Acne Vulgaris: A Nutrition and Natural-Health Reference
Definition and Overview
Acne is a multifactorial inflammatory disease affecting pilosebaceous follicles. Clinically designated as acne vulgaris, it is the most recognized form of the condition and ranges from mild non-inflammatory lesions to severe inflammatory disease. Acne vulgaris is a widespread chronic inflammatory dermatosis that affects millions of people worldwide, with a significant influence on patients' standard of living. The progression of this dermatosis results in the appearance of inflammatory and non-inflammatory changes, and, in severe cases, disfiguring scars and hyperpigmentation.
The Global Burden of Disease Study 2010 found that acne vulgaris is the eighth most common skin disease, with an estimated global prevalence (for all ages) of 9.38%. According to the Global Burden of Disease (GBD) study, acne vulgaris affects approximately 85% of young adults aged 12–25 years, and consistently represents one of the top three most prevalent skin conditions in the general population. In recent decades, the epidemiological profile of acne has evolved, with a rising incidence observed not only among adolescents but also in adult populations, particularly adult women. Acne vulgaris is the tenth highest cause of disability-adjusted life years (DALYs) in the late adolescent period (15–19-year-olds) across developed countries.
Clinical Presentation
Identifying both inflammatory (papule, pustule, nodule, and cyst) and non-inflammatory (blackheads, whiteheads) acne lesions is necessary for diagnosing and treating acne vulgaris. Comedones can be subdivided into two types: open comedones (blackheads), which are clogged follicles with openings exposing their contents to the air, and closed comedones (whiteheads), which are clogged follicles without an opening.
Clinically, acne presents with a variety of lesions such as comedones, papules, pustules, nodules, and, in severe cases, scarring. Acne is an inflammatory condition involving the pilosebaceous unit that affects up to 90% of teenagers. Severe forms of acne can cause disfiguration and scarring, resulting in low self-esteem, difficulties in social interaction, and psychological distress. Acne is a disorder of sebaceous glands and most commonly develops on the face, though it is also frequently found on the back, chest, and shoulders — areas with the highest concentration of sebaceous glands.
Body Systems Involved
The Pilosebaceous Unit
Acne's pathophysiology involves four important factors: excessive sebum production, hyperkeratinization of pilosebaceous follicles, hyperproliferation of Propionibacterium acnes (now renamed Cutibacterium acnes), and inflammation. The initial event in the development of an acne lesion is abnormal desquamation of the keratinocytes that line the sebaceous follicle, which creates a microplug or microcomedo. An increase in circulating androgens at the onset of puberty stimulates the production of sebum into the pilosebaceous unit. These events combine to create an environment within the pilosebaceous unit that is favorable for the colonization of the commensal bacterium Propionibacterium acnes. With proliferation, P. acnes secretes various inflammatory molecules and chemotactic factors that initiate and perpetuate the local inflammatory response and possibly induce keratinocyte hyperproliferation as well.
Cutibacterium acnes accounts for up to 90% of skin microbiota in areas with the highest concentration of sebaceous glands, including the head, face, chest, and back. This bacterium is rarely identified in childhood, and its counts increase gradually between puberty and adulthood, and decrease past the age of 50.
The Endocrine System
The key regulator IGF-1 rises during puberty by the action of increased growth hormone (GH) secretion and correlates well with the clinical course of acne. In acne patients, associations between serum levels of IGF-1, dehydroepiandrosterone sulphate, dihydrotestosterone, acne lesion counts, and facial sebum secretion rate have been reported. IGF-1 stimulates 5-alpha-reductase, adrenal and gonadal androgen synthesis, androgen receptor signal transduction, sebocyte proliferation, and lipogenesis. The production of androgens during puberty explains, in part, why acne vulgaris is so prevalent in this population regardless of socioeconomic status, nationality, or sex.
The Nervous System and Stress Axis
Substance P, which can be elicited by stress, promoted the development of cytoplasmic organelles in sebaceous cells, stimulated sebaceous germinative cells, and induced significant increases in the area of sebaceous glands. It also increased the size of individual sebaceous cells and the number of sebum vacuoles for each differentiated sebaceous cell, all of which suggests that substance P promotes both the proliferation and the differentiation of sebaceous glands. Findings support a potential bidirectional relationship between psychological stress and acne flare-ups. There is consistent evidence suggesting that stress significantly contributes to the prevalence and severity of acne.
The Gut–Skin Axis and Microbiome
The pathogenesis of acne is complex and multifactorial, involving genetic, metabolic, and hormonal factors in which both skin and gut microbiota are implicated. Numerous studies have shown the bidirectionality between the intestinal microbiota and skin homeostasis, a communication mainly established by modifying the immune system. Gut microbes and blood metabolites, as significant immune and inflammatory regulators in the body, have been hypothesized to form the "neurocutaneous axis."
Contributing and Associated Factors
Genetic Predisposition
Heritability estimates and twin studies suggest a genetic basis for acne; individuals with a family history of acne tend to have more severe acne. Adults with acne have a positive familial history more often than healthy controls, which indicates the genetic nature of adult acne.
Hormonal Factors
The development of acne may be associated with genetic factors, hormone levels, medication use, consumption of dairy products, a high-fat diet, and infection with Propionibacterium acnes. During adolescence, sex differences are noticed, probably due to androgen hormones, and acne is more common in male patients. An increased frequency is also reported in adult patients, especially in women, with up to 20% of women and 8% of men suffering from the disease.
Body Mass Index
Most studies have noted increased prevalence of acne in overweight and obese individuals relative to underweight individuals or individuals of normal weight. A pooled odds ratio of 2.36 (95% CI 1.97–2.83) suggests that BMI significantly influences acne presentation.
The Western Dietary Pattern
Intimately related to the composition and diversity of intestinal microbiota, diet is a decisive factor in the development of acne. A Western diet characterized by a high consumption of ultraprocessed foods, saturated fats, and refined sugars is a risk factor for acne aggravation. A typical Western pattern diet which includes foods with a complex mixture of fat (i.e., red meat), high glycemic index, and dairy may aggravate acne by raising the levels of insulin-like growth factor-1 (IGF-1) and insulin.
Gut Microbiome Dysbiosis
A high-fat diet implies a loss of diversity of gut microbiota and an increase in endotoxemia, which contributes to the deterioration in the integrity of the intestinal epithelium and its barrier function, a decrease in the thickness of the intestinal mucosa layer, and an increased secretion of pro-inflammatory mediators. A large body of evidence indicates that a low fiber–high fat Western diet causes fundamental changes in the intestinal microbiota, producing metabolic and inflammatory skin diseases.
Sleep
There is evidence suggesting a relationship between sleep quality and acne. Studies have shown that the severity of acne is directly linked to insomnia and poor quality of life, highlighting the importance of addressing sleep disturbances in patients with acne. There is a complex, bidirectional link between acne and sleep, requiring further research.
Additional Exogenous Factors
Genetic predisposition, hormones, the skin and gut microbiome, psychological stress, air pollutants, aggressive facial products, and certain medications are cited as factors influencing acne formation. A significantly higher frequency of alcohol consumption has been reported in patients with acne. Alcohol has also been shown to increase testosterone levels and the production of pro-inflammatory cytokines.
Dietary Factors: Evidence and Discussion
Glycemic Index and Glycemic Load
Diet and metabolism, specifically glycemic content and dairy, influence hormones such as insulin, insulin-like growth factor 1, and androgens, which affect acnegenesis. In multiple clinical trials, high-GI diets (>55) have been associated with worse glycemic control, higher postprandial insulin levels, and elevated insulin-like growth factor 1 (IGF-1) levels, whereas low-GI diets have been shown to decrease fasting IGF-1 concentrations.
A high glycemic diet increases the secretion of insulin, which in turn causes an increase in the amount of IGF-1. IGF-1 increases the growth of the sebaceous gland, sebum production, keratinocyte proliferation, and it activates androgen synthesis, thus contributing to acne pathogenesis.
A 2018 randomized controlled trial (RCT) examined this relationship directly. A high glycemic index (GI) and glycemic load (GL) diet may stimulate acne proliferative pathways by influencing biochemical factors associated with acne. This study examined changes in biochemical factors associated with acne among adults with moderate to severe acne after following a low GI and GL diet or usual eating plan for 2 weeks, using a parallel randomized controlled design, with 66 participants. A low GI and GL diet decreased IGF-1 concentrations, a well-established factor in acne pathogenesis; however, further research of a longer duration should examine whether a low GI and GL diet would result in a clinically meaningful difference in IGF-1 concentrations leading to a reduction in acne.
Despite this biological plausibility, not all meta-analyses confirm the association. Pooled estimates from one meta-analysis indicated no significant associations for glycemic load, glycemic index, fatty acids/adiponectin, or dairy consumption with acne risk. Heterogeneity ranged from moderate to high (I² = 65–90%). The certainty of evidence was moderate for glycemic and dairy outcomes, and low for fatty acids. Despite biological plausibility linking diet to acne via hormonal and inflammatory mechanisms, evidence remains inconsistent. High glycemic index, increased glycemic load, and carbohydrate intake have a modest yet significant pro-acnegenic effect. Increased dairy consumption may have been pro-acnegenic in select populations, such as those in which a Western diet is prevalent. The impact of diet on acnegenesis is likely dependent on sex and ethnicity. Further randomized trials are necessary to fully characterize the potential associations.
Dairy Products
Frequent dairy consumers have higher serum levels of IGF-1 and insulin compared with nondairy consumers, and the ingestion of either whey or casein, the protein dairy components, has been associated with increased levels of IGF-1 and insulin. Milk consumption results in a significant increase in insulin and IGF-1 serum levels comparable with high glycaemic food. However, evidence on dairy's real-world impact on acne remains mixed. One study analysed the possible link between milk consumption and acne in adulthood in subjects with or without lactose intolerance. They did not find a link between dairy products and adult acne, and this finding was not associated with lactose tolerance status.
Sugar-Sweetened Beverages
One study was conducted on a group of 8,197 students. It was demonstrated that frequent consumption of carbonated drinks, fruit-flavoured drinks, and sweetened tea (more than seven times a week, particularly consumption of more than 100 g sugar) was associated with moderate or severe acne vulgaris.
Fruits and Vegetables
A recent systematic review has shown that foods with a high glycemic index/load, dairy products, fatty foods, and chocolate promote the formation of acne lesions, while the intake of fruits and vegetables was protective.
Nutrients, Herbs, and Natural Ingredients
Zinc
Traditional Use
Zinc-containing preparations have been used topically in wound healing and skin conditions since antiquity; zinc oxide pastes and sulfate solutions are recorded in European pharmacopoeias as long-established dermatological treatments. Oral zinc sulfate therapy for acne was introduced in modern clinical practice in the 1970s.
Scientific Evidence
The published literature on the efficacy of oral and topical zinc as treatments for acne vulgaris was systematically reviewed. Each study was assessed for pathophysiologic results and quality of clinical evidence using Strength of Recommendation Taxonomy (SORT) criteria. A SORT strength of recommendation of B (inconsistent or limited-quality patient-oriented evidence) appears to be appropriate for both oral and topical zinc. The preponderance of evidence suggests zinc has antibacterial and anti-inflammatory effects and that it may decrease sebum production.
Supplementation with zinc was found to be beneficial in ten of 14 studies evaluating its effects on acne vulgaris. Adverse effects were rare for most therapies evaluated, but gastrointestinal tract adverse effects were reported for zinc therapy. Overall, the evidence base for zinc in acne is characterized as moderate-quality but inconsistent; zinc appears inferior to oral antibiotics in head-to-head comparisons, but represents a non-antibiotic option with a plausible mechanistic rationale.
Vitamin A (Retinol and Retinoids)
Traditional Use
High-dose vitamin A (retinol) was used clinically as an acne treatment before the development of synthetic retinoids such as isotretinoin. Its use was informed by the observed skin-normalizing effects of vitamin A in deficiency states, where follicular hyperkeratosis resembles comedone formation.
Scientific Evidence
Similar to isotretinoin, vitamin A addresses pathogenic factors that contribute to acne by decreasing sebaceous gland activity and inhibiting comedogenesis. However, randomized clinical trials to support the role of oral vitamin A in the treatment of acne are generally lacking, with much of the evidence base consisting of case reports and small case series published over 60 years ago. In one 12-week placebo-controlled trial, improvement was equivalent between vitamin A (150,000 IU/d) and placebo. Though no adverse effects were reported in that trial, vitamin A has the potential for teratogenicity, neuropsychiatric disturbances, and mucocutaneous adverse effects; the high doses required for acne therapy increase the likelihood of developing these adverse effects.
Niacinamide (Vitamin B3 / Nicotinamide)
Traditional Use
Niacinamide has been employed as a topical dermatological ingredient for several decades, particularly in Japanese and Korean cosmetic traditions, where it was recognized for its brightening and anti-inflammatory properties on the skin.
Scientific Evidence
Acne is a multifactorial disease characterized by excess sebum production, abnormal keratinization, bacterial colonization by Cutibacterium acnes, and inflammation. Niacinamide possesses anti-inflammatory and antibacterial activities, thereby contributing to the dual management of important acne symptoms. Several clinical studies report that preparations with 2% to 5% niacinamide can effectively reduce sebum production following topical application, notably in Asian and Caucasian populations. However, the mechanism which leads to the sebostatic action of niacinamide remains unknown. Niacinamide is widely used to combat inflammatory acne, with proven clinical effectiveness. Evidence is primarily for topical niacinamide; evidence for oral niacinamide in acne is limited, and few rigorous RCTs have examined oral formulations specifically.
Pantothenic Acid (Vitamin B5)
Scientific Evidence
In a systematic review of 3,346 participants in 42 unique studies, good-quality studies of nutraceuticals demonstrated effectiveness of vitamin D, green tea extract, probiotics, and a traditional herbal formula in the treatment of acne. The 11 fair-quality studies in the same review suggested potential effectiveness for pantothenic acid (vitamin B5), as well as omega-3 (EPA and/or DHA) and omega-6 (gamma-linolenic acid) fatty acids. Evidence for vitamin B5 in acne is therefore characterized as preliminary and fair-quality, based on a limited number of trials.
Vitamin D
Scientific Evidence
In a systematic review, one of four good-quality studies specifically evaluated vitamin D, with the finding supporting its effectiveness in acne management. Vitamin D is likely to be a relatively low-risk option to consider, as it was dosed similarly to the recommended daily allowance in its clinical trial. The mechanistic rationale centers on vitamin D's well-established immunomodulatory and anti-inflammatory roles. The evidence is preliminary but promising, from a single good-quality RCT; larger trials are needed.
Omega-3 and Omega-6 Fatty Acids
Scientific Evidence
Studies have shown that omega-3 fatty acids, along with other nutraceuticals like vitamin B5, vitamin D, green tea extract and probiotics, all have the potential to reduce acne lesions and improve overall skin health. Omega-3 and omega-6 fatty acids are reasonable options for interested patients, but the evidence is fair in quality and limited in scale. Randomized, placebo-controlled trials — the gold standard of scientific research — are needed to gain a more robust understanding of the role of omega-3s in the treatment of acne. Additionally, as many variables as possible should be controlled to minimize confounders, whether the patients' diets, dosage of omega-3s, or other lifestyle factors that could influence outcomes. The proposed mechanism involves competitive inhibition of pro-inflammatory arachidonic acid metabolites and reduction of leukotriene B4, a potent inflammatory mediator relevant to acne.
Green Tea (Camellia sinensis)
Traditional Use
Green tea has been consumed for centuries in East Asian traditions, with preparations of the leaf used in Chinese and Japanese medicine for a range of inflammatory and dermatological complaints. Topical application of tea preparations to skin conditions has also been documented in traditional Chinese medicine.
Scientific Evidence
Among four good-quality studies in one systematic review, one evaluated green tea extract and found it effective in improving acne outcomes. Although green tea extract led to statistically significant improvements in lesion counts, it did not result in statistically significant improvements in quality of life, suggesting the observed lesion count differences may not be clinically meaningful to patients. Based on this evidence, it is possible to state that green tea could be an alternative to conventional treatments for mild to moderate acne vulgaris. Both oral and topical formulations have been studied. Evidence is characterized as good quality for lesion count outcomes, but clinically meaningful improvements in patient-reported quality of life remain unproven.
Tea Tree Oil (Melaleuca alternifolia)
Traditional Use
Arthur Penfold described the medicinal value of tea tree essential oil in 1925, although the first official Australian report of its use in Western medicine was in a 1930 article published in the Medical Journal of Australia, where it was described as having "impressive wound healing and antiseptic qualities." According to the European Medicines Agency (EMA) monograph, tea tree oil has a well-established use as a traditional herbal medicinal product for, among other indications, the treatment of small boils (furuncles and mild acne).
Scientific Evidence
A small amount of evidence suggests that tea tree oil, applied topically, might be helpful for acne and athlete's foot, but more studies are needed before definitive conclusions can be reached. For other conditions, there is not enough evidence to determine whether topical tea tree oil is useful. (Source: NCCIH, National Institutes of Health.) More evidence is needed to confirm the benefits of tea tree oil for reducing acne lesions and severity. Local anti-inflammatory effects on skin, if any, also require further elucidation. One 12-week uncontrolled, open-label phase II pilot study showed that the use of tea tree oil products significantly improved mild to moderate acne and that the products were well tolerated. The overall evidence base is characterized as preliminary and weak; only a small number of controlled trials have been conducted, limiting firm conclusions.
Probiotics, Prebiotics, and Postbiotics
Traditional Use
Fermented foods containing live bacterial cultures have been consumed across many cultures for millennia, with recognized benefits for digestive and general health. The specific application of probiotics to acne emerged from modern understanding of the gut–skin axis and is not historically rooted in traditional botanical medicine as such.
Scientific Evidence
Trials investigating the effects of probiotics in acne patients are limited. The first clinical trial was performed by Siver et al. in 1961; in this study, a mixture of Lactobacillus acidophilus and Lactobacillus bulgaricus administered orally to 300 patients with acne demonstrated varying levels of improvement in 80% of patients, with effects more evident in cases of inflammatory acne.
Probiotics currently have the strongest evidence base among biotics investigated for acne, while prebiotics and postbiotics are promising adjuncts. Larger, standardized randomized trials are needed to clarify comparative efficacy, optimal formulations, and durability. While probiotics had the most studies supporting their efficacy, these were generally of very small sample size, and it is possible there could be publication bias. In addition, there is heterogeneity among probiotic formulations, and it is not clear which are optimal for use among patients with acne. Studies have also demonstrated that probiotic supplementation in patients with acne is associated with a reduction in inflammatory markers and an increase in anti-inflammatory markers.
Berberine and Berberis Species
Traditional Use
Berberis vulgaris is a plant of the Berberidaceae family widely found in Europe, Asia, and America. The reddish fruit of this plant is commonly included in gastronomic dishes, while the roots, stems, and bark are used in traditional medicine. In Ayurvedic and traditional Chinese medicine, barberry and related species containing berberine were used for skin inflammation, fever, and infections.
Scientific Evidence
The medicinal properties of B. vulgaris are mostly attributed to berberine, an isoquinoline alkaloid that belongs to the structural class of protoberberines. Berberine exhibits multiple pharmacological properties, including anti-inflammatory, antioxidant, antibacterial, antifungal, and anxiolytic properties. Additionally, a study has shown that berberine considerably suppresses lipogenesis in the sebaceous glands. The anti-acne properties of Berberis integerrima root extract have been mainly attributed to berberine. This isoquinoline alkaloid displays numerous anti-inflammatory and immunomodulatory activities in vitro, including downregulating the pro-inflammatory Th1/Th17 pathway, reducing the expression of inflammatory mediators (e.g., TNF-α, IL-6, COX-2, and prostaglandin E2). Clinical evidence remains limited; most data come from in vitro studies and small trials. A 2024 RCT examined a combination of Berberis integerrima root extract and spearmint essential oil, finding it was similarly effective as a 1% clindamycin topical solution at reducing the total number of acne lesions in 60 subjects with mild-to-moderate disease. This is a single small trial and evidence is characterized as preliminary.
Spearmint (Mentha spicata)
Traditional Use
Spearmint has been used in traditional European herbal medicine and Middle Eastern folk medicine as an anti-androgen herb, consumed as a tea to address hormonal symptoms in women, including hirsutism and menstrual irregularities.
Scientific Evidence
A study involving 21 patients who consumed a cup of spearmint tea twice a day for five days during the follicular phase of their menstrual cycles found a noteworthy reduction in free testosterone levels and an increase in luteinizing hormone, follicle-stimulating hormone, and estradiol. The anti-androgenic effect provides a plausible rationale for relevance to hormonally-driven acne, particularly in adult women. However, clinical evidence directly linking spearmint supplementation to improvements in acne lesion counts remains very limited, and the evidence is characterized as very preliminary.
Selenium
Scientific Evidence
Selenium is a trace element with antioxidant properties, functioning as a component of glutathione peroxidase enzymes. Research published in the Journal of Dermatological Science indicated that selenium supplementation, particularly in combination with vitamin E, can reduce the severity of acne. It works synergistically with vitamin E to protect cells from oxidative damage and reduce inflammation. The evidence for selenium in acne is characterized as very limited and preliminary, based on individual studies; no systematic reviews have specifically focused on selenium for acne.
Dietary and Lifestyle Factors: Summary of Authoritative Discussion
Overall Dietary Pattern
The link between nutrition and acne is extensively debated and is still relatively controversial. Diet is commonly recognised to have a direct relationship with certain biochemical markers and the transcription of genes related to sebaceous gland function, and the proliferation of bacteria and inflammation that encourage the progression of the disease. Appropriate food products and supplementation providing primarily vitamin D, omega-3 fatty acids, vitamins and minerals with antioxidant properties, prebiotics and probiotics, and additional use of green tea extract, as well as reducing the consumption of milk, salty and spicy foods and products with a high glycaemic index, may not only prevent acne vulgaris and alleviate lesions but also facilitate treatment of the condition.
High-Glycemic Foods
Acne is proposed to be an IGF-1-mediated disease, modified by diets and smoking increasing insulin/IGF-1-signalling. Diets low in milk protein content and glycaemic index reduce increased IGF-1 signalling. The totality of evidence from multiple systematic reviews indicates a moderate, biologically plausible association between high-glycemic dietary patterns and acne, though definitive proof from large, long-term RCTs is lacking.
The Western Diet and Gut Microbiome
Diet shapes the gut microbiota. A large body of evidence indicates that a low fiber–high fat Western diet causes fundamental changes in the intestinal microbiota, producing metabolic and inflammatory skin diseases. Intimately related to the composition and diversity of intestinal microbiota, diet is a decisive factor in the development of acne. A Western diet characterized by a high consumption of ultraprocessed foods, saturated fats, and refined sugars is a risk factor for acne aggravation.
Psychological Stress
Findings support a potential bidirectional relationship between psychological stress and acne flare-ups, with consistent evidence suggesting that stress significantly contributes to the prevalence and severity of acne. The neuroendocrine mechanism involves cortisol, substance P, and corticotropin-releasing hormone, all of which can influence sebum production and immune responses in skin.
Sleep
The severity of acne is directly linked to insomnia and poor quality of life, highlighting the importance of addressing sleep disturbances in patients with acne. Poor sleep is often linked to depression and anxiety, which are well-documented factors that negatively impact sleep quality. This relationship becomes even more complex when considering that acne itself can induce stress and contribute to sleep disorders. There is a complex, bidirectional link between acne and sleep, requiring further research.
Exercise and Physical Activity
Evaluating the influence of lifestyle factors such as exercise and sleep on stress and acne is an area of interest due to the lack of research in this field. Besides diet, lifestyle habits like sleep and physical activity have received attention in acne research. A Mendelian randomization analysis has been used to probe potential causal associations between genetically predicted sleep and physical activity traits and acne vulgaris, though conclusions from this work remain under investigation.
Evidence Gaps and Limitations
Many studies of nutraceuticals for acne are of small size, and future research should focus on larger randomized clinical trials to assess the utility of nutraceuticals in the treatment of acne. Dietary supplements are not evaluated with the same rigor and standard as medications by the United States Food and Drug Administration (FDA). As a result, the safety and efficacy of individual supplements is often unknown. Furthermore, supplement labels can be misleading and may even contain inaccurate information. Across the literature, methodological heterogeneity, small sample sizes, short durations, and inconsistent outcome measures make direct comparisons between studies difficult and limit the strength of conclusions that can be drawn about any single nutritional or herbal intervention.
References
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- PMC — Acne Vulgaris and Intake of Selected Dietary Nutrients—A Summary of Information
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