Topic
Skin, hair and nails
Skin moisture and stretch, and nail thickness and splitting.
This page is not a ranking. Ingredients appear in order of how much we have read here.
The 5 things measured here · ingredients read against each
Read here so far: 7 questions across 4 ingredients
Astaxanthin
- Astaxanthin and Skin moisture contentOne source, measured higherLow certainty, level 2 of 4
- Astaxanthin and Skin Elasticity (Cutometer)One source, measured higherVery low certainty, level 1 of 4
Biotin (vitamin B7)
- Biotin (vitamin B7) and Brittle nail severityTwo sources, all measured lowerVery low certainty, level 1 of 4
- Biotin (vitamin B7) and Nail plate thicknessTwo sources, all measured higherVery low certainty, level 1 of 4
Collagen peptides
- Collagen peptides and Skin Elasticity (Cutometer)One source, measured higherModerate certainty, level 3 of 4
- Collagen peptides and Skin moisture contentOne source, measured higherModerate certainty, level 3 of 4
Vitamin A Beta Carotene
- Vitamin A Beta Carotene and Skin HealthTwo sources, saying different thingsLow certainty, level 2 of 4
Where the sources say different things
Every side in full, because one line would have to pick one of them.
Vitamin A Beta Carotene and skin Health
Two sources here, and they say different things: one measured higher skin Health and one reported mixed results.
0.5
Systematic review, 2008
How much of this is one source
Read from 8 sources. 4 of the 7 questions here rest on a single source with nothing yet to check them against, and on 1 question the sources say different things.
What is still to read is kept per ingredient, not per topic, so every ingredient named above carries its own list.
Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.
The other 14 topics
- Sleep29 questions · 11 ingredients
- Mood, stress and thinking34 questions · 18 ingredients
- Heart and blood pressure50 questions · 24 ingredients
- Cholesterol and blood fats70 questions · 24 ingredients
- Blood sugar and insulin52 questions · 21 ingredients
- Inflammation and oxidative stress40 questions · 22 ingredients
- Energy and exercise27 questions · 18 ingredients
- Joints, muscles and pain18 questions · 16 ingredients
- Bone strength10 questions · 6 ingredients
- Hormones, thyroid and fertility30 questions · 12 ingredients
- Liver, kidney and digestion22 questions · 14 ingredients
- Vitamin and mineral levels15 questions · 9 ingredients
- Body weight and composition16 questions · 11 ingredients
- Long-term health and immunity20 questions · 17 ingredients
This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.