10.08.2024.
Nitrites and nitrates are naturally present in vegetables such as spinach, lettuce, celery and even beetroot. These are the main sources of dietary exposure to nitrates with only around 5% coming from its use as a food additive.
Nitrites and nitrates (E 249 – E 252) are used in certain cheeses and processed meats such as bacon, ham, corned beef and other cured meats to help keep it looking red and to aid the development of the ‘cured’ flavour. However, their main role is to reduce the growth of harmful microorganisms in particular clostridium botulinum, a bacterium that can be life threatening.
Are they safe?
All food additives must pass a robust safety assessment, a key element of which is looking at the actual risk to human health based on the levels at which an additive is likely to be present in the diet.
The UK FSA considers that existing levels of nitrites and nitrates are sufficiently protective for consumers. This is based on the view of the independent committees that advise the FSA, the rest of UK Government, and other scientific organisations such as the European Food Safety Authority (EFSA). These preservatives can only be used at the lowest effective levels which are kept under review.
Sodium and potassium salts of nitrite (E 249-250) and nitrate (E 251-252) were re-evaluated by EFSA (Opens in a new window) in 2017; following which it advised that nitrites and nitrates intentionally added at permitted levels to meat and other foods remain safe.
In June 2017 EFSA published two scientific opinions on its re-evaluation of nitrites and nitrates added to food. This summary explains why nitrites and nitrates are present in food, and what EFSA’s experts concluded on their safety.
EFSA’s Panel on Food Additives and Nutrient Sources Added to Food (ANS) based its assessment on previous evaluations, new scientific literature, and information provided following public calls for data.
Nitrate
The experts were able to derive an ADI for nitrate as they did not consider it to be genotoxic or carcinogenic (for substances that are potentially damaging to DNA or may cause cancer no safe level can be established). The panel considered the most relevant effect for setting a safe level was elevated blood concentrations of methaemoglobin, caused by nitrite converted from nitrate in saliva (see above). Based on this effect, the panel concluded that the ADI set by the SCF (1997) was sufficiently protective of public health.
Nitrite
The panel calculated an ADI of 0.07 mg/kg bw/day, corresponding to the safe level established by JECFA and close to the slightly more conservative current ADI of 0.06 mg/kg/bw/day derived by the SCF. As for nitrate, this is based on increased methaemoglobin levels in the blood following consumption as a food additive
What were EFSA’s findings on nitrosamines? Nitrites – including when used as food additives – contribute to the formation of a group of compounds known as nitrosamines, some of which are carcinogenic. Applying a number of conservative (i.e. worst-case scenario) assumptions, the panel concluded that the formation of nitrosamines in the body from nitrites added at approved levels to meat products was of low concern for human health. The panel further noted that nitrite unintentionally present in meat products from other sources such as environmental contamination can also contribute to the formation of nitrosamines. EFSA’s experts concluded that these levels of nitrosamines might give rise to potential health concerns but that more research was needed to address uncertainties and knowledge gaps in this complex area
Does red and processed meat cause cancer?
Whilst, links have been made between the over-consumption of red and processed meat and an increased risk of certain types of bowel cancer. It is not yet fully understood how this occurs; some contributory factors proposed are the processing method, how it is cooked (e.g. temperature) and may in part be a result of natural components in the meat.
Red and processed meat, whether produced with the use of nitrites and nitrates or without, can form part of varied and balanced diet when consumed within current UK NHS guidelines, and alongside healthy lifestyle choices.
What other work has been done in this area?
The SCF and JECFA have reviewed nitrite and nitrate added to food on several occasions, which led to the setting of the current ADIs. In 2010, EFSA’s ANS Panel issued a statement on nitrites in meat products considering data from Denmark, which did not lead EFSA to revise the existing ADI.
EFSA’s Panel on Contaminants in the Food Chain (CONTAM) has produced three opinions relevant to nitrites and nitrates, none of which proposed a revision of the ADIs previously set by the SCF and JECFA: In 2008, the CONTAM Panel assessed the risks and benefits to consumers from nitrates in vegetables. It concluded that the beneficial effects outweighed potential health risks from exposure to nitrate through vegetables, and that the average consumer would not exceed the ADI.
In its 2009 opinion on nitrites as undesirable substances in animal feed, the panel concluded that the low nitrite levels in fresh animal products did not raise any concern for human health. In 2010, a further opinion was delivered on the potential health risks for infants and young children from naturally occurring nitrate in leafy vegetables, in which the panel concluded that levels of nitrate in these vegetables are not of health concern for most children.
The International Agency for Research on Cancer (IARC) re-evaluated data available on nitrite and nitrate in 2010, but did not comment on the ADIs set previously by other organisations.
The IARC evaluation includes a review of the effects of ingested nitrate in experimental animals and in humans arising from epidemiological studies. In 2015, IARC classified processed meat as a carcinogenic hazard to humans (Group 1), with the formation of carcinogenic nitrosamines as one contributing factor. While IARC assesses the carcinogenic properties of substances, i.e. the potential hazard they pose, EFSA also evaluates the likelihood and level of exposure for different population groups in its risk assessments.
Acceptable daily intake – an estimate of the amount of a substance in food or drinking water that can be consumed over a lifetime without presenting an appreciable risk to health. It is usually expressed as milligrams of the substance per kilogram of body weight and applies to chemical substances such as food additives, pesticide residues and veterinary drugs.
Exposure – concentration or amount of a particular substance that is taken in by an individual, population or ecosystem in a specific frequency over a certain amount of time. When experts assess consumers’ dietary exposure to a chemical substance, they combine data on its concentrations in food with the quantity of those foods consumed. Children are often more exposed to substances because of their higher food consumption levels relative to their body weight.
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