When it comes to diet and the skin, there's a bit of controversy. Studies on the link between diet and acne specifically, have gone back and forth for decades; in the early 1930's to 1960s, diet was believed to play a major role in acne pathogenesis (development). But studies in the 1970s rejected this theory; they couldn't find a correlation between chocolate consumption and acne development. Recently though, diet has been coming back into the acne conversation. There's still no solid evidence to say that diet directly CAUSES acne to develop - but theres a strong case for dietary factors making existing acne worse.
The dietary factor I want to talk about specifically, is dairy (with the exception of yoghurt, interestingly). Dairy and acne are not friends, and I'm going to explain why.
During the first lockdown, I read a study on diet and acne, published in 2018 from UCSI University in Kuala Lumpur. In the study there was no significant association found between acne and: potato chips, nuts, yoghurt, and soda drinks. But patients in the study whose dairy milk consumption was 2 or more glasses daily, had double the incidences of acne.
In my professional experience, I've seen clients experience significant changes in their skin simply from going dairy free or simply switching to dairy-free protein. So let's get into why that is...
IGF-1 and Insulin
To understand the effects of dairy on acne, we first need to understand Insulin-like Growth Factor 1 (AKA IGF-1) and Insulin.
IGF-1 is a growth factor in the body that plays a major role in acne development, and it does this in two ways:
- By increasing sebum (oil) production: increased sebum leads to pimples and blackheads (or "comedones") in the skin
- By promoting follicular keratinisation: essentially, this means the cells inside your skin's follicles (essentially, your pores) over-produce keratin causing them to stick to each-other and clog the pore, resulting in blackheads or pimples.
IGF-1 isn't insulin - but it mimics insulin, and affects sebum production.
Insulin:
When there is too much insulin in the body, AKA, hyperinsulinemia, the amount of androgen hormones in our bodies increases. Increased androgen hormones results in higher production of sebum in the skin (amongst other things).
A note in regards to PCOS: insulin resistance, which is central to PCOS, results in over-production of insulin causing hyperinsulinemia and excessive androgens in the body - this is part of why acne is common in people who have PCOS.
Now back to milk...
The two major proteins in milk, are whey and casein.
Casein increases IGF-1 concentrations in the body, while whey stimulates production of beta cell insulin in the body, resulting in an excess of insulin (aka, hyperinsulinemia).
Now that we understand what IGF-1 and insulin do to our sebum production, its easy to see why dairy, particularly milk, aggravates acne.
Not only that but the lactose (milk sugar) content in dairy products can trigger high insulin production.
Whey Protein is something I consistently advise clients to avoid, because essentially what you're doing is extracting one of the most skin-problematic components of milk, and taking it in a concentrated form. Pea protein can be gritty and less pleasant than whey protein, but its a lot more skin-friendly.
Interestingly, there has been no association found between yogurt consumption and the incidences of acne. It's been suggested that levels of IGF-1 found in natural milk are reduced by probiotic bacteria in the fermentation process that makes yoghurt. However yoghurt that has added sugar can still be problematic, due to sugar being a trigger for high insulin production.
In conclusion
Theres still some uncertainty around diet and acne, but when it comes to milk and milk products the evidence is unequivocal.
If you're struggling with acne, try cutting dairy out for two weeks. Its long enough to know if it makes a difference for your skin, but short enough that you wont go crazy without your dairy fix... dietary changes aren't easy, but they can be key to changing your skin for the better - and why not try?