Food group categories used in dietary analysis can misrepresent the amount and type of fat present in foods.

Abstract

Objective: To determine whether analysis of food intake data using different food group classification systems changes the apparent contribution of defined food groups to total daily fat intake.

Design: Three food classification systems were used to assess dietary intake of male omnivore subjects from a food frequency questionnaire.

Setting: RMIT University, Melbourne, Australia.

Subjects: A total of 78 healthy men aged 20-55 years, divided by meat consumption into moderate meat-eaters (n = 60) and high meat-eaters (n = 18).

Methods: Dietary intake data were collected as semi-quantitative food frequency questionnaires and analysed using the NUTTAB 95 database. The contribution of food groups to nutrient intakes was determined using three food classification systems.

Results: When red meat was grouped with meat, poultry and game products and dishes, 'meat' contributed 19.8% of total fat to a diet typical of an adult Australian man. When lean meat cuts were distinguished from meat products or dishes and fast foods, 'red meat cuts' provided only 4.3% of the total fat in this diet, whereas 'fast foods' provided 18.7%.

Conclusions: Food classification systems have a profound impact on the apparent nutrient content of defined food groups, particularly the fat content attributed to meats. Less precise systems may result in provision of misleading dietary advice. Meats such as lean beef and lamb can be a valuable part of a healthy diet by providing important nutrients, especially iron, zinc and vitamin B12, but relatively little fat.

Key words: dietary advice, fat content, food classification system, food group, meat, omega-3 fatty acid.

INTRODUCTION

Population-based dietary studies can be very difficult to compare because of differences in food classifications systems used and definitions of food groups. There have been considerable variations in the foods included as part of a defined food group in various research studies. In order to identify the true source of nutrients, particularly fat, consumed in published diets, it is critical to examine how the food groups and any subsets within a food group were defined. Food classification systems with small numbers of groups such as the 'core food groups' used for dietary intake advice are limited in their use for dietary analysis aimed at determining nutrient intake patterns in both small-scale dietary studies and population studies. The greater the division of foods into groups for dietary analysis, the greater the detail that can be obtained on dietary nutrient contribution from specific food commodities. However, expanding food groups into an excessively broad range of categories with narrow content defeats the intent of simplifying analysis to a manageable level. Obviously, a realistic balance is needed, along with an appreciation of the inherent limitations.

A comprehensive Australian food grouping system consisting of 19 categories was developed and used for the National Nutrition Survey (NNS) of 1995. (1) However, even this system combined some dissimilar food items together into specific groups, a good example and the point of the present study being the 'meat, poultry and game products and dishes' group, which included processed meats, meat dishes and fast foods or takeaway foods. A re-evaluation of the 1995 NNS data by CSIRO nutritionists used a 21-food group system that subdivided two NNS food groups (meat, poultry and game products and dishes; fish and seafood products and dishes) into four new groupings (red meat cuts, red meat products and dishes, white meat cuts, and white meat products and dishes, where 'white meat' included poultry, pork, fish and seafood). (2) Application of this expanded and subtly differing grouping system to the 1995 NNS dietary intake data gave a substantially differing interpretation of some nutrient intakes from specific food groupings, particularly the total fat and fat subgroup quantities from the meat-based groupings. (2)

The quantity, type and source of fats consumed in people's diets have become an important area of study because of their considerable health implications. Excessive fat intakes, particularly of saturated fatty acids, have been linked with increased risk of coronary heart disease, obesity, some cancers and hypertension. (3) Obesity in turn is implicated in 75% of hypertension cases, (4) as well as maturity-onset (type 2) diabetes and cardiovascular disease (CVD). (5) The World Health Organization recommends that not more than 30% of energy intake be derived from fats, (3) with 10% or less coming from saturated fats, which are found mainly in animal-based products, coconut and palm oils and vegetable shortening. (6) Current Australian intakes, however, average 32.5% of energy intake from total fat, including 12.7% energy from saturated fats. (7)

The World Health Organization also suggests that not more than 300 mg/day cholesterol be consumed, as high-cholesterol levels appear to elevate the risk of CVD by increasing the risk of atherosclerosis. (8) Cholesterol is found almost entirely in animal-based foods, mainly egg yolk, offal, meat and dairy products. (9) Australian men have a mean cholesterol intake of 358 mg/day, compared with 240 mg/day in Australian women. (7)

In recent years, there has been a perception that 'red meat' is 'bad for you'. This arose because of advice from various public health agencies to eat less red meat and hence (it was implied) consume less fat in order to prevent CVD and cancer. (10) Animal fats were, therefore, equated with saturated fats and thereby linked with atherosclerosis and heart disease. (11) For this reason, people endeavouring to lead a healthy life may avoid eating meats in general. Yet lean meat is an important source of dietary protein, iron, zinc, vitamin B12, thiamine, niacin, potassium and omega-3 fatty acids, so that omitting meat from the diet means missing out on a rich source of these valuable nutrients. This is well illustrated by the poor iron and zinc intake recorded in the 1995 NNS for women aged 19-29 years who were low meat consumers. (7) More recently, analysis of the 1995 NNS food intake data using a fatty acid database of foods (12) revealed red meat to be a critical source of the beneficial long-chain n-3 polyunsaturated fatty acids (PUFA) in the Australian diet. (13)

The present study aimed to determine the contribution of defined food groups (particularly the meat groups) to the total fat and fat type consumed by male omnivore subjects through analysis of their diets with three different food group classification systems in which meat, meat products and meat dishes were either combined or separated.

METHODS

Subjects

Ethics approval for the present study was granted by the Human Research Ethics Committee of RMIT University and all subjects gave informed written consent. Data were collected from 78 healthy male non-smokers aged 20-55 years and originally recruited through university advertisements and the local newspaper for participation in a study of habitual diets and thrombotic risk factors. Subjects were excluded if they showed evidence of CVD or had a family history of CVD, hypertension, renal disease, hyperlipaemia, haematological disorders, diabetes or excessive alcohol intake, or took medications or nutrient supplements. Subjects were divided into two groups based on their food intake patterns using meat intake levels as a defining feature (see Data Collection), which was representative of their intake during the six months prior to the study.

Data collection and grouping of subjects

Subjects completed a semi-quantitative food frequency questionnaire with assistance from trained nutritionists and a dietitian, gave blood samples and had basic anthropometric measures including blood pressure taken, as reported previously. (14) The dietary information obtained was analysed using Diet 1 version 4 software (Xyris, Brisbane, Qld, Australia) combined with the NUTTAB 95 database, which is based on the published Composition of Foods, Australia. (15) Data were obtained for 29 nutritional factors, including total energy, total fat and the three fat subgroups: saturated fats, monounsaturated fats and polyunsaturated fats. (16)

Characteristics of the subjects and their daily dietary intakes have been published previously, (14) and are summarised in the Results section. As the meat intake of subjects was the main point of interest in the present study, the total mass of meat eaten daily by each subject (whether as lean cuts or as part of products, dishes or takeaway food) was plotted in a scatter diagram to investigate the range of intake. It was found that subjects divided naturally into two distinct groups: those who consumed less than 260 g meat per day (n = 60) and those who consumed 285 g or more meat per day (n = 18) (163.2 [+ or -] 48.4 g vs 387.2 [+ or -] 122.0 g, mean [+ or -] SD, P < 0.001). The two groups were, therefore, labelled as the 'moderate meat-eaters' (MME) and 'high meat-eaters' (HME), although these descriptions did not take into account the relative quantities of other food groups consumed. In general, the HME consumed considerably more total food by weight and energy intake than the MME (16.4 [+ or -] 3.3 MJ vs 11.3 [+ or -] 2.5 MJ, P < 0.001).

Food grouping systems

Three systems of food grouping were used to determine the primary dietary sources of fat and a range of other nutrients. The systems used were: (i) the 1995 NNS, a 19-food group system; (1) (ii) a 1999 CSIRO adaptation of the NNS 1995 system, which expanded upon the meat groups of the NNS categories; (2) and (iii) a 22-food group system developed by the RMIT University nutrition group, in which the NNS 1995 meat groups were reclassified and a group for 'fast foods/takeaway foods' added (Table 1).

In the NNS 1995 compilation, foods that contained ingredients from more than one food group were classified according to the major ingredient. The classification system consisted of 19 food groups but all types of meat were placed into one category. Hence, both 'fast foods' (such as KFC chicken nuggets) and a lean beefsteak were included in the single 'meat' category along with meat products or dishes with added fat (often not of animal origin) or prepared/cooked in added fat (also often not of animal origin).

The CSIRO system was based on the NNS system but was restructured to better determine the total nutrient contribution of red meat to the Australian diet. With this aim, the original 'meat' and 'fish' groups were subdivided into four groups: 'red meat cuts', 'red meat products and dishes', white meat cuts' and 'white meat products and dishes', creating a total of 21 food groups. Fish, seafood, poultry and pork were considered 'white meat'. Mixed meat products, such as sausages, and foods containing meat but placed in the 'cereal-based products and dishes' group for the NNS were added to 'red meat products and dishes' as part of the CSIRO investigation. (2)

The RMIT classification system was specifically developed to determine in more detail still, the contribution of actual meat to fat, fat type and a range of other nutrients in a cross-sectional dietary study conducted by the lipid research group at RMIT University in Melbourne. To achieve this, the 'red meat cuts' and 'white meat cuts' groups of the CSIRO classification were left unchanged, but foods included in either white or red 'meat products and dishes' were subdivided into 'meat products' and 'meat dishes' according to whether the food was a commercial product or a home-prepared dish. Foods that were predominantly prepared by food retailers were combined into a 'fast food/takeaway foods' group. This change affected foods previously located within the NNS and CSIRO 'cereal-based products and dishes', 'vegetable-based products and dishes', 'meat' and 'fish/seafood' groups. The other food groups of the NNS and CSIRO classifications remained the same, creating a total of 22 food group categories in the new RMIT system.

Dietary analysis

Foods consumed and subsequent nutrient intake data for each subject in the present cross-sectional, habitual diet study were placed in a spreadsheet and then categorised into food groupings according to each of the three classification systems. For each system, the nutrient content of each food group intake was combined for all subjects in the same habitual diet group (HME and MME). This produced an overall daily dietary total as well as average consumption per person of each nutrient by food group.

RESULTS

The characteristics of the MME and HME groups are displayed in Table 2. The HME group had a significantly greater energy intake from total fat, saturated fat and monounsaturated fat, as well as a higher dietary cholesterol intake. There was no significant difference between mean systolic or diastolic blood pressure in the two subject groups. Interestingly, despite the much greater intake of food and energy by the HME group, their average body mass index and waist to hip ratio were not significantly different to those for MME subjects.

Tables 3 and 4 show the average daily total fat intakes from different food groups calculated for MME or HME subjects, respectively, using the NNS, CSIRO and RMIT food group classification systems. As expected, overall total fat intakes for MME and HME were much the same regardless of which classification system was used for the dietary analysis, because the total food intake remained the same despite being categorised in different ways within the different systems.

As the classification system became more detailed, more information could be obtained on the source of fat in the diet of the two groups of subjects. The NNS system indicated that for the MME group (Table 3), 'meat, poultry and game products and dishes' provided the third-highest amount (20.0%) of total fat per day in the diet at 19.2 [+ or -] 9.0 g (less than 'fats and and oils' at 21.0%, and 'cereal-based products and dishes' at 20.1%). The CSIRO analysis went further, revealing that 'red meat products and dishes' provided more fat per day (14.9 [+ or -] 10.3 g, 15.4%) than any other meat group but that this intake trailed the 'milk products and dishes' group (15.4 [+ or -] 8.9 g, 15.9%) as well as 'fats and oils' (20.2 [+ or -] 14.7 g, 20.9%). The fat content of the 'cereal-based' group fell to 13.1 [+ or -] 9.6 g/day (13.5%), because of some foods being re-allocated to the 'red meat products and dishes' group (e.g. commercial hamburgers, lasagne and meat pies). When the detailed RMIT analysis was applied to the MME diet, the contribution of fat from the 'cereal-based' group again dropped, along with that from 'vegetable products and dishes', as foods from these groups that had been prepared by food retailers were moved into the 'fast foods' group (Table 3). Examples of such foods were KFC chicken nuggets, pizzas and doughnuts. The RMIT analysis indicated that only the 'fats and oils' group (20.2 [+ or -] 14.7 g, 20.9%) provided more fat than this 'fast foods and takeaways' group (18.2 [+ or -] 12.6 g, 18.8%). The fat contributions from 'red meat cuts' (4.2 [+ or -] 3.9 g, 4.3% of fat) and 'white meat cuts' (5.1 [+ or -] 3.7 g, 5.3%) were less than those from 'milk products' (15.4 [+ or -] 8.9 g, 15.9%) and 'cereal-based products' (6.5 [+ or -] 8.1 g, 6.7%).

Comparison of Table 3 (MME) and Table 4 (HME) also helps to clarify the sources of the much higher total energy and fat intake in the HME group. Approximately 200 g fat was consumed by HME subjects compared with the approximate 96 g consumed by MME. The larger amount of fat in the diet of HME subjects was due mainly to their much larger intake of foods from almost every food group. Figure 1, which shows the contribution of different food groups to total dietary fat intake by percentage, illustrates how a particular classification system can alter the apparent contribution of various food groups to total fat consumption. Both the MME and the HME diet are shown following analysis with the NNS classification system and then the RMIT system.

The re-allocation of meat-containing foods into more specific food groups for the RMIT analysis resulted, predictably, in more accurate identification of the sources of different types of fat in the diet. Table 5 gives data for the MME dietary intake of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids and cholesterol by food group, according to the NNS system and the RMIT system. (Data for the HME group are not shown, as MME subjects appeared to best reflect the total fat intake and percentage of energy intake of the average Australian men aged 19 years of more from the 1995 NNS.) Analysis of the MME diet with the NNS food classification system (Table 5) indicated that the major sources of SFA were the 'milk and milk products' (9.6 [+ or -] 5.8 g, 26.4%), 'cereal-based products' (8.3 [+ or -] 6.3 g, 22.9%), 'meat, poultry and game products and dishes' (6.2 [+ or -] 3.6 g, 17.1%) and 'fats/oils' (5.3 [+ or -] 6.7 g, 14.6%) groups. Re-analysis using the RMIT system adjusted this order, with the 'milk' group (9.6 [+ or -] 5.8 g, 26.4%) still the biggest supplier of SFA in the diet, but 'fast foods' placed second (7.1 [+ or -] 5.6 g, 19.5%), ahead of 'fats/oils' (5.3 [+ or -] 6.7 g, 14.6%) and 'cereal-based foods' (3.3 [+ or -] 4.5 g, 9.1%). The various meat categories provided only small fractions of the total SFA intake, with most obtained from 'meat dishes' (2.1 [+ or -] 2.0 g, 5.7%), followed by 'red meat cuts' (1.6 [+ or -] 1.5 g, 4.4%), 'white meat cuts' (1.2 [+ or -] 1.1 g, 3.3%) and 'meat products' (1.1 [+ or -] 1.3 g, 3.0%).

According to the NNS classification system, 'fats and oils' provided the most MUFA (8.6 [+ or -] 6.4 g, 26.9%) for the MME group, with 'meat, poultry and game products and dishes' next (7.3 [+ or -] 4.0 g, 22.8%) and then 'cereal-based' foods (6.2 [+ or -] 4.6 g, 19.4%). Re-analysis with the RMIT system showed that most MUFA were supplied by 'fats and oils' (8.6 [+ or -] 6.4 g, 26.6%), followed by 'fast food' (6.7 [+ or -] 5.1 g, 20.7%), 'milk products and dishes' (3.8 [+ or -] 2.5 g, 11.8%) and 'meat dishes' (2.3 [+ or -] 2.0 g, 7.1%). The MUFA levels in fast food and meat dishes were presumably due mainly to the use of oleic acid (18: ln9)-rich oils and margarines during the cooking process.

The NNS food classification system found that PUFA in the MME diet were largely supplied by 'fats and oils' (5.4 [+ or -] 5.5 g, 50.0%), 'cereals' (1.5 [+ or -] 1.2 g, 13.9%), 'meat, poultry and game products and dishes' (1.2 [+ or -] 1.6 g, 11.1%) and 'cereal-based' foods (0.9 [+ or -] 1.1 g, 8.3%). The RMIT system, however, found that 'fast foods' (1.0 [+ or -] 1.3 g, 9.2%) provided the third-largest amount of PUFA after 'fats and oils' (5.4 [+ or -] 5.5 g, 49.5%) and 'cereals' (1.5 [+ or -] 1.2 g, 13.7%), followed by 'meat dishes' (0.8 [+ or -] 1.1 g, 7.3%) and 'cereal-based foods' (0.3 [+ or -] 0.7 g, 2.8%).

Under the NNS classification system, the 'meat, poultry and game products and dishes' group was by far the largest supplier of cholesterol in the MME diet (132.3 [+ or -] 53.2 mg, 39.7%), followed by 'egg products and dishes' (58.6 [+ or -] 70.7 mg, 17.6%) and 'milk and milk products' (57.5 [+ or -] 29.2 mg, 17.2%). The RMIT analysis revealed that it was the 'white meat cut' group that actually supplied the largest single amount of cholesterol in the diet (59.4 [+ or -] 38.9 mg, 17.7%), followed again by 'egg products and dishes' (58.6 [+ or -] 70.7 mg, 17.5%) and 'milk and milk products' (57.5 [+ or -] 29.2 mg, 17.2%). 'Red meat cuts' (45.0 [+ or -] 32.0 mg, 13.4%), 'fast foods' (42.3 [+ or -] 28.4 mg, 12.6%) and 'meat dishes' (21.0 [+ or -] 15.3 mg, 6.3%) provided lesser amounts of cholesterol in the diet.

[FIGURE 1 OMITTED]

DISCUSSION

A previous RMIT study that compared the diets of the MME and HME subjects raised the issue as to whether the high fat intakes of HME were due to their high meat consumption or some other dietary factor. (14) As most Australian cuts of red meat do not have high levels of fat, it was a perplexing question. However, isolating the meat-eating habits of these subjects inferred that 'negative' elements of their diet such as total fat, saturated fat and cholesterol were indeed derived from their high meat intake. Results of analysis using the NNS 1995 food group classification system and the more detailed RMIT system indicated that the HME group actually consumed considerably more food of all types than the MME group, in terms of both quantity (4.1 kg/day vs 2.6 kg/day) and energy content (16.4 MJ/day vs 11.3 MJ/day). They could more accurately have been described as a high food intake group, rather than being identified purely by their meat intake.

Comparison of the NNS and the RMIT food classification systems clearly demonstrated that quite different conclusions can be drawn as to the sources of nutrients in a diet, depending on how specifically foods are divided up into food groups for analysis. Much more information on the source of total fat in the habitual diets of omnivorous subjects was obtained from use of the more detailed RMIT system. The RMIT system revealed that the greatest fat intakes for MME subjects were fats and oils, fast food/takeaway foods, and milk products and drinks, in that order, with the fat contributed by meat dishes and red or white meat cuts being much less than any of these. This finding was similar for the HME subjects, except that milk products and drinks were ranked second in their diet after fats and oils, contributing more fat than fast foods/takeaway foods.

According to the NNS 1995, Australian adults consumed an average of 98.5 g fat per day, (7) which provided 32.4% of the total energy intake. In adult men (aged over 19 years), the major food group contributing to this fat intake was the 'meat, poultry and game products and dishes' group, which provided 23.7% of the total fat intake. However, this is a large and complex grouping of foods, combining food items that contribute high levels of fat to the diet with those with healthy lipid profiles. When data for our MME subjects (who were male and aged 20 years or older) were analysed in the current study using the NNS food group classification system, the results were very similar to the NNS 1995 results for adult men. MME subjects in the present study consumed an average total of 96.2 g/day of fat (32.8% of energy intake), which was almost identical to the NNS 1995 figure of 98.5 g/day (32.4%) for adult men. This suggests that despite the small sample size of the MME group, the main findings for the 60 MME subjects might apply well to the population of Australian men aged over 19 years. The HME subjects, however, consumed far more food and total fat than the average Australian adult men in the NNS 1995 survey, with an average value of 196.7 g/day of total fat (37.8% of total energy intake) obtained using the NNS 1995 classification system. Analysis of both the MME and HME diets using the RMIT system provided similar results to the NNS data: an intake of 96.7 g of total fat per day for MME and 205.8 g/day for HME. This is to be expected as the classification systems all analysed the same pool of dietary data and differed only in their allocation of analysed foods to specified food groups. Minor differences (e.g. 196.7 g total fat/day with NNS vs 205.8 g with RMIT for the HME group) arose because of the way food items were categorised and data entries in the food composition database were selected as the most appropriate to use for coding given food items.

The differences in data derived using the NNS and RMIT food group classification systems resulted mainly from their different levels of complexity in the classification of meats (although the cereal-based and vegetable food groups were also affected). Although all meats were grouped together under the older NNS system, the RMIT system included sub-categories for meat-based items, such as processed meat products and takeaway foods. This was because 'meat products' and 'meat dishes' often contain significant amounts of added fats, whereas fast-foods and takeaway foods are often deep-fried or combined with high-fat ingredients. Therefore, they contain significant amounts of fat not of meat origin and/or levels of fat not encountered if lean cuts of meat are consumed as per public health messages. The RMIT results showed that the all-encompassing 'meat, poultry and game products and dishes' group of the NNS system, which in 1995 was considered to provide the highest or equal highest amount of total fat in the diet, in fact included large amounts of processed meats, meat dishes and fast foods or takeaway foods in which added fat was a common factor. This has contributed to a common misconception that eating any meat item contributes significant levels of fat to the diet.

The present study clarified that in the MME diet, which appears to closely resemble the average intake of adult Australian men, fast foods and takeaway foods supplied substantial amounts of the total fat and saturated fat intakes. In contrast, red meat cuts provided only the seventh-highest levels of both total fat and saturated fats in the diet (Table 5). Analysis with the RMIT system showed that the greatest amount of cholesterol was supplied by white meat cuts, with red meat cuts supplying less than the egg and milk groups.

Because margarines and cooking oils constitute the bulk of the fats and oils group, it is not surprising that the MME subjects consumed most MUFA in the form of fats and oils directly, followed by fast foods and milk products and dishes. However, meat dishes provided the next-highest levels of MUFA in the diet, and the other meat groups (white meat cuts, red meat cuts and meat products) also contributed significant amounts, as meats contain both MUFA and PUFA, including the omega-3 fatty acids, which are considered desirable because they make up one of the two essential groups of PUFA for humans and appear to reduce the risk of heart disease. (17) Most PUFA in the MME diet were supplied by the 'fats and oils' group, followed by 'cereals', 'fast food' and 'meat dishes'. Red meat has previously been shown to be a very important contributor of long-chain omega-3 fatty acids in the diet of Australians. (13)

The present study has shown that for some foods, particularly meats, food group classification systems can provide misleading data to members of the public and health professionals. Grouping a diverse group of foods into a single meat category, for instance, has given rise to a negative perception of the nutritional value of 'red meat' as a food. Re-analysis of dietary data typical of Australian men aged over 19 years using the relatively detailed RMIT food classification system indicates that the levels of total fat and saturated fat in 'meat cuts', as distinct from the broader classification of 'meat, poultry, game products and dishes', is quite low. Even a relatively fat-rich red meat cut such as lamb leg steak contains less fat (4.3 g lipid/100 g uncooked meat) than a portion of fatty fish such as Atlantic salmon (9.8 g/100 g) or the yolks from chicken eggs (32.2 g/100 g). (18) In a typical meat pie, only one quarter of the total fat is obtained from the meat filling; the remaining 74% total fat (and two-thirds of the SFA content) is contained within the pie's pastry. (19)

By eliminating or reducing takeaway products, as well as processed meat products and meat dishes incorporating added fat, in their diet, while maintaining their consumption of lean red meats and other lean meat cuts, health-conscious individuals can greatly reduce their intakes of total fat, saturated fats and cholesterol but enjoy the valuable benefits of nutrients found in meat such as protein, omega-3 fatty acids, iron, zinc and vitamin B12.

In designing dietary studies examining the contribution of foods to various nutrient intakes, dietitians face the dilemma of having to categorise foods into a manageable number of groups, but at the same time segregate food items with grossly dissimilar composition. The present study concentrated on the meat categories specifically to show the confused message that can result from differing approaches to grouping meat items. Similar reclassification of food items in the dairy group and to a lesser extent the other groups, can lead to similar anomalies in the dietary information obtained.

ACKNOWLEDGEMENTS

The present study was supported by a research grant from Meat and Livestock Australia.

REFERENCES

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3 WHO and FAO joint consultation. Fats and oils in human nutrition. Nutr Rev 1995; 53: 202-5.

4 Noakes M, Clifton P, McMurchie T. The role of diet in cardiovascular health: a review of the evidence. Aust J Nutr Diet 1999; 56: S3-17.

5 Lichtenstein A, Kennedy E, Barrier P et al. Dietary fat consumption and health. Nutr Rev 1998; 56: S3-15.

6 Lehninger A. Biochemistry, 2nd edn. New York, USA: Worth Publishers, 1975.

7 McLennan W, Podger A. National Nutrition Survey of Australia 1995: Nutrient Intakes and Physical Measurements, Australia 1995. Canberra: Australian Bureau of Statistics, Commonwealth Department of Health and Aged Care, 1998.

8 Kamel B, Kakuda Y. Technological Advances in Improved and Alternative Sources of Lipids. London, UK: Chapman and Hall, 1994.

9 Whitney E, Rolfes S. Understanding Nutrition, 7th edn. St Paul, MN, USA: West Publishing, 1996.

10 Briggs GM, Schweigert BS. An overview of meat in the diet. In: Person AM, Dutson TR, eds. Meat and Health: Advances in Meat Research, Vol. 6. London and New York: Elsevier Applied Science, 1990; 1-18.

11 Reiser R, Shorland FB. Meat fats and fatty acids. In: Person AM, Dutson TR, eds. Meat and Health: Advances in Meat Research, Vol. 6. London and New York: Elsevier Applied Science, 1990; 21-62.

12 Mann NJ, Sinclair AJ, Percival P, Lewis JL, Meyer BJ, Howe PRC. Development of a database of fatty acids in Australian foods. Nutr Diet 2003; 60: 42-5.

13 Meyer BJ, Mann NJ, Lewis JL, Milligan GC, Sinclair AJ, Howe PRC. Dietary intakes and food sources of omega-6 and omega-3 polyunsaturated fatty acids. Lipids 2003; 38: 391-8.

14 Li D, Sinclair A, Mann N et al. The association of diet and thrombotic risk factors in health male vegetarians and meat eaters. Eur J Clin Nutr 1999; 53: 612-19.

15 Thomas S, Corden M. Metric Tables of Composition of Australian Foods. Commonwealth Department of Community Services and Health Nutrition section, Canberra. Canberra: Australian Government Publishing Service, 1977.

16 Li D, Sinclair AJ, Mann NJ, Turner A, Ball M. Selected micronutrient intake and status in men with differing meat intakes, vegetarians and vegans. Asia Pac J Clin Nutr 2000; 9: 18-23.

17 Sinclair AJ, Oon KS, Lim L, Li D, Mann NJ. The [omega]-3 fatty acid content of canned, smoked and fresh fish in Australia. Aust J Nutr Diet 1998; 55: 116-20.

18 Mann NJ, Johnson LG, Warrick GE, Sinclair AJ. The arachidonic acid content of the Australian diet is lower than previously estimated. J Nutr 1995; 125: 2528-35.

19 Ashton Y. Lipid analysis of meat and fast foods. Honours Thesis. Melbourne: Department of Food Science, RMIT, 2000.

Neil MANN, Yvonne ASHTON, Stella O'CONNELL, Andrew SINCLAIR and Fiona KELLY

Department of Food Science, School of Applied Sciences, RMIT University, Melbourne, Victoria, Australia

Correspondence: N. Mann, Department of Food Science, School of Applied Sciences, RMIT University, GPO Box 2476v, Melbourne, Vic. 3001, Australia. Email: [e-mail]

N. Mann, PhD, Associate Professor of Human Nutrition

Y. Ashton, B.Sci, Honours Student

S. O'Connell, PhD, Research Assistant

A. Sinclair, PhD, Professor of Food Science and Nutrition

F. Kelly, B.Nutr & Diet (Hons), Research Assistant

Table 1 Comparison of the food groups used in the National Nutrition
Survey (NNS), CSIRO and RMIT classification systems

NNS system            CSIRO system             RMIT system

 1. Cereals and        1. Cereals and cereal    1. Cereals and cereal
    cereal products       products                 products
 2. Cereal-based       2. Cereal-based          2. Cereal-based products
    products and          products and dishes      and dishes
    dishes             3. Fruit products and    3. Fruit products and
 3. Fruit products        dishes                   dishes
    and dishes         4. Vegetable products    4. Vegetable products
 4. Vegetable             and dishes               and dishes
    products and       5. Legumes and pulse     5. Legumes and pulse
    dishes                products and dishes      products and dishes
 5. Legumes and        6. Milk products and     6. Milk products and
    pulse products        dishes                   dishes
    and dishes         7. Red meat cuts         7. Red meat cuts
 6. Milk products      8. Red meat products     8. White meat cuts
    and dishes            and dishes            9. Meat products
 7. Meat, poultry      9. White meat cuts      10. Meat dishes
    and game          10. White meat products  11. Fast foods/takeaway
    products and          and dishes               foods (a)
    dishes            11. Egg products and     12. Egg products and
 8. Fish and seafood      dishes                   dishes
    products and      12. Snack foods          13. Snack foods
    dishes            13. Sugar products and   14. Sugar products and
 9. Egg products and      dishes                   dishes
    dishes            14. Confectionery        15. Confectionery
10. Snack foods       15. Seed and nut         16. Seed and nut products
11. Sugar products        products and dishes      and dishes
    and dishes        16. Fats and oils        17. Fats and oils
12. Confectionery     17. Soup                 18. Soup
13. Seed and nut      18. Savoury sauces and   19. Savoury sauces and
    products and          condiments               condiments
    dishes            19. Alcoholic beverages  20. Alcoholic beverages
14. Fats and oils     20. Non-alcoholic        21. Non-alcoholic
15. Soup                  beverages                beverages
16. Savoury sauces    21. Miscellaneous        22. Miscellaneous
    and condiments
17. Alcoholic
    beverages
18. Non-alcoholic
    beverages
19. Miscellaneous

(a) Fast foods/takeaway foods included: hamburgers, hot dogs, pies,
deep-fried chips, seafood and chicken items, pizza and similar items.

Table 2 Characteristics of subjects and their average diets in the two
dietary groups (mean [+ or -] SD)

                    'Moderate meat-eaters'  'high meat-eater'
                    (MME) (n = 60)          (HME) (n = 18)

Age (years)          38.3 [+ or -] 7.3       34.2 [+ or -] 9.4
Body mass index      26.4 [+ or -] 3.4       27.0 [+ or -] 3.4
Waist/hip             0.88 [+ or -] 0.05      0.88 [+ or -] 0.06
Systolic blood      125.7 [+ or -] 10.5     129.8 [+ or -] 14.6
  pressure (mmHg)
Diastolic blood      81.7 [+ or -] 7.9       83.4 [+ or -] 8.0
  pressure (mmHg)
Energy intake (MJ)   11.3 [+ or -] 2.5       16.4 [+ or -] 3.3***
Total fat (% of E)   32.8 [+ or -] 6.1       37.8 [+ or -] 4.2**
SFA (% of E)         14.3 [+ or -] 3.2       17.4 [+ or -] 2.7***
MUFA (% of E)        13.0 [+ or -] 2.8       14.9 [+ or -] 1.4*
PUFA (% of E)         5.6 [+ or -] 2.3        5.6 [+ or -] 1.4
Cholesterol (mg)    332 [+ or -] 107        611 [+ or -] 150***

*P < 0.05, **P < 0.01, ***P < 0.001.
E = energy; MUFA = monounsaturated fatty acids; PUFA = polyunsaturated
fatty acids; SFA = saturated fatty acids.

Table 3 Intake of total fats (a) from different food sources in the diet
of 'moderate meat-eaters' (MME): a comparison of three different food
classification systems

Food groups                  NNS system     CSIRO system   RMIT system

Cereals and cereal products   5.2 [+ or -]   5.2 [+ or -]   5.2 [+ or -]
                                3.1            3.1            3.1
Cereal-based products and    19.3 [+ or -]  13.1 [+ or -]   6.5 [+ or -]
  dishes                       12.9           9.6             8.1
Vegetable products and        3.6 [+ or -]   3.6 [+ or -]   1.0 [+ or -]
  dishes                        3.6            3.6            2.2
Milk products and dishes     15.4 [+ or -]  15.4 [+ or -]  15.4 [+ or -]
                               8.9            8.9            8.9
Meat, poultry and game       19.2 [+ or -]  NA             NA
  products and dishes          9.0
Red meat cuts                NA              4.2 [+ or -]   4.2 [+ or -]
                                               3.9            3.9
Red meat products and        NA             14.9 [+ or -]  NA
  dishes                                      10.3
Fish and seafood products     1.8 [+ or -]  NA             NA
  and dishes                    1.6
White meat cuts              NA              5.1 [+ or -]   5.1 [+ or -]
                                               3.7            3.7
White meat products and      NA              3.6 [+ or -]  NA
  dishes                                       3.6
Meat products                NA             NA              3.3 [+ or -]
                                                              3.2
Meat dishes                  NA             NA              6.0 [+ or -]
                                                              4.8
Fast food/takeaway foods     NA             NA             18.2 [+ or -]
                                                             12.6
Egg products and dishes       1.9 [+ or -]   1.9 [+ or -]   1.9 [+ or -]
                                2.0            2.0            2.0
Snack foods                   1.7 [+ or -]   1.7 [+ or -]   1.7 [+ or -]
                                2.2            2.2            2.2
Confectionery                 2.9 [+ or -]   2.9 [+ or -]   2.9 [+ or -]
                                3.8            3.8            3.8
Fats and oils                20.2 [+ or -]  20.2 [+ or -]  20.2 [+ or -]
                               14.7           14.7           14.7
Total per person (b)         96.2 [+ or -]  96.8 [+ or -]  96.7 [+ or -]
                               6.6            5.8            6.0

(a) Mean total fat intake per person per day in grams [+ or -] standard
deviation (n = 60).
(b) Total includes contributions from food groups not shown in the table
that supply low levels of fat.
NA = not applicable, that is, the food group does not exist in this
classification system; NNS = National Nutrition Survey.

Table 4 Intake of total fats (a) from different food sources in the diet
of 'high meat-eaters' (HME): a comparison of three different food
classification systems

Food groups               NNS system      CSIRO system    RMIT system

Cereals and cereal          6.3 [+ or -]    6.3 [+ or -]    6.3 [+ or -]
  products                    4.2             4.2             4.2
Cereal-based products      27.7 [+ or -]   18.4 [+ or -]   17.7 [+ or -]
  and dishes                 17.4            14.5            13.6
Vegetable products and      7.1 [+ or -]    7.1 [+ or -]    1.3 [+ or -]
  dishes                      4.8             4.8             1.6
Milk products and dishes   29.7 [+ or -]   29.7 [+ or -]   29.7 [+ or -]
                             15.5            15.5            15.5
Meat, poultry and game     50.5 [+ or -]  NA              NA
  products and dishes        21.8
Red meat cuts             NA               15.6 [+ or -]   15.6 [+ or -]
                                             12.2            12.2
Red meat products and     NA               31.0 [+ or -]  NA
  dishes                                     15.8
Fish and seafood            2.6 [+ or -]  NA              NA
  products and dishes         3.2
White meat cuts           NA                9.1 [+ or -]    9.1 [+ or -]
                                              6.2             6.2
White meat products and   NA                4.7 [+ or -]  NA
  dishes                                      6.0
Meat products             NA              NA                9.9 [+ or -]
                                                              9.1
Meat dishes               NA              NA               13.1 [+ or -]
                                                             7.5
Fast food/takeaway foods  NA              NA               29.4 [+ or -]
                                                             16.5
Egg products and dishes     5.4 [+ or -]    5.4 [+ or -]    5.4 [+ or -]
                              6.2             6.2             6.2
Snack foods                 7.1 [+ or -]    7.1 [+ or -]    7.1 [+ or -]
                              14.3            14.3            14.3
Confectionery               7.4 [+ or -]    7.4 [+ or -]    7.4 [+ or -]
                              9.0             9.0             9.0
Fats and oils              40.2 [+ or -]   40.2 [+ or -]   40.2 [+ or -]
                             36.1            36.1            36.1
Total per person (b)      196.7 [+ or -]  194.7 [+ or -]  205.8 [+ or -]
                            15.0            11.4            11.1

(a) Mean total fat intake per person per day in grams [+ or -] standard
deviation (n = 18).
(b) Total includes contributions from food groups not shown in the table
that supply low levels of fat.
NA = not applicable, that is, the food group does not exist in this
classification system; NNS = National Nutrition Survey.

Table 5 Daily contributions of selected food groups to the saturated
(SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acid
intakes and cholesterol intake (by mass (a)) of 'moderate meat-eaters'
(MME) under the National Nutrition Survey (NNS) and the RMIT food
classification systems

               SFA (g)              MUFA (g)

NNS system
Cereals         0.9 [+ or -] 1.1   0.8 [+ or -] 0.9
Cereal-based    8.3 [+ or -] 6.3   6.2 [+ or -] 4.6
  products
  and dishes
Vegetable       1.3 [+ or -] 1.5   1.0 [+ or -] 1.2
  products
  and dishes
Milk products   9.6 [+ or -] 5.8   3.8 [+ or -] 2.5
  and dishes
Meat, poultry   6.2 [+ or -] 3.6   7.3 [+ or -] 4.0
  and game
  products
  and dishes
Fish and        0.5 [+ or -] 0.6   0.5 [+ or -] 0.6
  seafood
Egg products    0.4 [+ or -] 0.7   0.6 [+ or -] 0.9
  and dishes
Confectionery   1.7 [+ or -] 2.3   0.9 [+ or -] 1.2
Fats and oils   5.3 [+ or -] 6.7   8.6 [+ or -] 6.4
Total per      36.3 [+ or -] 2.6  32.0 [+ or -] 2.5
  person (b)

RMIT system
Cereals         0.9 [+ or -] 1.1   0.8 [+ or -] 0.9
Cereal-based    3.3 [+ or -] 4.5   1.5 [+ or -] 2.3
  products
  and dishes
Vegetable       0.2 [+ or -] 0.8   0.2 [+ or -] 0.8
  products
  and dishes
Milk products   9.6 [+ or -] 5.8   3.8 [+ or -] 2.5
  and dishes
Red meat cuts   1.6 [+ or -] 1.5   1.4 [+ or -] 1.7
White meat      1.2 [+ or -] 1.1   1.8 [+ or -] 1.7
  cuts
Meat products   1.1 [+ or -] 1.3   1.2 [+ or -] 1.4
Meat dishes     2.1 [+ or -] 2.0   2.3 [+ or -] 2.0
Fast food/      7.1 [+ or -] 5.6   6.7 [+ or -] 5.1
  takeaways
Egg products    0.4 [+ or -] 0.7   0.6 [+ or -] 0.9
  and dishes
Confectionery   1.7 [+ or -] 2.3   0.9 [+ or -] 1.2
Fats and oils   5.3 [+ or -] 6.7   8.6 [+ or -] 6.4
Total per      36.4 [+ or -] 2.5  32.3 [+ or -] 2.3
  person (b)

                PUFA (g)             Cholesterol (mg)

NNS system
Cereals          1.5 [+ or -] 1.2    1.3 [+ or -] 4.3
Cereal-based     0.9 [+ or -] 1.1   44.7 [+ or -] 33.3
  products
  and dishes
Vegetable        0.4 [+ or -] 1.0    3.5 [+ or -] 3.8
  products
  and dishes
Milk products    0.2 [+ or -] 0.5   57.5 [+ or -] 29.2
  and dishes
Meat, poultry    1.2 [+ or -] 1.6  132.3 [+ or -] 53.2
  and game
  products
  and dishes
Fish and         0.2 [+ or -] 0.4   15.6 [+ or -] 13.4
  seafood
Egg products     0.0 [+ or -] 0.2   58.6 [+ or -] 70.7
  and dishes
Confectionery    0.0 [+ or -] 0.0    2.0 [+ or -] 2.9
Fats and oils    5.4 [+ or -] 5.5   12.7 [+ or -] 33.2
Total per       10.8 [+ or -] 1.2  333.5 [+ or -] 33.6
  person (b)

RMIT system
Cereals          1.5 [+ or -] 1.2    1.3 [+ or -] 4.3
Cereal-based     0.3 [+ or -] 0.7   17.0 [+ or -] 24.9
  products
  and dishes
Vegetable        0.2 [+ or -] 0.7    0.1 [+ or -] 0.5
  products
  and dishes
Milk products    0.2 [+ or -] 0.5   57.5 [+ or -] 29.2
  and dishes
Red meat cuts    0.1 [+ or -] 1.0   45.0 [+ or -] 32.0
White meat       0.3 [+ or -] 0.5   59.4 [+ or -] 38.9
  cuts
Meat products    0.0 [+ or -] 0.2   12.7 [+ or -] 11.7
Meat dishes      0.8 [+ or -] 1.1   21.0 [+ or -] 15.3
Fast food/       1.0 [+ or -] 1.3   42.3 [+ or -] 28.4
  takeaways
Egg products     0.0 [+ or -] 0.2   58.6 [+ or -] 70.7
  and dishes
Confectionery    0.0 [+ or -] 0.0    2.0 [+ or -] 2.9
Fats and oils    5.4 [+ or -] 5.5   12.7 [+ or -] 33.2
Total per       10.9 [+ or -] 1.1  334.9 [+ or -] 22.1
  person (b)

(a) Mean total intake per person per day in grams or milligrams [+ or -]
standard deviation (n = 18).
(b) Total includes smaller contributions from food groups not shown in
the table.