A little-known ingredient in energy drinks was thrust into the spotlight this week after scientists theorized it could partially explain an increase in colon cancer among young people.
Taurine is an amino acid used in Red Bull to energize cells and improve mental clarity.
However, scientists in Florida hypothesize that this compound may ‘feed’ harmful bacteria that are ‘overrepresented’ in the intestines of people with colorectal cancer.
It’s still just a theory, and based on preliminary animal and lab studies, so experts say there’s no reason to panic just yet.
But Taurine is also found in Monster, Celsius and some Starbucks coffee drinks. So is this a reason to ditch energy drinks altogether?
The graph above shows the increase in colorectal cancer among young Americans from 1999 to 2020
The findings come as one in three adults aged 18 to 29 report regularly consuming energy drinks.
The US energy drink market is valued at around $23 billion, driven mainly by sales of Red Bull, Monster and Celsius.
The potential problem with taurine is mainly related to the amount of taurine a person consumes.
In small amounts, it is considered safe. However, high levels have been shown to cause vomiting, stomach upset, dizziness, fatigue, diarrhea and constipation.
Researchers from the University of Florida are launching a trial called ROSANNA to test their hypothesis about the substance’s harm.
Presenting the trial at the American Society of Clinical Oncology (ASCO) conference in Chicago this week, the team said they believe taurine is the ‘main source of energy’ for a bacterium thought to promote colon cancer.
The team is recruiting young Americans to consume Red Bull or Celsius energy drinks every day to test this hypothesis.
The researchers expected a 20 to 30 percent increase in bacteria—called H2S sulfide-metabolizing bacteria—from participants who drank a Red Bull or Celsius each day.
However, this prediction is based on a small number of animal studies.
Research published by the NIH says that 500 to 3,000 milligrams of taurine per day is safe (0.5 to 3 grams), although the European Food Safety Authority suggests that 6,000 milligrams (6 grams) is safe.
Excessive amounts can lead to vomiting, nausea, headache and stomach pain, according to the Mayo Clinic.
In some cases, the amino acid has been shown to stop the growth and spread of tumors by up to 44 percent.
In others, it has been shown to prevent protective T cells from fighting the cancer, allowing the disease to become more aggressive.
While the amino acid isn’t actually used to build proteins in the body like other amino acids, it does have a number of roles, including regulating the amount of calcium in nerve cells and controlling inflammation, among others.
Here are five of the most popular drinks that contain taurine.
Red Bull
Red Bull is rated as the most popular energy drink in the world, selling 12.1 billion cans last year alone.
One of two beverages studied by ROSANNA trial researchers, an 8.4-ounce can contains 1,000 milligrams of taurine and 80 milligrams of caffeine — about the same as an 8-ounce cup of black coffee.
The regular variety contains 27 grams of natural sugar, although sugar-free varieties are also available.
The brand says a can, which costs about $2.50, also contains vitamins B6 and B12, which help red blood cells carry oxygen throughout the body and maintain nerve cells in the brain, among other functions.
One can contains a third of the recommended daily limit of taurine.
centigrade
Celsius has soared in popularity in recent years, with its revenue growing from $75 million in 2019 to $1.3 billion in 2023. Research firm Circana found that it is now the third most popular energy drink in the US.
The brand’s Sparkling Peach Vibes flavor is the next drink being looked at in the ROSANNA trial.
Like Red Bull, Celsius contains 1,000 milligrams of taurine, though the can is slightly larger at 12 ounces.
Celsius contains no sugar and only 10 calories. However, one can has 200 milligrams of caffeine, equal to two cups of coffee and half the FDA’s recommended daily limit of 400 milligrams.
Monster
Similar to Red Bull and Celsius, a can of Monster contains 1,000 milligrams of taurine.
However, this can is larger at 16 ounces.
Each can also contains 160 milligrams of caffeine, or about the same amount as one and a half cups of coffee.
In addition to 230 calories, Monster has one of the highest amounts of added sugar at 54 grams.
That’s more than one McDonald’s Oreo McFlurry or five Krispy Kreme donuts.
The drink has been the subject of numerous lawsuits, including one involving the death of a 14-year-old girl who drank two cans of the drink.
Prime Energy
While taurine is listed as an ingredient for PRIME Energy, the brand does not disclose how much is in each can.
PRIME was launched in 2022 by internet personalities Logan Paul and KSI, and despite quickly achieving success, it has been the subject of controversy.
Last year, Senate Majority Leader Chuck Schumer asked the FDA to investigate PRIME for marketing to children despite an ‘astounding level of caffeine.’
Each 12-ounce can contains 200 milligrams of caffeine, but also only 10 calories and no sugar.
5-hour energy
This energy shot is the smallest on the list, but it contains a large amount of taurine and caffeine.
Each 1.93-ounce glass contains approximately 480 milligrams of taurine, nearly half of drinks more than four times its size.
It also has 230 milligrams of caffeine, more than the larger sizes of Red Bull, Celsius, Monster and PRIME.
The ingredient label also claims the shot has more than 20,000 percent of the daily value of vitamin B12.
Although rare, vitamin B12 overdose has been shown to cause headaches, dizziness, diarrhea, nausea, vomiting, and weakness.
Rock star
A 16-ounce can of Rockstar Energy contains 2,000 milligrams of taurine, double that of other popular brands like Red Bull and Monster.
Each can also contains 270 calories and 63 grams of added sugar, about as much as a small Dairy Queen Blizzard.
The drink also claims to contain vitamins B2, B6 and B12.
In a 2015 study from the Mayo Clinic, volunteers who drank Rockstar on an empty stomach in five minutes or less saw their blood pressure rise by nearly seven percent.
Additionally, their heart rate increased by an average of 3.1 extra beats.
Starbucks Double Shot Energy
Starbucks Double Shot Energy coffee drink contains coffee and 1,800 milligrams of taurine per 15-ounce can.
The drink also claims to be more energizing than coffee, which contains 225 milligrams of caffeine.
This is almost three times the amount in a normal cup of coffee.
Each can also has 12 grams of added sugar, about the same amount as a Kripy Kreme donut.
The ingredients label also lists 20 percent of the recommended daily value of potassium, which is key for hearing function, muscle contraction and blood pressure control.
