by Dr Harriet Holme28 Aug 2020
Does diet affect acne?
Have you wondered if diet affects acne? Does eating greasy food make your skin oily and spotty, or does chocolate cause break outs? There is so much misinformation about whether acne is related to diet, with particular foods and supplements labelled as ‘acne fighting’ superfoods. This article looks at the evidence behind these claims and provides practical tips that may help to keep your skin healthy and clear.
Acne, or more properly known as acne vulgaris, is a chronic skin disease characterised by inflamed spots and non-inflammatory comedones (blackheads and whiteheads) on the face, neck, back and chest, with inflammatory cysts and scaring forming in more severe disease (1). It is thought to affect up to 85% of adolescents and may persist into adult life (2), which approximately 9.4% of the global population (3). In approximately 15-20% of people affected, it is classified as moderate or severe (2). At a time in life, when appearance can feel very important, the psychological implications should not be underestimated (4). Acne is the eight most common disease globally and represents a considerable burden of distress (5). There are lots of other different types of acne, but this article will only focus on acne vulgaris, the most common form.
Hairs grow from hair follicles in the skin, that are associated with oil or sebaceous glands. Together this is called the pilosebaceous unit. Acne vulgaris is comprised of both inflammatory (papules and pustules) and non-inflammatory (open and closed comedones), together with seborrhoea (excess grease) and colonisation by a type of bacteria called Propionibacterium acnes or Cutibacterium acnes. The exact sequence of events and how they happen remains unclear (2).
Risk factors for acne vulgaris are still not fully known, but having a family member who suffers from the condition doubles the risk of significant acne, smoking is also associated with the condition, using greasy skin products, and sweating are also thought to contribute (2).
There is no good evidence that acne is caused or cured by washing, but antibacterial skin cleaners might help mild acne (2). However, excessive scrubbing and washing can remove oil from the skin surface, drying the skin, and stimulating more oil production which worsens the condition(2).
If you are affected by moderate or severe disease, or are struggling with the psychological impact of milder disease, then its best to seek medical advice. There are many pharmaceutical treatments that can be reviewed here and discussed with your GP. https://www.nhs.uk/conditions/acne/treatment/
Studies investigating diet are notoriously difficult, because ‘blinding’ the food to both the participant and medical staff running the trial is challenging and costly. Therefore, research is often of a lower quality than that for investigating a new drug, where it is easy to provide a visual replicate as a placebo. However, there are still a number of trials looking at the influence of diet on acne.
A Cochrane systemic review, looking at the results of multiple trials together, found that dairy products, especially milk, were associated with acne vulgaris. However, the observational studies that were included in this meta-analysis all had significant problems, and so it is difficult to draw robust conclusions about dairy from this review (6).
A number of small studies have found consumption of primarily skimmed milk was associated with increased breakouts, but did not find an association with other products made from milk such as yoghurt, and cheese (7). While there was some speculation that there might be fat soluble protective elements, there is other evidence that suggests that all dairy has a similar effect (8).
Another meta-analysis, combining the results of 14 studies (totalling over 78000 participants), some of which overlapped with the Cochrane review above, found that all dairy products were associated with acne (9). Whey protein has also been associated with exacerbated acne of the trunk in a cohort of bodybuilders (8).
When milk is digested and broken down into amino acids, this promotes Insulin secretion and Insulin Like Growth Factor 1 (IGF1) synthesis. Dairy also contains bovine IGF-1, and dihydrotestosterone (DHT), a precursor of IGF1. IGF1 stimulates follicular growth, sebum production, keratinisation (maturation of the skin cells as they rise to the top layers of the skin, becoming filled with keratin) and androgen hormone production. IGF1 is therefore suggested to be an important driver of acne (9). One study found that polymorphisms (genetic variants) of IGF1, were associated with increased risk of acne (10). While plasma levels of IGF1 have been found to correlate with severity of acne in a study of 80 people (11).
With a plausible mechanism of action and some clinical research, albeit it limited, it is worth considering a trial without dairy to see if this might help you.
A small cross-over study compared milk chocolate consumption with sugar in the form of jelly beans and found that chocolate consumption significantly increased the mean number of acne lesions (12). There are limitations with this study, including small size and that only milk chocolate was investigated, which is high in dairy. Further research is needed to look at dark chocolate to investigate if it was the dairy component of milk chocolate that might have been having an effect.
High Glycaemic Index
It has been proposed that high glycaemic loads in Western diets could have a role in acne, potentially again through increased insulin-like growth-factor 1 (IGF1), and altered retinoid signalling, (explained more below) (2). The apparent absence of acne in native non-Westernised people in Paraguay and Papua New with a whole food, unprocessed low glycaemic index diet lend some support this proposal (2).
As part of a wider Cochrane Review of complementary therapies for acne vulgaris, no clear evidence of difference between non-inflammatory lesion counts was seen between diets with a high or low glycaemic load after 12 weeks (1). However, data from one of these trials, found the low glycaemic index diet was associated with reduced inflammatory lesions and total skin lesion counts (1). Data from the second trial was not of sufficient quality to be able to draw further conclusions (1). It is not known what role if any low carbohydrate (ketogenic) diets play in the control of acne.
Western diets are more likely to be loaded with high glycaemic index or refined carbohydrates, saturated fat and dairy. Additionally, these factors contribute to the diversity of gut microbiota, that may play a wider role in skin health (13). Exactly how these different factors affect acne individually and combined together, needs to be further understood but seem mechanistically plausible (14).
Western diets provide an abundant source of branched chain amino acids (BCAAs), glutamine and palmitate (15). Increased insulin and IGF1 production as a result of high glycaemic load and dairy intake have been associated with increased production of androgen hormones and sebum, both seen in acne (14). Insulin and IGF1 also suppresses the activity of Forkhead Box protein 01 (FoxO1). FoxO1 is a transcription factor that has an important role in controlling the regulation of gluconeogenesis (synthesis of new glucose) and glycolysis (breakdown of glycogen for gluconeogenesis) by insulin signalling (16). Insulin, IGF-1, BCAAs, glutamine, and palmitate all activate the nutrient sensitive mechanistic target of rapamycin (mTOR) pathway, which is a key regulator of lipogenesis (fat synthesis) and promotes sebum production (15). Free palmitate functions as a “danger signal,” stimulating inflammation and keratinocyte proliferation (15). This thought to lead to the formation of comedones, but more research is needed (17).
There are theories that diets rich in omega 3 may help suppress inflammatory cytokine production, and therefore be beneficial to acne (18). Omega 3 inhibits synthesis of the pro-inflammatory molecule leukotriene B4 and decreases IGF1 (18). Limited studies have been performed to investigate the role of a diet high in omega 3 and acne, but of those small studies performed, results were supportive of omega 3 having a beneficial effect (18). Western diets are generally much higher in omega 6 than 3, and could therefore have a detrimental effect on acne (14), but more research is needed.
Levels of antioxidants vitamin A and E have been found to be lower in a small study of 100 people with acne compared to people without (18). Animal studies of topical antioxidants found naturally in green tea have been found to reduce sebum formation via inhibition of the mTOR pathway (15,18). Resveratrol, a polyphenol compound, naturally occurring in red grapes, red wine, peanuts and eucalyptus has been found to kill P. acnes in vitro (18). However, whether antioxidants from plants in our can provide a realistic benefit to acne in humans is yet to be established.
An expanding body of research has highlighted the presence of a gut–brain–skin axis that connects gut microbes, oral probiotics, and diet that is potentially connected to acne severity. There is evidence that metabolites formed by the gut microbiota (micro-organisms) exert some effect on the mTOR pathway, which as discussed above, is suggested to play a role in acne (13). Having good gut health is beneficial for many chronic diseases, and may benefit your acne (13). What role probiotics have in acne requires further research.
Topical tea tree oil has been found to reduce total skin lesion counts and acne severity scores, but more higher quality trials are needed (1). A meta-analysis, grouping multiple trials together found that there was a lack of evidence to support wet-cupping and acupuncture in the treatment of acne vulgaris (1).
Overall the most comprehensive guidance on diet and acne to date comes from the 2016 American Academy of Dermatology (AAD) guidelines on the management of acne that came to three primary conclusions (7).
While more research needs to be performed to understand the risk factors for developing acne, and how diet impacts this process, there is certainly emerging evidence that is difficult to ignore. Evidence at present only demonstrates that diet may influence of aggravate existing acne, but is insufficient to cure it. Therefore, if you have acne, trial what dietary adjustments might work for you, but don’t delay getting medical help and guidance from your GP.
Taking together all we know about the potential relationship between diet and acne, you may choose to incorporate these tips into your weekly diet, to see if they help your acne. Writing a food and acne diary might help you to log whether you see an improvement or not.
Aim for a diet rich in:
If you are suffering have a look at talkhealth https://www.talkhealthpartnership.com/ that provides free acne support and community support. Even mild acne can cause considerable psychological distress so make sure you get help if you feel you need it.
Article Credit: Dr Harriet Holme (https://healthyeatingdr.com/)
18. Bowe WP, Joshi SS, Shalita AR. Diet and acne. J Am Acad Dermatol. 2010 Jul;63(1):124–41.
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