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Animal Fat in the Australian Diet including in Service Rations during World War 2 - Executive Summary
This review was commissioned to analyse and report on the documentation available on the level of animal fat in the Australian diet with particular reference to the level pre-World War 2, during the War years 1939-1945 in the armed services' and civilian diets, immediately post-World War 2, and then until the present time. This review provides a background, within which to examine claims made in relation to the Amendment of Statement of Principles, concerning Malignant Neoplasm of the Prostate (Instrument No 191 of 1996 of the Repatriation Medical Authority). The review has been structured so that a particular issue or question was identified and then followed by the available evidence relating to this matter. This executive summary consists of a series of stated propositions in response to the issues and questions identified, followed by a short summary of supporting evidence for this conclusion.
2. Civilian diet before World War 2 - Animal fat level
The total fat level of the civilian diet before World War 2 for an adult male was high (range 130-149g/head/day). Due to the limited availability and so consumption of non-animal sources of fat, the level of animal fat was estimated also to be of a high level (range 114-130g/head/day). The evidence for the above proposition is based on the results of a national household dietary survey, conducted in 1936-38 under the auspices of the National Advisory Council on Nutrition.
3. Comparisons between the civilian and Armed Services' diets in World War 2 - Animal fat levels
The independent analysis of the civilian and service ration diets indicates that with one exception, the service rations operating in the Second World War did not contain a higher level of animal fat than the civilian diet for an adult male, as reported in the 1944 National Household Survey. For the service rations operating within Australia, the animal fat content ranged from 78.5 to 88.8 percent of that of the civilian diet. The service rations available in the Middle East, and in New Guinea and Pacific Islands approximated the animal fat level of the civilian diet (96.2 and 92.8 % respectively), with the amended ration for New Guinea and the Pacific Islands exceeding that of the civilian diet by 8.0 percent. Overall it can be concluded that there is no evidence from the analysis of civilian and service diets that the rations available to servicemen during the Second World War contained excessive amounts of animal fat compared to civilian diets. One factor contributing to this result is the availability of archival material, documenting that the meat ration for the services was based on carcass weight with a resulting marked reduction in edible portion, compared to butchers' weight available to civilians. Also an allowance of 10 percent kitchen wastage applied to the service rations to conform with the methodology of the 1944 National Household Survey, marginally modified the level of nutrients in the service diet, including that of animal fat.
4.1 Trends post-war in apparent food and nutrient consumption - The effect of food rationing on food consumption
Between 1936/39 and 1949-50 there were reductions in the availability of animal fats in the civilian diet due to reductions in the availability of total meats (carcass wt) and butter, despite an increase in the availability of milk and milk products (as total milk solids). The availability of butter and meat products were adversely affected by civilian rationing of these commodities in June 1942 and January 1944 respectively. The reduced availability of these food products continued in the immediate post-war years, as rationing of meat continued until June 1948, and that of butter to June 1950. However total fat generally remained similar over the time period 1936/39 to 1946-47 buffered by the increase in milk and milk products and a considerable increase in the production and availability of margarine, of which coconut oil was the major component. Continued rationing of meat and butter impacted on both available total fat and animal fat with lower levels of both these fats estimated in 1947/48 to 1949/50.
4.2 Ten yearly changes in available foods and nutrients for consumption 1938-39 to 1993-94 - Trends in available animal fats
Between the years 1938-39 and 1993-94, there has been a major change in the amount of animal fat available for consumption, falling from an estimate of 116.9g/head/day in 1938-39 to 56.0g in 1993-94. This change in animal fat availability has resulted from a reduction in the availability of total meat (carcass wt) and butter from 118.5kg/head/year and 14.9kg/head/year respectively in 1938-39 to 79.8kg/head/year and 3.0kg/head/year respectively in 1993-94. During the same period, milk consumption (total milk solids) increased from 17.8kg to 24.0kg/head/year. Overall, there has been little change in the amount of total fat available for consumption in Australia from a level of 133.5g/head/day in 1938-39 to 117.5g/head/day in 1993-94.
5. National dietary surveys - Levels and trends in animal fats
The results of surveys of actual food consumption conducted in 1983 and 1995-96, show that there has been a major decrease in the intake of both total and animal fat in the Australian community since the 1944 Household Dietary Survey. The average intake of animal fat for adult men has decreased from an estimate of 122.0g in 1944 to 63.4g in 1983 and to 56.8g/head/day in 1995-96. The average intake for older men of a comparable age to World War 2 veterans is estimated as 55.3g in 1983 and 49.9g/head/day in 1995-96.
The food intake data from 1983 and 1995-96 indicate that maintaining an intake of 70g animal-based fat a day from 1983 and also previous to this date (based on food availability data from the yearly ABS series Apparent consumption of foodstuffs and nutrients), is inconsistent with food and nutrient intake patterns in the Australian community. Together with a reduction in total fat, the contribution of non-animal fats to total fat intake has been increasing since the early 1970s at the expense of the contribution of animal-based fats to total fat. Therefore it is concluded that it has become increasingly difficult to maintain a level of animal fat intake above 70g per day, because of major changes in the Australian diet. Maintaining this level would present particular difficulties for older men, because of their reduced energy requirements and lower intakes of food.
6. Assessment of food intake in the distant past - How valid
The evidence from the literature clearly shows the questionable validity of recall of past diets when compared with previously recorded data. Problems identified in recalling food consumption in the past which are pertinent to the claims concerning animal fat consumption and malignant neoplasm of the prostate, include the age of the surrogate providing the information, the extensive time period for recall, errors of omission and commission, and unintentional elaboration with distortion of memory due to the effect of a range of factors, such as expectations and needs. These problems may be exacerbated when the information is given by a surrogate for a deceased person, though research has not been conducted to scientifically document this situation.
7. What are the factors influencing food choices in humans?
All the evidence in the literature supports the position that an individual's food patterns result from a wide range of factors that are complex and inter-related. Factors affecting dietary patterns and practices include physiological factors, food accessibility, food characteristics, environmental and psychological influences, food selection practices within the household, prestige value of foods, food experiences in the early years of life. The argument that the circumstance of service with exposure to service rations induced a food behavioural change to a diet higher in animal fats is supported by evidence linking food preferences to exposure to characteristics of foods, hedonistic characteristics intrinsic to many high fat foods, image of specific foods as comprising proper meals for men and constraint of women's food selection by their partner's preferences.
Alternately the literature lists a large range of factors influencing food choices, that generally would not be associated with a period of serving in the armed forces or other dependency on institutional feeding. Of these, major factors include experiences in early life (prior to 16 years), which are among the strongest controlling factors in food preferences, alternative reinforcers available to the subject in post-service life (eg meat and milk rationing post-war service, medical/health advice re saturated fat diet), positive effect of deprivation of specific foods (eg low fat foods enjoyed pre-war), avoidance of certain foods associated with insecurity, illness or hardship, central influence of women on family food choices, culturally determined patterns of early life, and interactions with family and friends. One major point emphasised in the literature is that food likes and dislikes function differently in relation to impact on consumption with dislikes being more strongly associated with rejection and non-use of a food, than a food like is associated with consumption of that food.
On the basis of the above review and the universal agreement in the literature that many complex factors affect an individual's food patterns, it is considered speculative to place much weight on a period of military service as responsible for food consumption patterns maintained for a minimum period of 20 years, especially during a period when medical/health advice, changing food patterns in the community, and food availability in the market-place are contrary to these food consumption patterns. It is proposed that such a link can only be described as tenuous, and unsupported by a reasonable level of evidence.