Choline is a nootropic: it enhances your ability to pay attention and learn efficiently, probably because you use a lot of acetylcholine during mentally-demanding tasks, and choline helps you synthesize enough to work harder and go longer. Choline also links to decreased brain inflammation in a dose-dependent manner — the more choline you eat, the less inflamed your brain tends to be.
Green tea is widely drunk in many cultures, especially in Asia, and is known to have potent health benefits. These benefits are attributed to its polyphenol content (particularly the flavanols and flavonols). In cell cultures and animal studies, the polyphenols have been proven to prevent neurotoxin-induced cell injury. Green tea also has anti-inflammatory properties and, according to a study performed on aged mice, may delay memory regression. It’s safe to drink several cups of green tea per day, though it may be more efficacious to take a green tea extract supplement to reach a daily dose of 400 to 500 mg of EGCG, one of the main active components of green tea.
I posted a link to the survey on my Google+ account, and inserted the link at the top of all gwern.net pages; 51 people completed all 11 binary choices (most of them coming from North America & Europe), which seems adequate since the 11 questions are all asking the same question, and 561 responses to one question is quite a few. A few different statistical tests seem applicable: a chi-squared test whether there’s a difference between all the answers, a two-sample test on the averages, and most meaningfully, summing up the responses as a single pair of numbers and doing a binomial test:
Nootropics (/noʊ.əˈtrɒpɪks/ noh-ə-TROP-iks) (colloquial: smart drugs and cognitive enhancers) are drugs, supplements, and other substances that may improve cognitive function, particularly executive functions, memory, creativity, or motivation, in healthy individuals. While many substances are purported to improve cognition, research is at a preliminary stage as of 2018, and the effects of the majority of these agents are not fully determined.