AD	Atopic Dermatitis
AGSS	Acne Global Severity Scale
AhR	Aryl Hydrocarbon Receptor
BMI	Body Mass Index
BSA	Body Surface Area
CCL17/27	Chemokines
CFUs	Colony-Forming Units
CI	Confidence Interval
CMPA	Cow’s Milk Protein Allergy
CSU	Chronic Spontaneous Urticaria
DLQI	Dermatology Life Quality Index
EASI	Eczema Area and Severity Index
ECP	Eosinophil Cationic Protein
FFAR2/3	Free Fatty Acid Receptor 2/3
FLG	Filaggrin
FOS	Fructo-oligosaccharide
GAGS	Global Acne Grading System
GPR41/43/109A	G Protein-Coupled Receptor 41/43/109A
GRADE	Grading of Recommendations Assessment, Development and Evaluation
HDAC	Histone Deacetylase
I-FABP	Intestinal Fatty Acid-Binding Protein
IGA	Investigator’s Global Assessment
IgE	Immunoglobulin E
IL	Interleukin
LBP	Lipopolysaccharide-Binding Protein
LGG	Lactobacillus rhamnosus GG
MCID	Minimum Clinically Important Difference
NRS	Numeric Rating Scale
PASI	Psoriasis Area and Severity Index
PICO	Population, Intervention, Comparison, Outcomes
POEM	Patient-Oriented Eczema Measure
PPARγ	Peroxisome Proliferator-Activated Receptor γ
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
PROSPERO	International Prospective Register of Systematic Reviews
RCT	Randomized Controlled Trial
Reg3A	Regenerating Islet-Derived Protein 3-Alpha
REML	Restricted Maximum-Likelihood
RoB 2	Risk of Bias tool version 2
SCFA	Short-Chain Fatty Acid
SCORAD	SCORing Atopic Dermatitis
SMD	Standardized Mean Difference
SPT	Skin Prick Test
TEWL	Transepidermal Water Loss
Th1/Th2/Th17	T Helper Cell Type 1/2/17
TNF-α	Tumor Necrosis Factor-alpha
Treg	Regulatory T Cell
VAS	Visual Analog Scale
WoSCC	Web of Science Core Collection