Does the cratered landscape on the face of many young people have anything to do with their diet?? Chocolate and chips with a high glycemic index are probably rather unfavorable, and milk is not good for clear skin either. Ultimately, however, the evidence on this is quite thin.
Published: 03.04.2013, 05:03
Consequence of sweet and fatty?
NEW YORK. When Christmas is over and all the chocolates, cakes and chocolate dolmas have been eaten, the after-effects of this gluttony of sweets and fats often make themselves felt on the skin.
Sebaceous pimples sprout quite unconcernedly on the face as otherwise not throughout the year, as if the body wanted to get rid of the excess fat and the excess of carbohydrates in this way again.
Doctors also made such observations more than a hundred years ago in pubescent adolescents, when industrialization meant that an increasingly large proportion of the population could afford a diet high in sugar and fat.
Researchers have also observed such consequences when primitive peoples who did not have acne adopted a Western lifestyle or when the poor rural population moved to the city.
A connection between acne and nutrition was suspected very early on, and severely affected pimple-faced people were advised to be more cautious about eating sweets and fats.
However, observations and personal experiences do not provide scientific evidence, even if everyone believes that they have had such experiences before.
So, from a scientific point of view, what speaks for the fact that sweet fats cause acne pimples to shoot out of the skin like a warm autumn rain causes mushrooms to shoot out of the forest floor??
Tallow bags under the magnifying glass
Actually quite little, if one takes the unwanted sebaceous pouches with the strict criteria of the evidence-based medicine under the magnifying glass, determine now nourishing scientists around Jennifer Burris of the University in New York.
There have been more than enough studies on the subject in the past hundred years, but most of them were so methodologically poor that one would rather spread the cloak of silence over them.
After all, after analyzing numerous databases, the U.S. researchers still found 27 studies that were worth a look (J Acad Nutr Diet 2013; 113(3): 416).
Thus, in the 1920s, it was believed that chocolate was not conducive to clear skin. At the time, researchers had recognized that this sugar and fat mixture increased blood lipid levels.
They suspected that the sebaceous glands as a consequence also increase oil production and thus aggravate an acne. In the 1930s, reports of impaired glucose tolerance in acne patients emerged and they were strongly advised to reduce their carbohydrate intake.
Early observational and case-control studies in the 1940s and 50s also suggested a link between acne and high dairy and fat consumption.
However, there was a lasting turning point in the 1960s, reports the team led by Burris.
In 1961, researchers in an experimental study found no improvement in acne with a reduction in carbohydrate consumption, nor did they find impaired glucose tolerance, and a 1967 case-control study showed no differences in sugar consumption between acne patients and healthy controls.
A particularly large influence had however a study from the year 1969, quoted again and again: The study participants with mild to moderate acne received an auxiliary ration chocolate or "Placebo" over four weeks in a double-blind crosswise study.
After a brief weaning period, chocolate was swapped for placebo. The result: in both groups, the researchers did not notice any differences in the progression of acne at any point in time.
However, the fat and sugar content of the "placebo bar" differed not that of chocolate. So with the study, all that was found was that the cocoa in chocolate didn’t cause pimples, yet this and similar studies have been incorrectly cited over and over again as evidence that diet doesn’t affect acne, Burris writes. The consequence: over 40 years the connection was hardly investigated further.
Sugar and chips rather unfavorable
It was not until the new millennium that researchers again ventured into the subject. This was triggered by large cohort studies that raised the correlation between lifestyle and disease to a new level of evidence.
With this data, it was also possible to re-examine, in part, the influence of diet on acne incidence and progression. In three such studies involving nearly 50.000 participants, the acne rate was significantly higher with high dairy consumption.
However, because these studies also have numerous limitations and sources of error, Burris and coworkers do not yet see sufficient evidence to warn against milk for acne.
The evidence is somewhat better for the effect of carbohydrates. A team of researchers did several intervention studies on this several years ago. Participants were fed a diet for several weeks that had a high or low glycemic load, meaning it was either particularly high or low in easy-to-blood carbohydrates.
With low glycemic load – such as low sugar and fries – acne actually attenuated, also improved insulin sensitivity. Finally, concentrations of hormones and growth factors that promote sebum production were also lower than at high glycemic loads.
However, participants with the low glycemic load also lost significant weight, which may have skewed the results. Still, Burris and colleagues see these studies as the most convincing evidence to date of the benefits of a low-glycemic diet for acne.
In a study from 2012, the results could be confirmed. With a low glycemic load, both inflammatory and non-inflammatory skin lesions decreased and the size of the sebaceous glands decreased, independent of weight changes.
Diet recommendations make little sense?
Less consistent, on the other hand, are modern studies on fat consumption and acne. Some study authors found a worsening of acne with fatty fast food in surveys and cohort studies, while others found no effect.
Fish appeared to be protective in some studies, but omega-3 fatty acids showed no benefit in others.
After sifting through all this data, Burris and her team assume that while diet doesn’t cause acne, it does influence its progression.
Sweets and foods with a high glycemic index seem to have a particularly unfavorable effect on sebum production, as does milk, although it is still unclear whether hormones, fat or milk proteins cause pimples to grow.
However, nutritionists still don’t see enough evidence to make specific diet recommendations for acne. As is often the case, many questions still need to be answered in further studies.
Perhaps the chances are not bad that at least by the end of this century we will be a little wiser.
Until then, you can continue to rely on your experience and trust that maybe not the acne, but at least the Christmas pimples will disappear again if you don’t see any chocolate or sweets for the next few weeks after the annual gluttony. (mut)