acne and gut health: understanding the gut-skin-immune axis.

If you’ve ever wondered whether your gut health could be affecting your acne, you’re not alone. It’s one of the most common questions I hear in clinic.

Over the last decade, scientists have become increasingly interested in what is known as the gut–skin axis-the complex two-way communication between our digestive system, immune system and skin. Research suggests that the microbes living in our gut, the foods we eat and our overall dietary pattern may influence inflammation throughout the body, including the skin.

That doesn’t mean acne is simply a “gut problem”. Nor does it mean that healing your gut will cure your skin. Acne is a complex condition with many contributing factors, including genetics, hormones, inflammation and the skin microbiome. Nutrition is one piece of the puzzle

The exciting news is that many of the same habits that support a healthy gut-eating a varied, fibre-rich diet, sleeping well, managing stress and exercising regularly-also support overall skin health.

In this article we’ll look at what the science really says about the gut–skin connection, where the evidence is strongest, and where we still need more research.

What Causes Acne?

Acne develops as a combination of several factors. Acne happens when oil, blocked pores (the pore is the hair follicle plus its oil gland) and the skin's own bacteria all interact. These in turn are influenced by many other factors such as genetics, hormones, skincare/makeup, pollution and nutrition. Let's break down these steps: 

1. Firstly, the sebaceous (oil) glands produce excess sebum. Sebum is essential for healthy skin, but too much can contribute to blocked pores.

2. Secondly, cells lining the hair follicle/oil gland become unusually sticky. Instead of shedding normally, they accumulate and block the follicle, forming congestion and comedones (blackheads and whiteheads).

3. Thirdly, a skin bacterium called Cutibacterium acnes normally lives on us harmlessly, but it can multiply inside blocked follicles. Certain strains appear more likely to trigger inflammation than others. This is how the skin microbiome contributes to acne and breakouts.

4. Finally, the immune system responds, leading to the red, swollen and sometimes painful spots that characterise inflammatory acne.

These processes are influenced by many factors, including:

• Genetics: If acne runs in your family, you are more likely to experience it

• Hormones: Hormonal fluctuations around the menstrual cycle, puberty and perimenopause can all contribute to acne flare up inflammation

• Stress: Increased cortisol can alter oil production and increase breakouts

• Certain skincare products: Pore-blocking ingredients and heavy makeup which is not properly removed can lead to congestion and breakouts

Rather than one single cause, acne results from several pathways interacting together.

Adult female acne

Although acne is often thought of as a teenage condition, many women continue to experience breakouts into their 30s, 40s and beyond. It is influenced by many factors but hormones are of particular importance. Sometimes Adult female acne can reveal itself when patients stop their contraceptive pill, which can sometimes mask symptoms.

Spots typically affect the jawline, chin and lower face and may flare before around the time of your periods. Hormonal fluctuations clearly play an important role, but inflammation, stress, sleep, diet and genetics can all contribute. If you also have irregular periods or notice other symptoms such as extra chin hair, it's worth getting checked for PCOS/PMOS (polycystic ovary syndrome/polyendocrine metabolic ovarian syndrome), which can drive adult acne. 

What Is the Gut–Skin Axis?

The gut contains trillions of bacteria, viruses and fungi, collectively known as the gut microbiome. These microorganisms help digest food, produce vitamins, ferment dietary fibre into anti-inflammatory short-chain fatty acids and play a crucial role in educating the immune system. As many skin conditions are governed by inflammation and the immune system, the gut-skin axis is an exciting area of research.

The skin also has its own microbiome. Although these are distinct communities, they communicate indirectly through the immune system, hormones and metabolites circulating throughout the body. This communication network is known as the gut–skin axis.

Can gut inflammation influence skin inflammation?

A large proportion of the body's immune cells are associated with the gut. A healthy gut helps to keep it balanced; an out-of-balance gut (sometimes called dysbiosis) may contribute to chronic low-grade inflammation. 

Inflammation is central to acne. Researchers are therefore investigating whether changes within the gut microbiome might influence inflammatory skin diseases, including acne. At present, this remains an area of active research rather than established clinical fact.

How might intestinal permeability affect the skin?

The intestine acts as a carefully regulated barrier, allowing nutrients into the bloodstream while keeping bacteria and toxins inside the gut.

Some inflammatory diseases have been associated with increased intestinal permeability (sometimes known as ‘leaky gut’). Whether this contributes directly to acne remains uncertain.

Although the phrase “leaky gut” is widely used online, it often oversimplifies a complex area of science. Current evidence does not support testing or treating “leaky gut” as a routine part of acne management.

Does the microbiome influence acne severity?

Gut bacteria produce many compounds that circulate throughout the body.

Short-chain fatty acids-particularly butyrate, acetate and propionate-are produced when gut bacteria ferment dietary fibre. These molecules appear to have anti-inflammatory effects and help maintain the intestinal barrier.

Researchers are exploring whether these metabolites could also influence inflammatory skin diseases, but much remains to be understood

How Does Hormonal Acne Connect to Gut Health?

Many women notice that their acne follows a hormonal pattern, flaring around the jawline and chin in the week before their period. It’s natural to wonder whether improving gut health might help.

The honest answer is that the gut is unlikely to be the primary cause of hormonal acne, but it may influence some of the biological pathways involved.

Hormonal acne is largely driven by androgens-hormones such as testosterone-which stimulate the sebaceous glands to produce more oil. Some women with hormonal acne have raised androgen levels, as seen in conditions such as polycystic ovary syndrome (PCOS), while many have completely normal hormone levels but increased sensitivity of the sebaceous glands to these hormones.

The gut microbiome does not directly control these hormones. However, it may influence broader metabolic and inflammatory pathways that interact with them.

One example is insulin and insulin-like growth factor-1 (IGF-1). Diets high in rapidly absorbed carbohydrates can increase insulin and a growth hormone called IGF-1. Both make the skin produce more oil, grow more cells and inflame more easily. These pathways are well recognised in acne biology and provide one of the strongest biological links between diet and acne.

There is also growing interest in the estrobolome-the collection of gut bacteria involved in oestrogen metabolism. The gut microbiome influences how oestrogens are metabolised and recycled within the body. Although this is a fascinating area of research, there is currently no convincing evidence that modifying the estrobolome improves acne, and much of the discussion online goes far beyond the available science.

Overall, it’s best to think of hormonal acne as the result of several interacting systems. Hormones, genetics, inflammation, diet, stress, sleep and the skin microbiome all play a role. The gut may influence some of these pathways, but it is unlikely to be the sole driver

Why does acne flare around your period?

Many women experience breakouts in the week before menstruation or a flare up of existing acne can also occur during this time.

This is thought to reflect changes in hormone levels across the menstrual cycle. Just before your period actually starts, progesterone levels are high and oestrogen levels are lower. Progesterone acts on oil glands and increases oil production during this time, contributing to breakouts and flare ups. In the same way, the progesterone only contraceptive or sometimes hormonal coil can worsen acne and breakouts.

Stress, poor sleep and dietary changes can compound this. Many people report stronger cravings for sugary foods during the premenstrual phase, although it’s important not to assume these foods directly “cause” the flare.

If your acne is predictable, tracking your menstrual cycle can be helpful. It may allow you to identify patterns and discuss targeted treatments with your dermatologist or GP.

Does Diet Affect Acne?

This is one of the most researched questions in dermatology, and the evidence has become much stronger over the last 15 years. That said, diet should be viewed as one contributing factor, rather than the single cause of acne. The strongest evidence relates to overall dietary patterns rather than individual “good” or “bad” foods.

What Does the Evidence Show?

1. Low-glycaemic diets

Studies suggest that diets with a lower glycaemic load can reduce acne lesion counts in some people, particularly inflammatory acne. These diets help reduce large spikes in blood glucose and insulin after meals. Raised insulin levels,/IGF1 particularly in those with hormonal imbalances can contribute to breakouts in some people.

Practical ways to lower the glycaemic load include:

• choosing wholegrain rather than refined carbohydrates

• including protein and healthy fats with meals

• eating plenty of legumes

• avoiding sugary drinks

• limiting highly processed snack foods.

This doesn’t mean carbohydrates are “bad”. Wholegrains, oats, beans and fruits and lentils are all excellent foods that support both gut and metabolic health. Sugar is part of a balanced diet and not something to be feared

2. Mediterranean-style diets

We don't have many trials yet, but observational studies -including our own work using UK Biobank data-suggest that greater adherence to a Mediterranean-style dietary pattern is associated with lower odds of adult acne.

Mediterranean diets are naturally rich in:

• vegetables

• fruit

• legumes

• wholegrains

• extra virgin olive oil

• nuts

• fish.

These foods are rich in fibre, plant compounds (called polyphenols) and unsaturated fats that are good for your heart and may calm inflammation throughout the body. 

However, it’s important to remember that these studies show associations rather than proof of cause and effect. People following Mediterranean diets may also have healthier lifestyles in other ways that contribute to better skin.

3. Dairy

Several observational studies link acne with milk - especially skimmed - while fermented dairy like yoghurt shows a weaker link, or none. 

Why might different dairy foods behave differently?

Several explanations have been proposed:

• differences in protein composition, particularly whey proteins

• insulin and IGF-1 responses

• fermentation

• the food matrix

• sugar content in flavoured dairy products.

At present, no single mechanism has been proven.

For most people, I do not recommend eliminating dairy routinely. Dairy is an important source of calcium, iodine and protein. If someone notices a clear and reproducible relationship between a particular dairy product and their acne, it may be reasonable to reduce that food while ensuring nutritional adequacy elsewhere.

4. Chocolate

Chocolate is frequently blamed for acne. The evidence is surprisingly mixed.

Small studies have suggested that certain types of chocolate may worsen acne in some individuals, but separating the effects of cocoa from sugar, milk and fat is difficult.

Current evidence is insufficient to recommend avoiding chocolate altogether, although frequent consumption of highly processed confectionery is unlikely to benefit overall health. Stick to dark chocolate where possible as this carries additional health benefits.

What Should You Eat Instead?

Rather than focusing on foods to avoid, think about what foods you can incorporate into your diet to improve your overall health and gut health including plenty of fibre and pre-biotic, probiotic foods.

Aim for a dietary pattern rich in:

• colourful vegetables

• fruit

• beans and lentils

• wholegrains

• nuts and seeds

• extra virgin olive oil

• oily fish

• fermented foods such as natural yoghurt and kefir

Importantly, there is no single “acne diet” that works for everyone. Individual responses vary considerably, and restrictive diets can often do more harm than good.

Can Probiotics Help With Acne?

Interest in probiotics has grown enormously over the past decade, fuelled by increasing research into the gut microbiome and the gut–skin axis. Although the biology remains compelling, clinical evidence remains limited. . A small number of clinical trials suggest that probiotics may be helpful alongside medical treatments for acne. Most studies used a different multi-strain probiotic making it difficult to identify one optimal species or strain

However, probiotics should not be viewed as a replacement for evidence-based acne therapies, and we cannot yet recommend one specific strain or product for everyone.

Scientists think probiotics could influence acne through several mechanisms.

Firstly, they may help support a more diverse gut microbiome. A healthy microbiome produces short-chain fatty acids, such as butyrate, which help maintain the intestinal barrier and regulate immune function.

Secondly, probiotics may help reduce systemic inflammation. Laboratory studies suggest some strains can influence inflammatory signalling pathways involved in acne, although demonstrating this consistently in humans is much more challenging.

Importantly, these mechanisms are still being investigated, and not every probiotic behaves in the same way.

How long do probiotics take to help skin?

Looking at published studies, if probiotics are helpful, participants typically saw an improvement by 12 weeks.

What Lifestyle Changes Support Gut Health for Clearer Skin?

One of the simplest ways to support your gut microbiome is to increase dietary diversity.

Different gut bacteria thrive on different types of fibre and plant compounds, so eating a wider range of plant foods helps support a more diverse microbiome.

A useful goal is to aim for around 30 different plant foods each week.

This includes:

• vegetables

• fruit

• beans

• lentils

• herbs

• spices

• nuts

• seeds

• wholegrains.

It’s not about eating large quantities of each food-small amounts all contribute.

This approach naturally increases fibre and polyphenol intake, both of which support beneficial gut bacteria.

Include fermented foods if you enjoy them

Fermented foods such as natural yoghurt, kefir, kimchi, sauerkraut and miso contain live microorganisms or fermentation products that may benefit the gut microbiome

The evidence is still evolving, but including fermented foods as part of a balanced diet is a sensible strategy for many people.

There’s currently stronger evidence for eating fermented foods than taking probiotic supplements indiscriminately.

Prioritise sleep

Poor sleep is associated with increased inflammation, impaired immune regulation and higher perceived stress-all of which may contribute to acne. Most adults should aim for around seven to nine hours of sleep each night.

Manage stress

Many patients notice their skin flares during stressful periods.

Stress doesn’t directly cause acne, but it can worsen existing acne through multiple pathways involving cortisol as previously discussed.

Regular exercise, mindfulness, spending time outdoors and maintaining social connections can all support mental wellbeing, with potential downstream benefits for skin health.

Putting It All Together

Acne is a complex condition. Genetics, hormones, inflammation, the skin microbiome, lifestyle and diet all interact, and no single intervention works for everyone.

The emerging science around the gut–skin axis is exciting because it encourages us to think about skin health in a more holistic way. However, it’s important not to overstate what we currently know.

At present, the strongest dietary evidence supports:

• a minimally processed dietary pattern rich in vegetables, fruit, legumes and wholegrains

• choosing lower glycaemic carbohydrates where possible

• eating plenty of fibre

• maintaining a healthy overall dietary pattern, such as a Mediterranean-style diet.

The evidence for probiotics is encouraging but remains preliminary. They may have a role as part of a broader approach, particularly in people interested in supporting gut health, but they should not replace proven acne treatments where these are needed.

For many people, the biggest gains come not from eliminating individual foods but from consistently building healthier habits that support both gut and skin health over the long term.

Minimise excessive alcohol and ultra-processed foods

Rather than completely avoiding, try to keep alcohol and ultraprocessed foods to a minimum as these can both impact the gut microbiome and long term health.