Milk is a dairy product that contains lactose and is exclusive in different species for its nutritional properties, in which it has become a food option in humans, even since we are born our main food substrate is breast milk that contains a large percentage of lactose, protein, fat, carbohydrates, antibodies, among other essential nutrients for the health of the newborn.
During the womb in the 34th week of gestation specifically, the body of the fetus begins to develop enzymes called B-galactosidase produced in the duodenum that is responsible for digesting lactose as soon as feeding with breast milk begins.
After weaning begins, the number of enzymes can decrease over time until adulthood and this can cause some alteration in terms of milk digestion.
It is important to mention that lactose is a disaccharide that is formed by glucose and galactose, that is, it contains sugar, a substrate necessary as a fermentation base to make different probiotic products such as milk kefir.
This enzyme when deficient in the body, the person can develop lactose intolerance and trigger a series of gastrointestinal symptoms such as diarrhea, flatulence, abdominal pain, and nausea, depending on factors such as the number of dairy products consumed, enzyme deficiency, alterations of the intestinal microbiota, among other factors.
For this reason, this has resulted in people with this type of condition limiting or completely eliminating the consumption of this product.
When we talk about lactose intolerance it is defined as the digestive symptoms that derive from the ingestion of lactose. For this reason, different scientific studies have been carried out in animal models of the use of probiotics and their effect on lactose intolerants.
Next, we will describe the consumption of milk kefir and its effect on lactose intolerant people.
Can you consume milk kefir if you are lactose intolerant?
Having given all the necessary context to develop this article in the introduction, we are going to tell you what the use of milk kefir can mean with this topic that is more in vogue than ever, lactose intolerance.
In general, foods rich in probiotics such as milk kefir reduce lactose intolerance, because microorganisms synthesize B-galactosidase generating a process of self-digestion of lactose. 
There are even studies where they indicate that the consumption of probiotics in lactose intolerant individuals is likely to significantly reduce the symptoms of inflammation or bloating, possibly as a result of the presence of lactase from lactic acid-producing bacteria, thus improving the digestion of lactose. 
B-galactosidase is found in the enterocytes of the duodenum of the human being and when dairy products are consumed, it is responsible for hydrolyzing lactose to be absorbed into the intestinal cells, now if this enzyme is deficient in people, the consumption of probiotics is recommended to help the digestion of it. 
To better understand why milk kefir can be consumed in this condition, is that the milk used in this probiotic is fermented by the different microorganisms and to be more specific, exactly by the lactic acid producing bacteria (LAB).
These consume a large amount of lactose that is hydrolyzed to obtain glucose and galactose, and that is finally converted into lactic acid by the BAL, thus, the more the kefir is fermented, the lower its lactose content.
With all this background it can be said that it is totally possible to consume milk kefir when there is a lactose intolerance, moreover, scientific evidence says that it even improves this condition.
How do milk kefir probiotics work in lactose intolerant people?
For an efficiency in lactose metabolism to occur, not only the presence of enzymes but also the ability of the intestinal microbiota to ferment lactose and the response of the large intestine to the effect of the milk substrate intervene.
Following this, the symptoms can vary from one person to another due to the ability of the colonic intestinal flora to ferment this product in which it can be variable, and this explains the different levels of tolerance.
There are scientific publications where they explain that excessive intestinal bacterial growth can alter the absorption of this substrate such as lactose, this is where probiotics act in general. 
In milk kefir as mentioned above contains microorganisms that will help balance the intestinal bacterial flora and effectively decontaminate bacterial overgrowth. 
In the case of Saccharomyces Boulardii, one of the yeasts present in kefir, it has been found that treatment in monotherapy or in combination with metronizazole improves bacterial overgrowth in patients with systemic sclerosis.  
Another important aspect is the presence of lactobacillus and Bifidobacteria that promote the decrease of lactose intolerance by increasing the enzymatic activity of the bacteria, improving the symptoms of diarrhea after taking dairy products and finally promoting intestinal maturation. 
It has been shown in study with animal models that the bacterium Lactococcus acts by stimulating the degradation of B-galactosidase for a better absorption of lactose in the intestinal mucosa and thus improve the symptoms of diarrhea after taking dairy products. 
In short, kefir probiotics will help restore the balance in the bacterial flora that causes the problems of poor digestion of lactose but will also reduce the content of the latter through the process of hydrolysis in fermentation.
Can milk kefir be consumed as monotherapy during lactose intolerance?
There are studies indicating that the use of dairy products with live bacteria was one of the fundamental pillars in the therapy in lactose intolerant people for many years, in which it had the degradative capacity of the milk disaccharide.
During lactose intolerance one of the causes is the alteration of the intestinal microbiota, for this same reason probiotic supplements have been included as a treatment for modulating the intestinal flora, which can alleviate the signs and symptoms of this condition. 
Recent studies have shown that poorly absorbed lactose is eliminated by lactic acid bacteria through the colon, these bacteria that help its elimination are Lactobacillus, Bifidobacterium, and Streptococcus in which they are found in kefir grains.
So if you want to consume milk kefir to improve your symptoms you can do it quietly as monotherapy using the appropriate doses, to obtain the benefits of it after taking a dairy product.
It is suggested to do it through this modality, remembering that lactose intolerance is the situation in which the symptoms are activated after having ingested a dairy product.
After the consumption of milk kefir can improve the digestion of lactose after having consumed a dairy product.
It is important to mention that milk kefir can also be consumed as monotherapy since it contains essential minerals for the body such as vitamin D and calcium.
What would be the recommended dose to consume milk kefir in lactose intolerant?
It is important that the person should educate themselves as to the amount of dairy product they want to consume and the types of products that contain the least amount of lactose in food.
There are several studies that show that a lactose intolerant person can tolerate up to 12g of lactose at a time or 18g during the day, but kefir usually contains about 3.5% lactose, that is, for every 100g of kefir, there is about 3.5g of lactose. 
Now after it was explained that kefir milk does not contain lactose practically because of its fermentation, it is still recommended to consume at an adequate dose to obtain the benefits of this probiotic, it can be started according to different studies with an amount of 180 ml up to 400 ml daily, you can follow it for 12 weeks.
Is it better to consume water kefir instead of milk kefir in lactose intolerant?
Both products are the same, contain the same benefit and microorganisms. The only difference between it is the base or the raw material, for the same reason that any you use will help you improve the digestion of lactose.
Therefore, I could not say that water kefir is better than milk kefir when talking about lactose intolerance, but it is a substitute product that also represents an alternative for those vegans. 
As always, we would like to know if you have any questions regarding the content, since we have given the topic of kefir and lactose intolerance closed so far, until further notice. You can continue to review our content that we have made for you in order to provide you with the highest quality of information possible.