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Phenylethylamine is Said To Stoke the Fire of Love. Here Comes the Water Bucket.

Chocolate sales usually skyrocket on Valentine’s Day fueled by media accounts linking phenylethylamine in chocolate with romance. That merits some scrutiny.

American humorist James Thurber reputedly once remarked that “love is a strange bewilderment which overtakes one person on account of another person.” Anyone who has ever been in love will agree. That strange bewilderment can take many forms, ranging from butterflies in the stomach to hours of mind-dominating thoughts and heart palpitations at the prospect of an encounter. Clearly, the body’s chemistry is being affected. But how? Is there a chemical trigger for that emotional rush?

Maybe, opined psychiatrist Michael Leibowitz in his 1983 book “The Chemistry of Love,” alluding to phenylethylamine (PEA). He had treated patients who had become depressed after a failed romance with an antidepressant in the monoamine oxidase inhibitor category (MAOI) and note an improvement in mood. These drugs inhibit an enzyme, monoamine oxidase, that breaks down naturally occurring “monoamines” such as norepinephrine, serotonin and dopamine, all of which play a role in controlling mood. Leibowitz was aware of low levels of another naturally occurring monoamine, phenylethylamine (PEA), being linked to depression. Since his romance deprived patients improved after being treated with an MAOI, he speculated that their depression had been caused by a deficiency in PEA. Not much to hang your hat on. But that is how phenylethylamine became the “love chemical.”

The PEA-love connection would likely have died on the vine had Leibowitz not mentioned, somewhat off-handedly, that perhaps eating chocolate can enhance romantic feelings since chocolate is full of phenylethylamine. To be fair, he did mention that PEA is likely to be broken down by monoamine oxidase during digestion and that the trace amounts that survived would be too small to affect the brain. That was ignored by a media eager to lure readers with headlines linking chocolate to love. Nowhere was it mentioned that the urine of tigers and lions contains far more PEA than chocolates. After all, showing up on your lover’s doorstep with a jar of tiger urine doesn’t sound very romantic.

What about showing up with a jar full of phenylethylamine capsules? Yes, PEA is available as a dietary supplement,  justified by its occurrence in foods such as chocolate and sauerkraut. Dietary supplements do not require proof of efficacy to be marketed. Capitalizing on the chocolate-phenylethylamine  saga, one producer claims that “this powerful psychostimulant is found in trace amounts in chocolate and has been dubbed the love neurotransmitter because natural levels of PEA are released and elevated when someone experiences the rush of falling in love.” That’s some rather imaginative copywriting. So is the claim that PEA suppresses the appetite and produces a “surge of mental energy.” The ad also states, without evidence, that PEA has a noticeable effect on mood, but “noticeable” is a rather flexible term.

While the link between phenylethylamine and love is tenuous to say the least, the chemical certainly has some points of interest. The granddaddy of phenylethylamine chemistry is Dr. Alexander Shulgin. Armed with a PhD in biochemistry from the University of California in 1954 and a couple of years of post-doctoral work in pharmacology, Shulgin secured a post as senior research chemist with Dow chemical where he developed mexacarbate, the first biodegradable pesticide. Then he got sidetracked. Intrigued by an experience with mescaline, a naturally occurring hallucinogen found in the peyote cactus, he pivoted to the study of psychoactive substances and synthesizing them in his home laboratory. Friends would be invited to sample his creations and describe their experience, all sanctioned by the Drug Enforcement Administration (DEA), a government agency interested in learning about methods clandestine chemists might seize to produce street drugs.

Stimulated by his adventures with peyote, Shulgin noted that mescaline shares part of its molecular structure with phenylethylamine (PEA), as well as with amphetamine, a synthetic stimulant. Furthermore, the molecular structure of PEA can be seen to be part of the more complex atomic framework of adrenaline and dopamine. This suggested to Shulgin that phenylethylamine itself may play a role in emotions such as affection, although he did not directly link it to love. In his 1991 book, “Phenylethylamines I Have Known and Loved,” he described the synthesis of dozens of such compounds. The book stirred up some controversy because the syntheses were detailed enough to allow underground chemists to cook up drugs such as methamphetamine and methylenedioxymethamphetamine known as “Ecstasy.”

Shulgin’s epic sparked interest in phenylethylamine among researchers as well as in athletes who were drawn by the chemical’s similarity to amphetamine and experimented with large doses with hopes of improved performance. Although there is no evidence that PEA can improve performance, the World Anti-Doping Agency has deemed it to be an illegal drug. As far as research goes, one interesting study of 160 university undergraduates in Nigeria found that PEA urine levels were significantly reduced in students who had low scores on comprehension tests and generally exhibited poor academic performance. Mood was also found to correlate with urine levels of PEA. Too bad they didn’t test if chocolate could improve test scores. Now I’ll go and have a piece of chocolate. For the simple reason that I like it.


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