لخّصلي

27.In this study a consistent association between acne and mental problems has been shown for both genders in a model which also includes diet, lifestyle factors and socio-demographic variables.The strength of the study is the non-healthcare-seeking sample with a relatively high rate of participation (80%), the use of validated instruments to measure acne and mental distress [35,36] and the inclusion of possible confounders in the multivariate analyses which are lacking in similar studies [15-17,21,22].Interestingly the protective effect of a high intake of vegetables and low intake of chocolate/sweets and potato chips in the present study is in coherence with the hypothesis that a low-glycemic diet is beneficial to arrest the development of acne.Regarding smoking our results are in correspondence with a study from Denmark among girls [50], but in contrast to studies showing both increased [11] and decreased prevalence of acne in smokers [12].In the adjusted analyses, the association between the socio-demographic variables and acne is no longer significant.In the present study an association between acne and a low intake of raw vegetables and a high intake of chocolate/sweets and potato chips has been found, but in the adjusted model the association with raw vegetables remains significant only among girls.Unfortunately we did not have data on the intake of milk in this study, and theoretically milk could have been a confounder in the exploration of the association between acne and mental distress.In the study we have found an almost doubled prevalence of self-reported acne among girls with a non-Western background compared to the reference population.Therefore we would suggest that measuring psychological parameters should be included in future studies on acne, especially in studies with a longitudinal design.This study shows that both dietary factors and mental health problems are candidates as causative factors in the development of acne among adolescents in a Western country.A small randomized controlled study has shown that a low glycaemic diet decreases the number of acne lesions after 12 weeks [23].This has never been shown before.28.29.30.Conclusion 31.

27. In the present study an association between acne and a low intake of raw vegetables and a high intake of chocolate/sweets and potato chips has been found, but in the adjusted model the association with raw vegetables remains significant only among girls. This has never been shown before. Recently there has been renewed interest in the link between acne and diet. A small randomized controlled study has shown that a low glycaemic diet decreases the number of acne lesions after 12 weeks [23]. Interestingly the protective effect of a high intake of vegetables and low intake of chocolate/sweets and potato chips in the present study is in coherence with the hypothesis that a low-glycemic diet is beneficial to arrest the development of acne. However, we did not find that high intake of fish had a protective role in the development of acne, contrary to what has been suggested [30,31]. Longitudinal observations have discovered that a high intake of milk is associated with acne [13,14]. Unfortunately we did not have data on the intake of milk in this study, and theoretically milk could have been a confounder in the exploration of the association between acne and mental distress. However, milk is probably not a confounder, since there is no established evidence for an association between consuming milk and mental problems. We have not found any studies that compare acne prevalence across populations with different diet. Our findings do not support the idea that diet influences the association between acne and mental health problems.


28. In the study we have found an almost doubled prevalence of self-reported acne among girls with a non-Western background compared to the reference population. Also among girls, acne is more frequently reported in those who have a low income. It has also been shown previously that acne can be associated with socio-demographic variables [8,9,17,49]. In the adjusted analyses, the association between the socio-demographic variables and acne is no longer significant. This highlights the importance of including relevant confounders, e.g. mental problems, in such models.


29. Cigarette smoking and the intake of alcohol were included in our measures but were not found to be associated with acne. Regarding smoking our results are in correspondence with a study from Denmark among girls [50], but in contrast to studies showing both increased [11] and decreased prevalence of acne in smokers [12]. No studies in the literature were found concerning acne and alcohol intake.


30. The major limitation of this study is the cross-sectional design which limits the interpretation of the direction of the associations. Further, collecting data using a questionnaire may be problematic, especially problematic concerning diet, but there is also the possibility of dependent misclassification [51]. The strength of the study is the non-healthcare-seeking sample with a relatively high rate of participation (80%), the use of validated instruments to measure acne and mental distress [35,36] and the inclusion of possible confounders in the multivariate analyses which are lacking in similar studies [15-17,21,22].
    Conclusion


31. In this study a consistent association between acne and mental problems has been shown for both genders in a model which also includes diet, lifestyle factors and socio-demographic variables. The findings do not support the hypothesis that diet may have a confounding effect on the association between acne and mental problems. This study points to mental problems as an important factor in acne, but the causal relationship remains elusive. Therefore we would suggest that measuring psychological parameters should be included in future studies on acne, especially in studies with a longitudinal design. Acne has been shown to have high heritability in twin studies [52]. However, it is important to be aware that this does not automatically imply that environmental factors have no influence. If the whole population is exposed to the same risk factors, genetic factors will emerge as a strong determinant of disease. The fact that acne is rarely seen in some non-Western societies [24] should encourage a further search for risk factors. This study shows that both dietary factors and mental health problems are candidates as causative factors in the development of acne among adolescents in a Western country.