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Nutrition and health

Food availability in Singapore from 1961 to 1983: implications for health research
Outpatient rehabilitation of severe protein energy malnutrition (PEM)

Food availability in Singapore from 1961 to 1983: implications for health research

Lee Hin Peng
Department of Social Medicine and Public Health, Faculty of Medicine, National University of Singapore, Singapore Singapore Cancer Registry, c/o University Department of Pathology, National University Hospital, Singapore

Lynn Gourley
Singapore Cancer Registry

INTRODUCTION

It is well established that diet plays an important role in health and disease. In Singapore, concern has changed from undernutrition to over nutrition and selective malnutrition. Obesity is now common in schoolchildren and adults [1, 2], and diseases of the circulatory system, especially ischaemic heart disease, are increasing [3] . Among some of the diet-related malignancies, cancers of the stomach and oesophagus are declining while those of the colon, rectum, and breast are increasing [4]. These facts point to an urgent need to study possible recent changes in dietary patterns.

Dietary surveys and nutritional surveys include studies of infants and children in Singapore, which have been either hospital-based or clinic-based [5, 6, 7] or community-based studies restricted to special groups [8, 9, 10]. Only two studies have reported on the general population: one of these surveyed the diets of urban Chinese households in Singapore [11], and the other considered only the intake of protein foods of high biological value in all three major ethnic groups in the lower income category [12]. A more recent study was confined to some male employees of a large public agency [13]. None of these provided representative data for a proper analysis of trends in nutritional intakes.

One important reason for this paucity of information is the difficulty of conducting nutritional assessments in a population such as Singapore's, where dietary habits are so varied. Local dishes usually have complex mixtures of ingredients, and dietary recall is, therefore, hindered, and dietary assessments to evaluate nutritional status are generally tedious and time-consuming.

This article seeks to document the trends in food availability in Singapore based on data compiled by the Food and Agricultural Organization (FAO) since 1961 [14, 15] and unpublished data for Singapore. The primary objective of this study is to describe the broad trends of food and nutrient availability or disappearance in Singapore, with the aim of identifying areas for further research.

METHODS

Food availability is calculated as the total quantity of a foodstuff produced, imported, and in stock, minus the quantity exported, fed to livestock, used for seed, put to industrial or other non-food uses, and lost during storage and transportation. The final figure for food availability represents the amount of food that reaches the consumer and is not necessarily equal to the amount actually consumed. Inevitably, the amount consumed is lower than that available because of losses of edible food and nutrients in the household during storage, preparation, cooking, and plate-waste.

The FAO food composition data indicate the availability of the major nutrients per capita of the population. These figures are derived statistics and are dependent on the accuracy of the underlying basic trade statistics, population census data, and data on the nutritive value of foods. Obviously the accuracy of these basic data varies a great deal from country to country. Moreover, gaps in the data inevitably occur, for which the FAO prepares estimates.

TABLE 1. Age- and sex-adjusted recommended daily allowances^a for the Singapore population, as at 1970 and 1980 census

a. Based on the recommendations of the Ministry of Health, Singapore (unpublished).

For the present study dietary fibre supply per capita was calculated using factors derived by Bright-See and McKeown [16] from data on the fibre content of selected foods. For comparison with the estimated average energy requirement (AER) and the recommended daily allowances (RDA) of various nutrients, the current recommendations of the Ministry of Health and the Department of Training and Health Education in Singapore (unpublished), age-and sex-adjusted for the population as a whole, were used (table 1).

RESULTS

Trends in the Food Supply

In the 20-year period from 1961 to 1980, there were increases in the supply of all the major food groups, with the exception of pulses (table 2). The most remarkable change was in the supply of meat and offal, which increased by almost two-and-a-half times, largely because more pork and poultry became available. Other substantial increases were seen for eggs 479 percent), animal oils and fats (72 percent), and fruits (61 percent). A trend towards decreased usage of vegetable oils and fats has been sharply reversed since 1975, but there has not been a corresponding decrease in animal fat usage.

Among the vegetables that have increased substantially in supply are cabbage, tomatoes, French beans, and long beans. Increased fruit availability is largely attributable to apples, oranges, and pears, all of which are imported.

Trends in Nutrient Availability

Calories

The per capita calorie supply in Singapore increased gradually from 2,335 kcal in 1961-1963 to 2,938 kcal in 19811983: an increase of 25 percent (fig.1). The proportion of calories from protein remained fairly constant at 9 to 11 percent, but that from fat rose from 16 to 22 percent, with a corresponding decrease in carbohydrate sources.

Protein

The supply of total daily protein rose by 34 percent from 55.5 9 to 74.5 9 per capita per day. Animal protein showed a greater rise than vegetable protein: a 52 percent increase compared to a 20 percent increase.

Fat

Fat supply markedly increased by 67 percent from 42.8 9 to 71.5 9. Fat from vegetable products was up by 29 percent while that from animal products increased by a drama tic 92 per cent.

Fibre

Estimates of dietary fibre availability over the last two decades revealed an increase from 25.5 9 to 41.6 9 percent capita per day. The factors used to arrive at these estimates and the relative proportions of fibre derived from various food groups are listed in table 3, which gives averages for the period 1976 to 1980.

TABLE 2. Singapore food supply per capita per day, 1961 to 1980

Source: FAO [15].

FIG. 1. Available calories per capita per day for Singapore, 1961 -1983

FIG. 2. Percentage RDA of selected nutrients available in Singapore, 1966-1980, based on age" and sex-adjusted RDAs for population according to 1970 census (1966-1971) and 1980 census (1975-1980)

Comparison with RDAs

Figure 2 illustrates the adequacy of the Singapore diet with regard to availability of calories, protein and selected vitamins and minerals. As can be seen, protein and ascorbic acid, kilocalories, iron, thiamine, and niacin are well in excess of the amounts currently recommended by the Ministry of Health, their availability having risen steadily since the mid 1960s.

There is still an insufficient supply of retinal and riboflavin, which have shown little change in availability over the last two decades. Calcium supply is marginally inadequate, although it did achieve over 100 percent of the RDA between 1969 and 1977.

Comparison with Other Countries

The countries chosen for comparison were two Western developed nations- the United Kingdom (UK) and Sweden - and two South-east Asian developing nations- Thailand and the Philippines. Figure 3 compares the daily calorie supply per capita of the different countries from 1961 to 1983, and as can be seen, the supply of available calories in Singapore almost squalled that of the UK, and even slightly exceeded that of Sweden. Singapore's calorie supply was much higher than that of its two South-east Asian neighbours.

FIG. 3. Total available calories per capita per day, average for 1979-1981, for Singapore and selected countries

DISCUSSION

The overall increase in food supply is an indication of the growing affluence of Singapore, which is evidenced by the increase in average monthly household income from S$591 to S$1,066 between 1972-1973 and 1977-1978 [17] . Obviously, these changes reflect rises in both income and price levels. As expected, average monthly household expenditure also rose from S$542 to S$908 between 1972-1973 and 1977-1978. The expenditures on food, while maintaining more or less the same proportion, increased from S$245 to S$406. Compared to the period from 1972 to 1973, per capita expenditure on food by households of all sizes rose substantially for the period from 1977 to 1978. Expenditures for meat and poultry rose at a faster rate than those for rice and other cereals.

From the data presented, it can be seen that there has been a marked increase in the supply of animal products, the main cause of an overall rise in calorie availability. Thus, the proportion of energy derived from animal products is two to three times higher than in Thailand and the Philippines, although this proportion is still lower than in the West.

Like calorie availability, the relative contributions to protein consumption of animal and vegetable nutrient sources in Singapore is mid-way between those of the developed and the developing nations. For fat, Singapore shows the Western pattern of being derived more from animal than vegetable products, albeit to a lesser extent. This trend in relative use of vegetable oils has, however, been reversed to some extent, which must reflect recent nutritional recommendations promoting the use of polyunsaturated fats. This increase has not been matched by a corresponding decline in the use of animal fats.

With such widespread availability of food, it is no wonder that obesity is increasing in Singapore. The School Health Service estimated in 1983 that about 2 per cent of the six-year-olds were obese (based on the Harvard standard weight for height tables) [1] . In addition, 10 per cent of the 11-year-olds were obese and another 10 per cent were in the borderline range. The cause was primarily one of overeating combined with insufficient physical activity. More than 65 per cent of these students had family histories of obesity.

In a sample survey of 2,300 adults aged 40 years and above attending government polyclinics in 1979, 31 per cent were found to be overweight: 20 per cent excess weight for height based on Jelliffe's standards [2]. It must be noted, however, that the sample was biased, since all were seeking medical attention, the majority of them having one of the chronic degenerative diseases like hypertension and diabetes mellitus.

TABLE 3. Estimated dietary fibre supply by food groups in Singapore, 1976-1980 average

a. Calculated by Bright-See and McKeown-Eyssen [16].
b. From FAO [15].
c. Based on 72 per cent extraction wheat flour.

It is interesting to note the increased availability of dietary fibre since 1961. The proportion from maize appears to be unusually high for this part of the world. In fact, the 1976 to 1980 figure for maize supply is four times higher than for the previous four-year period, and it is felt that this either represents an error or greatly increased use for animal feeding. If the maize consumption for this period is assumed to be the same as that in the period 1971 to 1975, the estimated dietary fibre availability is reduced to 36.6 9 per person per day, which still represents an increase since 1961, even when expressed per 1,000 kcal. Cereals are the largest contributors of fibre to the diet, but the increase in fibre availability appears to be due mainly to greater supplies of vegetables and fruit. A comparison of dietary fibre availability for 1972 to 1974 in 38 countries shows Singapore to be near the median in a range that stretches from 22.1 9 per day in Sweden and the Netherlands to 93.6 9 per day in Mexico [16] .

Note must also be made of the decline in the use of pulses as cheap vegetable sources of protein. Affluence and changes in taste have resulted in a preference for other more expensive and prestigious sources of protein. There is probably a need to promote the use of beneficial traditional foods through better marketing and the creation of more interesting recipes.

The two inadequately supplied nutrients are retinal and riboflavin, The main sources of retinal include fish oils, butter, egg-yolk and the carotene-rich vegetables and fruits such as carrot, tomato, dark-green leafy vegetables, manog, and papaya. The main sources of riboflavin include milk, liver, and enriched breads and cereals.

Unfortunately, it is not possible to make detailed comparison of food availability with actual food consumption. A study carried out by Kleevens [11] from 1963 to 1965 reported on available nutrients in Chinese households as a percentage of the RDA. The estimates were based on inventory of foods purchased and in stock, and not on actual consumption. It is interesting to note, however, that calcium and riboflavin were generally inadequately supplied in accordance with the national food disappearance data for the period. While such data do not identify how much of the food disappearing into the household is wasted or fed to animals, in Singapore these amounts are thought to be small.

Tan [12] reported an average daily per capita intake of 13 g high-biological-value protein in low-income groups during 1968, which is much lower than the 28.6 g animal protein available from 1966 to 1970. Intake was estimated, however, on the basis of a recall of the amount spent on selected animal foods; actual consumption was not measured.

A recent abstract by Tan et al. [13] reported nutrient intakes of 528 males, estimated by a 24-hour recall method, but full details of the methodology are not available. An average daily per capita intake of 2,210 kcal was reported, which, as expected, is considerably lower than the 2,928 kcal available from 1981 to 1983. The availability figure corresponds to an overestimation of 32 per cent, a finding that is consistent with the conclusion of Baghurst and Baghurst [18] that food supply figures usually overestimate energy intake by approximately 30 per cent.

Food availability data have shown definite increases in total calorie supply, protein, animal fats, ascorbic acid, and thiamine. The ready availability of food in general is a reflection of the growing affluence of the country. On the other hand, the very same socio-economic influences have resulted in the decline in demand for cheap vegetable protein sources. On the basis of experience in Japan and other industrialized countries, these changes can be expected to result in increased prevalences of heart disease, obesity, and diabetes, and a change in the patterns of cancers. It is clear that more detailed attention to this issue is needed.

Reference data on individual diets in Singapore would be useful. To this end, a survey of adult Singapore Chinese, using three-day food diaries, is at an advanced stage, as is a survey of foods purchased for home consumption.

The results can be compared with Kleevens' 1966 study [11] . This new study should provided a basis for relating the striking changes that have occurred in dietary patterns in Singapore to changes in the prevalence of acute and chronic disease.

REFERENCES

1. U. Rajan, "School Health Obesity Clinic," Singapore Comm. Health Bull., 24: 48-5411983).

2. A. J. Chen and L. s. C. Chiang, "Some Aspects of Lifestyles among Adults in Singapore," Singapore Comm. Health Bad, 21: 16-21 (1980).

3. A. J. Chen, "Recent Trends in the Mortality and Morbidity of Cardiovascular Diseases, Ann. Acad. Med. Singapore, 9:411416 (1980).

4. K. Shanmugaratnam, H. P. Lee and N. E. Day, Cancer Incidence in Singopore, 1968-1977, IARC Scientific Publication no. 47 (International Agency for Research on Cancer, Lyon, France, 1983).

5. S. K. Sung and D. L Pakshong, "A Survey of the Nutritional Status of infants and Pre-school Children Attending Pasir Panjang Maternal and Child Health Clinic," Singapore Public Health Bull., 11: 27-37 (1973).

6. F. M, Paul, "Nutritional Disorders Encountered in Children in the Department of Paediatrics, Singapore," Singapore Med. J., 15: 231-240 ) (1974).

7. V. C. Leong, ''A Study of Infant-feeding Practices as Seen in a General Practice," Singapore Fam. Physician, 1: 103-109 (1975).

8. J. Millis, "Dietary Regimes for the Pre-school Child in Singapore," Med. J. Malaya, 13: 215-221 (1959).

9. P. K. Chew, "A Dietary Study of the Singapore School for the Blind," DPH dissertation (University of Singapore, Singapore, 1963).

10. C. Y. Lo, "A Study of the Diet of a Small Sample of Chinese Cantonese Children Age 1-2 Years in Singapore," DPH dissertation (university of Singapore, Singapore. 1963).

11. J. W. L Kleevens, "Diets of Urban Chinese Households in Singapore in Relation to Income," Singapore Med. J., 7: 202-208 (1966).

12. N. Tan, "Intake of Foods Containing Protein of High Biological Value in Families of Low Income Groups in Singapore," Singapore Med. J., 11: 130- 137 (1970).

13. P. Y. Tan, T. B. Ng and N. Saha, "Dietary Intakes of Three Ethnic Groups of Singapore" (abstr.), Proc. Nutr. Soc., 43: 135A (1984).

14. FAO, Production Yearbook 1982, vol. 36 (FAO. Rome, 1983).
15. FAO Food Balance Sheets, 1979-81 Average (FAO, Rome, 1984).

16. E. Bright-See and G. E. McKeown-Eyssen, "Estimation of Per Capita Crude and Dietary Fibre Supply in 38 Countries," Am. J. Clin. Nutr., 39: 821-829 (1984).

17. Department of Statistics, Report on the Household Expenditure Survey, 1977/78 (Department of Statistics, Government of Singapore, Singapore, 1979).

18. K. I. Baghurst and P. A. Baghurst, "The Measurement of Usual Dietary Intake in Individuals and Groups" Transactions of the Menzies Foundation, 3: 139-1 60 (1981).

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