We do know that some foods are good for your skin. There are healthy fats like the ones found in fish that contribute to skin health. As for which foods lead to breakouts? Doctors and scientists are still narrowing down which foods make acne worse, and how exactly it happens. Acne has several root causes. Hormones also play a big role in skin health. Hormonal fluctuations can trigger outbreaks, which is why pimples are common in your teenage years. That said, plenty of adults get acne too.
Your skin naturally produces oil. Overactive sebaceous glands, where sebum is produced, create oily skin. When that oil mixes with bacteria and dead skin cells, pores clog and pimples form. This is one of the connections between dairy and acne. This creates conditions for acne to easily spread. Dealing with acne can be frustrating. Our free guide provides expert tips to help you take control.
Sign up and get yours today. Dairy intake and acne development: A meta-analysis of observational studies. Clin Nutr. Dairy intake and acne vulgaris: a systematic review and meta-analysis of 78, children, adolescents, and young adults. Published Aug 9. American Academy of Dermatology Association. Can the right diet get rid of acne?
Significance of diet in treated and untreated acne vulgaris. Postepy Dermatol Alergol. A low glycemic index and glycemic load diet decreases insulin-like growth factor-1 among adults with moderate and severe acne: a short-duration, 2-week randomized controlled trial.
J Acad Nutr Diet. Milk consumption and multiple health outcomes: umbrella review of systematic reviews and meta-analyses in humans. Nutr Metab Lond. Published Jan 7. Acne related to dietary supplements.
Dermatol Online J. Published Aug Acne: the role of medical nutrition therapy. Relationships of self-reported dietary factors and perceived acne severity in a cohort of New York young adults. Ferdowsian HR, Levin S. Does diet really affect acne? Skin Therapy Lett. Melnik BC. Linking diet to acne metabolomics, inflammation, and comedogenesis: an update.
Clin Cosmet Investig Dermatol. Your Privacy Rights. To change or withdraw your consent choices for VerywellHealth.
At any time, you can update your settings through the "EU Privacy" link at the bottom of any page. These choices will be signaled globally to our partners and will not affect browsing data.
We and our partners process data to: Actively scan device characteristics for identification. I Accept Show Purposes. Table of Contents View All. Table of Contents. Scores above five indicate moderate to high study quality. The NOS for cohort and case-control studies was retrieved from [ 43 ]. We also present inverse variance I-V fixed effects in supplementary Figures. Heterogeneity was assessed by Cochrane Q statistic test and I 2 -statistical analysis. The I 2 -statistical analysis assess what proportion of the observed variance reflects variance in true effect sizes rather than sampling error [ 44 ].
Four studies provided adjusted estimates for milk intake, with one study providing them as odds ratios [ 46 ], and three studies as prevalence ratios [ 15 , 16 , 17 ]. In a sensitivity analysis, we used only adjusted prevalence ratios from the studies by Adebamowo et al.
Stratification on acne severity was not possible because of too few studies. In total, 14 studies were eligible. Figure 1 shows the flow diagram of the selection of articles for the meta-analysis. The studies were published in — and included a total of 78, individuals of which 23, had acne and 55, were controls Table 1. Two studies used non-acne dermatological controls [ 23 , 26 ] and the rest used healthy controls. Five studies were cross-sectional [ 20 , 21 , 27 , 46 , 47 ], five studies were case-control [ 18 , 22 , 23 , 24 , 26 ], one study was retrospective [ 15 ], and three studies were longitudinal [ 16 , 17 , 25 ].
The age-group ranged from 7—30 years. Two studies were only in females [ 15 , 17 ], three studies only in males [ 16 , 26 , 46 ], and the rest included both males and females. The studies covered five continents: Africa [ 21 ], Asia [ 18 , 24 , 47 ], Europe [ 20 , 22 , 23 , 25 , 26 , 27 ], North America [ 15 , 16 , 17 ], and South America [ 46 ]. Four studies included less than individuals in total [ 18 , 21 , 22 , 23 , 47 ], whereas the rest ranged from to 46, individuals Table 1.
Four studies used the Willet food frequency questionnaire [ 15 , 16 , 17 , 21 ]. In six studies, acne was self-reported in a questionnaire [ 15 , 16 , 17 , 20 , 25 , 27 ], and in eight studies, acne was a physician verified diagnosis [ 18 , 21 , 22 , 23 , 24 , 26 , 46 , 47 ]. Five studies provided adjusted estimates, including four on milk intake and one on dairy, two of the studies reported odds ratios, and three studies reported prevalence ratios [ 15 , 16 , 17 , 25 , 46 ].
The reference group varied among the articles and included not weekly [ 15 , 16 , 17 , 18 , 25 ], not daily [ 20 , 21 , 46 ], never [ 23 , 27 ], and unclear [ 24 , 26 , 47 ].
Characteristics of included studies for the association of dairy intake with acne in children, adolescents, and young adults. Age: mean or range.
Q: Questionnaire. D: Dermatologist verified. P: Physician verified. Random effects pooled unadjusted odds ratios for acne were 1. Meta-analysis of dairy intake and acne vulgaris: individual studies. The figure shows the individual studies and the unadjusted pooled random effect estimate from the meta-analysis of dairy intake and acne vulgaris.
See Table 1 for references. Meta-analyses of dairy intake and acne vulgaris: summary estimates. The figure shows the unadjusted pooled random effects estimates from each of the meta-analyses, which can be found in the supplementary material.
To explore heterogeneity, we stratified the analysis for any dairy intake and acne by age, gender, number of cases, continent, design, acne diagnosis, and reference group Supplementary Table S1 , Supplementary Figures S11—S Stratifying by age did not show any differences. Stratifying by gender showed similar odds ratios in males and females, but meta-analyses of females had higher heterogeneity. Stratifying by the number of acne cases showed that larger studies had smaller odds ratios with more narrow confidence intervals, but higher heterogeneity compared to those of the smaller studies, but the confidence intervals were overlapping.
Stratifying analyses by continent showed that studies from Europe had the smallest odds ratios, followed by North and South American studies, and with Asian and African studies with the largest odds ratios. Stratifying by design removed heterogeneity and showed that prospective studies had the largest odds ratios. Stratifying by ascertainment of acne diagnosis showed that studies using self-reported acne as an outcome had higher heterogeneity compared to studies with physician verified diagnoses of acne.
The Newcastle-Ottawa qualitative assessment scale of bias with similar items as in the statistical heterogeneity assessments revealed scores of 2—5 in case-control studies [ 18 , 22 , 23 , 24 , 26 ] and 2—6 in cohort studies [ 15 , 16 , 17 , 20 , 21 , 25 , 27 , 46 , 47 ] out of a potential max of 9 points Supplementary Table S2. Leave-one-out analyses for any dairy or any milk intake did not show any gross deviations, but the retrospective study by Adebamowo [ 15 ] influenced the summary estimates the most Supplementary Figures S21—S The New-Castle Ottawa qualitative assessment scale of bias revealed a scores of 2—5 in case-control studies [ 18 , 22 , 23 , 24 , 26 ] and 2—6 in cohort studies [ 15 , 16 , 17 , 20 , 21 , 25 , 27 , 46 , 47 ].
Intake of cheese was associated with a borderline higher odds ratio for acne compared to no intake. Stratifying the association of any milk by frequency of intake revealed that intake of 1 glass of milk or more per day was associated with a higher odds ratio for acne, whereas 2—6 glasses per week was not, compared to intake less than weekly. The meta-analyses showed considerable heterogeneity reflecting the heterogeneous age and gender of the participants, various study characteristics, ascertainment of information about milk intake and acne, reporting of milk intake, and acne severity across the studies.
In general, stratifying on subgroups in sensitivity analyses revealed that heterogeneity diminished for most subgroups, but also revealed that especially meta-analyses conducted on females, whole milk, North America, and questionnaire ascertained acne diagnosis demonstrated high heterogeneity. Prospective studies and studies with physician-verified diagnosis of acne had low heterogeneity.
Stratifying on age and gender demonstrated similar odds ratios; however, the gender stratified analyses had higher odds ratios than in the gender combined analyses. Smaller studies had higher odds ratios than large studies, African and Asian studies had higher odds ratios than other studies, and prospective designs had higher odds ratios than other designs. A recent multinational European online questionnaire study in adolescents showed that acne prevalence did not differ by gender but differed by country, and acne was more prevalent in younger people and obese people [ 27 ].
Intake of milk varies globally and is largely dependent on genetically determined lactase persistency, which is high in people of Northern European descent, but lower in people of Southern European descent, patchy in Africa, and low in the Middle East and Asia [ 48 ].
The weaning of the lactase enzyme activity usually happens in childhood and early adolescent years. How the age of weaning of the lactase enzyme activity impacts acne development is not known. We used random effects method in all meta-analyses, which includes between-study variance and has a higher degree of statistical uncertainty built into the model. Even in these models, the results of the meta-analyses were significant. If the meta-analyses had captured all the relevant studies, we would expect the funnel plots to be symmetric.
The selective reporting may be explained by studies with null-findings or negative results being deliberately not published because of authors not submitting or editors rejecting them or authors not finding enough merit in a potential publishable study [ 49 ].
There are many limitations of the included studies [ 4 ]. Including other dermatology patients as controls [ 26 ] may attenuate associations, as seborrhea may play a role in several diseases.
The observational studies were cross-sectional [ 20 , 21 , 46 , 47 ], case-control [ 18 , 22 , 23 , 24 , 26 ], retrospective [ 15 ], or longitudinal [ 16 , 17 , 25 ]; thus, in most studies we cannot rule out reverse causation. Questionnaire ascertainment of dairy intake varied between the articles and only a few studies used validated food frequency questionnaires [ 15 , 16 , 17 , 21 ]. Despite the food questionnaire used, participants may deliberately over- or underestimate information bias or not accurately remember recall bias when filling out questionnaires about dairy intake and acne.
Furthermore, it was not possible to differentiate acne development, acne triggers, and severity of acne in the meta-analyses. Only a few studies provided adjusted results [ 15 , 16 , 17 , 25 ] so we based most of the analyses on raw numbers, which makes it difficult to rule out confounding from other dietary factors e.
The retrospective study by Adebamowo in with 7. Furthermore, the studies from and were offspring studies from the NHS in girls and boys [ 16 , 17 ]; however, leave-one-out analyses revealed that only the Adebamowo study was an outlier [ 15 ]. The observational studies may suffer from bias from confounding and reverse causation [ 9 ], are unable to indicate causality of the relationship between dairy and acne, and unable to prove preventive effects of abstaining from dairy.
Only one study exists on milk intake and acne. The study is uncontrolled and unblinded and is based on medical students who drank milk or consumed other potential acne provoking foods. In addition, the total number of people with and without acne lesions were counted for all foods combined, but with no formal statistical testing [ 51 ]. Thus, there is still a knowledge gap with respect to whether dairy intake is causally associated with acne, acne flare, or acne severity and to what extent.
Another approach which no previous studies have yet undertaken would be to perform a Mendelian Randomization study of lactase persistence, dairy intake, and acne using genetic lactase persistence as a proxy for lifetime dairy intake under the assumption that alleles are randomly distributed at conception [ 52 , 53 ]. Such a study design mimics an RCT and allows for the causal estimate of dairy intake and acne. The observational studies all assessed dairy intake as an isolated factor.
Instead, other factors which can affect the bioactive properties of nutrients in dairy and milk intake should be taken into consideration, such as macro- and micronutrients fat, protein, carbohydrates, vitamins, sodium, and minerals , the dairy structure liquid or solid , fermentation, and processing holistic approach [ 55 ]. Hyperglycemic carbohydrates enhance insulin signaling, which promotes insulin and IGF-1 signaling, which in a synergistic fashion with milk stimulate mTORC1 mammalian target of rapamycin complex 1 signal transduction [ 56 ].
There is accumulating evidence that acne belongs to the spectrum of mTORC1-driven diseases of civilization including metabolic syndrome, obesity, insulin resistance, and cancer [ 57 ]. A randomized trial has shown that a low-glycemic-load diet improves symptoms in acne vulgaris patients [ 58 ]. To present the pathological effects of milk in the Western diet it is therefore important to provide controlled studies that consider milk consumption in association with glycemic load and index as part of a mixed diet [ 60 ].
Using the double-counted studies by Tsoy, the authors also only used the most severe category of acne, which caused extremely high odds ratios of 10 and 12 to be included in the meta-analysis, further skewing the pooled estimates.
The previous meta-analysis also did not provide evidence for the exact search strategy to be replicated, for the bias assessment using the Newcastle Ottawa scale, for leave-one-out analyses, or funnel plots of publication bias. Furthermore, we excluded duplicate studies, and we included four more papers [ 24 , 26 , 27 , 47 ] that were not included in the previous meta-analysis but should have been as the studies were published before the search for the previous meta-analysis was done in August [ 29 ].
It is of crucial importance that authors of meta-analyses have a critical judgement of the reliability and validity of the papers they consider including in a meta-analysis, otherwise the conduct and assessment of systematic reviews may be hampered. In conclusion, this meta-analysis of observational studies has provided new insight into the direction and magnitude of the association between dairy intake and acne overall and by dairy type, amount, and frequency.
It has shed light on the knowledge gaps and the limitations of the studies included compared to previous systematic and narrative reviews with no meta-analysis, heterogeneity assessment, or bias assessment included [ 4 , 9 , 28 ]. Study concept and design: all authors.
Acquisition, analysis of data: C. Interpretation of data: all authors. Drafting of the manuscript: C. Critical revision of the manuscript for important intellectual content: all authors. Statistical analysis: C. Administrative, technical, or material support: N. Study supervision: G. He has furthermore received unrestricted research grants from AbbVie and Leo Pharma. None of the funding agencies had any role in the design, analysis, or writing of this article.
National Center for Biotechnology Information , U. Journal List Nutrients v. Published online Aug 9. Christian R. Juhl , 1 Helle K. Bergholdt , 2 Iben M.
0コメント