Topic

Mood, stress and thinking

Scores for mood, anxiety and stress, and tests of memory and attention.

This page is not a ranking. Ingredients appear in order of how much we have read here.

The 8 things measured here · ingredients read against each

Read here so far: 33 questions across 17 ingredients

Ashwagandha

Ashwagandha and AnxietyTwo sources, all measured lowerLow certainty, level 2 of 4
Ashwagandha and Cognitive performanceOne source, measured higherLow certainty, level 2 of 4
Ashwagandha and DepressionOne source, measured lowerLow certainty, level 2 of 4
Ashwagandha and Perceived stressOne source, measured lowerLow certainty, level 2 of 4
Ashwagandha and Serum cortisol (morning)One source, measured lowerLow certainty, level 2 of 4

5-HTP

5-HTP and AnxietyOne source, found no clear differenceLow certainty, level 2 of 4
5-HTP and DepressionOne source, measured lowerLow certainty, level 2 of 4
5-HTP and Serum cortisol (morning)One source, measured higherLow certainty, level 2 of 4
5-HTP and Serum serotoninOne source, measured higherLow certainty, level 2 of 4

L-theanine

L-theanine and AnxietyOne source, found no clear differenceLow certainty, level 2 of 4
L-theanine and Cognitive performanceOne source, measured higherLow certainty, level 2 of 4
L-theanine and Salivary cortisolOne source, found no clear differenceLow certainty, level 2 of 4

Vitamin B6

Vitamin B6 and AnxietyOne source, measured lowerLow certainty, level 2 of 4
Vitamin B6 and Cognitive performanceOne source, found no clear differenceLow certainty, level 2 of 4
Vitamin B6 and DepressionOne source, measured lowerVery low certainty, level 1 of 4

Creatine

Creatine and Cognitive performanceTwo sources, saying different things, and one source carries a noticeLow certainty, level 2 of 4
Creatine and DepressionTwo sources, saying different thingsLow certainty, level 2 of 4

Folate

Folate and DepressionOne source, measured lowerModerate certainty, level 3 of 4
Folate and Cognitive performanceOne source, measured higherLow certainty, level 2 of 4

Ginkgo biloba

Ginkgo biloba and Cognitive performanceOne source, measured higher, and one source carries a noticeModerate certainty, level 3 of 4
Ginkgo biloba and AnxietyOne source, measured lowerLow certainty, level 2 of 4

Omega-3 fatty acids (EPA/DHA)

Omega-3 fatty acids (EPA/DHA) and ADHD symptom severityOne source, reported mixed resultsLow certainty, level 2 of 4
Omega-3 fatty acids (EPA/DHA) and DepressionOne source, measured lower, and one source carries a noticeLow certainty, level 2 of 4

Vitamin B12

Vitamin B12 and Cognitive performanceOne source, found no clear differenceLow certainty, level 2 of 4
Vitamin B12 and DepressionOne source, found no clear differenceLow certainty, level 2 of 4

Beta-Alanine

Beta-Alanine and Serum cortisol (morning)One source, found no clear differenceVery low certainty, level 1 of 4

Choline

Choline and Cognitive performanceOne source, measured higherLow certainty, level 2 of 4

Curcumin

Curcumin and Cognitive performanceOne source, found no clear differenceLow certainty, level 2 of 4

Glycine

Glycine and Cognitive performanceTwo sources, saying different thingsLow certainty, level 2 of 4

Iodine

Iodine and Cognitive performanceTwo sources, saying different thingsLow certainty, level 2 of 4

Iron

Iron and Cognitive performanceOne source, reported mixed resultsVery low certainty, level 1 of 4

Panax ginseng

Panax ginseng and Cognitive performanceOne source, found no clear differenceModerate certainty, level 3 of 4

Tongkat Ali

Tongkat Ali and Salivary cortisolOne source, measured lowerLow 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.

Each bar is one source’s range, drawn against the line of no difference: left of the line is lower, right is higher. Widths are not comparable between rows.

Creatine and cognitive performance
Two sources here, and they say different things: one measured higher cognitive performance and one reported mixed results.
Low certainty, level 2 of 4The sources say different thingsOne source carries a notice
One source’s range. The sources here say different things. Systematic review, 2024 · 16 studies pooled
Glycine and cognitive performance
Two sources here, and they say different things: one found no clear difference in cognitive performance and one reported mixed results.
Low certainty, level 2 of 4The sources say different things
No number has been put on this yet.
Iodine and cognitive performance
Two sources here, and they say different things: one measured higher cognitive performance and one found no clear difference.
Low certainty, level 2 of 4The sources say different things
One source’s range. The sources here say different things. Systematic review, 2014 · 2 studies pooled
Creatine and depression
Two sources here, and they say different things: one measured lower depression and one reported mixed results.
Low certainty, level 2 of 4The sources say different things
One source’s range, crossing no difference: these numbers fit no effect too. The sources here say different things. Systematic review, 2025 · 11 studies pooled · 1,093 participants

How much of this is one source

Read from 34 sources. 28 of the 33 questions here rest on a single source with nothing yet to check them against, and on 4 questions 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

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.