a low glycemic load diet resulted in both clinical and histopathological
improvements in acne.17 Kwon et al recruited thirty-two
Korean subjects with mild to moderate acne and randomly assigned
them to either a Low Glycemic Load (LGL) Diet or a Control
diet. The authors defined the LGL diets as follows: 45% calories
from low GI carbohydrates, 25% protein, 30% fats; subjects in the
control group were instructed to eat carbohydrate rich foods daily.
Two dermatologists then assessed acne using the Leeds Revised
Acne Grading System. A self-assessment, photographs, and immunohistochemical
analyses of punch biopsies were also used to
assess the impact of the LGL on the skin.
Subjects adhering to the LGL diet showed significant clinical
improvements in the number of non-inflammatory and inflammatory
acne lesions as compared to the control group.
Histopathological evaluation showed that the size of sebaceous
glands was significantly reduced in those following the LGL
diet. Furthermore, the authors noted a decrease in the number
of inflammatory cells seen on H&E, and a decrease in the expression
of inflammatory cytokines such as IL-8. These findings
not only further bolstered the arguments made by Smith et al,
but they provided even greater insights into the timeline over
which one might appreciate these changes (Kwon et al saw
results in 10 weeks, while Smith et al study lasted 12 weeks).
The Kwon et al study had several strengths worth mentioning
here. Confounding variables in the Smith et al trial such
as BMI were eliminated in the Kwon et al study as total energy
intake and BMI were maintained throughout the study. Rigorous
nutritional counseling and reinforcement of diet adherence
through daily food records, nutritionist consults, and personalized
eating plans for each subject were provided. Furthermore,
histopathology assessment using 2mm punch biopsies stained
with H&E to evaluate inflammation, size of sebaceous glands,
and stained for inflammatory markers like IL-8. This study was
the first of its kind to confirm a decrease in clinical inflammation
on a microscopic scale. The inclusion of females (though
only eight in total), allowed for results to be universally applicable
to both male and females. Additionally, a wash out period
for patients previously on prescription treatment regimens was
included and acne assessments utilized a validated grading
system and two independent dermatologists as graders.
Despite breakthrough progress with this study, it did have several
limitations. First, the use of a self-reporting food diary may
have prevented accurate calculation of the nutritional composition
and amount of food consumed. Second, other dietary
factors were not considered including milk/dairy, omega-3 fatty
acids, antioxidants, probiotic consumption, saturated fat, fiber,
zinc, and iodine.
The results of a study conducted by Reynolds et al in 2010
are not as straight forward.18 This was an 8-week randomized
controlled trial looking at 43 Australian males, mean age 16.6, attending boarding school. In those who followed a LGL diet,
there was a trend towards greater improvement in acne severity,
but it did not reach statistical significance. Furthermore, no
change in insulin sensitivity was detected in this group. However,
this study suffered from major design flaws. First, the LGL
did not differ much from the control group (only a difference
of 10 points in GI), as the LGL was far from strict. Second, the
study duration was very short- only 8 weeks total. Given the
natural history of comedogenesis, one would not expect to see
a significant result in such a short time frame. Additionally, the
authors used non-validated and insensitive grading method
and noted inconsistencies to the acne grader. Minimal efforts
were taken to ensure dietary compliance. Despite all of these
limitations, there was clearly a greater improvement in facial
acne severity from week 0 to week 8 in the LGL group. Although
this trend didn’t reach statistical significance, it is hard to ignore
when you see the raw data. Although suffering from a number
of limitations, we listed this study after the Kwon study simply
because of its RCT design.
Jung et al conducted a cross-sectional study on 1,285 male and
female Korean patients.19 Acne triggers were evaluated using a
validated food frequency questionnaire and blood levels of insulin,
IGF-1, insulin-like growth factor binding protein-3 (IGFBP-3),
post-prandial 2 hours blood glucose, dehydroepiandrosterone
sulphate were measured. Two independent dermatologists using
Dr. Cunliffe’s Grading System conducted acne assessment.
Subjects were categorized into three groups: acne patients affected
by food (AF), acne patients not affected by food (NAF),
and a control group. 54% of acne patients reported that their
acne was aggravated by food. It was found that acne severity
was positively associated with high GL, dairy, high saturated
fat, and iodine intake as acne patients showed a greater preference
for hamburgers, doughnuts, instant noodles, carbonated
drinks, processed cheeses, high fat foods (nuts, fried chicken,
pork), and foods with high iodine levels such as seaweed.
Furthermore, blood levels of IGF-1 and IGFBP-3 showed sex-dependent
differences as males in the AF group showed increased
levels of IGF-1 and females in the AF group showed decreased
levels of IGFBP-3, both allowing for increased free and active
IGF-1 to be circulating in the blood. Control subjects without
acne showed more regularity of meal habits and increased intake
of vegetables and fish, which may prove to be protective
against the pathogenesis of acne.
The study had numerous advantages, including a large sample
size (783 patients and 502 controls), sensitive assays for insulin
resistance (postprandial 2-hour blood glucose test), validated
Food Frequency Questionnaire and objective dermatologist assessments
of acne severity. It also included female participants,
which was a strength compared to the Smith et al studies. With
that said, numerous limitations were also observed. The use of
