Tributyrin Side Effects: Common, Rare and Who Should Skip It

Most people who take tributyrin at supplement doses notice no side effects at all, and when something does show up it is usually mild and digestive: bloating, a slightly unsettled stomach or a change in stool, most often in the first days. More severe nausea and vomiting have only been described in early studies that gave many grams a day, roughly 12 to 140 times one 300 mg capsule.

This guide goes through what the human studies actually measured, which commonly reported effects are evidence and which are anecdote, how tributyrin is regulated, and who should skip it or ask a physician first.

What the human studies found

The very high dose studies (1998 and 2003)

The first human studies of oral tributyrin were early-phase drug studies in adults with advanced cancer, testing whether very large doses could raise butyrate levels in the blood. They did not study gut health and were not designed to show any benefit; their value here is what they show about tolerability at the extreme end.

In the 1998 study, 13 adults took 50 to 400 mg of tributyrin per kilogram of body weight per day, once daily after an overnight fast, for three weeks at a time. For a 70 kg (154 lb) adult, that is about 3.5 to 28 grams a day, or roughly 12 to 93 times one 300 mg capsule. The more significant side effects were nausea, vomiting and muscle aches. Milder ones included diarrhea, constipation, abdominal cramping, headache, lightheadedness, fatigue, rash and an unusual odor.

In the 2003 follow-up, 20 adults took 150 to 200 mg per kilogram three times a day, about 32 to 42 grams a day for a 70 kg adult, or roughly 105 to 140 times one capsule. There were no dose-limiting side effects, and the researchers stopped raising the dose because of how many capsules people had to swallow. One caution applies to both studies: the participants were seriously ill and there was no placebo group, so some symptoms may have had other causes.

The supplement-range studies (2024 and 2025)

A 2024 pilot study randomized 29 healthy adults (24 finished, average age 25) to one week of placebo capsules followed by 21 days of 200 or 400 mg a day of a branded tributyrin complex (100 or 200 mg of tributyrin). Two participants, under 10 percent, reported digestive discomfort. Blood triglycerides rose in the 400 mg group (11 people analyzed); a study this small and short cannot say whether that matters.

A 2025 open-label study gave 17 adults (14 with Parkinson's disease and 3 without) 500 mg of tributyrin three times a day with food, 1,500 mg a day in total, for about 30 days. Seven of the 17 reported mild, short-lived stomach upset or bloating, there were no moderate or serious side effects related to tributyrin, and nobody stopped because of side effects. The study tracked how butyrate moves through the body; it was not designed to show, and does not show, that tributyrin treats any condition.

A larger 2025 trial, funded by the ingredient maker, gave about 600 adults 100 mg of tributyrin a day or placebo for six weeks; side effects such as upset stomach, nausea, stool changes and headache were about as common on placebo (16 versus 14 percent). So the human picture is mostly small studies of three to six weeks: reassuring, but thin. Much of the remaining literature is animal research, such as a 2021 feed study in weaned piglets, which tells us little about how a person will feel.

Tributyrin supplement side effects: evidence vs anecdote

• Measured in people at supplement-range doses: mild stomach upset and bloating, usually early and short-lived.
• Plausible but not clearly linked to supplement doses: looser or firmer stools (about as common on placebo in the 2025 trial), extra gas, and burps with a bitter or buttery taste. Pure tributyrin tastes bitter, and food scientists have described its aroma as cheesy, so a capsule that opens early could leave an off taste. In the 2025 study, the capsules themselves were described as odorless and tasteless.

Is tributyrin safe? How it is regulated

Tributyrin is already used in food. Under 21 CFR 184.1903, the FDA affirmed it as generally recognized as safe (GRAS) as a direct food ingredient, for use as a flavoring agent and adjuvant in foods such as baked goods, beverages, frozen dairy desserts, puddings and soft candy, at levels limited by good manufacturing practice. It is also listed as a flavoring substance by FEMA (number 2223), and in 2002 the joint FAO/WHO expert committee on food additives found no safety concern at current intake levels when used as a flavoring.

What that does not mean: those reviews looked at the small amounts used to flavor food, not a daily capsule taken for weeks or months. They are reassuring about the substance itself, but they are not a supplement safety study, and they do not cover every person or every dose.

Who should skip tributyrin or check with a physician first

• Pregnancy, breastfeeding and children. I could not find any human safety study of tributyrin supplements in these groups, and the 2025 study excluded people who were pregnant or breastfeeding. Skip it unless your physician advises otherwise.
• Diagnosed digestive conditions, such as inflammatory bowel disease, IBS, past bowel surgery or a pancreatic condition. The 2025 study excluded people with significant digestive disease, so there is little data here. Persistent symptoms deserve a diagnosis before a supplement trial.
• Orlistat or prescription pancreatic enzymes. Tributyrin is broken down by the same lipase enzymes that orlistat blocks, and digestion works differently when the pancreas makes too little enzyme. This is reasoning rather than a tested interaction, but it is worth asking.
• GLP-1 medications. These commonly cause nausea, bloating and bowel changes on their own, which makes a new gut supplement harder to judge. Start with one capsule and tell your physician.
• High triglycerides. Given the small 2024 signal, mention tributyrin if your triglycerides are being treated or monitored.
• Prescription medications or a chronic condition. There are no published drug interaction studies for tributyrin, so bring your full supplement list to your physician or pharmacist.

How to lower the odds of side effects

• Take it with a meal. That is what the label directs and what the 2025 study instructed. Our guide on when to take tributyrin explains why.
• Start low. Use one capsule a day for the first week or two before considering two. Our tributyrin dosage guide covers the range.
• Change one thing at a time. Starting tributyrin the same week as a new probiotic or fiber supplement makes it impossible to tell which one is causing a change.
• Judge it fairly. Give it 4 to 8 weeks of consistent use, as described in our honest tributyrin timeline.

If you came here because sodium butyrate did not agree with you, our post on sodium butyrate side effects explains how the two forms differ.

How Vita Bloom fits

Our Tributyrin provides 300 mg of active tributyrin in each vegetable cellulose capsule (550 mg of 55 percent tributyrin). The label directs one capsule daily with food, up to two a day, which keeps you at 300 to 600 mg, far below the amounts used in the early high-dose studies. It is odorless, vegan and gluten-free, made in the USA in a GMP-certified facility and third-party tested.

Frequently asked questions

What are the side effects of tributyrin?

At supplement doses, mild bloating or stomach upset, usually in the first days. Severe nausea and vomiting have been described only at doses of many grams a day.

Is tributyrin safe?

The FDA affirms tributyrin as GRAS for use as a food flavoring, and human studies at 100 to 1,500 mg a day found it well tolerated for three to six weeks. Long-term data is limited, so check with your physician if you are pregnant, take medication or have a medical condition.

Can tributyrin cause diarrhea or constipation?

Both were reported as mild effects in a 1998 study at very high doses. At 100 mg a day, one 2025 trial found them about as common on placebo. Taking it with food and starting at one capsule is the usual approach.

Does tributyrin cause gas or bloating?

Bloating or mild stomach upset is the most reported effect in human studies, and it was mild and short-lived. If it does not settle after the first week or so, stop and speak with your physician.

Is tributyrin safe during pregnancy?

I could not find any human safety study of tributyrin supplements in pregnancy or breastfeeding, so skip it unless your physician advises otherwise.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.