Comment · Fri, August 14, 2020
L-theanine improves neurophysiological measures of attention in a dose-dependent manner: a double-blind, placebo-controlled, crossover study (2020)
What they were answering
chromosomalcrossover · 10 points
I would either use suntheanine brand or nootropicsdepot, the latter has a strong appreciation for lab testing, has hired qualified staff who have chemistry/lab experience to run test equipment, and they often cross-check with outside labs too. The owner is on reddit (/u/MisterYouAreSoDumb) so they may be able to comment on the l-theanine vs racemic here if they feel like it, or via pm.
u/MisterYouAreSoDumb
These days pretty much all theanine from a good supplier is the L form. The days of racemic theanine are in the past. There was a time like 10 years ago when Suntheanine's process was the only way to make enantiopure L-theanine, but there are half a dozen methods now. We have a polarimeter in our lab that tests the optical rotation of all L-theanine we sell. I don't believe we have rejected a single batch of it for optical purity in the last 2-3 years.