If you are male and have essential tremor (ET) you may be interested to learn about a molecule found in certain foods that has a bad effect on brain and nerve function. It is called harmane, and it is a known neurotoxin that is linked with ET. It is found in coffee and tobacco smoke. Also, “Harmane and other heterocyclic amines are found in high concentrations in cooked muscle foods (i.e., meats).”1 Without getting too technical, harmane is one of a group of neurotoxic chemicals called beta-carboline alkaloids. The effect of harmane-produced tremors has been observed in laboratory research with animals.
ET, animal studies, and harmane
In order to study where ET comes from and to develop treatments that work, researchers often turn to animal models for help in understanding what happens in humans with ET. But how do you get animals that don’t naturally have “the shakes” to produce tremors so you can conduct studies? One way is to inject them with harmane, or a similar related alkaloid called harmaline. “Action and postural tremor in the mouse began 5 minutes after subcutaneous harmaline injection and peaked at approximately 30 minutes. The tremor involved the head, trunk, tail, and four limbs and lasted for approximately 2 hours. The forelimb tremor was postural or action tremor, similar to that observed in ET.”2 [emphasis mine] The effect is the same in cats, rabbits and monkeys.
Harmane in humans
Harmane has been proposed as causal factor in ET. ET patients have higher levels of harmane in the blood and brain. Harmane crosses the blood-brain barrier; higher concentrations in the brain than the blood have been demonstrated with lab animals given harmane-induced tremors.
One study found that blood levels of harmane were higher in familial ET cases than sporadic (non-familial) cases, and were lowest in control (non-ET) subjects.3 The authors hypothesize that due to the hereditary aspect, familial ET patients share a genetic tendency to process harmane poorly, therefore increasing the concentration of it in their bodies. Still, no gene has been identified to account for this.
Another study took a dietary approach to look for patterns of meat consumption among those with ET. Based on their findings, they wrote, “Total current meat consumption was greater in men” with ET, but not in women with ET.
Is there a bottom line?
Cheng et al write that exposure to beta-carboline alkaloids from an external source “…seems to be associated with ET, as ET patients have higher levels of harmane in the blood and brain as compared to healthy controls.”4 They note that when lab animals are injected with harmaline, it appears to act on the same part of the brain where the “tremor pathway” is thought to begin. They also write that “…treatments for ET, such as ?-blockers and primidone, can dampen harmaline-induced tremor.” However, since not all cases of ET have an equal concentration of harmane, this may partly explain why pharmaceutical agents don’t work in every case.
Obviously, more study is needed to determine if men with ET who eat a lot of meat are unwittingly supporting or even boosting their tremors. At least for men, the issue of eating a lot of meat can be food for thought.
1Louis E, Keating G, Bogen K, Rios E et al. Dietary epidemiology of essential tremor: meat consumption and meat cooking practices. Neuroepidemiology. 2008 May; 30(3): 161–166.
2Cheng M, Tang G, Kuo S. Harmaline-induced tremor in mice: videotape documentation and open questions about the model. Tremor Other Hyperkinet Mov (N Y). 2013; 3: tre-03-205-4668-1.
3Louis E, Jiang W, Gerbin M, Mullaney M, Zheng W. Relationship between blood harmane and harmine concentrations in familial essential tremor, sporadic essential tremor and controls. Neurotoxicology. 2010 Dec; 31(6): 674–679.
4 Cheng et al, ibid.
About Dr. Dan Sperling
Dan Sperling, MD, DABR, is a board certified radiologist who is globally recognized as a leader in multiparametric MRI for the detection and diagnosis of a range of disease conditions. As Medical Director of the Sperling Prostate Center, Sperling Medical Group and Sperling Neurosurgery Associates, he and his team are on the leading edge of significant change in medical practice. He is the co-author of the new patient book Redefining Prostate Cancer, and is a contributing author on over 25 published studies. For more information, contact the Sperling Neurosurgery Associates.