Digestion is the process of breaking down food into nutrients that can be absorbed by the body. Some foods are easier to digest than others. The hardest foods to digest are those that are high in fiber, fat, or complex carbs that the body has trouble breaking down.
Why is digestibility important?
How easily a food can be digested affects how many nutrients you absorb from it. Foods that are difficult to digest may cause unwanted symptoms like gas, bloating, diarrhea, constipation, cramping, and abdominal pain. If a food can’t be properly broken down, the nutrients remain trapped inside and pass through your system unused. Over time, eating hard-to-digest foods can contribute to nutritional deficiencies. On the flip side, eating more easy-to-digest foods may help improve gut health and nutrient absorption.
Factors that affect food digestibility
There are a few key factors that determine how easily a food can be digested:
- Fiber content – Fiber provides structure to plants and is resistant to digestion. Soluble fiber absorbs water to become gel-like and slow digestion, while insoluble fiber adds bulk.
- Fat content – Fat takes longer to move through the stomach and be broken down by bile acids and lipase enzymes.
- Protein structure – Globular proteins like eggs are easier to digest than fibrous proteins like collagen.
- Cooking and processing – Raw foods with rigid cell structures are harder to break down than cooked or pureed foods.
- Anti-nutrients – Compounds like phytic acid, tannins, lectins, and oxalates inhibit digestion.
- Individual tolerances – People vary in their ability to produce digestive enzymes needed to process certain foods.
In general, foods that are high in fiber, fat, and connective tissue tend to be the most challenging for our bodies to digest efficiently.
The top 10 hardest foods to digest
Based on their fiber, fat, and protein contents, here are 10 of the most difficult foods to break down and absorb nutrients from:
| Food | Reason for Low Digestibility |
|---|---|
| Nuts and seeds | High in fat and fiber |
| Legumes | Contains anti-nutrients like lectins and phytic acid |
| Cruciferous vegetables | Fibrous structure and raffinose sugars cause gas |
| Whole grains | Packed with insoluble fiber |
| Popcorn | Starchy, low moisture snack with rigid hulls |
| Raw vegetables | Rigid cell walls resist breakdown |
| Beef and steak | Contains tough collagen proteins |
| Corn | Sheath protects starchy kernel from digestion |
| Greasy, fried foods | High in saturated fat that slows stomach emptying |
| Dairy products | May lack lactase enzyme to digest lactose sugars |
Tips for improving digestion of hard-to-digest foods
It’s possible to make these tricky foods a little easier on your digestive system:
- Soak, sprout, or ferment legumes, nuts, seeds, and grains to reduce anti-nutrients.
- Cook vegetables thoroughly to soften fiber and improve nutrient absorption.
- Chew foods very thoroughly to increase surface area for enzyme action.
- Eat fruits and vegetables at the peak of ripeness when pectin is more soluble.
- Choose sprouted and soaked whole grain breads over regular varieties.
- Limit portion sizes of high fat foods to prevent overwhelming bile output.
- Take a digestive enzyme supplement when eating foods with collagen or lactose.
- Avoid combining multiple hard-to-digest foods in one meal.
Food intolerances related to poor digestion
Ongoing issues digesting certain foods may be a sign of an underlying intolerance or sensitivity. Some common food intolerances tied to poor digestion include:
Lactose intolerance
Lactose intolerance is caused by a lack of lactase enzyme in the intestines needed to split lactose into glucose and galactose for absorption. Eating dairy products can lead to bloating, diarrhea, and cramping in lactose malabsorbers. Fermented dairy like yogurt is often better tolerated thanks to its active cultures that help digest lactose.
Fructose malabsorption
Fructose, a naturally occurring sugar in fruits, vegetables, and honey requires efficient absorption by the GLUT5 transporter to be utilized by the body. When this mechanism is impaired, unabsorbed fructose ferments in the gut causing gas, pain, and osmotic diarrhea.
FODMAP intolerance
FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) refer to a group of poorly absorbed short-chain carbs that can trigger IBS symptoms. A low FODMAP diet eliminates foods high in fructose, lactose, polyols, galactans, and fructans.
Gluten sensitivity
Those with celiac disease or non-celiac gluten sensitivity have an immune reaction to gluten proteins found in wheat, barley, and rye. This causes inflammation and damage to the small intestine cells responsible for nutrient absorption.
When to see a doctor
Occasional trouble digesting a meal is normal, but ongoing digestive distress could indicate an underlying condition that requires medical attention. See your doctor if you experience:
- Chronic diarrhea, constipation, or alternating between both
- Unintended weight loss
- Abdominal pain and cramping
- Bloating and gas after meals
- Heartburn
- Nausea and vomiting
- Blood in stool
- Fever along with digestive symptoms
- Ongoing symptoms that disrupt sleep and quality of life
Testing for things like food allergies, intolerance, celiac disease, IBS, inflammatory bowel disease, pancreatitis, gallstones, and gastrointestinal infections can help pinpoint causes of persistent digestive trouble.
The bottom line
Digestion difficulties can happen when eating foods with:
- High amounts of insoluble fiber like whole grains, vegetables, and bran
- Soluble fiber that forms gels like oats, beans, nuts, and flaxseed
- Lots of fat and grease that delays stomach emptying
- Tough connective tissue and collagen proteins in meats
- Complex carbohydrates like corn, potatoes, and quinoa
- Anti-nutrients found in raw legumes, grains, nuts, seeds, and cruciferous vegetables
- Sugars like lactose, fructose, and FODMAPs that rely on specialized enzymes and transporters for absorption
Cooking, fermenting, soaking, sprouting, and proper food combining can help take some of the burden off digestion. But those with ongoing troubles may need to restrict or avoid culprit foods and get testing for potential food intolerances. Paying attention to how your body reacts to different foods can help guide your optimal diet for healthy digestion.