A little-known ingredient in energy drinks was thrust into the spotlight this week after scientists theorized it could partly explain the rise in colon cancer in 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 ingredient could “feed” harmful bacteria that are “overrepresented” in the intestines of people with colorectal cancer.
It is still only a theory and based on preliminary studies in animals and laboratories. Experts say there is no reason to panic yet.
But Taurine is also found in Monster, Celsius and some Starbucks coffee drinks. Is this a reason to stop drinking energy drinks altogether?
The above graph shows the rise of colorectal cancer in young Americans between 1999 and 2020
The findings come as one in three adults aged 18 to 29 report regularly consuming energy drinks.
The U.S. energy drink market is estimated at approximately $23 billion, driven largely by sales of Red Bull, Monster and Celsius.
The potential problem with taurine mainly has to do with the amount a person consumes.
It is considered safe in small amounts. However, high levels have been shown to cause vomiting, stomach upset, dizziness, fatigue, diarrhea and constipation.
Researchers at the University of Florida are embarking on a trial called ROSANNA to test their hypothesis about the substance’s harm.
Introducing the trial at the American Society for Clinical Oncology (ASCO) conference in Chicago this week, the team said it believes taurine is the “primary energy source” for a bacterium thought to cause colon cancer.
The team is recruiting young Americans to consume Red Bull or Celsius energy drinks every day to test this hypothesis.
The researchers expect a 20 to 30 percent increase in bacteria – so-called H2S sulfide-metabolizing bacteria – from participants who drink a Red Bull or Celsius every day.
However, this prediction is based on a small number of animal studies.
Research published by the NIH states 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, headaches and stomach pain, according to the Mayo Clinic.
In some cases, the amino acid has been shown to stop tumor growth and spread by as much as 44 percent.
In other cases, it has been shown to prevent protective T cells from fighting cancer, which can cause the disease to become more aggressive.
Although the amino acid is not actually used to build proteins in the body like other amino acids, it has a number of functions, including regulating the amount of calcium in nerve cells and controlling inflammation.
Here are five of the most popular drinks that contain taurine.
Red Bull
Red Bull is hailed as the most popular energy drink in the world, selling 12.1 billion cans last year alone.
One of the two beverages studied by the ROSANNA study researchers, one 8.4-ounce can contains 1,000 milligrams of taurine and 80 milligrams of caffeine – about the same as a 25-ounce cup of black coffee.
The regular variant contains 27 grams of natural sugar, but there are also sugar-free variants.
The brand says that one can, which costs about $2.50, also contains vitamins B6 and B12, which, among other things, help red blood cells transport oxygen throughout the body and maintain nerve cells in the brain.
One can contains one third of the daily recommended amount of taurine.
Celsius
Celsius has exploded in popularity in recent years, with sales increasing from $75 million in 2019 to $1.3 billion in 2023. Research firm Circana found it is now the third most popular energy drink in the US.
The brand’s Sparkling Peach Vibes flavor is the other drink being looked at in the ROSANNA trial.
Like Red Bull, Celsius contains 1,000 milligrams of taurine, although the can is slightly larger at 12 ounces.
Celsius contains no sugar and only 10 calories. However, one can contains 200 milligrams of caffeine, the equivalent of two cups of coffee and half the FDA’s recommended daily limit of 400 milligrams.
Sample
Just like Red Bull and Celsius, a can of Monster contains 1,000 milligrams of taurine.
However, this can is larger: 16 ounces.
Each can also contains 160 milligrams of caffeine, or about as much as one and a half cups of coffee.
In addition to 230 calories, Monster has one of the highest amounts of added sugars at 54 grams.
This totals more than one McDonald’s Oreo McFlurry or five Krispy Kreme donuts.
The drink has been the subject of several lawsuits, including one over the death of a 14-year-old girl who drank two cans of the drink.
First energy
Although taurine is on PRIME Energy’s ingredient list, 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 finding rapid success, it has been the subject of controversy.
Last year, Senate Majority Leader Chuck Schumer asked the FDA to investigate PRIME because it was marketed to children despite an “eye-popping caffeine content.”
Each 12-ounce can contains 200 milligrams of caffeine, although it also contains only 10 calories and no sugar.
5 hours of energy
This energy shot is the smallest on the list, but packs a big taurine and caffeine punch.
Each 1.93-ounce shot contains about 480 milligrams of taurine, nearly half the amount of drinks more than four times the size.
It also contains 230 milligrams of caffeine, more than the larger sizes of Red Bull, Celsius, Monster and PRIME.
The ingredients label also claims that the shot contains 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
One 16-ounce can of Rockstar Energy contains 2,000 milligrams of taurine, twice as much as other popular brands such as Red Bull and Monster.
Each can also contains 270 calories and 63 grams of added sugar, almost that of a small Dairy Queen Blizzard.
The drink also claims to contain vitamins B2, B6 and B12.
In a 2015 study by the Mayo ClinicVolunteers who drank Rockstar on an empty stomach in five minutes or less saw their blood pressure rise by almost seven percent.
In addition, their heart rate increased by an average of 3.1 extra beats.
Starbucks Double Shot Energy
Starbucks Double Shot Energy coffee drink contains both coffee and 1,800 milligrams of taurine per 15-ounce can.
The drink also claims to be more energetic than the coffee, which contains 225 milligrams of caffeine.
This is almost three times as much as in a normal cup of coffee.
Each can also contains 12 grams of added sugar, about the same amount as a Kripy Kreme donut.
The ingredients label also lists 20 percent of the daily recommended amount of potassium, which is essential for hearing function, muscle contraction and controlling blood pressure.