Acne is in part a bacterial disease. Acne bacteria that lives in the skin is thought to often play a role in the inflammation that occurs in acne lesions.1,2 However, what about the bacteria in our gut? Can that have an effect on acne? The tentative answer at this point is "perhaps, especially while taking oral antibiotics or after taking oral antibiotics."
What Is Gut Bacteria?
Gut bacteria, also called the gut microbiota or microbiome, is the bacteria that lives in the gastrointestinal tract (gut). Trillions of bacteria, including many different species, live in the human gut. According to a 2011 article in the Journal of Clinical Gastroenterology:
“The [microbiome] of the human intestine is diverse and abundant. It is estimated there are as many as 1000 different bacterial species and >7000 different strains living in the tract.”3
The bacteria that live in the gut are not harmful. In fact, many of them are beneficial: they provide protection against viruses and harmful bacteria that enter the gut; they contribute to healthy digestion by extracting energy and nutrients from food, and they contribute to healthy immune function. Furthermore, research has shown that disruption of the normal balance of these bacteria is associated with a variety of conditions, such as obesity, inflammatory bowel diseases, and cancer.4
The variety of species and strains of bacteria living in the gut changes throughout life. Gut bacteria change according to various life situations such as age, diet, and certain medications, including antibiotics. Therefore, it is impossible to determine exactly what constitutes a normal gut microbiome. As the same 2011 article in the Journal of Clinical Gastroenterology explains,
“It has not been possible to determine what the [microbiome] is at any given time in a healthy individual that is varying their diet. Furthermore, once medications and drugs are taken for various clinical reasons, such as transient infections, the [microbiome] may be altered for a lengthy period of time.”3
What Is the Relationship Between Gut Bacteria and Acne?
According to a theory called the Gut-Brain-Skin theory, stressful psychological states such as depression, worry, and anxiety can change the composition of the gut microbiome. This change increases the likelihood of a phenomenon called intestinal permeability, which is the ability for substances such as bacteria to pass through the intestinal wall into the bloodstream. As the bacteria move through the body into the bloodstream, the body fights back through creating inflammation.5,6 Acne is at its core an inflammatory disease, so it makes common sense that this might lead to more acne.
Several studies have found increased intestinal permeability in acne patients, lending credence to the Gut-Brain-Skin theory.5
A 2014 article in the journal Beneficial Microbes reviewed two such studies. A century-old 1916 study found that 66% of a group of acne patients showed evidence of bacteria in the bloodstream that are found normally in the stool, suggesting that the intestinal walls in these patients were weak. No one in the control group, consisting of patients without acne, had such bacteria in their bloodstream.
Similarly, a 1983 study found that 65% of acne patients showed evidence of a toxin related to E. coli in the bloodstream, bacteria which normally is present in stool. Again, none of the patients without acne had this toxin in their bloodstream. The authors concluded, “intestinal permeability is a potential issue for many acne patients.”5
How Probiotics Affect Gut Bacteria
Probiotics can have an effect on the population of bacteria living in the gut and help to preserve a normal balance of the gut microbiome. In doing so, scientists believe that they might:
- Help prevent infections
- Help restore the normal balance of gut bacteria, particularly after antibiotic administration, which kills beneficial bacteria along with the targeted harmful bacteria
- Strengthen the immune system7,8
Probiotics can be found in small amounts in certain foods, particularly in fermented foods such as cultured yogurt, tempeh, sauerkraut, and miso, and in larger amounts in manufactured dietary supplements. Interestingly, scientists do not call the beneficial bacteria that naturally live in the body probiotics; they reserve this label for beneficial bacteria that are administered through food and oral and topical supplements.8
There is still much that researchers do not know about probiotics. For one thing, there are many different strains of probiotic bacteria, and each has a different effect on the human body. Probiotic supplements often contain many different strains, and different formulations of probiotic supplements contain different combinations of strains. Furthermore, probiotics can have different effects depending on the condition or disease that they treat. Therefore, we cannot generalize exactly about what probiotics do in the body: different strains and combinations of strains do not confer the same effects. This is an area of ongoing research.
The following is a list of ailments that might be suitable targets for probiotic supplementation, and the proposed mechanisms for how probiotics might alleviate the ailment:
You can see there are many ailments which researchers try to treat using probiotics through different proposed mechanisms. As a 2003 article in the journal Nutrition Reviews explains,
“Much remains to be learned about the role of probiotics in human health. This is clearly an emerging area of science and one requiring confirmation of efficacy and mechanisms of action in controlled studies. However, the cumulative information that does exist has begun to establish a credible hypothesis about the role of probiotics in enhancing human health.”8
The table below shows claims probiotic manufacturers make and the related probiotic product. However, keep in mind that supplement claims are unregulated by the FDA.
Taking Probiotics after Taking Antibiotics
Oral antibiotics can have profound effects on the bacteria living in the gut. Numerous studies have shown that taking antibiotics results in changes in the gut microbiome, including a loss of diversity in bacterial species and strains, that can last anywhere from six months to two years. This is because antibiotics not only kill the particular bacteria that they target but also many strains of bacteria at once.
No matter what condition oral antibiotics treat, they affect the whole body, which includes altering gut bacteria.9 This is why probiotics may be especially beneficial after taking oral antibiotics.
Do Probiotics Help Acne?
Several studies, using a variety of different probiotic strains, have shown positive effects on acne. The studies also show that probiotics may help restore a healthy skin barrier function, and potentially reduced skin oil production, both of which could help reduce acne symptoms. Taking probiotics at the same time as taking oral antibiotics may also help people tolerate the antibiotic better.6,10-12
A 2011 article in the journal, Gut Pathogens, reviewed two such studies. In a 1961 study, scientists gave acne patients a probiotic containing Lactobacillus strains and found that 80% of the patients had at least some improvement in their acne.
A 1987 study found that acne patients who took a probiotic supplement containing L. acidophilus and Bifidobacterium bifidum strains along with an antibiotic not only showed improvement in their acne but also tolerated the antibiotic better.6
A 2011 study in the European Journal of Dermatology found in the lab that a probiotic containing Lactobacillus paracasei reduced skin inflammation and accelerated recovery of the skin’s protective barrier.10
A 2013 study in the Journal of Cutaneous Medicine and Surgery examined the effect of a probiotic containing a combination of Lactobacillus acidophilus, Lactobacillus delbrueckii (subspecies bulgaricus), and Bifidobacterium bifidum on acne. This study divided acne patients into three groups: patients receiving only the probiotic, patients receiving only an antibiotic, and patients receiving both the probiotic and antibiotic. The researchers found that acne improved in all patients after four weeks but that after eight weeks, the patients who had received both the probiotic and antibiotic had the most improvement in their acne and, in addition, tolerated the antibiotic better. They concluded, “Probiotics may be considered a therapeutic option or adjunct for acne vulgaris by providing a synergistic anti-inflammatory effect with systemic antibiotics while also reducing potential adverse events secondary to chronic antibiotic use.”11
As we can see from these studies, there is some evidence that systemic probiotic supplementation might be beneficial in treating acne. According to a 2014 article in the Journal of the American Academy of Dermatology, “One of the potential benefits that systemic probiotics may offer is the reduction of inflammation in acne…Probiotics may also decrease sebum [skin oil] content, which can lead to lower…colonization by P. acnes and therefore decrease inflammation.”12
While most of the time we think of probiotics as something we ingest orally, one study provides some evidence that applying probiotics topically can improve acne.13
A 2009 study in The Journal of Microbiology found that a lotion containing a probiotic called CBT SL-5 performed significantly better than a lotion not containing a probiotic in reducing inflammatory acne lesions.13
The Bottom Line
Maintaining the balance of gut bacteria plays an important role in the health of the body. When this balance is disrupted, it can lead to increased inflammation and possibly to the formation of acne. Probiotics can positively impact the balance of bacteria in the gut, which may, in turn, benefit acne sufferers by (1) reducing inflammation, (2) decreasing sebum production, and (3) helping to lessen some of the negative side effects of antibiotics.
It is best not to look for dramatic improvement in your acne from simply taking probiotics, but, especially if you are on oral antibiotics or have recently finished a course of oral antibiotics, taking probiotics may help.