Young adults with acne at a Turkish skin clinic ate fewer vegetables and more butter than those without. The sugary-carb score that usually gets the blame was the same in both groups

Ask anyone with acne what they've been told to cut out and the list is usually sugar, white bread and milk. The idea behind it is that fast-digesting carbohydrates push up insulin and a growth hormone called IGF-1, which in turn drive oil production in the skin. A case-control study published in the Journal of Cosmetic Dermatology on 28 October looked at that idea alongside a broader one: whether the overall shape of the diet, measured as closeness to a Mediterranean pattern, sets people with acne apart.

The researchers, a dietitian and a dermatologist at Aydın Adnan Menderes University in western Turkey, recruited 115 people with acne from the university hospital's dermatology clinic and 164 people without acne who attended the same clinic over the same period. Both groups averaged about 23 years of age, 87% were women, and their body mass index was similar (about 22 to 23). Every participant kept a food diary for two weekdays and one weekend day and answered the 14-question Mediterranean Diet Adherence Screener, which scores a point for each habit met, such as olive oil as the main fat, two servings of vegetables a day or less than one serving of butter, cream or margarine. One dermatologist graded the severity of every acne case without seeing the diet data.

The acne group scored lower on the Mediterranean screener: 5.97 out of 14 against 7.02. Two thirds of them (67.0%) fell below the cut-off of 7 that the Turkish version uses for adherence, against 42.7% of the people without acne. After adjusting for age, sex, BMI, education and supplement use, each extra point on the screener went with about 19% lower odds of being in the acne group. Of the 14 habits, only two still differed once the researchers corrected for testing so many at once. Just 33.0% of the acne group ate two or more servings of vegetables a day, against 64.6% of the others, and 40.9% kept butter, cream or margarine under one serving a day, against 64.0%. Missing the vegetable mark went with about 3.2 times the odds of acne, and missing the butter mark about 2.4 times.

The glycaemic index of the diet, worked out from the food diaries, was almost identical: 57.6 in the acne group and 57.7 in the others, and it showed no link with acne after adjustment. The surprise was the dietary antioxidant score, an estimate of the antioxidant capacity of the food eaten: it was higher in the acne group (3.74 against 3.02 mmol a day) and stayed weakly linked to acne after adjustment. The authors are clear that this doesn't mean antioxidants cause spots. People who already have acne often change what they eat after reading about it, so a food diary may record the reaction to acne rather than its cause.

That reverse-causation problem applies to the whole study. Diet was recorded after the acne had appeared, so the lower vegetable intake could be a cause, a consequence or a sign of something else entirely. Education differed between the groups (30.4% of the acne group had a high-school education or less, against 13.4%) and was itself linked to acne; the diet findings held after adjusting for it. Hormones, oral contraceptives, stress, sleep, exercise and past acne treatments were not measured. Three days of diaries is a short window, some glycaemic index values had to be estimated, and the butter item lumps three foods together. Within the acne group, none of the 14 habits differed between mild and moderate-to-severe cases, though with 37 and 78 people that comparison had little power. The authors reported no funding and no competing interests.

How does this fit with earlier work? The best-known diet trial for acne, from Melbourne in 2007, put 43 young men on a low-glycaemic-load diet or a carbohydrate-heavy one for 12 weeks; total lesion counts fell by 23.5 on the low-glycaemic diet against 12.0 on the control, though that group also lost about 3 kg, which muddies the picture. A 2025 meta-analysis found that closer adherence to a Mediterranean diet went with milder acne. The Aydın study doesn't settle anything on its own, but it points to a pattern worth testing in a trial: more vegetables and less butter and cream, rather than a fixation on single foods.