If you are a slow caffeine metabolizer and consume too much caffeine, you run the risk of mild to severe complications, such as cardiovascular disease. There’s also the sleep disruption problem of having too much caffeine left in your bloodstream late in the day as a result of a longer caffeine half-life, a problem not faced by fast caffeine metabolizers (it’s so unfair if you love your cup of joe, right?). In addition, fast caffeine metabolizers actually run a reduced risk of cardiovascular complications if they consume at least one cup of coffee per day. While anyone can be a slow caffeine metabolizer, there are certain ethnic backgrounds that are indeed associated with slower and faster caffeine metabolisms. For example, it’s known that people with Asian and African ethnic backgrounds generally have slower rates of caffeine metabolism. To find out if you’re a fast or slow caffeine metabolizer, you can have a relatively inexpensive salivary genetic test performed by a company like 23andme and then use the online dashboard to jump straight to your CYP1A2 gene. When you’re there, you type into the search bar “rs762551”. If your rs762551 SNP variant is AA, then you’re a fast caffeine metabolizer, but if your variant is AC or CC, you’re a slow caffeine metabolizer. Fortunately, many genetic testing companies will now simply report directly on your results whether you’re a slow or fast metabolizer, without you needing to go through the SNP searching trouble.
Because it’s so nutrient-dense — packing loads of vitamins, minerals and nutrients with very little calories — it’s a great snack option if you’re looking to shed pounds. And while we often eat celery stalks, don’t skip the seeds and leaves; both provide extra health benefits and taste great in things like stir fries and soups. Not sure where to begin with eating more celery? Try my easy Ants on a Log or refreshing Super Hydrator Juice recipes.
Reason: Acetyl-L-carnitine can protect the brain from neurotoxicity. It can also ward off oxygen deprivation. Acetyl-L-carnitine can even preserve cells energy-producing mitochondria. Plus, it can rejuvenate mental and physical function. Dosages for studies have been in the 1,500 – 4,000 mg range. These are divided into two or three doses. However, we recommend no more than 1,000 mg of acetyl-L-carnitine a day without medical supervision.
Lost confidence.  If you can’t find your keys, much less get through your workday in a timely fashion without a slew of mistakes, you are going to lose confidence in both your brain and yourself.  When you cannot remember where you put things and it takes an absurd amount of effort just to do a simple task, you might question your very sanity.  As your confidence continues to nose-dive, you just end up making more and more mistakes.  It turns into a vicious cycle.
The nootropics community is surprisingly large and involved. When I wade into forums and the nootropics subreddit, I find members trading stack recipes and notifying each other of newly synthesized compounds. Some of these “psychonauts” seem like they’ve studied neuroscience; others appear to be novices dipping their toes into the world of cognitive enhancement. But all of them have the same goal: amplifying the brain’s existing capabilities without screwing anything up too badly. It’s the same impulse that grips bodybuilders—the feeling that with small chemical tweaks and some training, we can squeeze more utility out of the body parts we have. As Taylor Hatmaker of the Daily Dot recently wrote, “Together, these faceless armchair scientists seek a common truth—a clean, unharmful way to make their brains better—enforcing their own self-imposed safety parameters and painstakingly precise methods, all while publishing their knowledge for free, in plain text, to relatively crude, shared databases."

I’ve been actively benefitting from nootropics since 1997, when I was struggling with cognitive performance and ordered almost $1000 worth of smart drugs from Europe (the only place where you could get them at the time). I remember opening the unmarked brown package and wondering whether the pharmaceuticals and natural substances would really enhance my brain.

The Nootroo arrives in a shiny gold envelope with the words “proprietary blend” and “intended for use only in neuroscience research” written on the tin. It has been designed, says Matzner, for “hours of enhanced learning and memory”. The capsules contain either Phenylpiracetam or Noopept (a peptide with similar effects and similarly uncategorised) and are distinguished by real flakes of either edible silver or gold. They are to be alternated between daily, allowing about two weeks for the full effect to be felt. Also in the capsules are L-Theanine, a form of choline, and a types of caffeine which it is claimed has longer lasting effects.

Eugeroics (armodafinil and modafinil) – are classified as "wakefulness promoting" agents; modafinil increased alertness, particularly in sleep deprived individuals, and was noted to facilitate reasoning and problem solving in non-ADHD youth.[23] In a systematic review of small, preliminary studies where the effects of modafinil were examined, when simple psychometric assessments were considered, modafinil intake appeared to enhance executive function.[27] Modafinil does not produce improvements in mood or motivation in sleep deprived or non-sleep deprived individuals.[28]