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Energy drinks are big business. Marketed as quick fixes for fatigue and performance dips, energy drinks are especially popular among young people, athletes, sports enthusiasts, and so-called “weekend warriors” – people who pack their workouts into the weekend instead of exercising regularly. Gamers are now a major target too.

But as the market grows, so do concerns about what’s actually in these drinks – and what these ingredients might be doing to our bodies.

Many energy drinks contain some combination of three familiar stimulants: caffeine, found naturally in coffee, tea and cacao; guarana, an Amazonian plant rich in caffeine; and taurine, a naturally occurring amino acid found in scallops, mussels, turkey and chicken.

Taurine, in particular, has drawn both hype and hope. It is credited with performance-enhancing properties and potential health benefits. But new research is raising important questions about how it behaves in the body – and when it might do more harm than good.

In May 2025, a study published in Nature sparked headlines and unease in equal measure. It found that taurine may fuel the progression of leukaemia, a group of blood cancers that begin in the bone marrow.

The study showed that while healthy bone marrow cells naturally produce taurine, leukaemia cells cannot. But they can absorb taurine from their surroundings and use it as a fuel source to grow and multiply. Research on mice and in human leukaemia cell samples demonstrated that taurine in the tumour microenvironment – the area around a tumour that includes blood vessels, immune cells and structural support – accelerated the progression of leukaemia.

Crucially, when researchers blocked taurine uptake by leukaemia cells (using genetic techniques), cancer progression slowed significantly. The authors suggest taurine supplements could potentially worsen outcomes in people with leukaemia and propose that developing targeted ways to block taurine uptake by cancer cells might offer a new treatment strategy.

Taurine: friend or foe?

Taurine is one of the most abundant free amino acids in the human body, found in especially high concentrations in the heart, muscles and brain. In healthy people, it’s mainly obtained through diet, but the body can also synthesise taurine from the amino acids methionine and cysteine, provided it has enough vitamin B6, which is found in foods such as salmon, tuna, chicken, bananas and milk.

Most people consuming a typical western diet take in 40mg–400mg of taurine a day from food alone. This figure refers only to taurine that is directly ingested, not including the additional amount the body can synthesise internally, which may vary depending on age, diet and health.

Scallops contain high levels of taurine.
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Taurine is listed on the Food and Drug Administration’s (FDA’s) generally recognised as safe (GRAS) database, and according to the European Food Safety Authority (EFSA), it’s safe to consume up to six grams per day. By comparison, a serving of Red Bull or Monster contains around one gram – comfortably below that threshold.

Despite recent concerns about a possible link to blood cancer progression, taurine isn’t inherently harmful. In fact, some people may benefit from supplementation, especially those receiving long-term parenteral nutrition, where nutrients are delivered directly into the bloodstream because the gut isn’t working properly. People with chronic liver, kidney or heart failure may also have trouble producing or holding on to enough taurine, making supplementation helpful in specific clinical settings.

Ironically, some research suggests taurine may actually help reduce the side effects of chemotherapy in leukaemia patients – even as emerging studies raise concerns that it could also fuel the disease. This contradiction underscores how much context matters: the effects of taurine depend not just on dosage and delivery, but also on the patient’s underlying condition. What helps in one context, could harm in another.

But here’s the catch: taking taurine as a supplement for particular health reasons is very different from consuming large quantities through energy drinks, which often combine taurine with high levels of caffeine and sugar. This combination can put strain on the heart, interfere with sleep and increase the risk of side effects, particularly for people with underlying health conditions or those taking other stimulants.

The latest research raises important questions about whether taurine-heavy products could be harmful in some cases, especially for people with, or at risk of, blood cancers.

So, should you worry?

According to the current evidence, if you’re a healthy adult who occasionally sips an energy drink, there’s little cause for alarm. But moderation is key. Consuming multiple high-taurine drinks daily or taking taurine supplements (without prior professional consultation), on top of a taurine-rich diet might not be wise, especially if future research confirms links between taurine and cancer progression.

Until more is known, the safest approach would be to enjoy your energy boosts by consuming a nutritious diet rather than consuming energy drinks. If you have any underlying health conditions – or a family history of cancer – it’s always best to consult a healthcare professional before diving into taurine supplementation or consumption of energy drinks.

Gulshanara (Rumy) Begum does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.