatoes, Yams, Parsnips	Primarily Insoluble

Hydration and Lifestyle for Digestive Health

Beyond just food, proper hydration is critical for fiber to function correctly. Fiber absorbs water, and without enough fluid, it can exacerbate constipation rather than relieve it. Ensure you are drinking adequate amounts of water throughout the day. Lifestyle factors also play a significant role. Regular physical activity, even a daily 15-minute walk, and stress management are known to benefit digestive health.

For more information on the benefits of resistant starch for gut health, you can read more from the National Institutes of Health. Resistant Starch: Promise for Improving Human Health

Conclusion

Obtaining sufficient fiber on the AIP diet requires careful planning and a deliberate focus on a variety of compliant plant foods. By prioritizing a diverse range of high-fiber vegetables and fruits, strategically incorporating resistant starches, and maintaining adequate hydration, it is possible to support healthy digestive function and promote gut healing. While the elimination phase removes many traditional fiber sources, the bounty of AIP-compliant alternatives ensures your gut microbiome receives the nourishment it needs.

Frequently Asked Questions

Sweet potatoes, broccoli, Brussels sprouts, acorn squash, and artichokes are among the highest-fiber vegetables allowed on the AIP diet.

AIP-compliant fiber supplements, such as psyllium husk, can be used but should be introduced slowly with a lot of water and preferably under a healthcare provider's guidance. Most of your fiber should come from whole foods.

Constipation on AIP can be caused by the elimination of common high-fiber foods (like grains, nuts, and legumes) and potential dehydration. Increasing your intake of AIP-compliant vegetables and fruits, and drinking more water, can help.

Resistant starch is a prebiotic fiber that feeds beneficial gut bacteria. On AIP, you can get it from sources like unripe green bananas, cooked-and-cooled sweet potatoes, and plantains.

You can add riced cauliflower or sweet potato mash as a side, blend green bananas or berries into smoothies, and fill your plate with a variety of colorful vegetables at every meal.

Yes, both types are important for different aspects of gut health. Soluble fiber helps regulate digestion, while insoluble fiber adds bulk for regular bowel movements. Eating a wide variety of AIP-compliant plant foods will provide both.

Some dried fruits, like figs, are high in fiber and AIP-compliant, but they should be consumed in moderation due to concentrated natural sugars. Always check labels for added sweeteners.