High consumption of tea infusions is a possible long-term concern for human health due to their carcinogenic properties, the European Food and Safety Authority rules.
“The consumption of food supplements based on pyrrolizidine alkaloid-producing plants could also result in exposure levels causing short-term toxicity resulting in adverse health effects,” stated the European Food Safety Authority (EFSA).
The agency points primarily to the pyrrolizidine alkaloid (PA) content in tea, but also notes that it appears in honey and some dietary food supplements.
Updates to its risk assessment, which now take into account more recent data on exposure levels of these toxins establish a new Reference Point (RP) of 237 micrograms per kilogram per body weight per day (μg/kg bw/day).
This latest decision falls in line with other findings outlined in 2011, in which EFSA ruled there was a “possible health concern” for some high consumers of honey such as toddlers and children.
The panel at the time also concluded that 1,2-unsaturated PAs may act as genotoxic carcinogens in humans. An RP of 70 μg/kg bw/per day was thus calculated.
In increasing the RP, the report stated that the change “maintains the conservative nature of the previous risk assessment.”
“This considers the general degree of uncertainty related to the available studies used for the dose response analysis and the fact that both riddelliine and lasiocarpine are classified among the most potent PAs.”
Along with riddelliine and lasiocarpine, another PA, monocrotaline was also classified as possibly carcinogenic to humans by the International Agency for Research on Cancer (IARC) in 2008.
The EFSA Panel on Contaminants in the Food Chain (CONTAM) agreed, identifying a list of 17 PAs in total that required continued observation. These include lasiocarpine, lasiocarpine-N-oxide and senkirkine.
Upper and lower bounds
Following a Commission request, EFSA’s scientific report, published in August 2016, detailed dietary exposure to PAs through the consumption of honey, tea, and food supplements.
Here, they found the highest average concentrations of PAs consumed were found in the samples of rooibos (lower bound (LB) = 4.1 μg/L) and peppermint (LB = 3.5 μg g/L).
Concentrations of PAs in black tea were twice as high as reported for green tea (LB = 1.6 μg/L and LB = 0.8 μg/L, respectively).
Certain food supplements contained very high levels of PAs. Average PA concentrations of 235–253 μg/kg (LB– upper bound (UB)) were reported for pollen-based supplements. Retail honey contained PA concentrations of 14.5–27.5 μg/kg.
Using the RP of 237 μg/kg bw per day for the sum of all 1,2-unsaturated PAs, exposure levels were calculated for dietary exposure.
Acute exposure that also accounted for high contamination levels in all food commodities ranged from 1 to 300 ng/kg bw per day and from 6 to 170 ng/kg bw per day for mean consumers in the younger age classes (infants–adolescents) and adults, respectively.
Acute or short-term exposure to PAs related to the consumption of food supplements varied considerably depending on the type of supplement.
Consumption of PA producing plant extracts to be consumed following infusion led to exposure levels as high as 890 ng/kg bw per day.
Ingestion of one tablet/capsule based on PA-producing plants corresponded to estimates of acute/short-term exposure levels of about 800 or 1,800 μg/kg bw per day.
Acute/short-term exposure through the consumption of pollen-based supplements showed much lower exposure estimates in the range of 3–44 ng/kg bw per day.
“In view of the margin of more than three orders of magnitude between these exposure levels and the lowest known dose range associated with human acute/short-term adverse effects, the CONTAM Panel concluded that there is a low risk related to acute dietary exposure to PAs through the consumption of teas, herbal infusions and honey,” the report concluded.
“Consumption of pollen-based supplements is not considered to pose acute risks to human health,” the Panel added.