Last updated on 15 July 2009

3-MCPD in soy sauce and related products - Q&As

Your questions answered.

  • What is 3-MCPD?

    3-MCPD (3-monochloropropane-1,2-diol) is the most common of a group of chemical contaminants known as chloropropanols. It is usually formed when fat-containing foods that also contain salt are exposed to high temperatures during production. It occurs at low levels in many foods and food ingredients as a result of processing. It is most frequently found at high levels in soy sauces and the savoury food ingredient acid-hydrolysed vegetable protein (acid-HVP). Research has also indicated that it can be formed from 3-MCPD esters by thermal processing and by the action of lipases in the human digestive tract.

    3-MCPD has probably been present in foods since they were first cooked/processed, but it is only recently that scientists have been able to detect it reliably. 3-MCPD is an international issue affecting foods worldwide.

  • Why is 3-MCPD of concern?

    3-MCPD is of concern owing to its toxicological properties. It can cause cancer in laboratory animals when fed in large amounts over their lifetime. Although human consumption of these substances is at lower levels, there is still concern that they may present a risk to health.

  • Why is 3-MCPD found in some soy sauce?

    3-MCPD is produced as a contaminant by-product of a flavour enhancer known as acid-hydrolysed vegetable protein. Flavour enhancers are commonly added to commercially produced food products (for example frozen dinners, instant soups, snack foods) and some soy sauces to make them taste more 'savoury'. 3-MCPD was originally detected in acid-hydrolysed vegetable protein (HVP) and was subsequently found in HVP-containing soy sauces.

  • Is 3-MCPD found in other foods?

    Yes. In recent years, several studies, including the Agency’s two surveys, have found quantifiable levels of 3-MCPD in a range of foods and food ingredients. Foods with quantifiable levels of 3-MCPD included breads, savoury crackers, toasted biscuits, cheeses, doughnuts, burgers and salamis.

  • Why is 3-MCPD found in other foods?

    Although 3-MCPD is most frequently found in soy sauce, it is also known to be formed in the absence of acid-HVP. This has led to further research on the formation pathway. We now know that 3-MCPD appears to form from lipids present or naturally added salt during normal manufacturing and cooking processes, such as baking and grilling. More recently, they have been found to be generated from 3-MCPD esters.

  • What are 3-MCPD esters?

    3-MCPD esters are contaminants that can form during the processing and manufacture of certain foods and ingredients and are known by-products of the manufacture of acid-hydrolysed vegetable proteins. 3-MCPD esters are structurally related to the chloropropanols i.e. 3-MCPD. Recent research on 3-MCPD esters has indicated that 3-MCPD can be released from the esters of 3-MCPD by thermal processing and by the action of lipases in the human digestive tract. This therefore raises an indirect toxicological concern.

    Recent published research on 3-MCPD esters has indicated that their presence in various foodstuffs (e.g. refined fats and oils, infant formulae and follow-on formulae, bread) may be of possible health concern.

    The Agency is proposing to undertake research to establish the release of 3-MCPD from the esters and has used the opportunity presented by the on-going survey of process contaminants in retail foods to investigate the level of occurrence of the esters in the food groups sampled.

  • How can 3-MCPD be prevented from occurring/be removed from soy sauce?

    It is important to remember that not all soy sauces contain 3-MCPD. It is not present in fermented soy sauces. Therefore, most of the mitigation measures employed by industry centre around the careful control of the acid hydrolysis step during production of soy sauces.

  • How much 3-MCPD can be consumed without causing any harmful health effects?

    The Scientific Committee for Food (now European Food Safety Authority) set a level of 2µg/kg bodyweight/day for the amount of 3-MCPD which can be consumed daily over a lifetime without appreciable harm to health (i.e. Tolerable daily intake). The 67th meeting of the Joint FAO/Who Expert Committee on Food Additives (JECFA) retained this level after its evaluation in 2006.

  • Is there a regulatory limit for 3-MCPD levels in food?

    There is a European Commission regulatory limit of 0.02 mg/kg for 3-MCPD in Hydrolysed Vegetable Protein and soy sauce based on a 40% dry matter content. This limit is provided for in EC Regulation 1881/2006. The Codex Alimentarius Commission at their 31st session in 2008 adopted the draft maximum level of 0.4mg/kg of 3-MCPD in liquid condiments containing acid-hydrolysed vegetable protein (excluding naturally fermented soy sauce).

  • What surveys of 3-MCPD has the Agency carried out?

    The Food Standards Agency carried out a survey of 3-MCPD in acid-hydrolysed vegetable protein (acid-HVP) and soy sauce in 1999. Also, surveys of 3-MCPD in selected food groups and food ingredients were published in February 2001. The published Information Sheets, Nos 181(acid-HVP), 187(soy sauce), 12/01(foods) and 11/01(food ingredients) for these surveys are on the Agency website.

  • What work is the Agency doing on 3-MCPD levels in food?

    The Agency is currently conducting a survey of process contaminants which aims to investigate the levels of 3-MCPD and other process contaminants in UK retail foods. This three year rolling programme which began in 2007 will provide a clearer picture of the levels of 3-MCPD (and other process contaminants) in foodstuffs commonly consumed in the UK.

    The Agency is also proposing to undertake research to establish the release of 3-MCPD from the esters (see Q.5). The research proposal aims to assess the extent of release of 3-MCPD from its mono- and di-esters in food, i.e. by thermal processing/cooking and/or the action of lipases during storage as a means of investigating the mechanism of formation.

    Findings from the proposed research will clarify the extent to which 3-MCPD esters act as precursors to 3-MCPD in food. The project will also help in the understanding of the mechanism of such action and will help to facilitate the development of appropriate mitigation measures. The work will also inform future discussions at the EU level. Further information on the research proposal can be found on the Agency’s website.

  • What is the most recent advice to consumers?

    Consumers are advised to avoid products containing 3-MCPD levels above the regulatory limit of 0.02 mg/kg.

  • What is the most recent advice to industry?

    Soy sauce and hydrolysed vegetable protein products which are imported into the EC have to adhere to EC regulatory limits of 0.02mg/kg. Codex has adopted a code of practice which was developed as a means of disseminating best practice to assist manufacturers, particularly in developing countries, to take action to reduce the levels of 3-MCPD in their products.