Table 3.
Molecules with potential a modulatory effect on skin and gut either directly or indirectly.
| Molecule | Documented/Possible effect in gut | Documented/Possible effect on skin | Reference |
|---|---|---|---|
| Bacterial metabolites | |||
| SCFAs * | Anti-inflammatory effects | Anti-inflammatory effects | [132] |
| Vitamin D | Suppress inflammation in IBD* | Not reported | [133] |
| Urocanic Acid | Suppress inflammation in IBD* | Not reported | [134] |
| GABA * | Neurotransmitter modulation | Itch restriction | [135,136] |
| Dopamine | Neurotransmitter modulation | Inhibition of hair growth | [135,137] |
| Serotonin | Neurotransmitter modulation | Melatonin modulation | [135,138] |
| Acetylcholine | Neurotransmitter modulation | Barrier function | [135,139] |
| Phenol and p-cresol | Biomarker of gut dysbiosis | Impaired epidermal barrier function | [140] |
| Dietary components | |||
| Catechins | Anti-inflammatory effects | Anti-inflammatory effects | [141] |
| Polyphenols | Anti-inflammatory effects | Anti-inflammatory effects | [142] |
| Lycopene | Selectively utilized by host microbiota | Protection against photodamage | [143,144] |
| Prolamin | Not reported | Protection against AD * | [145] |
| Phytomolecules | Not reported | Anti-ageing | [146] |
| Gluten | Coeliac disease | Skin Rashes | [58,59] |
* Abbreviations: Atopic dermatitis (AD), gamma-aminobutyric acid (GABA), inflammatory bowel disease (IBD), and short chain fatty acids (SCFAs).