Diet and acne

18 Pages·2010·0.27 MB·English

ARTICLE IN PRESS
R
EVIEW
Diet and acne
Whitney P. Bowe, MD,a Smita S. Joshi, MD,b and Alan R. Shalita, MDa
Brooklyn, New York, and Chicago, Illinois
Historically,therelationshipbetweendietandacnehasbeenhighlycontroversial.Beforethe1960s,certain
foodswerethoughttoexacerbateacne.However,subsequentstudiesdispelledtheseallegedassociations
asmythforalmosthalfacentury.Severalstudiesduringthelastdecadehaveprompteddermatologiststo
revisit the potential link between diet and acne. This article critically reviews the literature and discusses
howdermatologistsmightaddressdietwhencounselingpatientswithacne.Dermatologistscannolonger
dismiss the association between diet and acne. Compelling evidence exists that high glycemic load diets
mayexacerbateacne.Dairyingestionappearstobeweaklyassociatedwithacne,andtherolesofomega-3
fattyacids,antioxidants,zinc,vitaminA,anddietaryfiberremaintobeelucidated.Thisstudywaslimited
bythelackofrandomizedcontrolledtrialsintheliterature.Wehopethatthisreviewwillencourageothers
to explore the effects of diet on acne. (J Am Acad Dermatol 10.1016/j.jaad.2009.07.043.)
Keywords:acne;dairy;diet;glycemicindex;glycemicload;nutrition;omega-3fattyacids;vitaminA;
vitamins;zinc.
H
istorically, the relationship between diet
Abbreviationsused:
and acne has been highly controversial. In
the 1930s through 1960s, patients were BMI: bodymassindex
DHT: dihydrotestosterone
often discouraged from eating a wide selection of
GI: glycemicindex
foods including chocolate, fats, and sweets. HGL: highglycemicload
Following a few critical studies,1,2 these alleged IGF: insulin-likegrowthfactor
IGFBP: insulin-likegrowthfactorbindingprotein
associationsbetweenfoodsandacneweredispelled
LGL: lowglycemicload
as myth for almost half a century. Consequently,
dietaryrestrictionshavenotbeenrecommendedasa
standardpartofacnetherapyfordecades.Recently,
paidtotheinfluenceofdairyproductsandcarbohy-
however,therelationshipbetweendietandacnehas
drateintakeonacneseverity.Althoughthemajority
been called back into question. Several carefully
ofevidencesupportingalinkbetweendietandacne
designed and thought-provokingstudies duringthe
falls under one of these two categories, a brief
last decade have prompted dermatologists and nu-
discussion of other dietary factors implicated in
tritioniststorevisittheallegedlinkbetweendietand
acne including omega-3 fatty acids, antioxidants,
acne. In particular, evidence that the ingestion of
zinc, vitamin A, and iodine follows. Very few, if
certain dairy products, carbohydrates, or both may
any, human data are available to support a role for
exacerbate acne has been particularly compelling
these factors in acne, but some in vitro and animal
andmeritsexamination.Acomprehensivereviewof
data exist. Prospective controlled trials, prospective
theliteraturetodatefollows,withparticularattention
and retrospective cohort studies, case-control stud-
ies,andlargecaseseriesexaminingtheroleofdietin
From the Department of Dermatology, State University of New acne, published in the English language and avail-
YorkDownstateMedicalCenter,aandNorthwesternUniversity able on PubMed, were included in this review
FeinbergSchoolofMedicine,Chicago.b (Table I). We have included several studies that we
Supported in part by the Skin Cancer Foundation and Orlando
believeareofinferiordesigninanefforttoprovide
Dermatology and Aesthetic Conference’s Leonard L. Mazur
historicalcontextformorerecentdevelopments,and
ResidentResearchAward(YoungInvestigatorResearchGrant;
DrBowe)andtheAmericanAcneandRosaceaSocietyClinical toaddressseveraldietaryfactorsthat,inouropinion,
ResearchGrant(DrBowe). meritfurtherstudy.
Conflictsofinterest:Nonedeclared.
Reprint requests: Whitney P. Bowe, MD, 450 Clarkson Ave,
Brooklyn,NY11203.E-mail:[email protected]. DIET AND ACNE: A HISTORICAL
PublishedonlineMarch23,2010.
FRAMEWORK
0190-9622/$36.00
Before the 1960s, dietary advice was a standard
ª2009bytheAmericanAcademyofDermatology,Inc.
doi:10.1016/j.jaad.2009.07.043 part of acne therapy. Data published in 1931
1
ARTICLE IN PRESS
2 Bowe,Joshi, and Shalita JAMACADDERMATOL
suggestedthatimpairedglucosetoleranceexistedin In1971,Anderson2alsochallengedtheacneand
patientswithacne.3Abnormalcarbohydratemetab- diet association by assigning 27 students with re-
olism was implicated in acne and patients were ported history of dietary acne triggers to consume
recommendedtoavoidconsumingexcessivecarbo- chocolate,milk,roastedpeanuts,orcolafor1week
hydrates and high-sugar foods.4 Major textbooks of underdirectsupervision.Theauthordidnotspecify
dermatology5-7popular inthe1940sand 1950s per- how many of the 27 subjects were subdivided into
petuatedthesebeliefsanddiscouragedfoodssuchas eachgroup.Beforeandafterthetrial,eachsubject’s
chocolate, fats, sweets, and acne lesions were mapped
carbonatedbeveragesaspart onto a sheet held over the
of acne therapy. However, CAPSULE SUMMARY face. Anderson2 found that
thecontentionthatarelation- Dermatologists can no longer dismiss the foods produced no
d
ship existed between diet the association between diet and acne. flares of acne. However,
andacnewasabandonedaf- lesion counts were not
Thereis reasonablycompelling evidence
d
terthefollowingtwostudies reported and statistical anal-
that high glycemic load diets may
showednoassociation. ysis was not performed.15
exacerbate acne.
Furthermore, it is unlikely
An association between dairy ingestion
EARLIER STUDIES d that any group had enough
and acne may exist, but evidence is
THAT SHOWED NO statistical power to provide
weak.
ASSOCIATION significant results, given that
BETWEEN DIET AND d The role of omega-3 fatty acids, the 27 patients were subdi-
ACNE antioxidants, zinc, vitamin A, and dietary vided into 4 treatment cate-
In 1969, Fulton et al1 in- fiber in acne is unclear. gories. This study suffered
vestigatedtheeffectofchoc- from many limitations in-
olate on acne vulgaris in a cluding small sample size
crossoversingle-blindedstudy.Atotalof65subjects and lack of controls, blinding, and
were assigned to eat either a chocolate bar or a randomization.11,12
control bar with similar appearance and caloric Finally,thestudiesbyFultonetal1andAnderson2
content. Subjects ate the assigned bar daily for 4 havebothbeencritiquedfortheirfailuretotakeinto
weeksandthenaftera3-weekrestperiod,consumed considerationsubjects’baselinediets,resultinginan
the alternate bar for 4 weeks. Acne was scored as inability to determine if the treatment diet varied
worsenedorimprovedifthetotalnumberoflesions from the subjects’ normal diet.12,13,15 This oversight
increased or decreased by 30%, respectively. The mayhaveobscuredthestudyresults.
authors found that acne severity did not change
during the chocolate bar and control bar study MORE MODERN STUDIES REVISIT THE
periodsandconcludedthatchocolatedidnotaffect LINK BETWEEN ACNE AND DIET: AN
the course ofacne. However,this study was flawed EXAMINATION OF THE INFLUENCE OF
forseveralreasons.Thedurationofthestudywasfar DAIRY PRODUCTS ON ACNE SEVERITY
tooshortforthechosenoutcomebecausemostacne The studies by Fulton et al1 and Anderson,2
clinicaltrialslast12weeks8-10toallowforthenatural although suffering from major design flaws, were
history of comedo formation and evolution. sufficienttodissociatedietfromacneinthemindsof
Furthermore, the placebo bar was an inappropriate most dermatologists. Textbooks were revised to
controlbecauseithadsimilartotalsugarandtotalfat reflectthisnewacademicconsensus,anddermatol-
contentasthechocolatebar.11Moreover,thecontrol ogiststookthestancethatanymumblingsaboutthe
barwaslargelycomposedofpartiallyhydrogenated associationbetweendietandacnewereunscientific
vegetable oil rather than cocoa butter and cacao and one of the many myths surrounding this ubiq-
paste,theformerofwhichcontainshighquantitiesof uitousdisease.
trans-fattyacidsthatcontributetoinflammation.12,13 Two decades before the studies of Fulton et al1
Finally, most patients with dietary acne triggers and Anderson,2 Robinson16 took note of what he
reportpustularflaresratherthancomedonalacne.14 believed to be an association between dairy intake
Fultonetal1groupedallacnelesionstogether.Thus, and acne severity. He documented that, based on
ifapatient’sacnelesionsshiftedfromacomedonalto 1925subjects whokept strictfooddiaries, milkwas
pustularpredominancewhereasthetotalnumberof the most commonly implicated food in acne flares.
lesions remained the same, this would have been However, Robinson16 failed to provide summary
scoredasunchangedeventhoughaclinicallysignif- statisticsandstatisticalanalyses.Hisreportismerely
icantchangewouldhavebeenpresent. anecdotalanddescriptive,basedonhisexperience.
Table I.Studies investigating relationship between dietand acne J
A
M
Levelof Conclusionsand
A
Study Design evidence Subjects Samplesize Intervention limitations C
A
Robinson,16 Caseseries 2 Subjects 1925 Dietdiary Milkwasmostcommonlyimplicated D
D
1949 with acne foodin acneflares. Limitations E
R
include shortstudy durationof1-2 M
A
wk and absenceof dataand T
O
statistical analysis. L
Grant and Caseseries 3 Subjects with acne 8 Milkchocolate barfor Chocolatedid notaggravate acne.
Anderson,106 5 d;halfof subjects Antacid did notaffectresults.
1965 consumed antacid Limitationsincludesmallsamplesize,
before chocolate short studyduration,lack ofcontrol,
lack ofrandomization, lackof
blinding,andlackofconsiderationof
subjects’ baseline diets.
Bett et al,107 Cross-sectional 3 Subjects with acne, 16Subjects with Questionnaire Subjects with acne didnotconsume A
1967 survey control subjects acne, 16control more sugarthan control subjects. R
T
with warts, and subjects withwarts, Limitationsincludesmallsamplesize
I
sex- andage-matched 16healthy control and lackof validated questionnaire. C
healthycontrol subjects L
E
subjects
Fultonet al,11969 Crossover, 1 Adolescents with 30Adolescents, Chocolate baror Severityofacnedidnotchangeduring IN
subject-blind acne and adult 35prisoners control barwith chocolate barand controlbarstudy
P
interventional male prisoners similar caloric periods.Chocolate does notaffect
R
study with acne composition acne. Limitationsinclude small E
sample size,shortstudy duration, S
similar amountsofsugar andfat in S
both bars,inappropriate grouping,
andlackofconsiderationofsubjects’
baseline diets.
Anderson,2 Caseseries 3 University students 27 Daily consumption Studyfoods did notproduce any acne
1971 whoreported ofchocolate, milk, flares. Limitationsinclude small B
o
dietary acne roastedpeanuts, or sample size,lackof control,lack of w
triggers cola for1 wk randomization, lack ofblinding, e,
J
absence oflesioncounts, lack of o
s
statistical analysis,and failure to h
i
,
consider subjects’ prestudy diets. a
n
Continued d
S
h
a
li
ta
3
Table I. Cont’d 4
B
Levelof Conclusionsand o
Study Design evidence Subjects Samplesize Intervention limitations w
e
Kligmanet al,98 Case series 2 Part 1:subjects Part 1:136 Part 1: daily Retinol iseffective treatment foracne ,
J
o
1981 with inflammatory Part 2:39 vitaminA300,000 atdosesof300,000Uforwomenand s
h
acne IU for3-4 mo 400,000-500,000 U formen. Toxicity i,
a
Part 2:menwith acne Part 2: eitherdaily isminimaland limited mainlyto n
vitaminA300,000 xerosis andcheilitis. Limitations d
S
IU for12wk or includelack ofcontrol,lack of h
a
daily vitaminA randomization,lack ofblinding, and li
300,000 IU for1 wk lackofdata on higherdosesof ta
followed by 400,000 vitaminAinwomen.Women were
IU forsecond wk givenoralcontraceptivesthatmay
and then500,000 IU haveconfoundedresults.
fornext10 wk
A
Aizawaand Cross-sectional 3 Womenwith acne 30Subjects with OGTT Mildinsulin resistance occurs during
R
Niimura,45 andage-matched acne,13 control OGTT, however,postprandial
T
1996 controlsubjects subjects hyperinsulinemiadoes not I
C
determinehyperandrogenemia in
L
patientswith acne. Limitations E
includesmallsamplesizeandlackof
I
generalizability beyond N
eumenorrheic women. P
Dreno etal,89 RCT, double-blind 1 Subjects with 332 3mo ofEitherelemental Zincandminocyclinearebotheffective R
2001 inflammatory zinc30 mgdailyor intreatment ofinflammatory acne, E
acne minocycline 100 mg however,minocycline hassuperior S
S
daily effect.
Cordainet al,37 Cross-sectional 2 Kitavanof Papua 1200Kitavan, Skinexamination No acne wasobserved inany subject.
2002 NewGuinea and 115 Ache´ Difference in prevalenceofacne
Ache´ ofParaguay betweenWestern vsKitavan and
Ache´ societiesmaybe partly caused
byenvironmental factors suchas
diet. LGL dietsmay reduce acne.
However, these isolatedsubcultures
mayhavegenetic and other
J
environmental factors thataccount A
M
forabsence ofacne. A
Chiu etal,108 Prospective 2 Universitystudents 22 Subject-perceived Worsening perceived dietquality is CA
D
2003 cohort with acne dietquality positivelyassociated withacne.
D
Limitationsincludesmallsamplesize E
R
anduse oftoolthathas notbeen M
A
validated formeasuring dietquality. TO
L
J
Adebamowo Retrospective 2 Women 47,355 Food frequency Acneis positivelyassociated with A
etal,17 2005 cohort questionnaire of intakeofmilk(particularlyskimmilk), M
A
distant dietary intake instantbreakfast drink,sherbet, and C
A
and subject reportof cottagecheese.Associationbetween D
D
physician-diagnosed acne and dairymay becausedby
E
R
severe acne hormones andbioactivemolecules M
presentinmilk.Thesefactorsmaybe AT
O
more bioavailablein skimmilk. L
Limitations ofthis studyinclude its
retrospective design, loosely
described definitionofacne,
subjects’ imprecise recallof diet,
failure tocontrol forheredityand
socioeconomic status,and low
clinical significance offindings.
Adebamowo Prospective 2 Girls aged 9-15y 6094 Food frequency Acneis positivelyassociated with A
etal,34 2006 cohort atbaseline questionnaire intakeofmilk(particularlyskimmilk). R
Limitations includelack ofvalidation T
I
ofsubjects’ self-report ofacne, low C
clinical relevance of findings,and L
E
failure toaccount forlack oftrend
between wholeorlow-fat milkwith I
N
acne.
Smith etal,49 RCT, 1 Male patientsaged 43 LGL diet or PatientsonLGL diet had decreased P
R
2007 investigator-blind 15-25 ywith acne conventional HGL totalacnelesions,decreasedweight,
E
diet (control) decreased freeandrogen index,and
S
increased IGFBP-1compared with S
control subjects. Majorlimitation is
thatindependent effects ofweight
loss anddietary intervention were
notisolated. Furthermore,study did
notaccount forpossible differences
B
indietary fatand fiber intake o
w
between twogroups. Finally, itis e
,
difficult togeneralizeresults ofthis Jo
s
study towomenwho undergo h
i
cyclical hormonal changesthatmay ,
a
influenceacne. n
d
Continued Sh
a
li
ta
5
Table I. Cont’d 6
B
Levelof Conclusionsand o
Study Design evidence Subjects Samplesize Intervention limitations w
e
Kaymak etal,46 Cross-sectional 3 University students 49Subjects with Foodfrequency Dietary glycemicindex, glycemic load, ,
J
o
2007 with acneand age- acne, 42control questionnaire andinsulin levels were similarin s
h
and sex-matched subjects patientswith acne compared with i,
a
controlsubjects controlsubjects. These factors may n
notbeinvolvedin pathogenesis of d
S
acnein youngerpatients. Study h
a
limitationsinclude lack ofvalidated li
questionnaire,failuretoprovidecopy ta
ofquestionnaire,questionable
timingofinsulinlevelmeasurements,
andfailure to accountfor significant
differences inIGF-1 andIGFBP-3
A
betweenacne andcontrol groups.
R
Smithet al,48 RCT, 1 Malepatients 43 LGL diet or Patients onLGL diet haddecreased
T
2007 investigator-blind aged15-25 y carbohydrate-dense acnelesions, decreased weight, I
C
with acne diet (control) decreasedBMI,andincreasedinsulin
L
sensitivitycompared with control
E
subjects. Majorlimitation isthat
I
independenteffects ofweight loss N
anddietary intervention were not P
isolated.Furthermore, studydid not R
accountfor possibledifferences in E
dietaryfat andfiber intake between S
S
twogroups. Finally, itis difficultto
generalizeresultsofthis studyto
womenwhoundergo cyclical
hormonalchanges thatmay
influenceacne.
Adebamowo Prospective 2 Boysaged9-15 y 4273 Foodfrequency Acne ispositively associatedwith
et al,21 2008 cohort atbaseline questionnaire intake ofskimmilk.Milkmay
influencecomedogenesis through
hormonalpathways. Limitations
J
includelackofvalidationofsubjects’ A
M
self-report ofacne andfailure to A
accountfor lackoftrend between CA
D
wholeorlow-fat milkwith acne.
D
E
R
M
A
T
O
L
Smithetal,50 Nonrandomized 1 Male patients aged 12 7-dAdmission to IGFBP-1 andIGFBP-3 increased from JA
2008 clinical trial 15-20y with acne researchfacility, baselineinLGLgroup,whereasSHBG M
A
controlledfeeding decreased frombaseline inHGL C
A
ofLGL orHGL diet group. Increased glycemicloadmay D
D
result inincreased activity ofsex
E
R
hormones and IGF-1,thereby M
contributing toacne development. AT
O
Limitationsincludesmallsamplesize, L
lack ofrandomization, and inability
to generalizeto female adolescents.
Smithetal,51 RCT 1 Male patients 31 LGL dietor Comparedwithcontrolgroup,LGLgroup
2008 aged15-25y controldiet hadincreasedratioofskinsurfaceSFAsto
with acne MUFAs.Thisincreasedratiowas
negativelyassociatedwithnumberof
acnelesions.Increasedfollicularsebum
outflowwasalsocorrelatedwith A
increasedproportionofsebumMUFAs. R
Limitationsincludefailuretoaccountfor T
I
confoundingeffectofweightlossinLGL C
group,lackofstandardstoensure L
compliancewithspecifieddiet,and E
inabilitytogeneralizetofemalepatients I
N
orsubjectsoutsideof15-to25-yage
P
range.
R
Rouhaniet al,56 2009 Cross-sectional 2 Subjects adhering 2528 WorldWide Subjectsreportedimprovementofacne
E
tolow-glycemic Webebased andreductionofacnetreatment
S
SouthBeach diet questionnaire whileadheringtolow-glycemicSouth S
Beachdiet.Limitationsincludelackof
validationofsubjects’self-reportof
acne,presenceofconfoundingfactors
suchasweightlossandexercise,
recallbias,andselectionbias.
B
o
w
BMI,Bodymassindex;HGL,highglycemicload;IGF,insulin-likegrowthfactor;IGFBP,insulin-likegrowthfactorbindingprotein;LGL,lowglycemicload;MUFA,monounsaturatedfattyacid;OGTT, e
,
oralglucosetolerancetest;RCT,randomizedcontrolledtrial;SFA,saturatedfattyacid;SHBG,sexhormone-bindingglobulin. J
o
Keytolevelofevidence:(1)prospectivecontrolledtrial;(2)retrospectivestudy,prospectivecohortstudy,largecross-sectionalstudy,orlargecaseseries;(3)smallcross-sectionalstudy,smallcase sh
series,orindividualcasereports. i,
a
n
d
S
h
a
li
ta
7
ARTICLE IN PRESS
8 Bowe,Joshi, and Shalita JAMACADDERMATOL
In 2005, Adebamowo et al17 re-examined this postulated that the fat content of milk itself was
alleged connection between dairy and acne. A total unlikely correlated to comedogenicity. In the study
of 47,355 adult women were asked to recall their of Adebamowo et al,17 there were also positive
high school diet using a validated food frequency associationsfoundbetweenacneandinstantbreak-
questionnaire.Subjectswerealsoaskediftheyever fast drink, sherbet, and cottage cheese. These asso-
had physician-diagnosed severe acne. The authors ciations were attributed to the milk content of the
found that acne was positively associated with foods.
reported quantity of milk ingested, particularly This study had several limitations, notably its
skimmilk. retrospective design. Adult women were asked to
Theauthorsspeculatedthatdairyinfluencesacne recall their high school dietary intakes. Patients’
through hormonal mediators and by increasing recollectionoftheirmilkconsumptioninthedistant
plasma insulin-like growth factor (IGF)-1 levels. past may have been imprecise.17 Women were also
Withregardtohormonaleffectsofmilk,itisknown askedtorecalliftheyeverhadphysician-diagnosed
that milk contains the testosterone precursors severe acne. The word ‘‘severe’’ is subjective and
androstenedione and dehydroepiandrosterone- patients may not have known how their physicians
sulfate.18 In vivo, endogenous testosterone is graded acne. Another drawback of this study was
converted via 5a-reductase to dihydrotestosterone thatitdidnotcontrolforconfoundingvariablessuch
(DHT), which stimulates the pilosebaceous unit. as heredity, nationality, and socioeconomic back-
However, DHTcan be produced without 5a-reduc- ground.32 Specifically, the study has been criticized
tase in the setting of exogenous 5a-reduced molec- for failing to account for the possibility that the
ues.19 Milk contains 5a-reduced steroids, notably iodine content of milk might be contributing to the
5a-androstanedione and 5a-pregnanedione, which apparent association between milk and acne.33
are DHT precursors.18 Both testosterone precursors Finally, the clinical significance of the results has
and5a-reducedmoleculesarethoughttocontribute been called into question. The percent of patients
to the comedogenicity of milk17,18,20 by stimulating whorememberedhavingphysician-diagnosedacne
sebum production and hyperkeratinization of the was 6% for those who drank less than one glass of
pilosebaceousunit. milk per week and 8% for those who drank more
It has been proposed that milk also increases than 3 glasses of milk per day.32 In a study with
comedogenicitythroughinteractionswiththeIGF-1 enoughpower,suchasthis47,355membercohort,it
pathway.21Milk,particularlyskimmilk,ispositively is relatively easy to show a statistically significant
correlated with higher plasma IGF-1 levels.22-24 association between two variables. However, the
IGF-1 stimulates synthesis of androgens in both incrementallyincreasedprevalenceofacneinthose
ovarian25andtesticular26tissuesandinhibitshepatic who consumed higher amounts of milk may not
synthesis of sex hormone-binding globulin27 result- havebeenclinicallysignificant.Thisstudymightalso
inginincreasedbioavailabilityofandrogens.15Both have been subject to information bias. The cohort
IGF-128and androgens29,30increasesebumproduc- studiedattendedhighschoolbetweenthe1960sand
tion,whichisimplicatedinacne. 1990s. During these years, although the medical
Whenbroken downintocategoriesofmilktype, community began to view the link between diet
including whole, low fat, and skim, Adebamowo and acne as myth, this information didnot immedi-
etal17foundthatonlyskimmilkshowedastatistical ately disseminate to the public. Therefore, sweet
correlation with acne. This may be surprising given foods and beverages such as soda were often
that one might expect bovine hormones to be avoided, even during the 1960s through 1980s, by
concentrated in the lipid fraction of milk.31 The thosewhohadacneinanattempttoamelioratetheir
authors hypothesized that the bioavailability of the disease. If these subjects were actively avoiding
factors responsible for comedogenicity of milk may soda,theymighthavebeenmorelikelytoconsume
be increased by skim milk processing.17 They also milk.
postulatedthatskimmilkismoreacnegenicbecause, In 2006, Adebamowo et al34 set out to uphold
in comparison with whole milk, skim milk contains their previous findings, this time using a prospec-
lessestrogen,ahormoneknowntoreduceacne.17It tive study design. The researchers examined 6094
is unknown how processing affects hormone levels girls aged 9 to 15 years at baseline who were
but it has been documented that fermentation that prospectively followed up for up to 3 years.
occurs with cheese production results in additional Subjects completed validated food frequency ques-
testosterone production from androgen precur- tionnaires and self-reported the frequency and
sors.20 Because the association between milk and amount of pimples they experienced. Positive as-
acne was more marked for skim milk, it was sociations were found between prevalence of acne
ARTICLE IN PRESS
JAMACADDERMATOL Bowe,Joshi, andShalita 9
and intake of total milk, whole milk, low-fat milk, reports rather than objective measures. In addition,
and skim milk. These trends were significant even they were all observational as opposed to random-
when girls using oral contraceptives and girls aged ized, controlled trials. Lastly, the associations that
11 years or older were each excluded. Like the weredetectedwereallweakbyepidemiologicstan-
previous study, there was also no association dards in that the odds ratios of associations were
between dairy fat and acne. The advantage of this consistently close to 1. However, the authors did
study was its prospective design. However, this demonstrateanassociationbetweenmilkandacnein
study was limited by the lack of validation of the 3separatepopulations,andthus,furtherinvestigation
subjects’ self-report of acne. Severity of acne as throughrandomizedcontrolledtrialsiswarranted.
assessed by a physician does not always correlate
with self-report of acne. A recent study measuring MORE MODERN STUDIES REVISIT THE
the validity of self-report for acne showed that LINK BETWEEN ACNE AND DIET: AN
college students cannot accurately report that they EXAMINATION OF THE INFLUENCE OF
have acne.35 CARBOHYDRATE INTAKE ON ACNE
Again, although statistically significant, the prev- SEVERITY
alence ratios demonstrating an association between Although those mentioned above were working
milk and acne were very low (maximum of 1.24). out the link between dairy and acne, others were
Thus, the clinical relevance of these results remains focusingonthepotentialassociationbetweencarbo-
in question. In 2008, Adebamowo et al21 demon- hydrateingestionandacneseverity.In2002,Cordain
strated similar results in a cohort of 4237 boys et al37 performed a cross-sectional study in which
followedupprospectively.Liketheadolescentgirls, 1300subjectsfromtwonon-Westernizedsocieties,the
these boys all completed food frequency question- KitavanIslandersofPapuaNewGuineaandtheAche´
naires and were asked about their pimples. There hunter-gatherersofParaguay,underwentskinexam-
was a positive association between intake of skim inationbyageneralpractitionertrainedinthedetec-
milkandprevalenceofacne.Themultivariateprev- tionanddiagnosisofacne.Amongthesesubjects,no
alence ratio of acne adjusted for age, height, and casesofacnewerereported.Cordainetal37suggested
energy intake was 1.19 (95% confidence interval thattheabsenceofacneinthesesocietiesmayhave
1.01-1.40, P value\.02) for those who consumed beenadirectconsequenceoftheirdiets.TheKitavans
skim milk more than twice a day compared with andAche´ssubsistonlowglycemicload(LGL)diets,
thosewhoconsumedlessthanoneservingperweek devoid of Western refined foods such as cereals,
ofskimmilk.Asidefromthissingleweakassociation, chips,cookies,andbread.
this study did not find a significant association Theglycemicindex(GI),developedin1981,isa
between total milk consumption and acne. There relativecomparisonofthepotentialofvariousfoods
wasalsonoassociationbetweenacnewithtotalfat, toincreasebloodglucosebasedonequalamountsof
dairy fat, nor vitamin A and thus these compounds carbohydratesinthefood.38Theconceptofglycemic
were not thought to contribute to the acnegenic load was developed in 1997, and is calculated by
propertiesofmilk. multiplying the GI times the carbohydrate content/
Thistrialdidhavetheadvantageofaprospective servingsize.39Ineffect,theglycemicloadtakesinto
design. However, once again, the authors did not account both the quality and quantity of carbohy-
account for the fact that there was no significant drates ingested. Dietary glycemic load is a measure
trend between intake of whole orlow-fatmilk with of the blood glucose- and insulin-increasing poten-
acne.31 As stated previously, bovine hormones tial, as it represents both the rate of carbohydrate
would likely be concentrated in the lipid fractions absorption(theGI)andthequantityofcarbohydrate
of milk, making this repeated lack of association consumed.40 Examples of low- and high-glycemic
between fattier milks and acne perplexing.31 foodscanbefoundinTableII.
However,itistheoreticallypossiblethatthefindings In a subsequent review article, Cordain et al41
maybearesultofdifferencesintheglycemicloadof postulatedthatdiet-inducedhyperinsulinemialeads
full versus skim milk. For a 250-g serving size, the toa cascade of endocrine responses that may influ-
glycemicloadoffull-fatmilkhasbeenreportedtobe ence the development of acne through androgens,
3whereastheglycemicloadofskimmilkis4.36The IGF-1, IGF binding protein (IGFBP)-3, and retinoid
nearly equivalent glycemic loads of skim milk and signaling pathways. The authors purport that a
full-fat milk can hardly explain the latter’s stronger hyperinsulinemic diet acts as a risk factor in the
associationwithacne. developmentof acnethrough influences on follicu-
DrawbacksofallthedairystudiesbyAdebamowo lar epithelial growth, keratinization, and androgen-
etal17,21,34werethattheywerebasedonsubjects’self- mediatedsebumsecretion.
ARTICLE IN PRESS
10 Bowe,Joshi, and Shalita JAMACADDERMATOL
Table II. Examplesof low-and high-glycemic with acne and 13 control subjects. Serum-free
foods36 testosterone, DHT, and dehydroepiandrosterone-
sulfate were significantly higher in the acne group.
Glycemic Glycemicloady
Basal insulin levels were similar between the two
Food index* (per100-gserving)
groups, but upon administration of a 75-g, 2-hour
Carrots,raw 16 1.6
Peanuts 14 1.7 oral glucose tolerance test, summed insulin levels
Oranges, raw 42 3.9 were significantly higher in the acne group.
Plums,raw 39 3.9 However, there was no significant difference in the
Apples, raw 38 4.8 change in serum testosterone or free testosterone
Porridgemadefrom 58 5.1 during the oral glucose tolerance test between the
rolled oats two groups. The authors concluded that there was
Chickpeas,boiled 28 5.6 mildinsulinresistanceduringtheoralglucosetoler-
Spaghetti,white,boiled 42 11.0
ance test in patients with acne, but that the post-
Whiteflour bread 70 32.7
prandial hyperinsulinemia did not determine
hyperandrogenemiainpatientswithacne.Thisstudy
*Listedglycemicindexiswhenglucosesugarisusedasreference
food. waslimitedbysmall samplesizeandlackofgener-
yAdapted from Foster-Powell et al.36 Glycemic load is estimated alizabilitybeyondeumenorrheicwomen.
bymultiplyingglycemicindexbygramsofcarbohydrateper100-g A recent cross-sectional study by Kaymak et al46
servinganddividingby100.
measured fasting glucose, insulin, IGF-1, IGFBP-3,
and leptin levels in 49 Turkish university students
The proposition of Cordain et al,37 linking the with acne and 42 healthy control subjects. All sub-
absenceofacneintheKitavanandAche´ toasingle jectsalsocompletedafoodfrequencyquestionnaire
variablesuchasdietaryGI,althoughintriguing,has from which investigators calculated overall GI and
been heavily criticized. Not only do these isolated dietary glycemic load. No significant differences in
subcultureshavesimilardiets,theyalsosharesimilar serum glucose, insulin levels, leptin levels, overall
genetic compositionand environmental factors.42,43 GI,anddietaryglycemicloadbetweenpatientswith
The findings of Cordain et al37 may have been acne and control subjects were found. The authors
bolstered if the acne-free subjects were given diets concludedthatthesevariablesarenotinvolvedinthe
rich in high-glycemic foods with subsequent devel- pathogenesisofacne.
opmentofacne.42 This study has been criticized for using a diet-
Recent noteworthy advances have been made in assessmenttoolthatwasnevervalidated,andfornot
ourunderstandingofthecomplexinterrelationships providing it in the article, making one unable to
among hyperandrogenism, hyperinsulinemia, and assesstherobustnessoftheinstrument.47Inaddition,
acne.Wesummarizethehighlightsoftheseadvances thetimingofphlebotomyhasbeencriticized.Fasting
below. However, despite our evolving knowledge, levels of serum markers were used, and do not
the link between hyperinsulinemic, high-GI diets represent insulin level excursions and total insulin
and acne pathogenesis remains tenuous. Recent exposureoverthecourseoftheday.47Todetectmild
studiespresentconflictingresults. insulinresistance,whichisthekindexpectedinthis
Ithasbeenpostulatedthatgrowthhormonemay otherwisehealthypopulation,repeatedmeasuresof
be involved in the pathogenesis of acne. IGF-1, a serum markers must be drawn at multiple intervals
surrogate marker of growth hormone, is often used postprandially. Another drawback of the study was
asanindicatorofgrowthhormonesecretionbecause thefailuretoassignGIandglycemicloadvaluesfor
it has little diurnal variation. In 1995, Aizawa and meat, poultry, fish, vegetables, and cheese. The
Niimura44 sought to investigate the relationship be- authors stated that these foods are not likely to
tweenacneand IGF-1.They studied 82postadoles- induce a significant increase in blood glucose.
cent eumenorrheic women with acne and 31 age- However, dietary fish rich in omega-3 fatty acids
andsex-matchedcontrolsubjectsandfoundthatthe can improve glycemic control, whereas processed
IGF-1 levels were significantly greater in patients meats can impair glycemic control. In addition,
with acne. However, there was no correlation be- vegetable cooking technique can affect glycemic
tween IGF-1 and testosterone, free testosterone, load.47Byfocusingonlyoncarbohydrates,thestudy
dehydroepiandrosterone-sulfate, or acne severity. failed to account for the impact of other foods.
Inasubsequentstudy,AizawaandNiimura45sought Interestingly, the levels of IGF-1 were significantly
to correlate basal insulin and glucose-stimulated higher among patients with acne as compared with
insulin levels with androgen levels in women with control subjects.Furthermore, the levels of IGFBP-3
acne. They investigated 30 eumenorrheic women weresignificantlyloweramongpatientswithacneas