Avocados are almost as good as blueberries in promoting brain health, Dr. Pratt told WebMD.com. These buttery fruits are rich in monounsaturated fat, which contributes to healthy blood flow in the brain, according to Ann Kulze, MD, author of Dr. Ann’s 10-Step Diet: A Simple Plan for Permanent Weight Loss & Lifelong Vitality. This helps every organ in your body—particularly the brain and heart. Avocados also lower blood pressure, thanks to their potassium. Because high blood pressure can impair cognitive abilities, lower blood pressure helps to keep the brain in top form and reduce your risks for hypertension or a stroke. The fiber in avocados also reduces the risk of heart disease and bad cholesterol.  These foods are good for your brain later in life.
Microdosing With Psilocybin: Psilocybin, AKA “magic mushrooms”, are naturally occurring fungi, with over 180 different species and research from archaeologist evidence has shown that humans have been using psilocybin mushrooms for over 7,000 years. I’ve personally found microdoses of psilocybin, AKA “magic mushrooms”, to be best for nature immersions, hiking, journaling or self-discovery.  Psilocybin primarily interacts with the serotonin receptors in the brain and has been used in therapeutic settings to treat disorders such as headaches, anxiety, depression, addiction, and obsessive-compulsive disorders (See additional studies here, here, here and here). There is limited data to show any adverse drug interactions with the use of psilocybin, and liver function, blood sugar, and hormonal regulation all appear to be unaffected during consumption (although it is best to avoid alcohol and any serotonin-based antidepressants while taking any psychedelics) (See studies here, here and here). A microdose of psilocybin is generally between 0.2 grams and .5 grams, and I’d highly recommend you start on the low end of the dosage range with these or any of the psychedelics mentioned here.
When asked if there’s a discrepancy between Qualia’s claims and that disclaimer, Dr. Stickler points out that products such as OS aren’t promising to treat or cure any diseases. That’s the line these companies can’t cross. They can claim their product makes you smarter or more focused without data from clinical trials, but they can’t claim their pill treats traumatic brain injury, ADHD, or Alzheimer’s.
Fish oil (Examine.com, buyer’s guide) provides benefits relating to general mood (eg. inflammation & anxiety; see later on anxiety) and anti-schizophrenia; it is one of the better supplements one can take. (The known risks are a higher rate of prostate cancer and internal bleeding, but are outweighed by the cardiac benefits - assuming those benefits exist, anyway, which may not be true.) The benefits of omega acids are well-researched.

The use of cognition-enhancing drugs by healthy individuals in the absence of a medical indication spans numerous controversial issues, including the ethics and fairness of their use, concerns over adverse effects, and the diversion of prescription drugs for nonmedical uses, among others.[1][2] Nonetheless, the international sales of cognition-enhancing supplements exceeded US$1 billion in 2015 when global demand for these compounds grew.[3]