Have you ever wondered whether diet affects your skin? You’re not alone. Over 40% of young adults believe certain foods aggravate their acne.[1,2]
Acne is the world’s most common skin condition, affecting 85% of adolescents and 50% of young adults aged 20-29.[3,4] Over the last few decades, doctors have reported a significant increase in the number of adult women, in particular, seeking help for acne.[5]
The relationship between your diet and acne, and more specifically dairy and acne, is a controversial topic that medical professionals have debated since the 1800s.
But, does dairy really cause acne? Let’s take a look at the basics before we delve into the specifics behind the dairy and skin relationship.
What is Acne?
Acne is an inflammatory skin condition characterized by the formation of pimples (whiteheads, blackheads, cysts, nodules, you name it) in areas rich in sebaceous glands, such as the face, back, and chest.
The condition is considered multifactorial, meaning it is caused by a variety of different elements, including increased sebum production, inflammation, bacteria, and abnormal skin cell renewal. The condition is largely under hormonal control but has been linked to genetics, psychological stress, and diet.
Is there a Link Between Dairy and Skin?
The relationship between dairy and skin dates back to 1885 when an observational study involving 1,500 patients reported the acne-exacerbating effects of milk consumption [6]. Another study in 1949 claimed milk was the most common food implicated in breakouts amongst 1,925 acne patients who kept food diaries [7]. Early studies like this formed the basis of acne treatment prior to the sixties, which routinely involved dietary advice such as limiting sugar and dairy intake.
It wasn’t until 2005, that the Journal of American Academy of Dermatology published the first large-scale epidemiology study on the topic. The Nurses Health Study II investigated the dietary habits of 47,000 nurses and found that those who drank more milk during adolescence had higher rates of severe acne than those who consumed little to no milk. Interestingly, skim milk had the strongest correlation with acne.[8]
In 2006, a prospective study called Growing Up Today observed the dietary habits of 6,000 girls aged from 9 to 15 years. An association between the prevalence of acne and the intake of whole milk, low-fat milk, and skim milk was demonstrated [28]. Two years later, the same researchers further corroborated the link between dairy and acne with another study that included over 4,000 teenage boys. However, in this study, the results demonstrated a stronger link between acne and skim milk again.[29]
Recent Studies into Dairy and Acne
Studies outside the United States have also demonstrated a link between dairy and acne. A case-control study in 2012 asked 88 patients from Malaysia to complete a food diary for three days. Researchers found that higher intakes of dairy, particularly ice cream and milk, increased acne severity.[9]
In 2016, a study examined the self-reported consumption of dairy products among Norwegian adolescents aged 15-16 years over the course of three months. The study found that high total intakes of dairy (classed as two or more glasses per day) were associated with moderate to severe acne [10]. In the same year, a cross-sectional study examined the dietary habits and history of acne among 464 adolescents in Nigeria over the course of 12 months and found the prevalence of acne was 10% higher among those who reported consuming dairy milk on a daily basis.[11]
A substantial amount of evidence has accumulated over the last decade to suggest consuming dairy and milk products exacerbate acne. However, it’s important to note, the majority of evidence relies on dietary recall and observational studies, which make it hard to draw a clear conclusion.
Acne and the Western Diet
While there’s a ton of evidence to support a link between diet and acne, the most damning could be that acne doesn’t exist in places unaffected by the Western diet. The “Western diet” is characterized by an overconsumption of refined grains, high-sugar foods, high-calorie dairy products, and animal meats. In recent years, the diet had been adopted by other developed and developing countries, which has accompanied a similar trend in the prevalence of acne as seen in the United States.
In 2002, Dr. Cordain studied the dietary habits and prevalence of acne among 1200 islanders in Papua New Guinea and 115 hunter-gatherers in Paraguay where eating habits were unaffected by the Western Diet. Both populations did not consume dairy and had low glycaemic diets rich in fruits, vegetables, and fish. Unsurprisingly, not one single case of acne was observed.[12] A similar pattern was observed amongst almost 2,214 adolescence in Peru. Indigenous people had a significantly lower prevalence of acne when compared to both white and mixed ancestry populations.[13] Another study reported the absence of acne in Canadian Inuits prior to adopting the Western diet.[14]
All of these studies suggest a plausible causative relationship between the consumption of dairy and the development and aggravation of acne. Skim milk and ice-cream appear to have the strongest association.
Why Does Dairy Cause Acne?
While the exact mechanisms remain largely theoretical, it is believed milk and dairy products exacerbate acne through hormonal interactions that increase sebum production and promote inflammation.
Here are the drivers of the dairy and acne connection.
#1. Dairy contains a myriad of acne-causing hormones
Dairy milk and milk products contain high levels of growth hormones and sex hormones. Remember, dairy milk is produced by a pregnant cow to fuel her growing calf, so just like human milk, dairy milk is rich in hormones— more than 60 different ones to be exact! The key culprits thought to be involved in the development of acne are:
- Testosterone
- Dihydrotestosterone
- Insulin
- Insulin-like Growth Factor-1 (IGF-1)
High concentrations of these acne-causing hormones or their precursors are detected in all types of dairy milk even after pasteurization and homogenization.[15] Dairy farmers have also been known to artificially treat cows with bovine growth hormone to increase milk production, which further elevates levels of Insulin-like Growth Factor-1 in milk.[16]
Acne patients who regularly consume dairy milk have higher circulating levels of testosterone, dihydrotestosterone, insulin, and IGF-1, which has led researchers to believe hormones consumed in dairy milk survive the digestion process and remain active in the human body. Circulating levels of IGF-1, in particular, are 10–20% higher among adults and a 20–30% higher among children who consume dairy milk.[15]
However, there is still a current debate concerning whether these hormones exhibit the same effects as the human versions, or cause hormonal imbalances that trigger a rise in acne-causing hormones.
Either way, hormones present in dairy exacerbate acne. Here is how it happens:
Dairy increases sebum production
An overproduction of sebum is one of the key factors in the development of acne. Sebum is an oily substance normally secreted by our sebaceous glands (the tiny pores in your skin where hairs grow out) to hydrate the skin. But, when hormones, like testosterone, over-stimulate the sebaceous glands, excess oils can combine with dead skin cells leading to clogged pores (whiteheads and blackheads). Harmless bacteria, including P. Acnes, that normally live on the skin can contaminate clogged pores causing inflammation and those painful, nasty lesions, we know as pimples, pustules, and cysts. Excess sebum further exacerbates acne by providing a rich nutrient source of fatty acids that fuel bacteria growth.
Consuming milk leads to an increase in hormones that stimulate sebum production, including IGF-1, testosterone, insulin, and dihydrotestosterone. Testosterone acts directly on sebaceous glands to stimulate sebum production, while IGF-1 activates androgen receptors on sebaceous glands, making them more susceptible to circulating testosterone. In vitro tests have shown increased lipogenesis (sebum production) in sebocytes (skin cells of sebaceous glands) when exposed to IGF-1 [17]. IGF-1 also stimulates an enzyme called 5α‐reductase, which converts testosterone to its potent version dihydrotestosterone (DHT). DHT is not nice to skin— it’s five times stronger than testosterone and plays an essential role in increasing the size of sebaceous glands and stimulating sebum production.[18]
Women with moderate-to-severe acne have elevated levels of IGF-1 and DHT [19]. The severity of acne also directly correlates with circulating levels of IGF-1.[20]
Dairy stimulates the buildup of dead skin cells
Our skin is constantly undergoing a process of regeneration. New skin cells emerge in a process known as keratinocyte proliferation, while dead skin cells are continually shed in a process known as desquamation.
Too often dairy and sugar go hand in hand =’s double trouble!
Hormones largely control this renewal of our skin. Elevated levels of insulin and IGF-1, due to dairy consumption, can speed up the process causing “hyperkeratinization” and resulting in an accumulation of dead skin cells within the sebaceous glands. This buildup, combined with the increased sebum production mentioned earlier, creates a sticky substance that eventually clogs your pores, leading to inflammation, and wah-lah! A sexy new pimple is born.
#2. Dairy products are commonly packed full of sugar
Processed dairy products like ice-cream, flavored milk, and cheesecake contain high quantities of added sugar, and as a result, have a high glycemic index. The glycaemic index (GI) indicates the degree to which a carbohydrate-based food sways a person’s blood sugar levels. The higher the GI, the faster a food increases your blood sugar levels. For instance, pure sugar has a GI of 100 and is absorbed rapidly into the blood.
Compelling evidence shows that high GI foods exacerbate acne. In 2008, Smith et al. reported a significant improvement in acne and sebum production among 31 Australian males with acne (aged 15-25) who ate a strict, low glycaemic load diet for 12 weeks.[21]
In 2012, a case-controlled study involving 44 patients aged 18 to 30 years with acne found that high glycaemic load, as well as increased milk and ice-cream consumption, increased the severity of acne [22].
Why are High GI foods bad for your skin?
When blood sugar levels rise, the pancreas releases insulin to help stabilize blood sugar levels. Foods with a higher GI, generally require more insulin. And let me tell you, insulin is not friendly to your skin.
Excess insulin circulating within the blood, also known as hyperinsulinemia, stimulates the production in IGF-1, the hormone responsible for increasing sebum production and the accumulation of dead skin cells, which leads to clogged pores and acne. Not to mention, chronically elevated insulin can lead to Type II Diabetes as well as other serious lifestyle diseases including obesity, heart disease and cancer [23].
A 2018 study, corroborated the role of IGF-1 demonstrating that low glycemic diets decrease IGF-1 concentrations. Furthermore, studies have shown that acne improves in women with polycystic ovarian syndrome who follow a low-carbohydrate diet in conjunction with medication to improve their ability to regulate blood sugar, both of which reduce insulin.[24]
#3. Dairy Milk has a High Insulin Index Comparable to High GI Food
While many dairy products have a high glycemic index, regular dairy milk has a naturally low glycaemic index of around 15-30. But, this doesn’t mean it’s safe.
Regular dairy milk, despite its relatively low GI, has three-to-six times higher insulin index of 90-98. The insulin index represents the degree to which a food elevates the concentration of insulin in the blood during the two-hour period following ingestion. The high insulin index of dairy milk appears to be related to the whey protein rather than the casein protein found in milk. This can help explain why acne is prevalent among bodybuilders who regularly consume whey protein to stimulate muscle mass gains. A 2017 study recently demonstrated that when bodybuilders stopped taking whey protein supplements their truncal acne resolved.[25]
#4. Dairy promotes inflammation
Inflammation is a key component in the pathophysiology of acne, and dairy is one of the most pro-inflammatory foods you can consume. But, researchers are still determining how dairy products increase inflammation. A recent study believes dairy-induced elevated levels of circulating insulin and IGF-1 increase the activity of a complex protein known as MTorc1. Signaling of this protein eventually leads to the activation of inflammatory cytokines within the sebaceous gland.[26]
The presence of the P. Acnes bacteria and increased dihydrotestosterone has also shown to increase inflammation in genetically predisposed individuals.
Why Does the Medical World Deny the Connection Between Dairy and Skin?
Since the advent of antibiotics in 1950’s, and two deeply flawed studies that filled early textbooks, the wider community of dermatologists has dismissed any links between diet and acne as unscientific.[27] Even the American Academy of Dermatology Association deems the current body of evidence as ‘insufficient’ to warrant recommending any specific dietary changes.
With that said, acne sufferers can take a sigh of relief. There are signs medical professionals are changing their mind on the matter. Several studies over the last decade have led the American Academy of Dermatology to acknowledge there is “emerging data” to indicate that acne is associated with high glycemic index (GI) diets, and “limited evidence” that some dairy products may contribute to acne. 
What Can I Take Away?
While the evidence may not be bulletproof, the vast majority of studies support the role of both diet, and more specifically, dairy in acne. There are plenty of questions that still remain unanswered. But, the mechanisms are plausible. We know that dairy affects hormone levels and hormones cause acne.
At the end of the day, no matter what the research says or does not say, you know your body better than anyone else on this planet. If you feel that your skin may be breaking out after dairy consumption, it is worth removing for a few weeks. It is perfectly safe to remove all dairy products as long as your diet remains balanced, and you include plant-based calcium-rich food sources such as nuts and dark leafy greens. If you would like to learn more about how to eliminate dairy yet still meet your daily calcium requirement, check out our post on Amazing Non-Dairy Calcium Rich Foods.
It’s unlikely diet, or dairy for that matter, is the be-all and end-all cure for acne. But, replacing dairy with plant-based alternatives certainly could help to alleviate your symptoms. If “milk” is a staple in your diet, you may want to try swapping dairy milk for coconut milk, hemp milk, flaxseed milk or almond milk. Alternatively, try focusing on a low glycemic diet rich in high-fiber fruits, vegetables, starchy grains, fish, and poultry. And, most of all, try to be patient. It can take up to 12 weeks to notice any significant dietary-related changes in your skin.
References
[1] https://www.ncbi.nlm.nih.gov/pubmed/11209112?dopt=Abstract
[2] https://www.ncbi.nlm.nih.gov/pubmed/17567312?dopt=Abstract
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4769025/
[4] https://www.ncbi.nlm.nih.gov/pubmed/17945383
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5300732/
[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4507494/#b139-ccid-8-371
[7] https://www.ncbi.nlm.nih.gov/pubmed/15394875/
[8] https://www.ncbi.nlm.nih.gov/pubmed/15692464/
[9] https://www.ncbi.nlm.nih.gov/pubmed/22898209/
[10] https://onlinelibrary.wiley.com/doi/full/10.1111/jdv.13835
[11] https://onlinelibrary.wiley.com/doi/full/10.1111/ijd.13166
[12] https://jamanetwork.com/journals/jamadermatology/fullarticle/479093
[13] https://www.ncbi.nlm.nih.gov/pubmed/9627819
[14] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884775/
[15] https://onlinelibrary.wiley.com/doi/full/10.1111/j.1600-0625.2009.00924.x#b77
[17] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5318522/#B5
[18] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5015761/
[19] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884775/#CIT0012
[20] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884775/#CIT0013
[21] https://www.ncbi.nlm.nih.gov/pubmed/18178063/
[22] https://www.ncbi.nlm.nih.gov/pubmed/22898209/
[23] https://diabesity.ejournals.ca/index.php/diabesity/article/viewFile/19/61
[24] https://www.sciencedirect.com/science/article/pii/S2212267218301643
[26] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4507494/
[27] https://www.bbc.com/news/magazine-21967574
[28] https://www.ncbi.nlm.nih.gov/pubmed/20338665/
[29] https://www.ncbi.nlm.nih.gov/pubmed/18194824/
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