Table 2.
Evidence of beneficial probiotic interventions: human studies.
| Author | Study design | Oral probiotic | Clinical response | Proposed mechanism |
|---|---|---|---|---|
| Siver, 1961 | Intervention group only; 300 subjects with acne | L. acidophilus and L. bulgaricus∗ (probiotic × 8 days, 2-weeks washout, then re-introduction × 8 days) | clinical improvement in 80% of patients, particularly those with inflammatory acne | Mechanism not established |
| Peguet-Navarro et al., 2008 | Randomized, double-blind, placebo-controlled; 54 healthy subjects | L. johnsonii (La1) for 6 weeks | ↑ Recovery of skin immune homeostasis following UV-induced immunosuppression | Normalization of epidermal expression of CD1a |
| Vijayashankar and Raghunath, 2012 | Case report; 47-year-old female with severe pustular psoriasis | L. sporogenes (Supplementation 3×/d) | Clinical improvement at 15 days, almost complete clearance at 4 weeks | Mechanism not established |
| Groeger et al., 2013 | Randomized, double-blind, placebo-controlled; 26 subjects with plaque psoriasis | B. infantis ∗35624 (1×1010 CFU∗/d × 8 weeks) | ↓ Systemic inflammation (↓ CRP∗, ↓ TNF-α∗) | Induction of mucosal immunoregulatory responses that can exert systemic effects |
| Guéniche et al., 2013 | Randomized, double-blind, placebo-controlled; 64 females with sensitive skin | L. paracasei NCC2461 (ST11) (1×1010 CFU/d × 2 months) | ↓ Skin sensitivity, ↓ TEWL∗ | ↓ Skin sensitivity neuromediators and neurogenic inflammation, positive effect on skin barrier function via ↑ circulating TGF-β∗ |
| Jung et al., 2013 | Randomized, controlled, open-label; 45 females with acne | L. acidophilus (NAS), LB-51∗, B. bifidum, (5×109, 5×109, 20×109 CFU 2×/d × 12 weeks | Significant ↓ in number of acne lesions with using probiotic together with Abs than Abs alone | Synergistic anti-inflammatory effect |
| Lee et al., 2015 | Randomized, double-blind, placebo-controlled; 129 females with dry skin and wrinkles | L. plantarum HY7714 (1×1010 CFU/d × 12 weeks) | ↑ Skin hydration, ↓ TEWL, ↑ skin elasticity, ↓ wrinkle depth | Molecular control of signaling pathways and gene expression in skin cells |
| Fabbrocini et al., 2016 | Randomized, double-blind, placebo-controlled; 20 adults with acne | L. rhamnosus SP1 (3 × 109 CFU/d (75 mg/d) × 12 weeks) | Improved appearance of adult acne | Normalized skin expression of genes involved in insulin signaling (↓ IGF-1∗ expression, ↑ FOXO1) |
| Ogawa et al., 2016 | Randomized, double-blind, placebo-controlled; 126 subjects with elevated TEWL | L. brevis SBC8803 (25 or 50 mg/d × 12 weeks) | ↓ TEWL, ↑ corneal hydration | Stimulation of serotonin release from intestinal enterochromaffin cells → ↑ vagal nerve activity |
∗L. bulgaricus, Lactobacillus bulgaricus; B. infantis, Bifidobacterium infantis; CFU, colony-forming units; CRP, C-reactive protein; TNF-α, tumor necrosis factor alpha; LB, Lactobacillus bulgaricus; TEWL, transepidermal water loss; TGF-β, transforming growth factor beta.