Consumption

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Root crops make an important contribution to the diet of many people in tropical countries, being consumed, as in the case of cassava, as a basic source of low-cost calories, or as a supplement to cereals. The cost of calories from cassava is about 25 to 50 percent that of the locally produced traditional grains and pulses (Goering, 1979), but other root crops, such as yams, are considerably more expensive. In most developing countries the dietary staples consist of starchy foods, which usually include some root crops. As indicated in Table 3.6, tropical roots may supply from as much as 1 060 calories per caput per day, (56 percent of the total daily calorie intake in Zaire), to as little as 200 calories (eight percent of the total daily intake in Belize).

Root crops are consumed not only by adults but are also important items in the diets of children. For example in Ghana and Nigeria infants are often weaned to an adult diet consisting of cassava or plantain. In Zaire, cassava fufu is the second most popular solid food for children under the age of one year, while in Cameroon, cassava is commonly given to infants 6 to 11 months old. Cassava can only form the basis for an adequate diet if it is consumed with other proteinrich foods such as oilseeds, pulses and fish. Young children have a limited stomach capacity and are unable to eat enough bulky foods, such as roots and tubers, to meet their energy needs. The results of a recent survey provide useful data on the frequency of cassava consumption in Zaire. In the survey area, sweet cassava is eaten raw in some localities as a snack or is boiled as ebe. The bitter varieties of cassava arc made into fuku, a cassava gruel, to which various amounts of corn are added, depending on the season. Mpondu, a vegetable dish made from cassava leaves, is frequently eaten with the fuku. In many areas, fuku with mpondu or other cassava derivatives was eaten about twice a day by over 90 percent of the population in the 24 hours before the interview.

The income elasticity of demand for root crops is low but positive, and the cross elasticities of demand among cereals and root crops are high so substitution is not difficult. A national socio-economic survey conducted in Indonesia in 1980 showed that the per caput consumption of fresh cassava tends to increase as minimal income level increases, but stabilizes or decreases at the higher income levels.

A similar result has been observed in Brazil where the elasticity of demand for cassava is positive at low income levels, and in Ghana where there is no further tendency for the consumption to increase as per caput income increases to levels well above subsistence. In Indonesia, there is a high cross elasticity of demand between cassava and rice. If better production or storage techniques could result in reduced consumer costs of cassava products, then the prospects for an increased consumption of cassava would improve appreciably (Cock, 1985). With some other root crops, especially yams, the consumption tends to increase with rising income as yams are a relatively expensive food. In some places there may also be a strong cultural preference for particular foods, such as sweet potatoes. However, the general tendency is that cereals are preferred to root crops, while wheat and rice are preferred to the coarser grains.

TABLE 3.6 - Tropical root crops as a source of calories In selected countries, 1974

Notes:

¹Figures rounded to the nearest 10.

Calorie consumption data are from FAO. Population and income figures are from World Bank Atlas, 1977.

Source: Goering, 1979.

As shown in Table 3.7 root crops contribute about 78 percent of the total calorie intake in the Group I region of sub-Saharan Africa, which is mainly in the tropical rain forest belt, and about 43 percent of the total calories in the Group II area, whereas in the more arid zones in Group III, cereals are more prominent. The details of the FAO country classification by groupings for subSaharan Africa are as follows:

Group I: Central African Republic, Congo, Mozambique, Zaire. In these countries both production and consumption patterns arc dominated by cassava, which accounts for over 50 percent of staple food consumption. Cereals provide 30 percent, and nearly one-third of these are imported.

Group II: Angola, Benin, Burundi, Cameroon, Comoros, Equatorial Guinea, Gabon, Ghana, Côte d'Ivoire, Nigeria, Rwanda, Tanzania, Togo, Uganda. A far more diverse production/consumption pattern is prevalent in this group. While roots and plantains are the main staple foods, cassava consumption is much less important than in the previous group. Included here are countries typical of the West African yam-producing belt. While plantains, sweet potatoes and taro are important foods in individual countries cereals account for one-half of calories consumed. Approximately 30 percent of cereals are imported.

Group III: Botswana, Burkina Faso, Cape Verde, Chad, Ethiopia, Gambia, Guinea, Guinea-Bissau, Kenya, Lesotho, Liberia, Madagascar, Malawi, Mali, Mauritania, Mauritius, Namibia, the Niger, Reunion, Sao Tome and Principe, Senegal, Seychelles, Sierra Leone, Somalia, Sudan, Swaziland, Zambia, Zimbabwe. In these countries cereals play a far greater role in both production and consumption, although roots are often staple foods in particular regions. The proportion of cereal consumption met from imports is also generally lower, averaging under one-fifth of the total.

TABLE 3.7 - Levels of consumption of staple foods In sub-Saharan Africa, 1981-83

¹See text for explanation of groups.
Source: FAO, 1987.

In the Pacific root crops still supply from 15 to 43 percent of the dietary energy, the type depending on the island: taro and yam provide 43 percent of the energy in Tonga while sweet potato, taro and yam are the chief suppliers of energy in Papua New Guinea and the Solomon Islands. The difference in cereal and root crops intake between rural and urban areas is striking. The rural population consumes as much as twice the quantity of root crops but less than a tenth of the quantity of cereals than the urban population. This is related to the high cost of transportation and the short shelf-life of fresh root crops. The picture is similar in Latin America and the Caribbean (Table 3.8). In these areas the cost of production of root crops is so high compared to that of cereals that some traditional root crops have become a luxury, except for potato in Bolivia and Peru and cassava in Brazil and Paraguay. In the Caribbean, cereals are definitely more important than roots in the diet though crops like plantain still contribute a substantial part of the dietary energy. In addition, some of the root crops produced are used for animal feed. About 33 percent of the cassava and about three to four percent of the other root crops are used for this purpose.

TABLE 3.8 - Rural/urban consumption of root crops In Latin America and the Carribean, selected crops and countries

Sources: Lynam, J.K. and Pachico. D.. Fresh cassava in Brazil, Cuba and Paraguay, farinha de mandioca, 1982. Sanint, L.R. et a Z., Fresh cassava and yam in Colombia, 1985.
Scott. G.. Potato in Peru, 1985.

Oñate et al. (1976) have shown in Table 3.9 that the consumption of root crops in Southeast Asia ranges from 6 kg/caput/year (16 g/caput/day) in Cambodia to 113 kg/caput/year (310 g/caput/day) in Indonesia. The per caput consumption of potato in Singapore is very high (9 kg/year or 25 g/day) compared to the other countries in the region (0 to 7 g/day). Banana makes up a substantial proportion of the Filipino food intake, ranging from 15 g/caput/day in eastern Visayas to 40 g in western Visayas region.

Tables 3.10 and 3.11 show the results of dietary surveys in eight regions in the Philippines varying from the urban population in metropolitan Manila to the rural populations in lowland and mountain areas.

Daily nutrient and food allowances for each individual were obtained from tables prepared by the Food and Nutrition Research Institute. Nutrients in the foods were calculated from food composition tables. Allowances for all members of the household were added together and divided by the number of household members to get the per caput allowances per household. The daily per caput nutrient allowances for each region were obtained by dividing the sum of allowances for all households surveyed in the area by the total number of individuals. Thus the percentages quoted in Table 3.10 give a comparative regional survey of dietary adequacy. The population with the poorest diet in terms of calorie, protein and iron intake is that of eastern Visayas where starchy roots and tubers contribute the bulk of the calories. Table 3.11 shows that the intake of supplementary foods such as legumes, fruit and vegetables, milk, eggs and oils and fats is exceptionally low in this region.

This reinforces the argument that an increased intake of dietary calories from roots and tubers must be supplemented by a variety of other foodstuffs in order to achieve a balanced diet. Studies by Oñate et al., 1976, show that in the Philippines the daily consumption of root crops varies with the region, ranging from about eight grams in metropolitan Manila to 222 grams in the rural area of eastern Visayas. This is true of many countries where food consumption in urban areas is characterized by a decrease in the consumption of root crops and an increase in the consumption of convenience foods from cereals and animal protein (see Table 3.11). The situation is different for processed root products with a relatively high bulk density and an extended shelf-life. In Ghana for example, after fresh cassava is made into dried gari, it can be transported relatively cheaply to the urban areas where it is as popular as in the rural areas. In the case of yarn, surprisingly there is a higher consumption in the urban areas than in the rural areas, indicating the importance of yam as an item of food and reflecting the inflated market price of this preferred root crop as a result of limited production (See Table 3.12).

TABLE 3.9 - Per caput consumption of starchy food In eight Southeast Asian countries (1964 66 average)¹ (thousand tonnes otherwise specified)

TABLE 3.10 - Average daily per caput nutrient Intake In percentage of recommended allowance¹ in eight regions In the Philippines²

TABLE 3.11 - Average daily per caput food intake in percentage of recommended allowance¹ in eight regions In the Philippines²

In Nigeria, although cassava as dry gari is consumed more in the urban areas than in rural areas the reverse is true with yam, probably because of the expense of transporting fresh yams and the ease of preparing meals using dried gari, which is of great convenience to urban workers (see Table 3.13).

Zones where root crops are consumed do not necessarily coincide with a high incidence of malnutrition. The Indian state of Kerala may serve as an example. This state has a population of about 25 million, whose staple food is rice. However, because of the high population density, fertile land suitable for the cultivation of rice is now in short supply and so most of the rice is cultivated on the poorly drained but fertile lowlands, while the well-drained hilly areas of low fertility are planted mainly with cassava. The main staples arc therefore rice and cassava.

As the population increased rapidly there was less land for the cultivation of rice and the production, yield and consumption of cassava increased.

This might have been expected to adversely affect nutritional status. Taking infant mortality as an index of nutritional status provides reassuring evidence, as the infant mortality in Kerala remained relatively low. Table 3.14 shows that in 1970/71 cassava supplied over 740 calories out of a total daily calorie intake of 2 519, which is probably adequate. Protein intake was less than 40 g per day. Cassava supplied very little but some of this deficit was made up by ingestion of rice and fish. So by varying the diet to include some cereal and animal protein, root crops like cassava are very useful in supplementing the energy obtained from cereals.

This has been confirmed by balance sheet data discussed by Goering (1979) indicating that serious protein deficiency is not necessarily common in countries where root crops arc one of the sources of calories. Thus in ten African countries where root crops supply between 500 to 900 calories or 20 to 40 percent of the total daily caloric intake, seven exhibited a per caput calorie consumption level of under 2 200 cal/day and only one showed an intake greater than 2 400 calories, yet none had a protein intake of less than 40 g per day, and only three had less than 50 g per day. Thus a limited intake of calories from root crops is not necessarily inconsistent with adequate protein intake.

TABLE 3.12 - Food consumption in Ghana In 1961-62 (g/caput/day)

¹Koko is a starchy paste or pap prepared from cereal or root flour.
Source: Calculated from Whitby, P.,A review of information concerning food consumption in Ghana. FAO, Rome. 1969.

Besides root crops, the leaves of cassava, sweet potato and cocoyam are commonly consumed in many tropical countries including Zaire, Papua New Guinea and central Java in Indonesia, especially during periods of food shortage. These leaves contribute some protein to the diet. They also contain minerals, particularly iron and calcium, and provide a valuable source of vitamins A and C. Increased consumption of these green leaves could help reduce the incidence of xerophthalmia in countries where nutritional blindness is prevalent. The use of edible cassava leaves as a green vegetable is popular in Africa (Hahn, 1984).

TABLE 3.13 - Food consumption In Nigeria (g/caput/day)

¹Rural figures based on studies by Collis, Dema, Lesi & Omololu (1962).
²Urban figures calculated on the basis of a study by McFie (1967) in Lagos.

TABLE 3.14 - Food consumption in Kerala, 1970/71 (average daily per caput value)

Source: United Nations, 1975.

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