5/6/15. I began taking 4 grams of oral citrulline a day, hoping to increase my brain arginine, thus nitric oxide, thus blood flow. I’d learned most ingested arginine is taken up by the liver, but citrulline (arginine’s precursor) bypasses the liver and forms arginine in the kidneys – increasing systemic arginine [Romero et al. 2006]. At the time I’d been taking 2g/day of arginine powder in orange juice before breakfast (fasted state) for one year, and 2g of creatine + 2g of taurine in morning and afternoon coffee for several years. I simply replaced the arginine with citrulline, then took another 2g of citrulline several hours after breakfast or lunch (between meals).

Within a few hours of the first 2 grams of citrulline I felt a curious calm, a sense of being ‘unhurried.’ Later that day I began talking spontaneously – reading aloud without intending to, then thinking aloud. This was my reaction to taurine when I began taking it in coffee several years earlier – reading aloud spontaneously, and thinking aloud. The effect became less obvious as I began taking taurine with every cup of coffee. Now it was back from citrulline.

As days passed, I had a curious sensation I was not my usual ‘self.’ My usual self is emotional, impulsive, and doesn’t like to speak. This ‘me’ felt calm, unhurried, and spoke spontaneously in private and public (despite some anxiety). I saw I was planning, noticing details, and anticipating effects – further signs my left hemisphere was more engaged. I also procrastinated less; when something needed to be done I did not hesitate. Yet I felt unhurried.

The most obvious adverse effect was significant aggravation of my (undiagnosed) left-hand intention tremor, though it’s mild as I write this. I also startled strongly at sudden sounds – a sign of excitability – yet usually felt calm, and slept better. Another early effect: citrulline suppressed voluntary emotional ‘flashbacks’ but not involuntary ones. At times of unusual stress another 2g of citrulline helped.

A friend trying 3g/day of citrulline reported: “I am increasingly convinced the citrulline does have a positive effect on me. I didn’t take it for maybe three days, and found myself getting edgy....  I started again and within twenty-four hours found that sense of calmness had returned.... Citrulline has an overall calming effect on me. I can’t affirm that my concentration is better, but I can say that I don’t get as agitated over things.” [personal communication 2015] He noted citrulline relieved “situational depression.”

I’m convinced citrulline becoming arginine then nitric oxide has increased blood flow in my left brain, because citrulline stimulates spontaneous speech, calms anxiety, and increases planning and focus. More challenging to explain was spontaneous speech from taurine. After reading Pangborn’s report (2002) that taurine was the amino acid most wasted or depleted in urine of ASD children I’d learned taurine is an inhibitory brain transmitter secondary to GABA, primary brain osmolyte, regulates active calcium in excitable cells, and suppresses arginine vasopressin. But I didn’t know taurine is also a vasodilator, which relaxes blood vessels via endothelial nitric oxide (Abebe et al. 2011). Why citrulline (and taurine) stimulate my left hemisphere preferentially – but arginine doesn’t – is another question.

I diagnose myself a high-functioning autist – childlike, self-centered, with strong right-hemisphere emotions/impulses, love of music, movies, sports, adept at auto repair (electrical specialist) but also left-hemisphere writing, editing, and research. I usually speak awkwardly, self-consciously, even with friends. I’d rather be alone without distractions; everyone wants so much ATTENTION (intense world!). People often talk more than I like to listen. Double messages get to me most; who speaks their mind any more? Baron-Cohen’s (2003) description of Aspergers hits home: “They do not know why they are not allowed to say what they think, and they wish that others would just speak their mind. It is difficult for them to understand why just speaking one’s mind could cause offense or lead them into social difficulties.” I don’t argue with neurodiversity – I love my talents – but like Pinocchio, I’ve always wanted to be a real boy.

Was my trial of citrulline too subjective? My best evidence is spontaneous speech. I rarely notice right away I’m reading or thinking aloud; in other words, I hear myself speaking – I didn’t intend to. Who is speaking?


Abebe W, Mozaffari MS. Role of taurine in the vasculature: an overview of experimental and human studies. Am J Cardiovasc Dis 2011;1(3):293–311.

Baron-Cohen S. The Essential Difference. The Truth About the Male and Female Brain. NY: Basic Books; 2003.

Pangborn JB. Introduction to the diseases of autism and laboratory testing options. In: Pangborn JB, Baker SM. Biomedical Assessment Options for Children with Autism and Related Problems. San Diego: Autism Research Institute; 2002. p. 1–130.

Romero MJ, Platt DH, Caldwell RB, Caldwell RW. Therapeutic use of citrulline in cardiovascular disease. Cardiovascular Drug Reviews 2006;24(3-4):275–290.