Many people report back that kefir helps relieve their constipation. It's probably one of the most reported benefits of kefir. And now there's a lot of research to back up those reports.
A study from Turkey gave 20 patients (10 with constipation and 10 with normal bowel transits) kefir twice a day for 4 weeks. 50% of the patients with constipation reported having normal stool after the 4-week trial. Overall though, kefir helped increase stool frequency and consistency and the patients also rated a higher satisfaction.
Interestingly, for the 10 that did not have constipation, it did not change their stool consistency. So even though kefir may act as a mild laxative, it did not cause diarrhea or softer stools for people who have normal bowel movements.
Another small study looked at giving kefir to disabled people. Due to the lack of movement with disabled people, constipation is more common. Out of the 11 people given kefir, 4 of them showed significant improvement in bowel movements. Two of those showed a very large improvement almost immediately after drinking the kefir.
A study on keferin (the good goey stuff on the grains), shows that it too helps alleviate constipation. It was a study on mice, but after ingesting the keferin, they showed improvements in constipation as they had greater fecal moisture.
Does eating the grains help constipation as well?
Currently there are no studies on whether eating the grains helps with constipation. However, there are some anecdotal evidence. A recent comment on our grain eating article said that his brother, who had constipation issues from birth, accidentally ate some grains when he was 4 or 5 and then seemingly miraculously, the next day he did not have any constipation. He continued to eat the grains and essentially had no constipation issues from there. Very fascinating story. There are other similar anecdotal stories out there too.
Can kefir cause constipation?
Typically kefir relieves constipation and does not cause it. However, there are some people out there that report constipation when drinking kefir. Keep in mind that the microbiome is extraordinarily complex and sometimes has the opposite effect with some people.
There are claims that 12 hours of milk kefir fermenting has a mild laxative effect and 36-48 hours can cause constipation. It’s repeated in several places over the internet, but the original study is no where to be found.
However it does make sense to some degree.
In the previous study that came out of Turkey, the researchers believe that a possible reason as to why kefir is effective in reliving constipation is because:
The probiotics lower the pH in the colon by producing lactic acid, acetic acid, and other acids. These effects result in enhanced peristalsis and, subsequently, in decreased colonic transit time.
So according to the researchers, some acid might help peristalsis (digestive movement), but what about too much acid?
One rare study on apple cider vinegar, which is basically acetic acid, shows that the acid actually slowed emptying on people that already had slow digestion. So its reasonable to assume that too much acid may not relieve constipation and may even contribute to it. So perhaps that’s the reason why 36-48 hour ferments may cause constipation in some people. Longer ferments certainly have more acids, but not necessarily more probiotics. And too much acid may slow movement in some people.
What about drinking too much kefir?
It’s also stated that too much kefir can cause constipation. It may be due to the large amount of acids, but it may be also due to the large amounts of protein without any fiber. Drinking large amount of milk seem to have the same kind of issues.
Can Kefir help alleviate chronic diarrhea?
Unfortunately, there’s not much evidence that kefir helps stop diarrhea. Even anecdotal evidence is very slim. It usually doesn't cause diarrhea or make diarrhea worse, but its also not known to reverse diarrhea symptoms.
One study tested to see if kefir would help alleviate diarrhea instigated by antibiotics. Unfortunately it did not have any significant effect. Although it should be noted that the study was done with commercial kefir and not homemade kefir which is a big difference.
Does Kefir help IBS?
In one sense, yes. Kefir will promote better gut health, especially if it manages to propagate within the intestines. Probiotics in general can help alleviate many of the symptoms of IBS.
For some people with IBS, it’s the lactose that causes issues. Kefir is much lower in lactose than regular milk and for some people, that really helps.
On the flip side, kefir is considered fairly high on the FODMAPs. FODMAP are foods that contain sugar that may not be properly absorbing, possibly leading to symptoms for people with IBS.
So, when it comes to IBS, its quite different for every sufferer and people seem to react to kefir in very different ways. What we recommend is just to trust your senses and your body. Start slow and if your body continually reacts to the kefir, try coconut milk kefir or water kefir. Water kefir has similar effects on bowel movements.
Kefir is most effective at alleviating constipation not directly related to IBS. Eating grains may also help people with constipation. Some people who consume kefir experience constipation, but its more rare. If you have normal bowel movements, then the kefir probably won't change much. Nor it kefir likely to improve diarrhea issues, although more research is needed in that area.
What are your experiences with kefir? Has it changed your bowel movement in anyway?