For years, researchers have studied the relationship between dairy and acne, and to date, there is no conclusive evidence that dairy causes acne. So there is no solid reason that acne-prone people need to remove dairy from their diet at this time.1
However, several factors lead researchers to believe dairy might contribute to acne. According to authors of a 2014 article in the Journal of the Academy of Nutrition and Dietetics:
“Milk may contribute to acne development because of the hormonal, carbohydrate, or protein content. Milk contains a magnitude of hormones, including reproductive, nonreproductive, and growth hormones, which may individually or synergistically influence acne development.”2
Let’s discuss some ways hormones, carbohydrates, and proteins in milk might contribute to acne formation. Keep in mind that, at this time, there is no direct and compelling scientific support for eliminating dairy from the diet. The hypotheses below are simply initial thoughts that need to be tested.
Fair warning: Deep science ahead!
Dairy & Acne Hypotheses
Milk Hormone Hypothesis: Hormones are signaling molecules that send messages to certain cells. Hormones found in milk, such as insulin-like growth factor (IGF-1) and the male hormone testosterone, might send messages throughout the body that lead to the development or worsening of acne.
- In acne, fat formation is important because skin oil is made from various fats. Sebaceous glands, which are located inside the skin’s pores, produce this skin oil. mTORC1 is a protein that stimulates fat formation. The hormone IGF-1 activates mTORC1. Higher levels of mTORC1 may increase the number of cells in the sebaceous gland and ultimately the amount of oil produced. These processes are known to cause or intensify acne.
- Male hormones are present in both males and females. Higher male hormone levels can lead to increased acne. The precursor to DHT can be converted to DHT, the primary acne-stimulating male hormone.
Milk Carbohydrate Hypothesis: Carbohydrates found in milk might cause the body to produce more insulin. In turn, insulin promotes overactivity of mTORC1, leading to acne formation or acne worsening.
Milk Protein Hypothesis: Whey and casein are the main proteins found in milk and both have growth-stimulating effects. Casein stimulates IGF-1 in the blood and whey promotes insulin secretion. Both IGF-1 and insulin contribute to mTORC1 overactivity, leading to acne formation or acne worsening.2
The image below shows how milk and dairy products may hypothetically lead to inflammation and acne production.3Insulin and IGF-1 regulate certain proteins, such as mTORC1 and foxO1, which in turn affects another set of proteins, which go on to alter the fat formation in our skin cells. The resulting composition of fats forms the breeding ground for P. acnes (the bacteria linked to acne vulgaris), which activate inflammatory molecules, triggering inflammation and breakouts.
The Studies: Investigating the Link Between Dairy and Acne
In order to test the hormone, carbohydrate, and protein hypotheses, researchers would need to perform a type of study called a randomized controlled trial (RCT). RCTs are the most reliable type of study because they can prove whether one factor causes another – for example, whether dairy causes acne. To date, there have been no RCTs analyzing the effects of dairy on acne; therefore, researchers cannot conclude that there is a direct cause.
We do have some studies to look at, however. They are called observational studies, and are less reliable than RCTs. Observational studies, unlike RCTs, cannot test or prove hypotheses. In observational studies, researchers only describe what they observe. Surveys and questionnaires are examples of observational studies. Still, observational studies can provide some insight into the relationship between dairy and acne. Here are the 6 we have thus far, with 5 out of 6 showing an association between some types of dairy and acne.
However, remember, because these studies are observational, they are not proof. Here are some of the limitations of the above studies:
- Questionnaires based on past habits require participants to remember and recall information. Some participants may not be able to recall accurately or may intentionally misreport information.
- Questionnaires are not always validated, which means that the questionnaire was not tested to see if the questions it contains will produce reliable answers.
- Cross-sectional studies, such as those performed by Burris and Cerman, only capture information about a specific moment in time. For example, participants were asked about their milk-drinking habits at the time. The questionnaires did not include questions about how much milk they drank in the past or about how much milk they planned to drink in the future. Cross-sectional study results do not provide insight into past trends, nor do they indicate what trends may be in the future.2-3,6
None of these studies are RCTs and, therefore, cannot establish whether there is a causal link between dairy and acne. The observational results, however, do tend to suggest that dairy intake may influence acne in some way.
The Science: Dairy’s Effect on Chemical Processes in the Body and Acne Formation
“Metabolism” describes the chemical processes that occur in the body to help it survive and function appropriately. Foods can boost metabolism, helping the body function more effectively, or lower metabolism, making it function less effectively.
These chemical processes happen when hormones send messages and signals throughout the body. In addition to helping the body function properly, certain messages or signals might also contribute to acne formation.
The following chart displays some milk and dairy products and how they might affect the body’s metabolism. Recall from the discussion above that the hormones insulin and IGF-1 and the protein mTORC1 can lead to acne formation.3Inflammation is also considered to be a major cause of acne.
The Bottom Line
Although researchers have not established a causal link between dairy and acne, you may find it beneficial to see if limiting dairy intake improves your acne. Don't stress out about it too much since there is not enough evidence to compel us to eliminate dairy in order to reduce acne, but it could be an interesting experiment if you'd like to try it.
Keep in mind that if, by eliminating dairy, you end up reducing calories, it may simply be the reduction in calories that temporarily helps to reduce your acne.