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Dietary evaluation: World regions and countries

World regional data

Dietary data from selected world regions and countries are evaluated and data are expressed so as to demonstrate the availability of essential amino acids both in milligrams per day and in milligrams per gram of dietary protein. Food availability data, provided in the computer version [17] of the FAO food balance sheets, are the source of the dietary data used to calculate the essential amino acid supply. The FAO/Agrostat computer database contains information for individual countries and for regional groupings showing the daily availability, in grams of protein per day, of up to 114 specific food items (wheat, potatoes, milk, chicken, meat) or food groupings (cereals, starchy roots, animal foods) as well as the grand totals for daily protein, fat, and food energy availability.

It has been observed [13] that, in practice, for both countries and regions, a much smaller number of items (typically 20 to 30) will provide most of the protein and will allow for a simplified calculation procedure. These items include the major cereals, such as wheat, rice, corn, millet, and sorghum; the starchy roots cassava, sweet potato, and potato; the pulses soya bean, groundnut, and common beans; and fruits and vegetables, both individually and as groups, as well as the animal food products, primarily meat, milk, fish, and eggs.

Amino acid composition data were available as a computer data set from the Massachusetts Nutrient Data Bank. These data originated mainly from the US Department of Agriculture food tables [18] but also from a number of other food tables such as those of FAO [19] and tables for Middle Eastern foods [20], as well as laboratory data for individually analysed samples. On average, more than 95% of the dietary protein could be accounted for in the simplified calculation procedure using a combination of individual foods and food group data.

In table 4, data for food energy, protein, and the essential amino acid supply are shown for selected world regions. The amino acid data are in the form of milligrams per day for the eight essential amino acids. The sulphur amino acids (Sea) are expressed as the total of methionine and cystine, whereas the aromatic amino acids (Aaa) are expressed as the total of phenylalanine and tyrosine. Because of the equivocal status of histidine in terms of both requirement and food composition analytical data, this amino acid was omitted from consideration. Data from both developed and developing countries are tabulated and compared throughout with the estimated requirements for a man aged 18 to 30 years weighing 65 kg [3]. For this stage of the evaluation, the small but important correction for dietary digestibility was not included in the comparison. Inclusion of this variable would have the effect of further increasing the difference between supply and requirement for the poorest diets, since digestibility would be lower in poor, cereal-based diets.

TABLE 4. Food energy, protein, and essential amino acid supply (mg/day) for selected world regions (data for 1992)

Source: calculated from FAO/Agrostat [17]. Requirement values from FAO/WHO/UNU [3] and FAO/WHO 15]
a. Male 18-30 yr: wt = 65 kg.
b. Depending on activity level.
c. High-quality protein of high digestibility.

Group data will first be compared. Table 4 shows a very significant difference between nutrient availabilities in developed and developing regions. Developed regions, as a group, have average availabilities of 3,384 kcal and 102.1 g protein/day, and between 1,249 (tryptophan) and 8,147 mg (leucine) per day for the individual essential amino acids. In contrast, developing countries as a group have far lower availability of food energy, with only 2,542 kcal and 62.3 g protein/day and between 743 and 4,992 mg/day for the individual essential amino acids. All values for these group data exceed the requirement values for a young male by factors ranging from 10% to 100%.

The comparison for food energy is the most difficult to assess because of the need to consider activity levels. However, of the others, the difference between supply and requirement is the smallest for lysine and further comparisons will be made primarily in terms of daily lysine availability. For lysine only 3,127 mg/day is available, on average, in the developing countries, compared with 6,633 mg/day for the developed regions. This can be compared to estimated requirement values for young men of some 2,840 mg/day. This value is based on a multiple of the lysine expressed as milligrams per gram of protein (58 mg/g protein) from FAO/WHO [5] multiplied by the protein allowance (49 g/day) from FAO/WHO/UNU [3] for a 65-kg man aged 18 to 30 years.

These average data show an even greater range when specific regions are considered. For example, lysine availability in North America is 7,480 mg/day compared with 2,542 and 2,972 mg/day, respectively, in the developing regions of Africa and Asia.

In table 5 the essential amino acid availabilities for the year 1992 in the same selected world regions are expressed in milligrams per gram of protein. These values are indicative of mean dietary protein quality, and comparison here shows that, for the developed regions as a group, the mean availability of lysine is 65 mg/g protein, in contrast to only 50 mg/g protein for the developing countries. These values may be compared with a requirement estimate from FAO/WHO of 58 mg/g protein [5].

TABLE 5. Essential amino acid supply (mg/g protein) for selected world regions (data for 1992)^a Essential amino acids (mg/g protein)

a. Calculated from FAO Agrostat [17].

When comparison is made for the other essential amino acids, only lysine shows possible limitation in both the developing and the developed regions of the world. The lowest values for lysine are 46 and 47 mg/g protein for the developing regions of Africa and Asia, respectively. For the developed regions, only "Africa, developed" (50 mg/g protein) shows values for lysine below requirement. This anomaly arises because the value mainly refers to South Africa (developed economically but not necessarily nutritionally) and reflects the high quantities of corn (maize) in the diet.

Figure 1 (see FIG. 1. Dietary comparisons for developed, developing, and least developed countries (LDCs) in 1992 [17]. Lys/d = milligrams of lysine per day; kcal = kilocalories per day; TP g = total grams of protein per day; Lys/g=milligrams of lysine per gram of protein; AP%= percentage animal protein) shows the progressive decline in the availability of food energy, total protein, animal protein percentage, and lysine (milligrams per day and milligrams per gram of protein) as one moves from the developed to the developing to the least developed countries. The most rapid declines with decrease in wealth are for animal protein percentage and lysine (milligrams per day).

Selected country data

In tables 6 and 7, the food energy, protein, and essential amino acids (milligrams per day and milligrams per gram of protein) for a number of developing countries in Asia, Africa, and South America are compared with data for a number of developed and transitional countries. The picture that emerges is similar to that already discussed for the regional data, but in a more extreme form. The poorest countries, such as Afghanistan, Nepal, and Bangladesh, have food energy availabilities of less than 2,000 kcal/day, with protein availability ranging from 42 to 50 g/day. Most of the protein in these countries is in the form of cereal protein. Such diets show daily availabilities for lysine on the order of 2,000 mg/day, which may be compared with the estimated requirement value for a young man of 2,840 mg/day. In the Indian subcontinent, the average lysine availabilities range from 1,883 mg/day for Bangladesh to 2,839 mg/day for India, with Pakistan showing an intermediate availability of 2,644 mg/day. Of populations in other developing countries, those in Africa are generally most at risk, with values of 2,492 mg/day for Guinea, 1,959 mg/day for Malawi, and 1,741 ma/day for Sierra Leone. These very low values should be compared with the value of 3,918 mg/day for Brazil, a moderately wealthy developing country, and with availabilities approximating 6,500 to 8,000 mg/day for most of the developed and transitional countries.

TABLE 6. Food energy, protein, and essential amino acids (mg/day) for selected countries (data for 1992)

Table 7 shows food energy, protein, and essential amino acid data for these same selected countries. Essential amino acid data are expressed as milligrams per gram of protein in order to emphasize protein quality considerations. The developing countries of Asia, particularly those of the Indian subcontinent, show quite low values, ranging from 44 mg/g protein in Bangladesh to 49 mg/g protein in India. Indeed, all of the 12 Asian countries tabulated, except Thailand and the Philippines, show lysine values significantly below the requirement value of 58 mg/g protein. Lysine values calculated for regions of Pakistan and for states of India from nutrition survey data are also low but are tabulated and discussed later.

TABLE 7. Food energy, protein, and essential amino acids (mg/g protein) for selected countries (data for 1992)

Some other developing countries of Africa, such as Burkina Faso and Sierra Leone, also show quite low values of lysine availability. The developed and transitional countries, in comparison, generally show lysine values ranging from 59 for South Korea (still with much cereal in the diet) to 69 for a number of countries, including Japan. These again should be compared with an adult requirement value of 58 mg/g protein.

Some statistical evaluation of the country data from tables 6 and 7 is presented in table 8. The countries are grouped into 25 developing countries and 8 developed and transitional countries according to the classification used by FAO/Agrostat [17], and the mean levels and their standard deviations are shown for total protein and for the content of essential amino acids. The latter are expressed both as milligrams of amino acids per day and as milligrams per gram of protein. Also shown are the values for Student's t in order to express the significance of the differences in the means.

TABLE 8. Comparison of mean values of essential amino acids for developing and for developed and transitional countries

Source: tables 6 and 7 for 25 developing countries and 8 developing and transitional countries.
Significance limits for Student's c df = 31.
p < .05, t = 2.04; p < .01, t = 2.74; p < .001, t = 3.63.
NS = not significant.
a. p < .01, all others p < .001.

The mean level of total protein available, as would be expected, differed significantly (p < .001) between the diets of the developing and the developed countries, with mean values of 57.9 ± 13.9 and 102.1 ± 11.3 g/day, respectively. Since the level of total protein differed so markedly, it is not surprising that the daily availability of all the essential amino acids (milligrams per day) also differed significantly (p < .001). Lysine, however, had the highest value for t at 13.3, compared with the average for the rest of 8.6. This is not unexpected, since the amount of lysine per unit of protein is also lower in cereals, which contribute to the protein supply to a much greater extent in developing country diets.

When amino acid data were expressed as milligrams per gram of protein, as an indicator of protein quality, it was noted that leucine, aromatic amino acids, tryptophan, and valine did not differ significantly between the groups of countries. Sulphur amino acids differed (p < .01), while the amounts of isoleucine, lysine and threonine were significantly higher (p < .001) in the diets of developed countries than in developing countries.

The biggest difference between mean values was for lysine (48.2 versus 66.6 mg/g protein), although the highest value for t was for isoleucine where the differences were much smaller (41.8 versus 46.9 ma/g protein); this was because of the much smaller standard deviations for the isoleucine observations. This analysis illustrates the major importance of lysine in distinguishing between the diets of developed and developing countries. Although the level of leucine did not differ significantly between the two groups, this was the only essential amino acid for which the level was estimated as higher (85.5 versus 79.9 mg/g protein) in the diets of developing countries than in developed countries. Leucine is generally high in cereal diets, especially corn (maize). The lack of statistical significance for the leucine differences is a reflection of the high standard deviation in the developing country diets.

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