Acne and Digestive Health
What we eat is important for digestive and cardiovascular health, but did you know that diet relates to the health of another part of the body? Our digestive health has an impact on our skin!
What is the skin microbiome?
The skin is the largest organ of the body.1 One of its primary roles is to protect against invading germs. It does this by acting as a physical barrier and by housing helpful microorganisms.1 Much like the intestinal microbiome, our integumentary (skin) microbiome consists of beneficial bacteria, fungi, and archaea.2 Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes are bacterial phyla commonly found on the skin.2 The diversity of each person’s microbiome depends on how well their skin accommodates these microbes, which comes down to genetic and environmental factors.
Gland secretions play an important part in creating a home for bacteria. Since different areas of skin have different glands (sebaceous, eccrine, apocrine, ceruminous), secretions and consequently microbe populations vary from region to region. Sweaty areas like the armpits, foot soles, and back of the knee have many sweat glands (apocrine and eccrine). This type of environment attracts Staphylococcus and Corynebacterium.1 Sebaceous (or oily) areas like the forehead, back, and sides of the nose have more sebaceous glands, which favours Cutibacterium ().1 Dry areas like the forearm have fewer glands but still a variety of bacteria.1
Microbial composition also changes as we age, typically becoming more diverse over time. In infants, Firmicutesbacteria make up most of the skin microbiome.1 In adolescence, sebaceous (oil) glands are activated and Actinobacteria become more common. This increases microbiota diversity but may also contribute to acne.1
What is acne?
We all know what this is! Acne is an inflammatory condition that often appears as bumps on the surface of the skin.1 Severe forms of acne can lead to scarring. It is one of the most common skin concerns, reported at 9.4% worldwide, with the highest numbers in adolescents and young adults.3 Acne is thought to be caused by colonisation of Cutibacterium acnes (C. acnes) in the skin.1 Higher levels of sebum (oil) production, inflammation, and keratinisation of follicles may create an environment that allows the survival of these bacteria.1
C. acnes make up a significant proportion of microbiota in oily skin.1 This includes areas such as the scalp, face, upper limbs, and trunk, where acne is most prevalent.1 Current research shows C.acnes interact with sebocytes, monocytes, and keratinocytes of the skin. In doing so, these microbes activate chemical messengers that increase the inflammation associated with acne.1
How is acne treated?
Acne can be managed in many ways including antibiotics, antiseptics, and retinoids.1 Antibiotics work to reduce inflammation and suppress C. acnes to clear acne. Benzoyl peroxide is an antiseptic that fights bacteria. Retinoic acid is derived from vitamin A and can help reduce sebum production.
As research continues, new treatment options become available. For example, there is increasing evidence of a connection between acne and digestive health, making diet another important consideration when managing acne!
What is the relationship between different foods and acne?
Certain diets have been studied to determine their impacts on acne. Some research looks at specific foods like dairy, chocolate, carbohydrates, fats, or probiotics. Other research focuses on combinations of foods that make up Western, Mediterranean, ketogenic, vegetarian, or vegan diets.
- Western diet: high in processed foods, dairy, and refined sugars
- Mediterranean diet: low carbohydrate, moderate fish, high oil and vegetables
- Ketogenic diet: low carbohydrate, high fat
- Vegetarian diet: no meat, fish, or poultry
- Vegan diet: no animal products
In developed countries, the Western diet (high carbohydrate and dairy) is common and so is acne.4 Several studies showed that high carbohydrate, dairy, and chocolate intake can worsen skin inflammation.3 One randomized control trial assigned participants to either a low carbohydrate or normal diet, then measured levels of biochemical factors.5The researchers saw lower levels of insulin-like growth factor-1 (IGF-1), a marker for acne, in the low carbohydrate group.5 This suggested that a lower carbohydrate diet may reduce acne.
Interestingly, research shows that different types of fats have varying effects on acne. Dairy consumption (specifically milk) increased insulin and IGF-1 levels in participants, leading investigators to correlate dairy-rich diets with acne.6 In general, increased trans and saturated fat intake were associated with more severe acne.7 On the other hand, diets high in omega-3 fatty acids showed a decrease in acne markers (lower IGF-1 and leukotriene B4).3 Fish, chia seeds, walnuts, and canola oil are all sources of omega-3 fatty acids.8 This indicates that a Mediterranean diet, rich in fish and oil, and may improve acne.
Probiotics may also be helpful in treating acne. Probiotics can eliminate bacteria, improve insulin levels, and increase anti-inflammatory fatty acids by interacting with intestinal microbiota.3
How does diet affect acne?
The intestines are home to a diverse population of microbes that digest food, make vitamins, and protect us from invading microorganisms. It also appears that the gut microbiome influences skin health, which may explain why our diet can impact acne.1
Our skin and gut have rich blood and nerve supplies, meaning that they can communicate with each other and that a change in one can affect the other in many ways. Firstly, our diet influences the diversity of the intestinal microbiome.1 Significant changes in the gut’s microbe population can disrupt homeostasis, leading to a host of problems that may include acne.1 Secondly, digestion produces many metabolites and chemical messengers, which can cause widespread inflammation (including the skin).1 As previously mentioned, increased inflammation often appears in severe acne cases.
This article provides a snapshot of current research on digestive health and acne. Investigations into this relationship are ongoing.
- Lee YB, Byun EJ, Kim HS. Potential role of the microbiome in acne: a comprehensive review. J Clin Med. 2019 Jul 7;8(7):987. Available from: https://www.mdpi.com/2077-0383/8/7/987
- Carmona-Cruz S, Orozco-Covarrubias L, Saez-de-Ocariz M. The human skin microbiome in selected cutaneous diseases. Front Cell Infect Microbiol. 2022 Mar 7;12:834135. Available from: https://www.frontiersin.org/articles/10.3389/fcimb.2022.834135/full
- Baldwin H, Tan J. Effects of diet on acne and its response to treatment. Am J Clin Dermatol. 2021;22(1):55-65. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7847434/
- Kostecka M, Kostecka J, Szwed-Gulaga O, Jackowska I, Kostecka-Jarecka J. The impact of common acne on the well-being of young people aged 15-35 years and the influence of nutrition knowledge and diet on acne development. Nutrients. 2022 Dec;14(24):5293. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9784447/
- Burris J, Shikany JM, Rietkerk W, Woolf K. A low glycemic index and glycemic load diet decreases insulin-like growth factor-1 among adults with moderate and severe acne: a short-duration, 2-week randomised control trial. J Acad Nutr Diet. 2018 Apr 22;118(10):1874-1885. Available from: https://www.jandonline.org/article/S2212-2672(18)30164-3/fulltext
- Rich-Edwards JW, Ganmaa D, Pollak MN, Nakamoto EK, Kleinman K, Tserendolgor U, Willett WC, Frazier AL. Milk consumption and the prepubertal somatotropic axis. Nutr J. 2007;6:28. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2098760/
- Burris J, Rietkerk W, Woolf K. Relationships of self-reported dietary factors and perceived acne severity in a cohort of New York young adults. J Acad Nutr Diet. 2014 Jan 9;114(3):384-392. Available from: https://www.jandonline.org/article/S2212-2672(13)01681-X/fulltext
- Omega-3 Fatty Acids. National Institutes of Health; 2018 Nov 21 [updated 2022 Jul 18]. Available from: https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/