The authors reported patients treated with a probiotic had improved clinical outcomes and reported fewer side effects from the standard antibiotics. Likewise, a Russian study tested the effectiveness of probiotics as adjuvants to standard acne treatment and found that patients taking probiotics experienced improvements sooner in their acne treatment compared to controls. While the mechanism of probiotics is not well understood, recent research has shown that they may reduce oxidative stress and inflammation. Patients with acne have a high local burden of lipid peroxidation placing a high demand on blood-derived antioxidants. Orally-consumed pre- and pro-biotics have been shown to reduce systemic markers of inflammation and oxidative stress. Additionally, oral probiotics have been shown to regulate the release of inflammatory cytokines in the skin and reduce interleukin-1 α . Lastly, probiotics can change the microbial community at distant sites outside of the gastrointestinal tract. Therefore, the ability of oral probiotics to reduce systemic oxidative stress, regulate cytokines, and reduce inflammatory markers may all contribute to its effects on acne. Taken together, these studies suggest that the gut microbiome may play an important role in acne pathogenesis and that we can modulate it for clinical improvements, but further investigation into the mechanisms and effects of oral probiotics in acne vulgaris is needed.The beneficial role of fruits and vegetables in health maintenance is well known, drainage for plants in pots though the mechanisms have only been elucidated in recent years. The gut microbiome plays an integral role in almost every aspect of human health through transformation of food and through direct signaling.

Most research on dietary effects do not consider whether the effect on the host or the effect on the host’s microbiome is primarily affecting the observed response. One of the first dietary intervention studies on acne vulgaris was performed in 2007 by Smith et al. and compared the effect of a low-glycemic load diet on acne severity. Forty-three males aged 15–25 with moderate acne were fed a low-glycemic load diet for 12 weeks. The number of acnelesions, sex hormone levels, and insulin markers were compared at baseline and after intervention. The patients both lost weight and showed improvement of acne compared to a conventional Western diet. Free androgen and fasting insulin levels were significantly lower in patients on the low-glycemic load diet. The patients designed their own diets, based on nutritional counseling, which instructed the experimental group to consume more protein and lower glycemic index carbohydrates, such as whole grains and fruits. The evidence suggests that high-glycemic load diets can contribute to acne by inducing hyperinsulinemia, while low-glycemic load diets may prevent hyperinsulinemia by lowering postprandial insulin. In 2016, Çerman et al. again probed the relationship between glycemic load and acne, collecting self-reported food logs from 86 patients over seven days. The study included male and female patients with mild to severe acne and tracked adiponectin in addition to insulin/insulin resistance markers. Adiponectin is a protein involved in the regulation of glucose and fatty acid breakdown. Both the presence and the severity of acne positively correlated with glycemic load, but not with insulin or insulin resistance markers. Adiponectin levels were lower in acne patients than in controls, though not significantly different by severity.

The glycemic load disparity between experimental and control groups was less than that in Smith’s interventional study , which may explain the differences in insulin markers and reflect the normal dietary differences between young adults in Turkey and in Australia. A low-glycemic load diet balances carbohydrate intake with dietary fiber, slowing digestion and the release of sugar into the bloodstream. The recommended daily allowance of dietary fiber is 25 g, based on a 2000 kilocalorie diet. Dietary fiber intake from 2001–2010 was 16.1 g/day for adults over age 19. This deficient consumption of dietary fiber reflects the whole grains, vegetables and fruits that average Americans are lacking on a daily basis. Though the mechanism by which this diet improves acne is unknown, complex carbohydrates, like resistant starch, insoluble fiber, and fructooligosaccharides, have been correlated with greater insulin sensitivity and less inflammation. In addition to prebiotic polysaccharides, plant-based foods are also sources of bioactive polyphenols, which we discuss later.Insulin is a peptide hormone made by the pancreas that regulates carbohydrate metabolism through its influence on glucose. Evidence from multiple studies, including Smith et al., suggest insulin and carbohydrate metabolism may have a role in the etiology and severity of acne. The occurrence of acne as part of various syndromes associated with insulin resistance further supports the association between insulin and acne. For example, 70% of polycystic ovary syndrome cases have acne symptoms. PCOS is characterized by hyperandrogenism, anovulation, polycystic ovaries, insulin resistance and hyperinsulinemia. Emiroglu et al. investigated the relationship between acne and insulin resistance in males with acne. All 22 subjects with resistant acne had impaired metabolic profiles and decreased insulin sensitivity. The mechanism linking high insulin levels and acne may be through the altered proliferation of keratinocytes in the pilosebaceous unit. Hyperinsulinemia increases serum levels of insulin-like growth factor-1 and reduces serum levels of insulin-like growth factor binding protein-3.

Both of these factors have been shown to increase keratinocyte proliferation and stimulate hormone production, which may contribute to the pathogenic factors of acne. The gut microbiota may also contribute to insulin resistance. A Danish study of 277 non-diabetic individuals found increased populations of specific gut microbes and an association with insulin resistance. Insulin resistance and the gut may represent a new target for therapy in acne patients. There are many plant-based foods that can improve insulin sensitivity, thereby reducing overproduction and stabilizing blood sugar. Many of the compounds responsible appear to be polyphenols, though the molecular mechanism of action is generally not understood and may vary depending on the molecule. In vitro, berry extract exposure reduced glucose uptake by human intestinal epithelial cells. Foods/supplements that exert a positive effect on insulin sensitivity include olive leaf, berries , grapes and red wine, cinnamon, and green tea. Green tea extract supplementation has been shown to decrease the number of acne lesions in post pubescent females with a trending decrease in fasting blood sugar and a significant decrease in total triglycerides. It is important to note that there are few studies on most of these foods and their effects on glucose metabolism; therefore, results should be cautiously accepted until more, larger clinical trials are performed. Plants from the family Berberidaceae are commonly used in traditional Chinese medicine for a variety of ailments, including the chronic skin conditions eczema and psoriasis. This family includes the genus Mahonia and Berberis, which produce flowers and edible berries. Among many bioactive compounds in these plants, berberine is one of the most well studied. It has been shown to relieve insulin resistance in hepatic cells in vitro and to be anti-inflammatory. Berberine and other components are antimicrobial against common skin microbes, like Propionibacterium acnes, Staphylococcus spp. and Malassezia spp.. One of the reasons it may be effective in treating eczema and psoriasis is an antiproliferative effect on keratinocytes, which may also attenuate acne lesion development. Additionally, in hamsters, growing raspberries in pots berberine appeared to decrease lipogenesis by sebaceous glands, which may translate to human sebaceous glands. Berberine showed strong activity against clinical isolates of Propionibacterium acnes isolated from acne patients. A Chinese study using Gong Lao Qu Huo herbal supplements comprised of Mahonia fruits was used to treat 92 patients with acne vulgaris. Ninety eight percent of the treatment group on berberine improved compared to 91% of the control group taking minocycline. Statistical analysis suggested there was no difference between the berberine and minocycline groups. This suggests that herbal supplementation may be just as effective as the standard antibiotics without the drawbacks. Fruits from the genus Garcinia are best known for their antibacterial and weight loss effects. Weight loss may be due to leptin-like activity and the resultant decreases in insulin and insulin sensitivity, in addition to appetite suppression. In sucrose-loaded mice fed Garcinia cambogia rind extract, there was a significant decrease in serum insulin levels compared to controls.

Male rats consuming a high fat diet showed increased serum leptin levels and decreased glucose intolerance when fed Garcinia cambogia ethanolic extract. α and γ mangostin and phenolic ethers in Garcinia mangostana improved insulin sensitivity and attenuated lipopolysaccharide -induced inflammation in vitro. Garcinia mangostana extract led to an increase in the insulin-producing pancreatic β cells in normal and diabetic rats. The loss of β cell number and function is associated with type I and II diabetes, and increasing the population has been hypothesized as a cure. Although topically applied α mangostin clinically improved acne severity and inhibited growth of both Staphylococcus epidermidis and P. acnes in vitro, orally-administered extracts have not been tested as an acne treatment. The various activities suggest that Garcinia fruits may be worth studying for their effects on acne with oral supplementation. A prebiotic supplement containing inulin, β-glucan, and blueberry polyphenols led to significantly improved glucose tolerance in adult humans, though no statistically-significant difference was observed in insulin sensitivity. In diet-induced obese rats, a combination probiotic containing Bifidobacterium, Lactobacillus, Lactococcus and Propionibacterium strains improved insulin sensitivity and decreased body mass. Turmeric, the ground dried root of the Curcuma longa plant , is known for its prominent role in curries and traditional medical systems like Chinese medicine and Ayurveda. It has shown promising results as an antimicrobial, anti-inflammatory, and antidiabetic, all activities that may improve acne vulgaris. Several studies in mice have shown that curcumin supplementation results in reduced glucose intolerance, hypoinsulinemia, and hyperglycemia. The growth of the common skin bacteria Staphylococcus epidermidis and Staphylococcus aureus is inhibited by curcumin, which also acts synergistically with several antibiotics. When curcumin was photoactivated,it was also able to inhibit the growth of Propionibacterium acnes, though unactivated curcumin did not inhibit growth. Sex hormones, including androgens and progestins, have been implicated in acne pathogenesis. Progesterone, which peaks before menstruation and is elevated throughout gestation, has been correlated with flares of acne, psoriasis, rosacea, herpes lesions, and both atopic and allergic dermatitis. However, progesterone also inhibits the enzyme 5α-reductase that transforms testosterone into 5α-dihydrotestosterone , a hormone that has been shown to increase proliferation of sebocytes in ex vivo sebaceous glands to a greater degree than testosterone. High levels of 5αDHT have also been correlated with acne vulgaris. The effect of sex hormones on acne pathology is likely more complex than absolute levels of particular hormones and could result from an imbalance between several or from the activity of 5α-reductase. Female to male transsexual patients have in some cases suffered severe chronic acne after beginning testosterone supplementation. Typical treatments like doxycycline and topical retinoids did not show an improvement, but oral isotretinoin led to clearance followed by a delayed recurrence of severe acne in both patients. Another study with a larger sample size showed that acne presence and severity did increase over the first six months on testosterone, but that this condition was temporary and that only ~6% of patients had acne after long-term supplementation. One explanation for the development of acne in this population is an overall increase in sebum production. Giltay and Gooren studied sebum production and hair growth in both female and male transsexual patients, where testosterone supplementation increased overall sebum production and estrogen supplementation decreased sebum production. Several other studies show that women with acne have elevated levels of free testosterone and total testosterone, though this same relationship is not seen in men. Estrogen can counter androgens through negative feedback loops, suggesting that increasing dietary phytoestrogens may be a better solution than attempting to decrease testosterone, which can have negative effects on male fertility since testosterone is necessary for spermatogenesis. Estrogen seems to have a beneficial effect on skin, decreasing sebaceous gland size, sebum production and acne. Phytoestrogens are present in a variety of edible plants and are famously high in soy products in the form of isoflavones. Plants from the genus Vitex have been used to treat premenstrual acne, menopause symptoms and polycystic ovary syndrome. There are several polyphenols in Vitex agnus-castus fruit, which were able to strongly bind to estrogen receptors in human breast cancer cells in vitro and are likely responsible for their clinical responses/usage.