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Skip to 0 minutes and 1 secondThere are generic difficulties associated with measuring dietary intake of any food or nutrient in the human diet. For example, people forget or don't give the reality of what they're eating. However, measurement of HCA intake has some of its own unique difficulties. The first difficulty in relation to measuring HCA intake is the gaps in the databases for HCA content of food. This is either due to inaccurate or incomplete data sets for particular countries. Or indeed due to complete lack of data in other countries. Therefore, we are left with poor or inaccurate data on food content. HCA food levels vary significantly according to food cooking methods and even subtle changes.

Skip to 0 minutes and 47 secondsSuch as the number of times a meat is turned during cooking can result in a large variation in HCA formation. There's also variations in cooking methods between countries. There are technical laboratory analysis challenges such as, cumbersome extraction methods, and highly sensitive method required due to low levels in foods. As a result of this paucity of data, there are currently no recommendations or guidelines in any country on safe upper intake thresholds. The types of variations or subtleties in cooking practises that can significantly alter HCA formation include, the type of meat, chicken, or fish. The frequency of consumption. How often cooked meats are consumed will affect the intake of HCAs. The portion size also affects the amount of HCAs consumed.

Skip to 1 minute and 40 secondsHowever, portion size can be difficult for people to report accurately. The thickness of the meat and fish during cooking. For example, as HCAs are formed on the outside, less HCAs are formed on thick meat. Cooking methods, cooking temperature. Different types of HCAs form at different temperatures. Therefore the cooking temperature has a significant impact on the production of these compounds. Cooking duration. This is related to doneness. The extent to which pan residues and gravy are ingested. For example, HCAs leech from meat into gravy during cooking. The use of marinades. Marinating meat before cooking reduces HCAs due to the water reducing the cooking heat. The number of times a food is flipped during cooking can affect the amount of HCAs formed.

Skip to 2 minutes and 38 secondsThe more often food is turned, the fewer HCAs are produced.

Skip to 2 minutes and 44 secondsThe country that has gathered data on HCAs formation and cooking methods most extensively is the USA. The USA database is used as a guide for many countries. However, it is not reflective of all countries. The ideal situation would be for all countries to have their own databases. Difficulties in measuring HCAs for some countries also relate to the expense of the equipment needed to measure. One of the most comprehensive databases for HCAs levels in food was developed by the National Cancer Institute in the US, known as the Charred database. This website also provides software that can be used to estimate the HCAs levels in cooked meats.

Skip to 3 minutes and 28 secondsUsing this database you can review PhIP, DiMeIQx and MeIQx levels in various meats according to what method of cooking has been used, and also depending on how well it was cooked. In addition to difficulties associated with measuring intakes of HCAs consumed in diets, there are parallel difficulties in measuring relationships between HCAs intakes or exposure and disease occurrence. There are a number of difficulties. Data on human exposure is only available for a small number of countries. There are currently no reliable markers of status. As cancer is a multi-factorial disease, it's not clear yet whether the link between HCAs and cancer is due to HCAs or something else.

Skip to 4 minutes and 18 secondsIt is difficult for a country which does not have data on population intakes to produce such data without first developing food level databases. As there are between country variations in cooking methods and therefore each country needs their own database. This is potentially quite complex and expensive, and is not available for most countries. Without such detailed global data, there is therefore insufficient evidence to produce upper intake or range guidelines for intakes of HCAs. The Queen's University Food Cap study was funded by the World Cancer research fund. Its broad aims were to describe intakes and sources of HCA in the diets of a subset of the UK population in Northern Ireland.

Skip to 5 minutes and 7 secondsIt was a six week study with consenting subjects to compare HCA intake between a control group and a group on a low HCA diet. The study sought to find the level of intake of the following types of HCA. MeiQX, DiMeIQx, and PhIP. The data shown here is the first data on HCAs intakes in the Northern Ireland population.

HCA exposure using dietary information

There are difficulties with measuring dietary HCA exposure using dietary information, due to the poor and inaccurate data on food content and cooking methods.

Most countries don’t gather data on how food is cooked, how long it is cooked, or the temperature of cooking. Therefore, we don’t have data on the subtle differences of cooking in different countries – and these subtle differences can have significant effects on the formation of HCAs.

This lack of data means variations in cooking methods and the impact on HCA formation cannot be analysed and reliably compared between countries. It also means that we have no clear recommendations for food safety.

In this video, we’ll look at the challenges to measuring intakes of these compounds in the human diet in more detail.

  • Different nations and cultures have different food preferences and cooking styles - do you believe that HCAs could be a particularly relevant food safety issue in your country?

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This video is from the free online course:

Tackling Global Food Safety

Queen's University Belfast