Acne and nutrition

Source: Jeleefstijlalsmedicijn

Reviewer: Drs. Samantha Jordaans, Knowledge Institute Nutrition and Skin

Key messages from this article (14 minutes reading time):

How common is acne: Acne affects 80-95% of young people (12-24 years) and 40-54% of adults over 25 years, with higher percentages in people with overweight.
Western paradox: Acne is virtually absent in traditional peoples such as the Inuit and Kitavan, suggesting a connection with Western diet and lifestyle.
Known causes: Acne is conventionally attributed to four factors: excessive sebum production, accumulation of dead skin cells, bacterial growth, and inflammatory reactions.
Medical treatments: Conventional treatments (retinoids, antibiotics, isotretinoin) fight symptoms but have side effects and do not address the underlying cause.
Metabolic connection: Recent research shows that insulin resistance plays a crucial role in acne by influencing all four traditional causal factors.
Insulin resistance: Is caused by ultra-processed food (61% of Dutch calorie consumption), foods with high glycemic load, chronic stress, and lack of exercise.
Influence of nutrition: A 2007 study showed 51% decrease in acne lesions with a low glycemic load diet; a 2024 study found 31% reduction of acne with a ketogenic diet.
Metformin effect: The diabetes medication metformin, which counteracts insulin resistance, also appears effective against acne, further confirming the metabolic link.
Natural approach: A low-carbohydrate diet rich in unprocessed products can reduce acne by improving insulin sensitivity, without the side effects of medication.

1. Introduction

Everyone knows acne, whether it involves a few stubborn pimples or severe inflammations that leave scars. Although acne is often seen as a typical puberty problem, millions of adults also struggle with it. Traditional treatments focus on fighting bacteria and reducing sebum production, but this approach only treats the symptoms, not the underlying cause.

What if acne is not just a skin problem, but also a signal of underlying metabolic processes influenced by our Western lifestyle and diet? Recent scientific insights suggest that insulin resistance may play an important role in acne. The traditional explanation for acne is based on four mechanisms: increased sebum production, accumulation of dead skin cells, bacterial growth, and inflammatory reactions. New research shows that nutrition, particularly dietary patterns with a high glycemic load, can influence these mechanisms. This may explain why changes in dietary patterns show a positive effect on the severity of the condition in some studies.

In this article, we look at the role of nutrition and insulin in the development of acne. We show how reducing refined carbohydrates and sugar and a dietary pattern of mainly unprocessed products can reduce acne, supported by scientific evidence.

2. What is acne?

Acne vulgaris is a chronic inflammatory skin condition that occurs in the sebaceous glands and hair follicles. It is characterized by a combination of blackheads, pimples, and cysts, which mainly occur on facial skin, chest, and back, where the sebaceous glands are most active. The severity of acne can range from mild blackheads to deep inflamed cysts that can leave permanent scars. Acne has not only a physical impact but can also have psychological consequences, such as reduced self-confidence, anxiety, and depression (Behrangi, 2019).

3. How common is acne?

Acne is one of the most common dermatological conditions and affects an estimated 80-95% of people between 12 and 24 years old. Although acne is often associated with puberty, it also occurs frequently in adults, especially in women. Studies show that 40-54% of people over 25 years old still suffer from acne, while 12% of women and 3% of men even struggle with acne into middle age (Smith, 2007). Notably, in people with overweight and obesity, acne occurs two to three times more often than in people at a normal weight (Heng, 2020).

Acne: a disease of Western civilization?
Studies show that acne is almost completely absent in traditional peoples such as the Inuit, the inhabitants of Okinawa (Japan), Kitavan (an island in Papua New Guinea), and the Aché hunter-gatherers from Paraguay (Smith, 2007).

To give an example, during a medical inspection in 1990 of 1,200 inhabitants of Kitavan (including 300 people aged 15 to 25), not a single person had acne. When examining the skin of all 115 Achés, no one had a pimple or blackhead (Cordain, 2002).

In short, these people eat and live completely differently than we do in the West. This leads to the question: could our dietary pattern and lifestyle play a role in the development of acne? To investigate this, we first need to know more about the causes of acne.

4. What are the causes of acne?

According to the traditional medical approach, the four main factors that contribute to the development of acne are:

Excessive sebum production: Sebum is an oily substance that is produced by the sebaceous glands and protects the skin. When production is increased, pores can become clogged and inflamed.
Accumulation of dead skin cells: Hyperkeratinization is a process where skin cells grow and die too quickly in the hair follicles. These dead cells accumulate and clog the pores, resulting in the formation of blackheads.
Bacterial growth: The bacterium Cutibacterium acnes feeds on excess sebum and causes inflammatory reactions in the skin.
Inflammation: The accumulation of sebum and bacteria triggers an immune response, leading to redness, swelling, and pus formation.

5. Current pharmacological treatments and their limitations

The conventional treatment of acne focuses mainly on reducing sebum production, bacterial growth, and inflammation. For this, topical retinoids, benzoyl peroxide, oral antibiotics, hormonal therapies, and isotretinoin are often used (Behrangi, 2019). Although these agents can suppress acne, they do not solve the underlying cause and are accompanied by significant side effects.

Topical agents such as retinoids and benzoyl peroxide often cause skin irritation and dryness, while oral antibiotics with prolonged use can lead to antibiotic resistance and intestinal problems. Hormonal therapies only work in women and carry risks such as mood swings and changes in the menstrual cycle (Yen, 2020). Isotretinoin, the most effective therapy, has potentially serious side effects, including liver function disorders and depressive symptoms, and requires strict medical monitoring (Behrangi, 2019).

The biggest disadvantage of these treatments is that they focus on symptom management and do not address the underlying metabolic factors, such as insulin resistance and hormonal disruptions. As a result, acne often returns after stopping medication. This underscores the need for a broader approach, where not only the skin is treated but also metabolic health is optimized (Smith, 2007, Yen, 2020).

6. Metabolic causes and background

As discussed, acne is traditionally attributed to four factors: increased sebum production, hyperkeratinization and clogging, bacterial overgrowth, and inflammation. Recent research, however, shows that these factors are in turn influenced by insulin resistance, a metabolic disruption that has a profound effect on the skin (Szefler, 2024).

6.1. What is insulin resistance?

Insulin resistance occurs when cells in the body become less sensitive to the action of insulin, a hormone that helps regulate blood sugar levels. Consuming a lot of ultra-processed food (such as candy and soft drinks) and quickly digestible carbohydrates (from white bread, pasta, and fruit juices) forces the pancreas to produce extra insulin, leading to chronically elevated insulin levels (hyperinsulinemia). This condition is a characteristic of various metabolic conditions, including obesity, type 2 diabetes, and PCOS (polycystic ovary syndrome), but also plays a crucial role in acne.

6.2. How common is insulin resistance?

Insulin resistance is common. The exact numbers are not known because doctors do not routinely test for it. What is known is that 2.5 million Dutch people have prediabetes or type 2 diabetes (Diabetes Fonds, 2024). In these conditions, insulin resistance is already advanced, with the body already unable to keep blood sugar levels at healthy levels. The number of people with insulin resistance is probably much higher than these 2.5 million, because insulin resistance occurs years, sometimes even decades, earlier before the diagnosis of (pre)diabetes is established.

6.3. How does insulin resistance contribute to acne?

Insulin resistance affects the four traditional causes of acne in various ways:

Increased sebum production: Insulin directly stimulates the sebaceous glands to produce more sebum (skin oil), which increases the chance of clogged pores. Additionally, insulin increases the release of androgens (male hormones like testosterone), which make the sebaceous glands even more active (Smith, 2007).
Accumulation of dead skin cells: Insulin and the related hormone IGF-1 (insulin-like growth factor 1) accelerate the growth and shedding of skin cells (keratinocytes). This leads to an accumulation of dead skin cells, which together with excess sebum clog the pores (Smith, 2007).
Bacterial overgrowth: An environment with excess sebum and dead skin cells forms an ideal breeding ground for Cutibacterium acnes, the bacterium that worsens acne. Additionally, an insulin-driven increase in glucose in the sebum can be an extra growth factor for this bacterium (Melnik, 2012)
Inflammatory reactions: Insulin resistance increases systemic inflammation by stimulating pro-inflammatory cytokines, such as TNF-alpha and interleukins. This leads to an overreaction of the immune system, resulting in the redness, swelling, and pus formation that are characteristic of severe acne (Szefler, 2024).

Box: Metformin as treatment for acne

Metformin is a medication used for the treatment of type 2 diabetes, an advanced form of insulin resistance. Metformin works by improving insulin sensitivity and reducing insulin production.
However, metformin also appears to work for acne. Several studies have shown that metformin can reduce acne (Behrangi, 2019, Yen, 2020, Szefler, 2024). Why is this relevant? This research shows that by counteracting insulin resistance, acne improves.

2024](https://pubmed.ncbi.nlm.nih.gov/38931395/)\
We mention this not to recommend metformin as a medication for acne, but as evidence that acne has a metabolic component and is related to insulin resistance.

6.4. What causes insulin resistance?

Several factors contribute to the development of insulin resistance, the most important being:

Ultra-processed food. Industrially produced food (such as fast food, chips, cookies, soft drinks, and ready-made meals) contains many added sugars, refined carbohydrates, and unhealthy fats that contribute to insulin resistance. We eat a lot of this ultra-processed food: 61% of the calorie consumption of the average Dutch person is ultra-processed food (even 75% for children) (Vellinga, 2022). In the supermarket, 70% of all food products are ultra-processed.
Foods with high glycemic load: Diets rich in refined carbohydrates (white bread, pasta, fruit juice) cause rapid blood sugar spikes, leading to increased insulin production and contributing to insulin resistance in the long term.
Chronic stress: Stress hormones like cortisol indirectly increase insulin resistance by raising blood sugar levels, which in turn increases insulin production.
Sleep deprivation and sitting: Lack of sleep and lack of physical exercise reduce the effectiveness of insulin and contribute to metabolic disruptions.

7. Treatment of acne with a low-carbohydrate diet

More and more research indicates that nutrition plays a crucial role in the development and severity of acne. A dietary pattern with lots of ultra-processed food and a high glycemic load seems to worsen acne. As a result, researchers have become increasingly interested in the possible benefits of a low-carbohydrate diet as treatment for acne. A number of studies show effect:

7.1. Study on a low-glycemic diet and acne

Low-glycemic foods cause a slower rise in blood sugar levels and include whole grain products, legumes (such as lentils and chickpeas), non-starchy vegetables (such as broccoli and leafy greens), and certain types of fruit (such as berries and apples)

In a groundbreaking 2007 study, it was first demonstrated that a diet with a low glycemic load had a significantly positive effect on acne. Men with acne who followed a diet rich in proteins and complex carbohydrates (whole grain bread, legumes, broccoli) for twelve weeks saw a 51% decrease in the number of acne lesions and improvements in their insulin sensitivity (Smith, 2007).

In this table you can find the glycemic load of more than one hundred foods.

7.2. Effects of a ketogenic diet on acne

A ketogenic diet is characterized by a very low carbohydrate content (usually less than 50 grams per day) and a high fat intake, with emphasis on foods such as fatty fish (salmon, mackerel), meat, eggs, cheese, nuts, seeds, avocados, and healthy oils (coconut oil, olive oil).

Recently, in 2024, a study was published examining the effects of a very low-calorie ketogenic diet on acne. For 45 days, women with moderate acne and an elevated BMI followed a strict low-carbohydrate diet. The study showed that acne severity decreased by 31% (measured with the Global Acne Grading System score) and the impact on quality of life improved by 45% (measured with the Dermatology Life Quality Index) (Verde, 2024).

Carbohydrate restriction seems to work here as well. We do want to note that a low-calorie diet (a diet with few calories) is sustainable for almost no one. It is not a good idea to follow such a diet without guidance.

Box: what about dairy, chocolate, and fats?

Much research has been done on the elimination of individual foods, such as dairy, chocolate, or fats. However, this research does not provide convincing evidence that eliminating such food really helps control acne.
Much of this research is ‘observational research,’ where large groups of people are followed. From this type of research, associations can emerge, but this kind of research cannot demonstrate that one thing (dairy) causes or worsens the other (acne).

Only randomized studies (so-called RCTs or randomized controlled trials) can provide such evidence. RCTs are studies where one group does and the other group does not eat these foods. If it then turns out that one group has more acne than the other, only then can you speak of a cause-and-effect relationship. But even then, it is important that the studies were well conducted and enough people participated to prove this conclusively.

Is there such strong RCT evidence for these three foods? We use a recent review study by Rygula from 2024:

* Dairy. Rygula found 19 studies that showed the connection between acne and dairy. However, only one of these studies was a randomized study (Kara, 2020). This one study showed that eating more cheese led to more scars. However, it is a small study with 53 participants. In short, the evidence for a causal relationship between dairy and acne is weak.

* Chocolate. Here Rygula found three randomized studies. From these studies, it appeared that chocolate contributed to acne. However, these are small studies with a total of only 72 participants.

* Fat. Rygula identified four studies that showed a connection between fatty food and acne. None of these studies was a randomized study. The evidence from this research is therefore weak.

In short, it may be that these three foods contribute to acne, but there is much less evidence for this than for adjusting the complete dietary pattern, aimed at avoiding insulin resistance. Should someone nevertheless want to find out if one of these foods is a ‘trigger’ for acne, it helps to do this under the guidance of a dietitian and — if it is a trigger — to look for adequate alternatives.

8. Conclusion

Although further studies are needed to better understand the exact mechanisms and long-term effects of carbohydrate restriction or a low-glycemic dietary pattern on acne, the current findings seem to confirm that nutrition can be a powerful tool in the treatment of acne. This offers an attractive, natural approach that not only improves the skin but also contributes to better overall health (and a healthy weight).

Veelgestelde vragen

Is there a connection between nutrition and acne?

Yes, recent scientific insights show that dietary patterns with many refined carbohydrates and sugars can cause insulin resistance, which negatively affects sebum production, accumulation of dead skin cells, bacterial growth, and inflammatory reactions.

Does a low-carbohydrate diet help against acne?

Research shows that carbohydrate restriction can be effective. A 2007 study showed a 51% decrease in acne lesions with a low-glycemic diet. Recent 2024 research on a ketogenic diet showed a 31% reduction.

What is the link between insulin resistance and pimples?

Insulin resistance increases sebum production, stimulates androgens, accelerates accumulation of dead skin cells, and strengthens inflammatory reactions - all factors that contribute to acne.

Why do adults also suffer from acne?

Acne occurs in 40-54% of people over 25 years old, especially in women. The cause often lies in metabolic factors such as insulin resistance, which are influenced by nutrition.

How can I treat acne naturally without medication?

A natural approach is avoiding ultra-processed food, limiting foods with high glycemic load, eating more unprocessed products, reducing stress, and getting enough sleep. This addresses the underlying metabolic causes.

10. Scientific references on acne and nutrition

Behrangi, E., Sadeghi, S., Sadeghzadeh-Bazargan, A., Goodarzi, A., Ghassemi, M., Sepasgozar, S., & Rohaninasab, M. (2019). The effect of metformin in the treatment of intractable and late onset acne: A comparison with oral isotretinoin. Iranian Journal of Dermatology, 22(2), 47—52.\
Cordain, L., Lindeberg, S., Hurtado, M., Hill, K., Eaton, S. B., & Brand-Miller, J. (2002). Acne vulgaris: A disease of Western civilization. Archives of Dermatology, 138(12), 1584—1590. https://doi.org/10.1001/archderm.138.12.1584\
Diabetes Fonds. (2024). Diabetes in cijfers. https://www.diabetesfonds.nl/over-diabetes/diabetes-in-het-algemeen/diabetes-in-cijfers\
Heng, A. H. S., & Chew, F. T. (2020). Systematic review of the epidemiology of acne vulgaris. Scientific Reports, 10(1), 5754. https://doi.org/10.1038/s41598-020-62715-3\
Melnik, B. C. (2012). Diet in acne: Further evidence for the role of nutrient signalling in acne pathogenesis. Acta Dermato-Venereologica, 92(3), 228—231. https://doi.org/10.2340/00015555-1358\
Ryguła, I., Pikiewicz, W., & Kaminiów, K. (2024). Impact of diet and nutrition in patients with acne vulgaris. Nutrients, 16(10), 1476. https://doi.org/10.3390/nu16101476\
Smith, R. N., Mann, N. J., Braue, A., Mäkeläinen, H., & Varigos, G. A. (2007). A low-glycemic-load diet improves symptoms in acne vulgaris patients: A randomized controlled trial. American Journal of Clinical Nutrition, 86(1), 107—115. https://doi.org/10.1093/ajcn/86.1.107\
Szefler, L., Szybiak-Skora, W., Sadowska-Przytocka, A., Zaba, R., Wieckowska, B., & Lacka, K. (2024). Metformin therapy for acne vulgaris: A meta-analysis. Pharmaceuticals, 17(6), 728. https://doi.org/10.3390/ph17060728\
Vellinga, R. E., van Bakel, M., Biesbroek, S., Toxopeus, I. B., de Valk, E., Hollander, A., van ‘t Veer, P., & Temme, E. H. M. (2022). Evaluation of foods, drinks and diets in the Netherlands according to the degree of processing for nutritional quality, environmental impact and food costs. BMC Public Health, 22(1), 877. https://doi.org/10.1186/s12889-022-13282-x\
Verde, L., Frias-Toral, E., Cacciapuoti, S., Simancas-Racines, D., Megna, M., Caiazzo, G., Potestio, L., Maisto, M., Tenore, G. C., Colao, A., Savastano, S., Muscogiuri, G., & Barrea, L. (2024). Very low-calorie ketogenic diet (VLCKD): A therapeutic nutritional tool for acne? Journal of Translational Medicine, 22(1), 322. https://doi.org/10.1186/s12967-024-05119-5\
Yen, H., Chang, Y.-T., Yee, F.-J., & Huang, Y.-C. (2021). Metformin therapy for acne in patients with polycystic ovary syndrome: A systematic review and meta-analysis. American Journal of Clinical Dermatology, 22(1), 11—23. https://doi.org/10.1007/s40257-020-00565-5

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