Nuts and seeds. Nuts and seeds are good sources of vitamin E, says Pratt, explaining that higher levels of vitamin E correspond with less cognitive decline as you get older. Add an ounce a day of walnuts, hazelnuts, Brazil nuts, filberts, almonds, cashews, peanuts, sunflower seeds, sesame seeds, flax seed, and unhydrogenated nut butters such as peanut butter, almond butter, and tahini. Raw or roasted doesn't matter, although if you're on a sodium-restricted diet, buy unsalted nuts.

Caffeine metabolism is primarily determined by the cytochrome enzyme P-450 1A2 (CYP1A2), and studies have shown that different ethnic populations exhibit widely varying expressions of the gene responsible for CYP1A2. Evidence suggests that a particular CYP1A2 impacts caffeine consumption by modifying the risks of certain diseases that are associated with caffeine consumption. It has also been shown that variations in the expression of genes that code for adenosine and dopamine receptors play a role in mediating your response to caffeine. For example, in Caucasians, the presence of certain genetic expressions for both adenosine and dopamine receptors is associated with caffeine-induced anxiety. Variations in CYP1A2 are also responsible for the speed at which different people metabolize caffeine.
The metal magnesium (, like potassium (which didn’t help me), plays many biological roles and has an RDA for me of 400mg which is higher than I likely get (most people apparently get less, with 68% of American adults
This research is in contrast to the other substances I like, such as piracetam or fish oil. I knew about withdrawal of course, but it was not so bad when I was drinking only tea. And the side-effects like jitteriness are worse on caffeine without tea; I chalk this up to the lack of theanine. (My later experiences with theanine seems to confirm this.) These negative effects mean that caffeine doesn’t satisfy the strictest definition of nootropic (having no negative effects), but is merely a cognitive enhancer (with both benefits & costs). One might wonder why I use caffeine anyway if I am so concerned with mental ability.
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.[1] 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.