BUBBLE tea, commonly known as milk tea, has become a comfort drink and social ritual for many young Filipinos, with thousands of shops nationwide. But as the craze continues, food experts are raising a more sobering question: What does this sugary, chewy drink actually do to the body?
Asst. Prof. Essence del Castillo, chair of the UST food technology department, said boba pearls or tapioca pearls are made from cassava starch, known locally as kamoteng kahoy or balinghoy.
The signature “chewiness” of the pearls comes from gelatinizing starch, a process in which heat and moisture cause starch granules to swell and soften. After boiling or steaming, the bland pearls are usually soaked in sugar syrup or flavored syrup before being added to drinks.
However, del Castillo warned that repeatedly chilling and thawing pearls — a common practice in milk tea shops — can alter the starch structure and make it more resistant to digestion.
“Because of frequent consumption, it can accumulate. You will have indigestion of gelatinized starch in the intestine,” she said.
A study by Consumer Reports found that some tapioca pearls abroad contained detectable amounts of heavy metals such as lead, cadmium, arsenic, and mercury.
While levels did not reach immediate danger thresholds, the findings raised questions about food safety. Del Castillo explained that contamination usually comes from soil and water pollution where cassava is grown.
Even so, occasional consumption is unlikely to push people beyond safe limits, she said.
Short-term heavy metal exposure can lead to nausea, abdominal pain, and vomiting, though she noted that this is rare in milk tea because pearls only make up 10 to 20 percent of the beverage and concentrations from tested samples were very low.
Cadmium, for instance, has a tolerable weekly intake of 2.5 micrograms per kilogram of body weight.
“It is rare to exceed this allowable or tolerable intake just by consuming milk tea with contaminated tapioca pearls at least once a week,” she said.
Beyond contamination concerns, del Castillo said the more immediate health risks come from milk tea’s sugar, starch, stimulants, and milk content.
On its own, freshly brewed tea contains antioxidants that protect cells from free-radical damage, but adding milk weakens its antioxidant function.
Milk tea also contains natural stimulants found in tea such as caffeine, theobromine, theophylline, and thein — a tea-specific stimulant similar to caffeine.
“It can boost your alertness. Pero ‘yun ‘yung isa sa mga effects, no? Pwede magkaroon ng palpitation, lalo na nga kapag hindi ka gano’n kasanay mag-consume ng mga beverage with stimulants,” she said.
Most shops use sugar syrups made from concentrated table sugar and water, which have a high glycemic index and can rapidly raise blood sugar levels.
Milk can also trigger digestive issues for lactose-intolerant individuals and may cause allergic reactions in those with milk allergies.
“Mataas ang caloric value lalo na ng combination of sugar, milk and starch, ‘yung tapioca pearls. So mahirap i-burn, lalo na kapag walang physical activity,” she said.
Given the contamination reports, some customers may opt for “sinkers” like nata de coco or popping boba if they are worried about tapioca pearls, del Castillo said.
“Shops should be cautious of their suppliers. They need to request Certificates of Analysis to verify heavy metal content and make sure ingredients meet standards,” she said.
She said establishments should conduct periodic testing — per batch if possible — for heavy metals, microbial contaminants, and mycotoxins.
Following Good Manufacturing Practices and complying with the Food Safety Act of 2013 are also crucial to protecting both consumers and the shop’s reputation.
More than 5,000 tea shops operate across the country, based on 2023 data.
