Gut Health
Butyrate Supplement Side Effects: What Human Trials Found
Nausea, gas, the smell, sodium, cholesterol, and the blood pressure finding most labels leave out. What was measured in people, and what nobody has tested yet.
Butyrate supplement side effects are mild for most people in the trials we have: a little nausea, a headache in the first weeks, and a strong smell when you open the bottle. In placebo controlled studies, stomach symptoms were no more common on butyrate than on a dummy pill. There is one real caution. In a 2024 trial of adults with high blood pressure, oral sodium butyrate raised blood pressure instead of lowering it. So the honest summary is that butyrate looks gentle on the gut and deserves more care if your blood pressure runs high.
This guide goes through each side effect people ask about, what was measured in people, and what nobody has measured yet. If you are still deciding which kind to buy, start with our comparison of which form of butyrate actually reaches your blood.
A quick word on what butyrate is
Butyrate is a short chain fatty acid. Your gut bacteria make it when they ferment fiber, and it is the main fuel for the cells that line your colon (Hajjar, 2021). The supplement version is the same molecule, usually bound to sodium, calcium, magnesium, or an amino acid so it can go in a capsule or powder. It is sold as a postbiotic, and we explain how postbiotics differ from probiotics and prebiotics in a separate guide.
One thing to know before the list. The human trials on butyrate are small, usually 20 to 70 people, and short, usually 4 to 12 weeks. Small trials can miss uncommon problems. A clean result in 50 people is reassuring. It is not a promise.
The most common butyrate side effects
Nausea and headache
These are the two side effects that actually show up in trial reports. In a six month trial of 54 children with obesity, two children in the butyrate group had mild nausea and headache during the first month, and both passed on their own (Coppola, 2022). That is the usual pattern with butyrate: if something happens, it tends to be early and short.
Gas, bloating, and loose stools
Labels and product reviews often mention gas, bloating, or looser stools in the first days. The trials are calmer than the reviews. In a 12 week study, 53 adults took 3.6 grams of sodium butyrate a day or a placebo, and the researchers tracked gut symptoms on purpose. They found no difference between the two groups (Tougaard, 2022). In another trial, 72 children and teenagers took 300 mg a day or a placebo for 12 weeks, and none of them reported a side effect (Pietrzak, 2022).
That does not mean your gut will feel nothing. It means that across a group, butyrate did not cause more stomach trouble than a dummy pill did. If you are prone to bloating already, our guide to what actually helps with bloating is worth a read before you add anything new.
The smell
Butyric acid is the compound that gives rancid butter and aged parmesan their smell. Open a bottle of sodium butyrate and you will notice it. This is unpleasant, not harmful, and it is not a sign the product has gone bad. Coated capsules hide it better than powders. Some people get butter flavored burps for an hour or so after a dose. Taking it with food helps.
Does butyrate raise blood pressure?
This is the side effect worth taking seriously, and the evidence points in two directions.
In animal studies butyrate lowers blood pressure, which is why researchers expected it to help people. So a team in Amsterdam tested it. Twenty-three adults with high blood pressure, a little over half of them women and about 59 years old on average, stopped their blood pressure medicine under supervision. They then took sodium butyrate capsules or a placebo for four weeks. Daytime systolic pressure, the top number, rose by about 9.6 points in the butyrate group compared with placebo. The bottom number rose by about 5 points (Verhaar, 2024).
Could that be the sodium? The researchers thought of that. The placebo capsules carried a matching amount of salt, so sodium alone does not explain the rise. The authors said their findings call for caution in future butyrate studies.
A second trial points the other way, weakly. Forty-two people with type 2 diabetes took sodium butyrate or placebo for six weeks. Blood pressure dropped within the butyrate group, but the difference between butyrate and placebo was not statistically significant (Khosravi, 2022). In plain words, that drop could be chance.
So what do we know? One small, careful trial in people with high blood pressure found a rise. One small trial in people with diabetes found no clear change. Nobody has tested this in healthy women with normal blood pressure. If your blood pressure is high, borderline, or treated with medicine, talk to your doctor before you take butyrate, and check your numbers at home for the first few weeks if you do.
Sodium butyrate side effects: the salt question
Sodium butyrate is about one fifth sodium by weight. At the 300 to 600 mg doses on most labels, that is 60 to 125 mg of sodium, which is small. At the 4 gram doses used in some research (Bouter, 2018), it is over 800 mg of sodium a day, more than a third of the 2,300 mg daily limit. If you are watching your salt, read the label for the sodium line, or choose a calcium and magnesium butyrate, which carries no sodium.
Butyrate and cholesterol
In the diabetes trial above, total cholesterol and LDL cholesterol went up from where they started in the butyrate group. The difference from the placebo group was not statistically significant, so this is a signal to watch, not a proven effect (Khosravi, 2022). It was six weeks in 42 people. If you take butyrate for months and have your cholesterol checked anyway, it is reasonable to compare the before and after.
Is it safe to take butyrate every day?
Every trial we cite used a daily dose, for 4 weeks up to 6 months, and none reported a serious problem from the supplement. That is the extent of what we know. There are no long trials running a year or more. Daily use for a few months at label doses looks well tolerated in the people studied so far. Beyond that, nobody has looked.
How much butyrate is too much?
There is no official upper limit for butyrate. Trials have gone as high as 3.6 to 4 grams a day for 4 to 12 weeks without a rise in gut symptoms over placebo (Tougaard, 2022; Bouter, 2018). Most products suggest 300 to 1,200 mg a day. More is not clearly better. In the 4 gram trial, blood and stool butyrate did not even rise, and the blood pressure finding above is a good reason not to push the dose on your own.
Who should not take butyrate supplements
- Women who are pregnant or breastfeeding. We found no trials of butyrate supplements in pregnancy or nursing. No data is not the same as safe. Skip it unless your doctor says otherwise.
- Anyone with high or borderline blood pressure, or on blood pressure medicine, without a doctor's input.
- Anyone on a salt restricted diet, for heart or kidney reasons, if the product is sodium butyrate.
- People with inflammatory bowel disease or kidney disease. Butyrate has been studied in these groups, but as an add-on to medical care, not a replacement. Ask your specialist first.
- Children. The pediatric trials were run by medical teams. This is not one to try at home.
Butyrate side effects in women
Most butyrate trials enrolled men, or mixed groups without reporting women separately. The blood pressure trial is the exception, with women making up a little over half the group. Blood pressure tends to climb through perimenopause and after menopause, so that caution matters more in midlife than it did at 30. If you have IBS, which is more common in women, start low. Our guide to why IBS hits women differently and what helps covers the options with more evidence behind them.
How to lower your odds of side effects
- Start with the lowest dose on the label for the first week or two.
- Take it with food. It is easier on the stomach and cuts down on the burps.
- Choose a coated capsule if the smell bothers you.
- Check your blood pressure before you start and again after two to four weeks.
- Stop if nausea or headaches last more than a couple of weeks.
The other option has no side effect list worth worrying about: feed the bacteria that make butyrate for you. Oats, beans, lentils, and cooked then cooled potatoes or rice all help. Our guide to how much fiber women need and where to get it is the place to start.
The bottom line
Butyrate supplement side effects are usually mild and short lived: some nausea or a headache early on, and a smell you will not forget. Placebo controlled trials did not find more gut symptoms on butyrate than on a dummy pill. The one finding to respect is the 2024 trial where sodium butyrate raised blood pressure in adults who already had high blood pressure. If that is you, talk to your doctor first. If you are pregnant or breastfeeding, wait, because nobody has tested it. For everyone else, start low, take it with food, and give it a few weeks. More on this in our gut health coverage.
This is general information, not medical advice. Talk to your doctor before starting a butyrate supplement, especially if you have high blood pressure, are pregnant, or take other medicines. Research cited was retrieved from PubMed.
References
- Verhaar BJH, Wijdeveld M, Wortelboer K, et al. Effects of oral butyrate on blood pressure in patients with hypertension: a randomized, placebo-controlled trial. Hypertension. 2024;81(10):2124-2136. PMID: 39034917
- Tougaard NH, Frimodt-Møller M, Salmenkari H, et al. Effects of butyrate supplementation on inflammation and kidney parameters in type 1 diabetes: a randomized, double-blind, placebo-controlled trial. Journal of Clinical Medicine. 2022;11(13):3573. PMID: 35806857
- Coppola S, Nocerino R, Paparo L, et al. Therapeutic effects of butyrate on pediatric obesity: a randomized clinical trial. JAMA Network Open. 2022;5(12):e2244912. PMID: 36469320
- Pietrzak A, Banasiuk M, Szczepanik M, et al. Sodium butyrate effectiveness in children and adolescents with newly diagnosed inflammatory bowel diseases: randomized placebo-controlled multicenter trial. Nutrients. 2022;14(16):3283. PMID: 36014789
- Khosravi Z, Hadi A, Tutunchi H, et al. The effects of butyrate supplementation on glycemic control, lipid profile, blood pressure, nitric oxide level and glutathione peroxidase activity in type 2 diabetic patients: a randomized triple-blind, placebo-controlled trial. Clinical Nutrition ESPEN. 2022;49:79-85. PMID: 35623879
- Bouter KEC, Bakker GJ, Levin E, et al. Differential metabolic effects of oral butyrate treatment in lean versus metabolic syndrome subjects. Clinical and Translational Gastroenterology. 2018;9(5):155. PMID: 29799027
- Hajjar R, Richard CS, Santos MM. The role of butyrate in surgical and oncological outcomes in colorectal cancer. American Journal of Physiology. Gastrointestinal and Liver Physiology. 2021;320(4):G601-G608. PMID: 33404375
Common questions
What are the side effects of butyrate supplements?
In human trials the side effects were mild and uncommon: brief nausea and headache in the first weeks, plus a strong smell from the product itself. In placebo controlled trials, gut symptoms were no more common on butyrate than on placebo. The main caution is blood pressure. One 2024 trial found sodium butyrate raised blood pressure in adults who already had high blood pressure.
Does butyrate raise blood pressure?
Sodium butyrate raised blood pressure in one small trial. Twenty-three adults with high blood pressure took sodium butyrate or placebo for four weeks, and daytime systolic pressure rose about 9.6 points more on butyrate. A separate trial in people with type 2 diabetes found no clear difference from placebo. It has not been tested in healthy women with normal blood pressure. If yours is high or treated, ask your doctor first.
Can butyrate cause gas, bloating, or diarrhea?
Some people report it in the first days, but trials have not confirmed it. In a 12 week trial of 3.6 grams a day, gut symptoms were the same on butyrate and placebo. Starting with a low dose and taking it with food is a sensible way to find out how your own gut responds.
Is it safe to take butyrate every day?
Trials have used daily butyrate for 4 weeks up to 6 months without serious problems from the supplement. There are no trials lasting a year or longer, so long term daily safety has not been studied.
Who should not take butyrate?
Women who are pregnant or breastfeeding, because there are no trials in those groups. People with high blood pressure or on a salt restricted diet should talk to a doctor first, especially with sodium butyrate. People with inflammatory bowel disease or kidney disease should ask their specialist.
Why does my butyrate supplement smell so bad?
Butyric acid is the same compound that gives rancid butter and aged parmesan their smell. The odor is normal and does not mean the product has spoiled. Coated capsules hide it better than powders.
