Skin problems and gut issues have a long history of connection. It is well known that one symptom of food allergies are hives. During your adolescent years, you also probably heard a lot of advice on what foods to eat to prevent acne breakouts, even if the advice was not always valid. More and more studies are coming out demonstrating a strong association between skin disorders and gut health, leading many to determine there is a gut-skin axis. Could keeping your gut healthy be the key to having flawless, radiant skin? Let's find out.

The Gut-Skin Axis: What Is It?

The gut and the skin have much in common, which contributes to the gut-skin axis. Both the gut and the skin play key roles as defenders against pathogens invading from the outside environment. Additionally, they are large players in the neuroendocrine messaging system, as they have nerves that send and receive signals from the brain with the ability to send messages to other parts of the body.

Another similarity between the two is that the skin has its own microbiome that is just as important to health as that of the gut microbiome. Although it has not yet been studied as in depth as the gut microbiome, studies have found it to be one of the most diverse microbiomes in the body. The microbiota provides protection through acting as a barrier against potential issues. It is essential to have a good balance between the commensal and pathogenic bacteria, and dysbiosis has the potential to contribute to skin disorders and diseases, just as in the gut. These similarities also lead to many connections between disorders of the gut and skin.

The brain has a role to play as well, making many call it the gut-brain-skin axis. In this theory, anxiety and stress lead to intestinal permeability and dysbiosis in the gut. This, in turn, leads to inflammation that contributes to skin inflammation.

The gut and skin interact, each one affecting the other through several pathways, especially the microbiome and its metabolites. Because they can interact, they also have the ability to influence one another's health, with the gut having a greater impact on skin health. This creates the gut-brain axis. As such, your health is highly dependent upon the health of your skin and gut.

The Connection Between Gut Disorders and Skin Disorders

There are many skin disorders that are more common in those with gut issues and vice versa. For example, rosacea has an association with SIBO (small intestine bacteria overgrowth). In one study, there was a higher number of patients with rosacea who tested positive for SIBO than the group without the skin disease. The researchers randomly assigned the patients with a positive SIBO breath test to either take a placebo or rifaximin (an antibiotic) therapy at 1200 mg/day for 10 days to clear the SIBO. Some patients also underwent the therapy despite having a negative breath test. Upon treating the SIBO, 20 of 28 patients had a clearance of cutaneous lesions, while there was either no change or worsening of the lesions in those who were on the placebo. The researchers then switched the patients taking the placebo to the antibiotic treatment, resulting in 17 of the 20 experiencing an eradication of SIBO. Out of that group, 15 also saw a complete resolution of their rosacea. The improvement of rosacea lasted for at least 9 months. There was no change in rosacea in 13 of the 16 patients who tested negative for SIBO. This study demonstrates that not only is there a strong association between SIBO and rosacea, but that treating the SIBO improved rosacea.

Inflammatory bowel disease (IBD) is also associated with a higher risk of developing an inflammatory skin condition, such as psoriasis, atopic dermatitis, and rosacea. In one population-based cross-sectional study, the researchers found a significant association between IBD disorders, including both ulcerative colitis and Crohn's disease, and inflammatory skin conditions. The same association was not found for autoimmune skin conditions, such as alopecia and vitiligo. In another study, the incident of IBD was higher in patients with rosacea compared to those without, with an adjusted hazard ratio of 1.94(95% CI 1.04 - 3.63 p= .04).

This relationship is most likely due to the chronic inflammatory diseases of IBD and psoriasis having similar pathogenic pathways. This might begin in the gut microbiome. In IBD, it has been shown that there is a decrease in Saccharomyces cerevisiae (baker's yeast, known to support the immune system). A study found that in patients with psoriasis, there was a lower level of S. cerevisiae. Through using dimethylfumarate, a common treatment for psoriasis, they were able to increase the level of this yeast to bring the numbers to a similar abundance to the healthy controls.

Celiac disease is also associated with skin problems, and one subset of the disease, dermatitis herpetiformis, presents with skin problems rather than gut issues. There is also a strong association between gut health and acne, with several studies linking dysbiosis to the development of acne. These are just a few examples of ways in which the health of the gut and the skin are closely related.

Probiotics for Skin Care

Because of the high association between gut disorders, especially dysbiosis, and skin problems, researchers have looked into the potential of probiotics for treating skin conditions. Several studies have found relief for certain skin conditions with taking probiotics orally, altering the gut microbiome rather than that of the skin. For example, Lactobacillus rhamnosus GG has been found to reduce the severity of atopic dermatitis in those with IgE-sensitive reactions, while Lactobacillus rhamnosus TB helps with eczema.

One probiotic strain, Lactobacillus rhamnosus SP1, provides benefits for those suffering from acne. In a double-blinded, placebo-controlled study, 20 adult subjects who had acne consumed either LSP1 at 3x109 CFU/day (75 mg/day) in a liquid formula for 12 weeks, while the control group consumed a liquid without the probiotics. The researchers took skin biopsies prior to the treatment and at the end of the 12 weeks to look for insulin-like growth factor 1 (IGF1) and forkhead box protein O1 (FOXO1) gene expression. There was a 32 percent reduction in acne in the treated group, and they also had a 65 percent increase in the IGF1 and FOXO1. The placebo group experienced no changes.

Probiotics also have the potential to protect against sun-induced damage. In one mice study, researchers found consuming probiotics provided protection from UV damage. In this study, one group of hairless mice were given oral administrated live Bifidobacterium breve strain Yakult for nine days, and another group consumed fermented milk containing the strain for 14 days. During the final four days of the study, the mice of both groups were irradiated using UV light for each day. Then, after a period of 24 hours, the skin was evaluated to determine elasticity, appearance, and interleukin-1beta levels (a marker for inflammation). The researchers found that there was a significant level of prevention through consuming the probiotics with both groups compared to a control group.

Another study found that lipoteichoic acids, which are in the cell wall of lactobacilli and have immunomodulatory properties, help mitigate the UV damage that leads to skin cancer. In a study using LTA from Lactobacillus rhamnosus GG, the researchers treated mice with either a chronic irradiation with daily treatments for 20 days and long term where during 34 weeks the mice underwent irradiation three times per week. In the mice treated with LTA, the T-cells had higher levels of T-cells, including helper, and cytotoxic, as well as higher levels of interferon-y. There was also a delay in growth of tumors.

Studies have also found a connection between dry skin problems and abnormal bowel movements. Phenols, which are toxic metabolites from certain bacteria that point to disturbances in the gut. These phenols have the potential to disrupt the differentiation of keratinocytes, which are cells in the skin. Consuming probiotics and GOS, a specific type of prebiotics, led to less phenol and better skin condition, including less dryness in the skin.

Certain probiotics also help with the general health of the skin. For example, consumption of the probiotics strain Lactobacillus paracasei NCC2461 has been found to reinforce the skin barrier function, as well as modulating the skin's immune system and reducing sensitivity. This helps to maintain homeostasis for healthier skin. Additionally, Bifidobacterium longum sp has helped to strengthen the barrier and decrease sensitivity, while kefir with probiotics assists with wound healing.

Treating the Gut for Radiant Skin

Keep your Gut Healthy: the 5 R's

Whether you have a skin disorder like rosacea or eczema or simply want to prevent skin cancer and maintain a youthful appearance, it is beneficial to look to your gut. Dysbiosis or other gut problems might be the cause of the issue–or it might simply exacerbate it.

In functional medicine, we have a standard gut protocol known as the 4 Rs: remove, replace, reinoculate, and repair. It sometimes also includes a fifth R: rebalance. Let's look at each one a little closer.

As the word implies, remove means to take away anything that might be contributing to an unhealthy gut. This might include stress, pathogenic microbes, environmental toxins, or food allergens. One of the most common treatments for this stage of the 4 Rs is the elimination diet. This diet removes all of the most common foods that trigger inflammation and gut reactions for a period of time and then reintroduces them to determine what might be the cause of the issue. For some people, the remove stage might also include protocols to eradicate any pathogenic species residing in the colon or the small intestine contributing to dysbiosis or SIBO respectively.

Proper digestion and subsequent absorption require digestive enzymes, hydrochloric acid, and bile acids. In the replace step, these are supplemented, as needed, depending on the situation.

Reinoculate is the step when good bacteria are reintroduced into the gut, typically through taking a strong probiotic. It is beneficial to also consume a diet high in fiber, and you might choose to supplement with prebiotics, which are non-digestible fibers known to fuel the commensal bacteria in the gut and further mitigate the building of a healthy microbiome.

In the repair stage, vitamins, minerals, and other nutrients are introduced to assist in repairing any damage to the gut, including any inflammation or leaky gut. This typically includes zinc, antioxidants, fish oil, and glutamine, an amino acid that is the gut lining's major fuel source.

The final stage, rebalance, goes beyond just diet; it looks at your overall lifestyle to determine if there are negative aspects affecting the gut, such as lack of sleep or excessive stress. Modifications are made to create a lifestyle pattern supportive of a healthy gut.

As discussed above, healing any inflammation or disorders of the gut can have a significant impact on the health of the skin. Removing triggers like allergenic food can also mitigate skin reactions. A healthy microbiome also provides metabolites and other benefits to alleviate skin problems. Therefore, following the 5 Rs is a great first step to balancing the gut-skin axis.

Foods to Eat for Radiant Skin

There is one more action you can take to maintain a healthy gut-skin axis beyond the 5 Rs: consuming the right foods, herbs, and nutrients to support not just gut health but also skin health. Nutrient deficiencies often manifest themselves through the skin and sometimes cause skin disorders. Of course, you will need to have a healthy gut ready to absorb these healthy nutrients to benefit from this, which is why it is key to start with the 5 Rs. If you have an issue with your gut that affects absorption, such as celiac disease or SIBO, then you might become deficient in some key nutrients, requiring supplementation.

The main vitamins necessary for skin health include vitamin A, C, E, and D. Vitamins C and E have the potential to act as antioxidants to fight against UV damage and other oxidative stress in the skin, which can contribute to aging. Carotenoids and omega-3 fatty acids are also essential for skin health, and they not only protect against aging but also provide benefit to the skin's immune response. Vitamin D helps keep skin hydrated to prevent dry skin. In one study, women with more wrinkles had lower intakes of protein, phosphorous, potassium, vitamin A, and vitamin C than those without. Those with dry skin had lower levels of vitamin C and linoleic acid. Additionally, certain key minerals aid in skin health, namely zinc, selenium, and copper. Many of these also provide antioxidant properties as well as elements in the structure of the skin. For example, copper plays a role in maturing collagen and melanin synthesis.

In addition to micronutrients, phytonutrients have been shown to be beneficial in health. Antioxidants are one of the key contributors to fighting aging skin and other issues. Pollution, UV rays, and other environmental toxins create significant reactive oxidant species, which can lead to wrinkles, sagging skin, discoloration, and other signs of aging, not to mention skin cancer. Consuming adequate antioxidants to counter the oxidative stress is essential. However, it requires more than just isolated supplements of specific antioxidants. It is best to consume antioxidants in their natural state in plant foods. As an added bonus, it also provides numerous nutrients and phytonutrients to act in synergy that also have vitamins, nutrients, and in some cases, anti-inflammatory benefits.

A healthy diet rich in colorful fruits and vegetables will go a long way to providing the nutrients necessary for radiant skin. Add in some omega-3 fatty acids and vitamin D rich foods, and you will nourish your skin from the inside out, especially if you maintain a healthy gut-skin axis. Don't forget to hydrate as well!

What is more, the same diet will also help you maintain a healthy gut, especially if you avoid any foods that might be inflammatory to you. This will keep both the gut and the skin healthy so that they can continue to protect your body from the dangers of the outside world.