All stool smells, but what you eat, how well you digest it, and the balance of bacteria in your gut determine how much. The most effective way to reduce stool odor is to limit sulfur-rich foods like processed meat, cruciferous vegetables, eggs, and alcohol, while increasing fiber and supporting healthy gut bacteria. Most people who notice a change in how bad their stool smells can trace it back to something in their diet.
Why Stool Smells in the First Place
Fecal odor comes from chemical byproducts created when bacteria in your colon break down the food your small intestine didn’t fully absorb. The main offenders are sulfur-containing compounds, particularly hydrogen sulfide (the “rotten egg” smell), along with a compound called indole. At low concentrations, indole is surprisingly found in flowers and perfumes. At high concentrations, like those in your colon, it smells putrid. Another related compound, skatole, contributes the distinctly fecal quality of the odor.
The more sulfur and protein your gut bacteria have to work with, the more of these compounds they produce. That’s why a heavy steak dinner or a night of drinking tends to produce noticeably worse-smelling stool the next day, while periods of lighter, plant-forward eating often come with milder odor.
Foods That Make Stool Smell Worse
Sulfur is the biggest dietary driver of stool odor. When gut bacteria metabolize dietary sulfur, they produce hydrogen sulfide, which is responsible for that sharp, unmistakable smell. Research from Massachusetts General Hospital has linked a high-sulfur dietary pattern specifically to increased hydrogen sulfide production in the gut. The foods most associated with this pattern include:
- Processed meat: bacon, sausage, deli meats, and hot dogs are particularly high in sulfur-containing preservatives and amino acids
- Red meat: beef, lamb, and pork contain more sulfur-containing amino acids than poultry or fish
- Cruciferous vegetables: broccoli, cauliflower, cabbage, Brussels sprouts, and kale are healthy but naturally high in sulfur compounds
- Eggs: especially the yolks, which are rich in sulfur
- Garlic and onions: packed with sulfur compounds (the same ones that make your eyes water)
- Alcohol: liquor in particular, though beer and wine contribute too
- Artificial sweeteners and low-calorie drinks: sugar alcohols like sorbitol and xylitol ferment aggressively in the colon, producing extra gas and odor
You don’t need to eliminate all of these. Cruciferous vegetables, garlic, and onions are genuinely good for you. But if you’re eating several of these categories heavily every day, dialing back on the processed meat, eggs, and alcohol will likely make the biggest difference.
Foods That Help Reduce Odor
Fiber is the single most helpful nutrient for reducing stool odor. Soluble fiber (found in oats, beans, lentils, apples, and sweet potatoes) feeds beneficial gut bacteria that produce less odor as a byproduct. It also speeds up transit time, meaning food spends less time fermenting in your colon. The longer stool sits in the large intestine, the more time bacteria have to produce those sulfur compounds and indole.
Fruits and fruit juices, legumes, and non-cruciferous vegetables are all associated with lower sulfur metabolism in the gut. A simple shift toward more whole grains, berries, citrus, carrots, and squash, while reducing processed meat and alcohol, can produce a noticeable change within a few days. Staying well-hydrated also helps keep things moving efficiently, which limits fermentation time.
How Gut Bacteria Affect Stool Odor
Your gut microbiome is essentially the factory producing stool odor. Different bacterial species produce different amounts and types of smelly compounds. A gut dominated by sulfur-reducing bacteria will produce more hydrogen sulfide. A healthier, more diverse microbiome tends to produce less.
Probiotics may help shift that balance. Research on people with irritable bowel syndrome found that certain probiotic strains reduced flatulence and bloating, both of which share the same underlying mechanism as stool odor: bacterial fermentation in the colon. The strains with the most evidence for reducing gas include Bifidobacterium breve, Bifidobacterium infantis, Lactobacillus casei, and Lactobacillus plantarum. You can find these in supplement form or in fermented foods like yogurt, kefir, kimchi, and sauerkraut.
Probiotics aren’t a quick fix. It typically takes two to four weeks of consistent use to notice digestive changes, and the effects vary from person to person. But for people whose stool odor is accompanied by bloating, irregular bowel movements, or excess gas, they’re worth trying.
Do Chlorophyll Supplements Work?
Chlorophyll and chlorophyllin supplements are widely marketed as “internal deodorants” on social media, but the evidence doesn’t support the claims. Studies have tested chlorophyllin specifically for reducing urine and stool odor in patients with ostomies and catheters, where odor control matters most. These studies did not show a statistically significant improvement in smell. Despite being used for over 50 years, no significant benefits for odor reduction have been proven. Most of what circulates online about chlorophyll’s deodorizing effects is anecdotal.
Bismuth subsalicylate (the active ingredient in Pepto-Bismol) does bind to hydrogen sulfide in the gut and can reduce stool odor temporarily. It’s the reason your stool turns black after taking it. This is fine for occasional use but isn’t a long-term strategy.
When Foul-Smelling Stool Signals a Problem
Everyone’s stool smells. But a persistent, unusually foul odor, especially combined with other symptoms, can point to a digestive condition worth investigating.
Fat malabsorption is one of the most common causes of exceptionally smelly stool. When your small intestine can’t properly absorb fats, they pass into the colon and produce greasy, runny, light-colored stools that float and smell significantly worse than normal. Unabsorbed carbohydrates cause a similar problem: bacteria in the colon ferment them into gases and short-chain fatty acids, amplifying both odor and bloating.
Conditions that cause malabsorption include celiac disease, chronic pancreatitis, Crohn’s disease, and parasitic infections like giardia. If your stool has changed dramatically in smell, consistency, or color, and those changes persist for more than a couple of weeks, a stool test can measure fat content and check for parasites. Blood tests can reveal nutrient deficiencies and markers for conditions like celiac disease. These are simple, routine tests that can rule out or identify the underlying cause quickly.
The key warning signs to watch for alongside increased odor: stools that are pale, greasy, or float consistently; unintentional weight loss; persistent bloating or cramping; and diarrhea that doesn’t resolve on its own.
A Practical Starting Point
If you want less smelly stool starting this week, the highest-impact changes are straightforward. Cut back on processed meat, eggs, and alcohol for a few days and see what happens. Add a serving or two of high-fiber food like oats, lentils, or berries. Drink more water. These changes alone often produce a noticeable difference within two to three days, since that’s roughly how long it takes food to move through your entire digestive tract.
For a longer-term shift, consider adding a probiotic with Bifidobacterium or Lactobacillus strains, or eating fermented foods regularly. Focus less on eliminating every sulfur-containing food and more on rebalancing your overall diet toward fiber-rich whole foods. Your gut bacteria will adjust, and the odor will follow.