What Is Essential Hand Tremor and How to Prevent and Treat It

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What is the role of dietary beta-carboline alkaloids in the development of the most common movement disorder?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

As documented in the book The Case of the Frozen Addicts, a bad batch of so-called synthetic heroin caused, within days, what appeared to be advanced-stage Parkinson’s disease. Thanks to a chemical contaminant known as MPTP, young men and women were left trapped inside their bodies, with near complete immobility, in some cases able to move only their eyes. The seminal paper describing the phenomenon ended with the silver lining that maybe this will help us find the culprit in Parkinson’s.

Attention turned to a class of chemicals called beta-carboline alkaloids, due to their structural similarity to MPTP. And, indeed, higher levels of these toxins were found in the brain fluid of Parkinson’s patients. In How Not to Die, I address Parkinson’s, since it’s one of our leading killers, but the most common movement disorder is what’s called “essential tremor” —affecting up to one in 25 adults older than 40, and up to one in five people in their 90s. In addition to the potentially debilitating hand tremor, there can be other neurological manifestations, including cognitive impairment, depression, and sleeping problems.

In medical lingo, “essential” can mean “of unknown cause,” like essential hypertension, the rise in blood pressure as we age. Just as there have been calls for decades to rename that phenomenon once it became clear that lifestyle behaviors played a critical role, there are those suggesting we rename essential tremor as we come to understand it better as well. Identical twin studies suggest it may only be 60 percent genetic. Though there have been studies linking the development of essential tremor to lead exposure, most attention has focused on beta-carboline alkaloids.

Beta-carboline alkaloids induce tremor in a wide variety of animals, from mice to monkeys, that’s similar to essential tremor in humans both clinically and in the type of brain damage they cause. As such, beta-carboline alkaloid administration produces the main animal model for essential tremor upon which to try out new drugs. Harmane is the most potent of these tremor-producing beta-carboline alkaloids. Expose people to high-dose harmane, and they develop tremors too; take it away, and the tremors disappear. What if we’re exposed to small doses over time?

All six studies found that those with essential tremor have significantly higher levels of this toxin in their bloodstream compared to those without tremor—five out of six significantly so. Furthermore, the higher the harmane levels, the worse the tremor. The highest levels are found in those who have both essential tremor and cancer, suggesting harmane may be playing a role in both diseases.

Elevated harmane levels have also been found directly in the brains of essential tremor patients on autopsy. Due to its high fat solubility, harmane accumulates in brain tissue. Using a fancy brain scan called “proton magnetic resonance spectroscopic imaging,” higher harmane levels were found to be a significant predictor of signs of nerve degeneration in the cerebellum, the part of the brain that controls movement.

How do we get exposed to these chemicals? Small amounts of harmane are produced endogenously, but the main source is meat. Beta carboline alkaloids are a type of heterocyclic amine, the class of carcinogens that are formed in a high-temperature chemical reaction between some of the components of muscle tissue. Under the same cooking conditions, chicken may produce the most harmane (more than twice as much as beef steak, for example), but the highest single per-serving levels have been found in fried pork, flame-broiled steak, flame-broiled chicken, and grilled salmon.

Researchers gave people a slice of fried turkey and saw a bump in harmane blood levels within five minutes. Five minutes? It’s not even digested by then. The researchers suspect the rapid uptake is indicative of significant absorption directly through the mouth and straight into the bloodstream, bypassing the stomach and, most importantly, bypassing the detoxifying enzymes of the liver before it makes it up into our brain. So, if this “potent, tremor-producing neurotoxin” is concentrated in “cooked muscle foods,” is meat consumption associated with a higher risk of essential tremor? A study out of Columbia University found that men who ate the most meat (about 1.5 servings a day) had a whopping 21 times the odds of essential tremor compared to men who ate closer to a half-serving a day. To put that in context, if we go back to the original studies on smoking and lung cancer, we see that smoking was only linked to about 14 times the odds.

Arguing against meat’s role in essential tremor through harmane exposure is the fact that a similar relationship was not found in women, and there appeared to be no difference in tremor rates between those who preferred their meat rare versus well-cooked. A reverse causation explanation was also proposed: instead of greater meat consumption leading to essential tremor, perhaps the essential tremor led to greater meat consumption, as a solid stable food that may be more easily handled with a tremulous hand. Or perhaps the elevated harmane levels in tremor victims is due to a reduced capacity to detoxify it, or a combination of greater intake and lesser excretion.

For those reluctant to reduce their meat consumption, different marinades have been tested to reduce harmane production. Hibiscus extracts seemed to make things worse, and so did red wine, increasing formation up to 10-fold. However, a Caribbean marinade and a variety of berry extracts worked. For example, marinating camel meat in strawberry juice for 24 hours before frying can reduce the formation of harmane by as much as 40 percent.

Are there any dietary treatments once you already have the disease? Vanillin—the primary fragrance compound in vanilla extract—was found to be beneficial against beta-carboline-induced tremors in rats, but there have yet to be any clinical studies.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

As documented in the book The Case of the Frozen Addicts, a bad batch of so-called synthetic heroin caused, within days, what appeared to be advanced-stage Parkinson’s disease. Thanks to a chemical contaminant known as MPTP, young men and women were left trapped inside their bodies, with near complete immobility, in some cases able to move only their eyes. The seminal paper describing the phenomenon ended with the silver lining that maybe this will help us find the culprit in Parkinson’s.

Attention turned to a class of chemicals called beta-carboline alkaloids, due to their structural similarity to MPTP. And, indeed, higher levels of these toxins were found in the brain fluid of Parkinson’s patients. In How Not to Die, I address Parkinson’s, since it’s one of our leading killers, but the most common movement disorder is what’s called “essential tremor” —affecting up to one in 25 adults older than 40, and up to one in five people in their 90s. In addition to the potentially debilitating hand tremor, there can be other neurological manifestations, including cognitive impairment, depression, and sleeping problems.

In medical lingo, “essential” can mean “of unknown cause,” like essential hypertension, the rise in blood pressure as we age. Just as there have been calls for decades to rename that phenomenon once it became clear that lifestyle behaviors played a critical role, there are those suggesting we rename essential tremor as we come to understand it better as well. Identical twin studies suggest it may only be 60 percent genetic. Though there have been studies linking the development of essential tremor to lead exposure, most attention has focused on beta-carboline alkaloids.

Beta-carboline alkaloids induce tremor in a wide variety of animals, from mice to monkeys, that’s similar to essential tremor in humans both clinically and in the type of brain damage they cause. As such, beta-carboline alkaloid administration produces the main animal model for essential tremor upon which to try out new drugs. Harmane is the most potent of these tremor-producing beta-carboline alkaloids. Expose people to high-dose harmane, and they develop tremors too; take it away, and the tremors disappear. What if we’re exposed to small doses over time?

All six studies found that those with essential tremor have significantly higher levels of this toxin in their bloodstream compared to those without tremor—five out of six significantly so. Furthermore, the higher the harmane levels, the worse the tremor. The highest levels are found in those who have both essential tremor and cancer, suggesting harmane may be playing a role in both diseases.

Elevated harmane levels have also been found directly in the brains of essential tremor patients on autopsy. Due to its high fat solubility, harmane accumulates in brain tissue. Using a fancy brain scan called “proton magnetic resonance spectroscopic imaging,” higher harmane levels were found to be a significant predictor of signs of nerve degeneration in the cerebellum, the part of the brain that controls movement.

How do we get exposed to these chemicals? Small amounts of harmane are produced endogenously, but the main source is meat. Beta carboline alkaloids are a type of heterocyclic amine, the class of carcinogens that are formed in a high-temperature chemical reaction between some of the components of muscle tissue. Under the same cooking conditions, chicken may produce the most harmane (more than twice as much as beef steak, for example), but the highest single per-serving levels have been found in fried pork, flame-broiled steak, flame-broiled chicken, and grilled salmon.

Researchers gave people a slice of fried turkey and saw a bump in harmane blood levels within five minutes. Five minutes? It’s not even digested by then. The researchers suspect the rapid uptake is indicative of significant absorption directly through the mouth and straight into the bloodstream, bypassing the stomach and, most importantly, bypassing the detoxifying enzymes of the liver before it makes it up into our brain. So, if this “potent, tremor-producing neurotoxin” is concentrated in “cooked muscle foods,” is meat consumption associated with a higher risk of essential tremor? A study out of Columbia University found that men who ate the most meat (about 1.5 servings a day) had a whopping 21 times the odds of essential tremor compared to men who ate closer to a half-serving a day. To put that in context, if we go back to the original studies on smoking and lung cancer, we see that smoking was only linked to about 14 times the odds.

Arguing against meat’s role in essential tremor through harmane exposure is the fact that a similar relationship was not found in women, and there appeared to be no difference in tremor rates between those who preferred their meat rare versus well-cooked. A reverse causation explanation was also proposed: instead of greater meat consumption leading to essential tremor, perhaps the essential tremor led to greater meat consumption, as a solid stable food that may be more easily handled with a tremulous hand. Or perhaps the elevated harmane levels in tremor victims is due to a reduced capacity to detoxify it, or a combination of greater intake and lesser excretion.

For those reluctant to reduce their meat consumption, different marinades have been tested to reduce harmane production. Hibiscus extracts seemed to make things worse, and so did red wine, increasing formation up to 10-fold. However, a Caribbean marinade and a variety of berry extracts worked. For example, marinating camel meat in strawberry juice for 24 hours before frying can reduce the formation of harmane by as much as 40 percent.

Are there any dietary treatments once you already have the disease? Vanillin—the primary fragrance compound in vanilla extract—was found to be beneficial against beta-carboline-induced tremors in rats, but there have yet to be any clinical studies.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Doctor's Note

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