Why Acne Is Not Just a Bacterial Problem
For decades, acne has been blamed on a single culprit: the bacterium Cutibacterium acnes, formerly known as Propionibacterium acnes. This bacteria does play a role in acne development, but the story is far more complex than scientists once believed. The reality is that acne results from multiple interconnected factors working together, and understanding this complexity is key to finding effective treatments.
The Bacteria Myth
When acne research began, scientists focused heavily on C. acnes as the primary cause. This bacterium can indeed contribute to inflammation in the sebaceous gland, which produces oil in your skin. However, here is the surprising part: C. acnes is abundant in the skin of most adults, yet only some people develop acne. This means the presence of the bacteria alone does not determine whether someone will break out.
What matters more is not simply whether the bacteria exists, but which strains are present, how they function, and what environment they live in. Different strains of C. acnes behave differently. Some strains found on healthy skin have different genetic profiles than those found on acne-prone skin. This suggests that the bacteria’s activity and type matter far more than its mere presence.
The Four-Part Problem
Acne actually develops from four interconnected biological processes. The first involves follicular hyperkeratinization, which is when skin cells build up abnormally inside hair follicles, creating blockages. The second factor is sebum overproduction. Androgens, which are male hormones present in all bodies, stimulate sebaceous glands to produce excess oil. This oily environment creates the perfect breeding ground for bacteria and blocks pores.
The third factor involves the bacteria itself, but not in the simple way people think. C. acnes produces enzymes that break down sebum and damage the skin barrier, which promotes inflammation. The fourth factor is the immune system’s response. When pores become clogged, the immune system can react strongly to the blockage, making inflammation worse.
Hormones: The Hidden Driver
Hormonal fluctuations play a major role in acne that many people overlook. When androgen levels rise relative to estrogen, sebaceous glands produce more oil. This is why acne often worsens during puberty, before menstruation, during pregnancy, and during menopause. Women with polycystic ovary syndrome, or PCOS, often experience persistent acne because this condition elevates androgen levels.
Stress also influences hormones. When you experience stress, your body produces cortisol and other stress hormones that indirectly increase oil production and inflammation. Poor sleep and irregular eating patterns can amplify these hormonal effects.
The Gut Connection
Recent scientific research has revealed another surprising factor: gut health. The intestines play a central role in immune regulation, inflammation, and hormonal balance, all of which directly impact the skin. When the intestinal barrier becomes disrupted or the gut microbiome becomes unbalanced, it can lead to systemic low-grade inflammation that manifests as acne.
Scientists have found links between acne and conditions like small intestinal bacterial overgrowth, or SIBO, and irritable bowel syndrome, or IBS. This discovery has opened an entirely new avenue for understanding and treating acne.
Diet and Lifestyle Matter
What you eat significantly influences acne development. Dairy products, particularly those high in whey protein, can trigger breakouts because they contain hormones and growth factors that affect your skin. High-glycemic foods like sugar, refined carbohydrates, and processed foods spike insulin levels, which can disrupt hormone balance and worsen inflammation.
Food allergies and intolerances can also trigger acne flares. Beyond diet, lifestyle factors like stress management, sleep quality, and exercise all influence skin health. When you wash your face too frequently with harsh cleansers, you can damage your skin barrier, causing your skin to produce even more oil to compensate.
The Products You Use
The skincare and cosmetic products you apply to your face matter more than many people realize. Heavy makeup, pore-clogging moisturizers, and harsh cleansers can irritate your skin and trap oil and bacteria. Some products contain comedogenic ingredients specifically designed to clog pores. An inconsistent skincare routine allows buildup to accumulate, triggering inflammation.
Genetics and Individual Differences
Your genes influence how susceptible you are to acne. Some people inherit a tendency toward overactive sebaceous glands or a more reactive immune system. This is why the same treatment does not work for everyone. Two people with seemingly identical acne may have completely different underlying causes.
A Multifactorial Approach
The key insight is that acne is multifactorial. It involves genetics, hormones, diet, stress, gut health, skincare habits, and yes, bacteria too. But bacteria alone cannot explain why some people break out while others do not. Understanding acne as a complex condition involving multiple systems in your body opens the door to more effective, personalized treatments that address root causes rather than just surface symptoms.
Sources
https://www.skin-gut-axis.com/post/acne-why-the-skin-and-the-gut-are-inseparable
https://pmc.ncbi.nlm.nih.gov/articles/PMC12735603/
https://www.britannica.com/science/acne
https://www.medicaldaily.com/hormonal-acne-adults-acne-causes-skin-hormones-explained-474128
