How To Choose a Probiotic?

How To Choose A Probiotic

Health benefits of probiotics are being actively investigated, specifically with regard to the gut microbiome, the collection of microorganisms in the gastrointestinal (GI) tract. However, data suggest a complex relationship between the gut and skin microbiomes, suggesting that probiotic intake may impact the skin in addition to the gut. This article will focus on probiotics for three common skin issues: eczema, acne, and wrinkling.

What Are Probiotics?

Probiotics are live, commensal microorganisms that provide various health benefits when consumed in adequate amounts. As living microorganisms, they utilize undigested substances, such as fiber.  

In addition to probiotic supplements, there are many dietary sources of probiotics including yogurt, sauerkraut, kefir, kimchi, tempeh, miso, and fermented beverages such as kombucha. The functionality of specific probiotics is altered by their survivability both in packaging and as they pass through the GI tract. It is important to follow packaging instructions (i.e., refrigeration if necessary). The FDA does not currently regulate probiotics as it considers them food ingredients and dietary supplements.

Strains

Probiotic strains of the following genera confer health benefits upon consumption: Lactobacillus, Bifidobacterium, Saccharyomyces, Enterococcus, Streptococcus, Pediococcus, Leuconostoc, Bacillus, and Escherichia coli.1 These genera of bacteria are categorized by species, which are further categorized by strain. Distinct strains can have specific effects on the host and may be indicated for varied purposes. 

Doses

Probiotics are usually dosed in colony forming units (CFUs). Products can vary by amount of CFUs, and thus it is important to refer to the nutritional information and package instructions. Common doses for children typically range from 5-10 billion CFUs, whereas doses for adults are greater, ranging from 10-20 billion CFUs.²

What Do Probiotics Do?

The mechanisms by which probiotics influence health are complex and depend on their mechanism of action and effects on microbiome diversity and composition. Probiotics are hypothesized to exert their effects by altering the gut microbial composition directly and indirectly, such as via bacterial or host biproducts. Some of the therapeutic effects of probiotics include:⁴

• Immune system regulation

• Anti-inflammatory actions

• Alteration in bacterial adhesion sites in the intestinal tract and vagina

• Antagonism against bad bacteria and viruses

• Intestinal barrier repair

• Production of beneficial compounds including vitamins and short chain fatty acids

Probiotics for Eczema

The skin microbiome plays a central role in the pathogenesis of atopic dermatitis, commonly known as eczema. Atopic dermatitis flares are characterized by skin microbial dysbiosis, with over-colonization of Staphylococcus aureus at the extent of Staphylococcus epidermidis.⁵ In addition to decreased barrier function of the skin, children with atopic dermatitis also have decreased barrier function of the intestinal mucosa, which permits the transfer of foreign organisms into the body.⁶  

Multiple studies evaluated the use of probiotics for both prevention and treatment of eczema. A meta-analysis found that probiotic consumption in children prevented the development of atopic dermatitis in the general population as well as those at high risk for allergies.⁷ Studies involving both pregnant women and infants have depicted similar protective benefits.^7-10

Other findings have examined probiotics as treatment for atopic dermatitis. Probiotics reduce severity, itching, inflammation, and steroid use and improve the overall quality of life in individuals with this atopic dermatitis.^11-14 

Specific probiotics and their associated benefits for atopic dermatitis are listed in Table 1. 

Probiotics For Acne 

Acne is characterized by increased sebum production, inflammation, and colonization by the bacteria Propionibacterium acnes.²² Propionibacterium acnes, a microorganism prevalent on human skin, may mediate inflammatory events contributing to acne development. Topical and oral antibiotics and topical benzoyl peroxide are well-established acne treatments that target Probiobacterium acnes.²³ Oral and topical probiotics for acne may be effective treatments.

In 2010, Al-Ghazzewi and Tester found that four strains of Lactobacilli inhibited the growth of Propionibacterium acnes in vitro, highlighting a potential mechanism of action by which probiotics can mediate P. acnes prevalence.²² Patients with acne treated with oral probiotics had reduced inflammatory acne lesions:

• An Italian study found that individuals who took a dietary probiotic supplementation, specifically Lactobacilli acidophilus and Bifidobacterium bifidum, had greater acne resolution than individuals who did not receive probiotic supplementation.²⁴

• In Korea, researchers found that consuming a Lactobacillus-fermented dairy drink for twelve weeks significantly decreased the total number of acne lesions and amount of oil production²⁴

Topical probiotics appear to directly inhibit Propiobacterium acnes through the production of antibacterial proteins.²⁴ A 2020 review of acne and microbiota described in-vitro and in-vivo studies on topical probiotics and acne, further providing insight into potential mechanisms of action.²⁵ For example, a significant reduction in inflammatory lesions was observed following application of a lotion containing Enterococcus faecalis SL-5 (compared to a control lotion omitting the CBT SL-5 powder). The authors suggest that the CBT SL-5 lotion inhibited P. acnes and its associated inflammatory mediators.

In general, topical probiotics had immunomodulatory activities via inhibition of cytokine IL-8 in epithelial cells and keratinocytes. Furthermore, specific probiotics, such as Staphylococcus epidermidis, were found to inhibit the overgrowth of P. acnes.²⁵ A list of commonly-used probiotics and their associated benefits for acne are detailed in Table 2. 

In addition to an altered skin microbiome, patients with acne also appear to have an altered gut microbiome. In a study of 114 patients with acne vulgaris, more than half had disruptions in their gut microbial composition.²⁶ Furthermore, acne-prone patients are more likely to have gut dysfunction, such as gastric reflux, abdominal bloating, and constipation.²⁷ However, the authors did not specify the proportion of acne patients who had been previously treated with oral antibiotics. This is an important confounding factor, as oral antibiotics can modulate the gastrointestinal microbiome, potentially contributing to gastrointestinal symptoms. 

Probiotics For Wrinkles

Intrinsic factors, including genetics and hormones, as well as environmental factors such as sunlight, trauma, pollution, and toxins contribute to the aging process. These factors can affect the skin’s ability to protect and repair itself. 

The average pH of the natural skin surface is slightly acidic (below 5.0, though sources have reported a broad range from pH 4.0 – 7.0).³¹ Intrinsic and environmental factors affecting the process of aging can potentially raise the pH of our skin.³² This, in turn, can negatively influence resident skin microflora, as acidic skin (pH 4.0-4.5) keeps resident bacteria attached to skin, whereas alkalotic skin (pH 8-9) promotes bacterial dispersal from skin.³¹ The consumption of probiotics, however, can correct skin pH, as some microorganisms generate acidic molecules.³³ 

Ultraviolet radiation (UVR) exposure accelerates the aging process via inflammatory reactions and suppression of immune function of the skin. Ultraviolet radiation promotes the formation of reactive oxygen species, and the resulting imbalance between pro-oxidants and antioxidants can damage lipids, proteins, and DNA.³⁴ Some probiotics generate anti-oxidants capable of neutralizing free radicals that otherwise could damage skin and accelerate aging.³⁵ Other probiotics have anti-inflammatory properties capable of regulating immune function and accelerating the recovery of the skin’s immune system, which together mediate UVR damage.^15,36

Skin hydration is associated with a youthful appearance. Individuals who take probiotics may maintain skin hydration.³⁷

Specific probiotics and their associated benefits for wrinkle prevention are listed in Table 3.

Key Takeaways

• Probiotics are composed of various microorganisms, each with different benefits for the skin

• Probiotics play a role in immune function and inflammatory skin reactions

• Scientific evidence supports the use of probiotics for skin conditions including eczema, acne, and wrinkles