Why Doctors Are Raising Red Flags About Boba

Once an occasional treat, bubble tea may carry underestimated risks when consumed frequently.

Bubble tea shops are now a common sight in cities, rivaling coffee chains with their brightly colored, Instagram-ready drinks offered in countless flavor combinations.

The beverage originated in Taiwan in the 1980s and typically combines black tea, milk, sugar, and chewy tapioca pearls. Its rapid rise in global popularity has been striking, but recent research suggests the drink may deserve closer attention.

From trendy drink to contamination concern

An investigation by Consumer Reports found elevated levels of lead in some bubble tea products sold in the United States, reinforcing earlier concerns linked to foods made from cassava. (No equivalent testing has been published in the UK.) The tapioca pearls, often referred to as the drink’s “bubbles,” are produced from cassava starch. As it grows, the cassava root readily absorbs lead and other heavy metals from the surrounding soil.

The pearls may also pose risks unrelated to contamination. Because they are dense and highly starchy, consuming large amounts can slow the movement of food through the stomach, a condition known as gastroparesis, or in more severe cases, contribute to intestinal blockages.

Both can cause nausea, vomiting, and abdominal pain, and symptoms can be particularly severe in people who already have slow-moving digestion. Even guar gum — a thickener often added to bubble tea and harmless in small amounts – can lead to constipation if you drink it often.

The drink’s composition also affects kidney health. In 2023, Taiwanese doctors removed over 300 kidney stones from a 20-year-old woman who’d been drinking bubble tea instead of water. Certain components, including oxalate and elevated phosphate levels, can contribute to stone formation. However, this extreme case probably reflects exceptionally high consumption.

For children, the risks are more immediate. The pearls can be a choking hazard – a risk that is well documented by pediatricians. Adults are not immune to this risk. According to media reports in Singapore, a 19-year-old woman died after inhaling three pearls when sucking harder on a partially blocked straw, while another woman narrowly avoided the same fate thanks to fast-acting bystanders.

The sugar problem

The sugar content raises longer-term health concerns. Most bubble teas contain 20–50g of sugar, comparable to or exceeding a can of Coca-Cola (35g). Research in Taiwan found that by age nine, children who regularly consumed bubble tea were 1.7 times more likely to have cavities in their permanent teeth.

In California, the drink is considered a contributing factor to the youth obesity epidemic, yet many young adults remain unaware of these risks. The high sugar and fat content increases the likelihood of developing type 2 diabetes, obesity and metabolic disease, while prolonged consumption may contribute to fatty liver disease – outcomes associated with any high-sugar product that spikes blood glucose and promotes fat storage in the liver.

Perhaps most surprisingly, emerging research suggests potential mental health implications. Studies of Chinese children who frequently consume bubble tea show an association with increased rates of anxiety and depression. Similar patterns appear in adults: research on Chinese nurses found that regular bubble tea consumption was associated with anxiety, depression, fatigue, job burnout and reduced wellbeing, even after controlling for other factors. The same study linked lower consumption to reduced thoughts of suicide, though establishing causation remains complex.

Strange scans

There’s even a curious medical phenomenon associated with consuming bubble tea: tapioca pearls appearing on scans of patients admitted for unrelated emergencies.

Doctors treating people after car accidents or with appendicitis have found dozens of pearls visible in stomachs and digestive tracts. These can occasionally cause diagnostic confusion, as they appear denser than the surrounding tissues and have stone-like properties similar to those seen with kidney- or gallstones.

This doesn’t mean bubble tea should be banned, but it does suggest we treat it as an occasional indulgence instead of a daily habit. And if you do indulge, consider skipping a straw. Drinking directly from the cup gives you better control, and allows your mouth’s sensory receptors to properly prepare for what’s coming.

Adapted from an article originally published in The Conversation.

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