Table 2.

Summary of dietary components to boost photoaged skin health in clinical trials.

Ingredients	Country	Sample Subjects and Size	Study Design	Dose	Duration	Main Results	Reference
Phytochemicals
Astaxanthin	Japan	Human, 23	a randomized, double-blind, placebo-controlled trial	4 mg	10 weeks	skin moisture ↑ skin texture ↑	[97]
Lycopene	UK	Women, 20, mean age 33 years	a randomized controlled study	55 g tomato paste (16 mg lycopene)	12 weeks	MED ↑ MMP-1 ↓ mtDNA ↓	[99]
Lycopene and lutein	Germany	Human, 65	a double-blinded, placebo-controlled, crossover study	5 mg lycopene and 10 mg lutein	12 weeks	HO-1 ↓ intercellular adhesion molecule 1 ↓ MMP-1 ↓	[99]
Lycopene, β-carotene and Lactobacillus johnsonii	France	PLE patients, 17 males and 43 females, 60	a randomized, placebo-controlled, double-blinded study	nutritional supplement containing 2.5 mg lycopene, 4.7 mg of β-carotene and 5 × 108 cfu of the probiotic Lactobacillus johnsonii	12 weeks	ICAM1 ↑ PLE score ↓	[101]
Resveratrol– procyanidin blend	Italy	Men and women, 50, aged 35–65 years	a placebo-controlled, double-blind study	8 mg transresveratrol and 14.63 mg procyanidin	60 days	skin moisturization, elasticity ↑ values for systemic oxidative stress, plasmatic antioxidant capacity, skin antioxidant power ↑ skin roughness, wrinkles ↓	[110]
Green tea polyphenols	Germany	Women, 60, aged 40–65 years	a double-blind, placebo-controlled study	1402 mg green tea polyphenols	12 weeks	skin elasticity, roughness ↓ water homeostasis ↑ blood flow and oxygen delivery to skin ↑ erythema ↓	[114]
Curcumin	Japan	Human, 47	a randomized, double-blind, placebo-controlled trial	30 mg curcumin	8 weeks	water content ↑ TNF-α ↓ IL-1 ↓	[111]
Rosemary (Rosmarinus officinalis) and grapefruit (Citrus paradisi) polyphenols	Spain	Women, 90	a randomized, parallel-group study	Long-term: 250 mg/day; Short-term: 100, 250 mg/day	Long-term: 2 weeks; Short-term: 24, 48 h	skin redness ↓ wrinkles ↓ skin elasticity ↑	[115]
Functional proteins and peptides, sugars, or oils
Bioactive collagen peptide VERISOL®	Brazil	Women, 114, aged 45–65 years	a double-blind, placebo-controlled study	2.5 g	8 weeks	procollagen I, elastin, fibrillin ↑ wrinkles ↓	[122]
collagen peptide	Japan	Women, 33, aged 40–59 years	an ex vivo model and randomized, placebo-controlled clinical trial	10 g specific mixture of collagen peptides of fish origin (Peptan®F) or porcineorigin (Peptan®P)	12 weeks	skin hydration ↑ collagen density ↑ glycosaminoglycan ↑	[123]
A collagen hydrolysate and antioxidant- containing nutraceutical	India	Women, 34, mean age 39.5 years	-	Marine collagen peptides (5 g of fish collagen peptides) and antioxidant blend (natural tomato extract, grape seed extract, green tea extract, vitamin C and vitamin E)	30 days	skin hydration, firmness, elasticity, barrier function ↑ wrinkle width, open pores, skin roughness, the color of hyperpigmented blemishes ↓	[124]
Galacto-oligosaccharides	Korea	Women	a randomized, double-blind clinical trial	1 g twice a day	12 weeks	TEWL ↓ wrinkles ↓	[125]
Squalene	Korea	Women, 40, >50 years	-	13.5, 27 g/day	90 days	procollagen ↑ MED ↑ facial erythema ↓ keratinocytic apoptosis ↓ thymine dimer level ↓ wrinkles ↓	[131]
Fish oil	US	Human, 10	-	10 capsules per day of fish oil containing each 280 mg EPA and 120 mg DHA	4 weeks	MED ↑	[132]
Argan oil	Morocco	Postmenopausal women, 60	-	25 mL/day	60 days	gross elasticity of skin, net elasticity of skin, biological elasticity ↑ resonance running time ↓	[134]
Aloe sterol	Japan	Men, 48	a randomized, double-blind, placebo-controlled study	40 mg/d	12 weeks	skin elasticity ↑	[135]
Aloe sterol	Japan	Women, 64	a randomized, double-blind, placebo-controlled study	aloe sterol yogurt contained 40 µg of aloe sterol per 100 g	12 weeks	skin elasticity ↑ skin hydration ↑ collagen ↑	[135]
Probiotics
Lactococcus H61	Japan	Women, 30	a double-blind, placebo-controlled trial	4 × 1010 cfu	8 weeks	balance of intestinal microbes and intestinal health ↑ antioxidant activity ↑ skin immune response ↑	[14]
Lactobacillus paracasei NCC 2461	France	Women, 64, aged 18–40 years	a randomized, double-blind, placebo-controlled study	1 × 1010 cfu	4 weeks	barrier function ↑ skin sensitivity ↓	[142]

Abbreviations: HO-1, heme oxygenase-1; ICAM, intercellular adhesion molecule; IL, interleukin; MED, minimal erythema dose; MMP, matrix metalloproteinase; mtDNA, mitochondrial DNA; PLE, polymorphic light eruption; TEWL, transepidermal water loss; TGF, transforming growth factor.