Most people experience acne at some point in their lifetime. It is particularly common in puberty, to the point that it could almost be considered a rite of passage into adulthood. However, around 80% of 18-30 year-olds, as well as 5% of those over the age of 30, are affected by acne after their teenage years .
So why is acne so common? Do certain foods trigger it? Does yogurt cause acne? What about chocolate? If food causes acne, then what do we need to eat in order to avoid it?
Here is everything you need to know about the various acne diet myths and facts.
One thing you can be sure of is that diet is not a direct cause of acne. This is because acne is directly caused by four overlapping, biological factors:
- Excessive oil production
- The build-up of dead skin cells on the surface of the skin
- A bacteria known as p.acnes (or c.acnes)
- Inflammation/Immune response to the presence of bacteria
The amount of oil our oil glands produce is largely determined by our genetics and our hormones. This can lead to ‘greasy’ skin and hair but, on its own, does not cause acne.
However, when there is a build-up of dead skin cells on the surface of the skin, this oil becomes trapped within the hair follicle (commonly referred to as the ‘pore’). This blockage is referred to as a comedone which can either be ‘closed’ or ‘open’. With closed comedones (whiteheads), the blockage is covered and appears as a tiny, skin-colored bump on the skin. In the case of open comedones (blackheads), the dead skin cells and sebum are uncovered and exposed to oxygen which causes oxidation of the blockage and a brown/black appearance on the skin.
The p-acnes bacteria live within the pore and feed off the oil produced by the oil glands. When there is an excessive amount of oil, the bacteria go on a feeding frenzy which enables them to rapidly multiply.
The increase in p-acnes bacteria causes inflammation, which can be seen on the surface of the skin as red bumps (papules), and initiates an immune response. White blood cells are sent into ‘fight’ the bacteria which leads to an increase in ‘pus’ in the pore (pus is essentially dead white blood cells) and the appearance of ‘pustules’.
While there are only four direct causes of acne, research suggests that a number of other factors may contribute to the skin condition, including:
- Skin barrier damage 
- An altered skin pH 
- Free radical-induced oxidative stress 
- Diet 
So how exactly do these factors influence acne?
They can affect acne by influencing one or more of the following:
- Oil Production
In terms of how our diet can cause acne, this is mainly down to how the foods we eat affect our hormones.
Does Diet Affect Acne?
There has always been speculation regarding the role that diet plays in the development of acne.
Hands up those of you who have heard something along the lines of:
“You shouldn’t eat too much chocolate; it will give you spots!”
You’re not alone. In fact, many people claim that there is a link between chocolate and acne. This includes dermatologists and their patients who report an increase in breakouts after eating chocolate, although, the majority of research studies have found no link between the two .
Most of these studies compared a chocolate bar with an equally sugar-laden control bar that contained similar ingredients but no chocolate. This may explain why no link was found regardless of many people’s experiences. In other words, if chocolate does cause acne it’s not due to the ingredients that specifically make chocolate, well, chocolate.
So how might chocolate be linked to acne?
Three words – High Glycaemic Index (GI)!
High GI foods are those that raise blood sugar levels quickly, for example, white bread, pasta, and potato products.
It has been observed that acne is linked to the Western diet which is rich in refined carbohydrates/ high GI foods. Whereas populations with diets that consist of low-GI foods, such as the Kitavan Islanders of Papua New Guinea, do not appear to experience acne .
It is thought that this is due to the fact that the increased levels of insulin in the blood experienced after consuming high GI foods stimulate androgen hormones which increase the production of oil in the skin. This means that high GI foods can indirectly cause acne via their effect on insulin metabolism .
Some research has found that the severity of acne can be improved by switching to a low GI diet and that this improvement corresponded with improved insulin sensitivity .
Does Dairy Cause Acne?
One food group that has often been blamed for acne is milk and dairy products. Dairy products are low GI foods but contain hormones that are produced by cows during pregnancy, including insulin-like growth factor 1 (IGF-1) – a hormone that increases oil production.
The levels of IGF-1 appear to be higher in those with acne than in those without and the more severe a persons acne is, the higher their blood levels of IGF-1 appear to be .
This would imply that dairy products may cause acne or may worsen existing acne. However, research suggests that it is only certain types dairy products that are an issue. For example, in one study, acne was associated with an increased consumption of milk and ice cream, but not with yogurt, cheese, or chocolate .
Another study found positive correlations between acne and the consumption of cottage cheese, instant breakfast drinks that contained dairy, and milk (particularly low-fat milk) . Other research has found a link between acne and low-fat milk but not full-fat milk .
Overall, this would suggest that acne may be associated with milk, particularly low-fat milk, but not with other dairy products .
Does Yogurt Cause Acne?
Although it is made from milk, yogurt has not been found to cause acne. In fact, certain types of yogurt may even help improve acne. These types of yogurts contain probiotics that can treat bacterial overgrowth within the small intestine.
Some research suggests that there is a link between inflammatory skin conditions and the gut microbiome . While the research regarding acne and the gut microbiome is limited, other inflammatory skin conditions, such as rosacea, have been linked to a ten-fold increase in small intestine bacterial overgrowth compare to those without skin inflammation . This means that they had ten times the amount of bacterial overgrowth than was considered ‘normal’.
When medication was used to return this bacterial overgrowth back to ‘normal’ levels, inflammatory skin lesions cleared almost completely. Interestingly, oral probiotics, such as those found in yogurt drinks (e.g. Yakult), can reduce this bacterial overgrowth in a similar way .
Altogether, this means that, in theory, probiotic yogurt drinks may improve the appearance of acne.
Summary & Takeaway
Overall, there isn’t a huge amount of evidence to support the role of diet in acne. The strongest evidence appears to be for high GI foods which can indirectly cause acne by altering hormones and increasing oil production.
Dairy consumption is often anecdotally said to cause acne and plenty of people have found that cutting out dairy has reduced their breakouts. However, with the exception of milk (particularly low-fat milk), there is very little evidence to suggest that dairy products, as a whole, cause acne.
Based on what limited evidence there is, you might find that the following diet-based tips may improve acne:
- Basing your diet around low GI foods and avoiding sugar and other foods that may spike insulin levels.
- Choosing whole-fat milk over skimmed milk or avoiding milk altogether.
- Including probiotics in your diet.
Examples of low GI foods:
- Fats and Oils
- Dairy & Milk Alternatives
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