Does diet really affect acne?
More than 17 million Americans suffer from acne of varying severity, and among adolescents, this figure reaches 80 to 90%. In addition to an aesthetic defect, acne is recognized for its role which causes more important clinical results, including depression. Studies before 2005 only reflected the subjective opinions of patients on the relationship between acne and the consumption of certain foods, while literature reviews did not show a clear convincing link between specific eating habits and the occurrence of acne. A review published in 2010 analyzed the publications devoted to the problem of the dependence of the risk of onset and the severity of acne on the food consumed. Dairy and high carbohydrate products have been shown to increase the risk and severity of acne, while no convincing evidence has been obtained for other foods, such as chocolate and salt.
In the migration studies conducted, there was a trend towards an increase in the prevalence of acne during peoples' transition to a Western diet or to resettlement in Europe with a change in nutrition stereotypes. Examples include the Canadian Inuit, who significantly increased their consumption of beef, dairy, and specially processed foods, as well as the Japanese of Okinawa, who reduced their consumption of starch and increased their overall consumption of dairy products..
The authors of a large case-control study evaluated the relationship between the quantity of milk consumed during adolescence and the occurrence of acne in nurses (n more than 47,000). In a group of study participants who were diagnosed with severe forms of acne in adolescence, the amount of milk consumed per day was analyzed. It turned out that among the people with the highest level of milk consumption (more than three servings per day), acne was recorded much more often compared to those who had the highest level of milk consumption low (less than one serving per week). The resulting dependence was most pronounced (a 44% increase) for skim milk. Thus, it can be assumed that the fat content of milk is not a determining risk factor for acne.
Two large prospective cohort studies have examined the relationship between diet and the development of acne in children aged 9 to 15 years, including 6,094 girls and 4,273 boys. In girls, a pattern has been found between the severity of acne and the consumption of all categories of cow's milk (whole, low-fat, skim, chocolate). In the case of boys, a similar pattern was obtained for plain and skim milk. In girls who consumed more than two servings of milk per day, severe acne was recorded on average 20% more often than girls who consumed less than one serving of milk per week. For boys, this indicator was 16%.
There is an opinion that a certain role in the onset of acne is played by the hormonally active substances that are part of milk, which, as shown in a study conducted in 2005, have insulin stimulating properties. As is known, insulin activates insulin-like growth factor 1 (IPFR-1, insulin-like growth factor 1 - IGF-1), which in turn increases testosterone levels and reduces the production of sex hormone-binding globulin (SHBG). Another study demonstrated the relationship between an increase in IPFR-1 and the risk of acne.
The authors of two large cross-sectional studies in Papua New Guinea (n = 1,200) and Paraguay (n = 115) found no cases of acne in the population. Researchers have suggested that one possible reason for this is a diet low in fats and carbohydrates in the local population.
A randomized controlled trial evaluated the risk of acne and insulin sensitivity in a low-carbohydrate diet. Study participants who followed a low-carbohydrate diet showed a decrease in acne components compared to the control group. In addition, a low-carbohydrate diet contributed to weight loss, insulin sensitivity and SHBG levels increased and androgen levels decreased accordingly, which in turn was correlated with a decrease in the number of acne elements. Thus, a low-carbohydrate diet, by its effect on hormone levels, as well as improving insulin sensitivity, helps reduce the risk of acne, and if there is an active process, a low carbohydrate diet has a healing effect.
Unfortunately, to date, no large and sufficiently controlled study has been conducted to study the effect of consuming fats and fatty acids on the risk and severity of acne. However, it is well known that omega-6 fatty acids are pro-inflammatory mediators and can therefore increase the risk of acne. In contrast, omega-3 fatty acids have anti-inflammatory properties and can reduce the risk of acne by reducing the level of IPFR-1 in the blood and the severity of the inflammatory process. A hallmark of Western diets is the low ratio of omega-3 and omega-6 fatty acids. Such diets high in fat and saturated fatty acids are associated with an increased level of IPFR-1, while diets low in fat and high in dietary fiber are associated with reduced content.
A cross-sectional study was conducted to study the effect of chocolate on the risk of development and evolution of acne, whose participants were divided into two groups. 65 people who make up the study group, daily for 4 months consumed a chocolate bar weighing 112 g, without milk and enriched with cocoa. The individuals in the control group consumed chocolate with the usual cocoa content. There was no significant difference in the risk of onset and the severity of the course of acne between the two groups of researchers.
Thus, in the population and migration studies carried out, the dependence of the risk of development and evolution of acne on the diet has been clearly demonstrated. Large, well-controlled observational studies have shown that diets high in dairy, including all varieties of milk, increase the risk of acne and contribute to a more severe process. The resulting dependence is due to the presence of sex steroid hormones in milk or to an increased production of polypeptide hormones, such as IPFR-1, which can increase the level of androgens and thus contribute to appearance of acne.
There are reports in the literature on the association of a high carbohydrate diet with high risk, as well as the duration and severity of acne. In randomized clinical trials, it has been shown that a low-carbohydrate diet, to some extent, normalizes hormone levels and increases insulin sensitivity, thereby greatly reducing the risk of acne. None of the studies included in the systematic review have demonstrated the dependence of the risk of acne on the consumption of chocolate, salt and saturated fatty acids.