Why do I have diarrhea after a smoothie?

Smoothies are a popular and delicious way to get more fruits and vegetables into your diet. However, some people experience diarrhea or other digestive issues after drinking a smoothie. There are several potential reasons why smoothies may cause diarrhea.

Ingredients That Can Cause Diarrhea

Certain ingredients commonly found in smoothies can irritate the digestive system and cause diarrhea in some people. These may include:

• Fruits high in fiber and sorbitol like apples, pears, prunes, and cherries
• Vegetables like spinach, kale, lettuce, and broccoli
• Seeds like chia and flaxseeds
• Sweeteners like honey, agave, maple syrup
• Dairy products like milk, yogurt, kefir
• Additives like protein powders, probiotics, supplements

The high fiber and sugar content from the fruits and veggies may overstimulate the digestive system. Insoluble fiber from skins and seeds can also accelerate transit time in the colon. People with irritable bowel syndrome (IBS) may be especially sensitive.

Lactose Intolerance

Using dairy products like milk, yogurt, ice cream, and whey protein in smoothies can cause diarrhea if you are lactose intolerant. People with lactose intolerance lack enough of the enzyme lactase to properly digest the milk sugar lactose.

When undigested lactose reaches the colon, it draws water into the intestines through osmosis leading to diarrhea. Even small amounts of dairy can trigger symptoms in lactose intolerant individuals.

Fructose Malabsorption

Fructose, a natural sugar found in fruits, vegetables, and honey can also cause diarrhea if you have fructose malabsorption. People with this condition lack the transporters needed to absorb fructose efficiently in the small intestine.

Unabsorbed fructose travels to the large intestine where it causes an osmotic effect and pulls water into the colon resulting in loose stools. Common high fructose fruits used in smoothies like apples, mangoes, cherries, and pears should be avoided.

FODMAPs

FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) are short chain carbohydrates that can ferment in the gut causing gas, bloating, and diarrhea especially in people with IBS. Vegetables and fruits high in FODMAPs like:

• Apples
• Pears
• Mangoes
• Watermelon
• Cauliflower
• Onions
• Garlic

Should be limited in a low FODMAP diet. Look for suitable vegetable and fruit replacements when making smoothies.

Artificial Sweeteners

Sugar substitutes like sorbitol, mannitol, xylitol, and maltitol can have laxative effects in some people. These sugar alcohols are poorly absorbed by the body and ferment in the colon leading to gas, bloating, and diarrhea.

Always check ingredient labels for these sweeteners. Sorbitol in particular is commonly added to “sugar-free” smoothies and juices.

Too Much Fiber

Getting extra fiber from whole fruits, vegetables, seeds, and grains can be beneficial but dramatically increasing fiber intake too quickly can overwhelm the digestive system. Gradually ramp up fiber intake over several weeks.

Additionally, some sources are more likely to cause issues like raw veggies, fruit/veggie skins, seeds, bran, and psyllium husk. Cook or peel produce when possible and avoid adding too many seeds.

Probiotics

While probiotics have many benefits, they can initially cause loose stools and diarrhea in some people as the gut microbiome adjusts. Start with lower potency probiotics and slowly increase intake to allow time for adaptation.

Probiotic side effects usually resolve within 1-2 weeks but consult a doctor if severe or persistent diarrhea occurs.

Contaminated Produce

Eating contaminated, raw fruits and vegetables can transmit foodborne pathogens that cause diarrhea. Bacteria like Salmonella, Listeria monocytogenes, and E. coli infect the digestive tract usually via produce contaminated with fecal matter.

Always thoroughly wash produce, especially leafy greens. Prep and store smoothies promptly in the refrigerator. Discard old batches.

When to See a Doctor

Occasional diarrhea after a smoothie likely requires little intervention. However, consult a doctor if you experience:

• Diarrhea lasting more than 3 days
• Severe abdominal pain or cramps
• Blood or mucus in stool
• Fever over 101.5°F (38.6°C)
• Dehydration symptoms like dizziness, dry mouth, and dark urine

These may indicate a more serious condition or infection requiring medical treatment.

Tips to Prevent Smoothie-Induced Diarrhea

You can take steps to avoid or minimize diarrhea after drinking smoothies:

• Gradually increase high fiber ingredients
• Limit/avoid common trigger foods
• Peel and cook produce when possible
• Wash all produce thoroughly before use
• Try probiotics for adaptation
• Use lactose-free milk or lactase if lactose intolerant
• Avoid excess added sweeteners
• Drink smoothies chilled or over ice
• Consume smoothies slowly – don’t “chug”

Tips for Managing Smoothie-Induced Diarrhea

If you develop diarrhea after drinking a smoothie try these remedies:

• Stay hydrated – drink water, broths, diluted juices
• Choose bland foods like bananas, rice, toast, applesauce
• Avoid caffeine, alcohol, spicy or fatty foods
• Take an over-the-counter anti-diarrheal medication if needed
• Rest and avoid strenuous activity
• Manage symptoms until diarrhea resolves in 1-3 days

The Bottom Line

Smoothies can trigger diarrhea due to ingredients like fiber, FODMAPs, lactose, and sugar alcohols. Food poisoning can also cause issues if produce is contaminated. Start with small servings and modify recipes to determine your tolerance. See a doctor for severe, prolonged diarrhea after drinking a smoothie.

With some adjustments and care, smoothies can often be enjoyed even by those with sensitive digestion. Pay attention to your body’s signals and discontinue any ingredients that seem to provoke an unpleasant reaction.