The European Food Safety Authority's (EFSA) Contaminants Panel (CONTAM) has found that the beneficial effects of eating vegetables and fruit outweigh potential risk to human health from exposure to nitrate through vegetables.
The Panel said that the average consumer eating approximately 400g of mixed vegetables and fruit per day would not exceed the Acceptable Daily Intake (ADI) for nitrate.
Higher levels of nitrate tend to be found in leaves whereas lower levels occur in seeds or tubers. Thus leaf crops such as lettuce and spinach generally have higher nitrate concentrations.
The Panel noted that consumers eating more than 47 grams of rucola per day might already exceed the ADI without taking into account any other sources of nitrate exposure.
However, EFSA said that consumption of rucola at this level on a daily basis is not likely to occur over a long period of time and therefore considers that exceeding the ADI on occasion would not represent a health concern.
"Consumers should continue to eat their five portions of vegetables and fruit per day as they are essential for good health and could help to reduce the risk of certain diseases," a spokesperson for EFSA told FoodProductionDaily.com
"The body of evidence in the report does not point to a cancer risk for the EU population in regard to nitrate concentrations in vegetables," he added.
Nitrate per se is relatively non-toxic, but its metabolites and reaction products such as nitrite, nitric oxide and N-nitroso compounds, have raised concern because of implications for adverse health effects such as methaemoglobinaemia and carcinogenesis, according to EFSA.
Variation in nitrate levels
As a response to a call for data on nitrate levels in vegetables, EFSA said that it received 41,969 analytical results from 20 Member States and Norway.
The Panel said that the study showed a large variation in concentrations of nitrate in different vegetables from a low of 1 mg/kg (peas and Brussels sprouts) to a high of 4,800 mg/kg (rucola).
An Acceptable Daily Intake (ADI) for nitrate of 3.7 milligram per kilogram body weight per day, equivalent to 222 mg nitrate per day for a 60 kg adult was established by the former Scientific Committee on Food (SCF) and was reconfirmed by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 2002.
The CONTAM Panel said that no new data were identified that would require a revision of the ADI.
The CONTAM Panel said that further mitigation of nitrate intake may result from washing, peeling and/or cooking, thus providing an extra safety margin for consumers.
Meanwhile a US mice study, from November 2007, claimed that nitrites and nitrates may help heart attack survival and recovery.
Published on-line in the prestigious Proceedings of the National Academy of Sciences, the researchers report that the compounds reduced heart cell death in the mice following a heart attack by 48 per cent.
"The public perception is that nitrite/nitrate are carcinogens but they are not," said lead author Nathan Bryan.
"Many studies implicating nitrite and nitrate in cancer are based on very weak epidemiological data. If nitrite and nitrate were harmful to us, then we would not be advised to eat green leafy vegetables or swallow our own saliva, which is enriched in nitrate."
The study also reported that mice fed an extra helping of nitrite had a survival rate of 77 per cent compared to 58 per cent for the mice that were nitrite deficient.
The mice were supplemented with nitrite (50 mg per litre of drinking water) for seven days. A comparison group received no nitrite supplementation. The researchers subsequently simulated a heart attack by stopping blood flow to the animals' hearts for 30 minutes, followed by 24 hours of reperfusion.