The origin of fluorescent nanoparticles in common drinks
Fluorescent nanoparticles found in beverages are a category of foodborne nanomaterials, meaning they are not intentionally engineered or added to products. Instead, they typically emerge as an intrinsic byproduct of high-heat food processing, such as the Maillard reaction that occurs between amino acids and reducing sugars during cooking and manufacturing. These particles, often referred to as fluorescent carbon dots (CDs), are tiny clusters of carbon, oxygen, and hydrogen, with their specific fluorescent properties influenced by their elemental composition and size.
Examples of drinks containing fluorescent nanoparticles
Research has specifically identified fluorescent nanoparticles in several types of beverages, both carbonated and non-carbonated:
- Colas: A 2017 study published in Nanotoxicology was the first to report the presence of fluorescent nanoparticles (roughly 5 nm in size) in samples of Coca-Cola and Pepsi-Cola. The study characterized the physiochemical properties and toxicity characteristics of these nanoparticles.
- Beers and other fermented drinks: In 2015, researchers reported finding fluorescent carbon dots in several commercial beverages, including Pilsner beer, Kvass, and Pony Malta. Other fermented beverages may also contain similar particles.
- Instant coffee: A 2015 study also extracted and characterized fluorescent carbon dots from commercial Nescafé instant coffee, noting their strong fluorescent properties.
These discoveries highlight that these nanoparticles are far more common than previously assumed, appearing in a wide range of thermally processed foods and drinks.
The current scientific understanding of health implications
Due to their extremely small size, nanoparticles behave differently in the body than larger particles. While research is ongoing, initial animal studies provide some key insights into their potential effects, especially on biodistribution (how they travel in the body) and toxicity.
Biodistribution and cellular uptake
Animal studies involving fluorescent nanoparticles extracted from colas and other foods have revealed that these particles can be absorbed from the digestive tract into the bloodstream. More concerningly, some studies found that they can cross the blood-brain barrier and accumulate in various major organs, including the liver, heart, and brain, although they also appear to be excreted over time. Within cells, these nanoparticles have been observed accumulating in the cell membrane and cytoplasm.
Toxicity studies and long-term effects
Toxicology studies, often in cellular (in vitro) or animal (in vivo) models, have shown mixed results, which depend heavily on the specific type of nanoparticle, its dose, and the duration of exposure. Some findings suggest that at high concentrations or with prolonged exposure, these nanoparticles may cause cellular stress, inflammation, and potential DNA damage. However, other studies show little to no acute toxicity at typical consumption levels. The long-term effects on human health from regular, low-level consumption of these foodborne nanomaterials remain largely unknown and require further research.
Regulatory landscape and consumer information
Regulations regarding nanoparticles in food vary significantly by region. In the European Union, for example, stricter rules exist regarding the labeling of engineered nanomaterials in food. However, the fluorescent carbon dots found in sodas and coffee are typically not classified as intentionally added ingredients, and therefore are not explicitly labeled. In the United States, the Food and Drug Administration (FDA) monitors the use of nanomaterials but does not have specific regulations mandating labeling for these unintentionally formed particles.
This regulatory gap means it is difficult for consumers to determine which products contain these nanomaterials without relying on independent scientific studies. For manufacturers, the responsibility remains to ensure product safety, even when dealing with intrinsic byproducts of manufacturing processes.
Comparison of foodborne vs. engineered nanoparticles
| Feature | Foodborne Fluorescent Nanoparticles | Engineered Food Nanoparticles |
|---|---|---|
| Origin | Formed naturally during thermal food processing (e.g., Maillard reaction). | Intentionally added for a specific functional purpose. |
| Examples in Drinks | Colas (e.g., Coke, Pepsi), beer, instant coffee. | Titanium dioxide (E171) in some cloudy sodas. |
| Material | Carbon dots (carbon, oxygen, hydrogen). | Titanium dioxide (E171), Silicon dioxide (E551). |
| Purpose | None; an unintentional byproduct of processing. | Whitening, color enhancement, anti-caking, or preservation. |
| Labeling | Not explicitly labeled in most regions, as they are not additives. | Must be labeled as an additive in regions like the EU, where rules apply. |
| Health Context | Long-term human exposure risks are unknown; more research is needed. | Some, like E171, have been banned in the EU due to safety concerns. |
Conclusion
Fluorescent nanoparticles are not science fiction; they are a real and, based on scientific studies, common byproduct found in thermally processed beverages like Coca-Cola, Pepsi, and instant coffee. These carbon dots form naturally during manufacturing and, unlike engineered nanomaterials, are not intentionally added. While initial animal toxicology studies offer some clues, the full extent of the long-term health implications from regular human consumption remains a topic of active research and scientific debate. The current lack of mandatory labeling for these foodborne nanoparticles in many countries puts the onus on consumers and researchers to stay informed about what's in our food and drinks. The best approach is to stay updated on the latest scientific findings and support further research into the safety of these ubiquitous nanomaterials.
Read the original 2017 study on Coca-Cola and Pepsi from the National Institutes of Health
