Poverty and The Nutrition Transition

Data from the past decade and projections for the next 20 years (Murray and Lopez, 1996) indicate a continuing rise in the contribution of no communicable diseases to mortality rates in developing countries, where a large proportion of the global poor lives. But within the developing world population, there are clear differences between the upper and lower socioeconomic groups. Among the poorest 20%, communicable diseases still account for about 60% of deaths, whereas they account for only 8% among the richest 20% (Gwatkin et al., 1999). A confounding factor may be the difference in population patterns between richer and poorer countries, with the latter having as much as twice the number of under-15 population, which has higher rates of communicable disease than older groups. Although it is likely that the younger population of the developing world still faces infectious diseases as a major threat to health and quality of life, the burden of no communicable diseases continues to mount for the older poor. As economic status and education improve, populations in developing countries around the world respond quite consistently by demanding more animal protein in their diet. In many cases, this demand is justified, since their typical diet is usually low in zinc, iron, selenium, retinol, and other essential nutrients found primarily in animal sources. However, increases in the animal protein content of diets almost invariably increase the content in saturated fats, which is undesirable. The role of genes in the human adaptation to rapid environmental changes has been postulated for many decades, but only with advances in molecular genetics can we identify with some clarity the interactions between genes and environmental components such as diet. Populations living under subsistence conditions are forced to maximize their potential for survival, and it is likely that specific sets of genes are activated to facilitate this process. Thus, rapid changes in the environment, even when positive (e.g., more food available) will tend to perturb that precarious equilibrium between the genome and the environment. If the genetic makeup of some individuals does not allow for a rapid shift to the new environmental conditions, adverse health effects may result. This hypothetical but probable phenomenon can be seen within the same generation, i.e., children who were malnourished early in life becoming more prone to obesity as adults. The particular genetic makeup of populations in developing countries, of which we know so little, adds a unique and important element to the impact of the nutrition transition on health. Individuals “miss-adapted” to the new dietary conditions may have a higher risk of adverse health effects.

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Economic and technological development and their relationships to body size and productivity

Robert W. Fogel and Lorens A. Helmchen, The growth in material wealth has been matched by changes in body size over the past 300 years, especially during the twentieth century. Perhaps the most remarkable secular trend has been the reduction in mortality. Between 1900 and 1998, life expectancy at birth in the United States increased by 65% for women, from 48.3 years to 79.5 years, and by 60% for men, from 46.3 years to 73.8 years (National Center for Health Statistics, 2001). Table 2.1 provides an overview of the long-term trend in life expectancy at birth for seven nations. The data show that in England life expectancy has more than doubled since the early eighteenth century. France has recorded even larger gains in longevity. French children born today can expect to live nearly three times longer than their ancestors 250 years ago.

Table 2.1

Life expectancy at birth (years) in seven nations, 1725–1990 (both sexes combined)

Country 1725 1750 1800 1850 1900 1950 1990

England or UK 32 37 36 40 48 69 76

France 26 33 42 46 67 77

US 50 51 56 43 47 68 76

Egypt 42 60

India 27 39 59

China 41 70

Japan 61 79

Source: Fogel (in press).

Table 2.2

Estimated average final heights (cm) of men who reached maturity between 1750 and

1875 in six European populations, by quarter centuries

Date of maturity by Great Britain Nor way Sweden France Denmark Hungary

century and quarter

18-III 165.9 163.9 168.1 168.7

18-IV 167.9 166.7 163.0 165.7 165.8

19-I 168.0 166.7 164.3 165.4 163.9

19-II 171.6 168.0 165.2 166.8 164.2

19-III 169.3 168.6 169.5 165.6 165.3

20-III 175.0 178.3 177.6 172.0 176.0 170.9

Source: Author’s calculations.

Although not as significant numerically, final heights of European men who reached maturity have also been increasing over the past two centuries, as shown in Table 2.2. In some countries, average heights increased by as much as 10 cm per century. Body weight has also increased. Figure 2.1 shows that for some age groups, the body mass index (BMI), a measure of weight adjusted for height (equal to kg/m increased by about 10–15% within the past 100 years. This chapter aims to elucidate the long-run relationship between labor productivity and body size. In particular, it will be shown that improvements in the nutritional status of a number of societies in Western Europe since the early eighteenth century may have initiated a virtuous circle of technophysio evolution. The theory of technophysio evolution posits the existence of a synergism between technological and physiological improvements that has produced a form of human evolution that is biological but not genetic, rapid, culturally transmitted, and not necessarily stable over time. In the con-text of the present study, we suggest that an increase in agricultural efficiency and labor productivity improved human physiology, in turn leading to further gains in labor productivity. The next two sections identify how the early modern advances in agriculture and the increased availability of calories per capita raised labor productivity over the course of successive generations. This is followed by an analysis of the determinants and consequences of accelerating productivity gains in American agriculture after World War II to illustrate the changing relationship among nutrition, body size, and labor productivity.

Energy cost accounting

Nutritional status is most commonly measured by the amount of calories available per person balanced against caloric requirements, also referred to as net nutrition

The principal component of the total energy requirement is represented by the basal metabolic rate (BMR). The BMR, which varies with age, sex, and body size is the amount of energy required to maintain body temperature and to sustain the functioning of the heart, liver, brain, and other organs. For adult males aged 20–39 years living in moderate climates, BMR normally ranges between 1350 and 2000 kcal/day depending on height and weight. For comparison across time and different populations, it is convenient to standardize for the age and sex distribution of a population by converting the per capita consumption of calories into consumption per equivalent adult male aged 20–39, also referred to as a consuming unit. Since the BMR does not allow for the energy required to eat and digest food, or for essential hygiene, an individual cannot survive on the calories needed for basal metabolism. The energy required for these additional essential activities over a period of 24 hours is estimated at 0.27 of BMR or 0.4 of BMR during waking hours. In other words, a survival diet is 1.27 BMR, or between 1720 and 2540 kcal/day for a consuming unit. A maintenance diet contains no allowance for the energy required to earn a living, prepare food, or any other activities beyond those connected with eating and essential hygiene.

Whatever calories are available beyond those claimed for basal metabolism and maintenance can be used at the discretion of the individual, either for work or for leisure activities.

Chronic malnutrition in late-eighteenth century Europe

According to recent estimates, the average caloric consumption in France on the eve of the French Revolution was about 2290 kcal per consuming unit, that for England was about 2700 kcal per consuming unit. These averages, however, do not reveal the variation in caloric consumption within the French and English populations. Table 2.3 shows the probable French and English distributions of the daily consumption of kcal per consuming unit toward the end of the eighteenth century. The principal finding that emerges from this table is the exceedingly low level of food production, especially in France, at the start of the Industrial Revolution. The French distribution of calories implies that 2.48% of the population had caloric consumption below basal metabolism, whereas the proportion of the English population below basal metabolism was 0.66%. For the remainder of the population, the level of work capacity permitted by the food supply was very low, even after allowing for the reduced requirements for maintenance because of small stature and reduced body mass. In France the bottom 10% of the labor force lacked the energy for regular work and the next 10% had enough energy for less than 3 hours of light work daily (0.52 hours of heavy work).

Although the English situation was somewhat better, the bottom 3% of its labor force lacked the energy for any work, while the balance of the bottom 20% had enough energy for only about 6 hours of light work (1.09 hours of heavy work) each day. Thus, at the end of the eighteenth century, the lack of access to sufficient calories effectively restricted the amount of activity (whether for income or leisure) that most laborers could perform, and it effectively precluded others from working at all.

Table 2.3

A comparison of the probable French and English distributions of the daily caloric

consumption (kcal) per consuming unit toward the end of the eighteenth century

Decile France c. 1785  England c. 1790

X 2290 (s/X) 0.3 X 2700 (s/X) 0.3

Daily kcal Cumulative % Daily kcal Cumulative %

consumption consumption

1. Highest 3672 100 4329 100

2. Ninth 2981 84 3514 84

3. Eighth 2676 71 3155 71

4. Seventh 2457 59 2897 59

5. Sixth 2276 48 2684 48

6. Fifth 2114 38 2492 38

7. Fourth 1958 29 2309 29

8. Third 1798 21 2120 21

9. Second 1614 13 1903 13

10. First 1310 6 1545 6

Sources and procedures: Author’s calculations.

Table 2.4

Secular trends in the daily caloric supply in France and Great Britain 1700–1989

(kcal per capita)

Year France Great Britain

1700                                                                                                 2095

1705 1657

1750                                                                                                 2168

1785 1848

1800                                                                                                 2237

1803–12 1846

1845–54 2480

1850                                                                                                 2362

1909–13                                                                                           2857

1935–39 2975

1954–55 2783 3231

1961                                                                                                 3170

1965 3355 3304

1989 3465 3149

Source: Fogel et al. (in press).

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How better nutrition raised output per capita

Table 2.4 shows secular trends in the daily caloric supply in France and Great Britain from 1700 to 1989. Per capita availability of calories more than doubled in this period in France, and increased by about 50% in Great Britain, where caloric supply was 30% larger than that in France at the beginning of the period.

Framework

How did the substantial increase in calories per capita affect labor productivity? Labor productivity can be defined as the output of marketable goods and services that a typical worker can produce over the span of one day. Daily output per worker, in turn, can be decomposed into the output per calorie expended at work and the daily amount of calories expended on the job by a typical worker. By multiplying the daily output per worker by the number of workers per inhabitant (which is called the labor force participation rate) output per worker is transformed into output per capita, which is used as a measure of the standard of living: Output of goods and services produced per capita per day daily output of goods and services per calorie expended in their production daily amount of calories expended in production per worker labor force participation rate In this decomposition, the technological breakthroughs in farming raised yields for a given effort level, represented here as increases in the output per calorie expended in production. At given levels of annual calories expended in production per worker and labor force participation rate, this must have raised the volume of agricultural output per capita. Higher levels of labor productivity in agriculture also allowed parts of the labor force to be employed in nonagricultural sectors of the economy without reducing farm output per person, thus diversifying the range of goods and services produced domestically. To understand the full effect of gains in agricultural efficiency, however, it is necessary to take into account how the additional calories were used. Those adults who had been working before the development and diffusion of more productive farming methods could now increase the annual amount of calories expended while working, either by performing more energy-intensive tasks or by working additional hours, or both. This increase in calories expended in production by a typical worker further increased the amount of calories produced (and ultimately consumed) per capita. In addition to boosting the calories available to workers, the expansion of the food supply also made more calories available for members of the poorest segment of the adult population who had had only enough energy above maintenance for a few hours of strolling each day – about the amount needed by a beggar – but less on average than that needed for just one hour of the heavy manual labor required in agriculture. To the extent that these persons now had the energy to work, they raised the labor force participation rate, which led to a further increase in per capita output. Table 2.5 summarizes the daily amount of energy available for work in France, and England and Wales from 1700 to 1980. The most impressive gains are reected by the data for France, where calories available for work increased nearly fivefold within less than 200 years. In total, by increasing agricultural yields per calorie expended, the Second Agricultural Revolution expanded the availability of calories per capita, drawing more people into the labor force and raising on-the-job calorie expenditures of those working. This boost in the population’s productive capacity in turn fueled further growth not only in food output per capita. It also helped to raise the output in all other, nonagricultural sectors of the economy that benefited from an increase in workers and hours worked.

The effect of improved nutrition on productivity and output

Table 2.5

A comparison of energy available for work daily per consuming unit in France, and England and Wales, 1700–1980 (in kcal)

Year France England and Wales

1700                                                                                                       720

1705 439

1750                                                                                                       812

1785 600

1800                                                                                                       858  

1803–12

1840

1845–54

1850                                                                                                       1014

1870 1671

1880

1944

1975 2136

1980                                                                                                       1793

Source: Fogel et al. (in press).

Empirical estimate

Time series of anthropometric and macroeconomic statistics can be combined to estimate the contribution of better nutrition to the growth of output per person. The most reliable and complete data in this regard have been collected for England. As noted in the introduction, between 1780 and 1979 British per capita income grew at an annual rate of about 1.15% (Maddison, 1982). Data are now available to measure the changes in calories available for work and the labor force participation rate. For Britain, it has been estimated that the increases in the supply of calories lifted as much as one fifth of all consuming units above the threshold required for work. As a result, the labor force participation rate increased by 25% over 200 years, contributing 0.11% to the annual British growth rate between 1780 and 1980 (1.25 1 0.0011). 0.005 The increased supply of calories also raised the average consumption of calories by those in the labor force from 2944 kcal per consuming unit in c.1790 to 3701kcal per consuming unit in 1980. Of these amounts, 1009 kcal were available for work inc. 1790 and 1569 in 1980, so that calories available for discretionary activities increased by about 56% during the two centuries. If it is assumed that the proportion of the avail-able energy devoted to work has been unchanged between the end points of the period, then the increase in the amount of energy available for work contributed about 0.23% per annum to the annual growth rate of per capita income (1.561 0.0023).0.0053 Thus, in combination, bringing the ultra-poor into the labor force and raising the energy available for work by those in the labor force, explains about 30% of British growth in per capita income over the past two centuries [(0.0023 0.0011) 0.0115 0.30]. As incomes in OECD countries have risen, the share of discretionary time devoted to working for income has declined. Consequently, it is unlikely that further increases in the amount of calories available per person in those countries will raise labor force. However, the immediate effect of better nutrition on labor productivity still holds enormous potential in poor countries where malnutrition is widespread.

The self-reinforcing cycle of greater body size and higher productivity

In addition to the direct effect of better nutrition on the growth of output per person, the conquest of chronic malnutrition has had a long-term effect on human physiology, which has taken several generations to unfold. The role of long-term changes of nutritional status in altering body size is inferred from applying energy cost accounting to an analysis of food balance sheets. In particular, to have the energy necessary to produce the national product of either France or England c. 1700, the typical adult male must have been quite short and very light in weight. The smaller body size reduced the basal metabolic rate and thereby freed up calories that could be used for work. As per capita food supplies expanded, so did not only hours worked but also body size. The increase in body size, in turn, improved health and the capacity of individuals to raise labor productivity further, thus rein-forcing the initial increase in labor productivity.

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The effect of improved nutrition on body size, morbidity and mortality The gain in weight 2

As was pointed out earlier, the energy that an individual takes in through food consumption will be spent to maintain body temperature and vital organ functions, as wellas for eating, sleeping, and essential hygiene. The remainder is available for discretionary use, such as work and leisure. It was also shown that the additional calories that became available in the wake of the Second Agricultural Revolution were used to engage in more energy-intensive tasks and increase labor force participation. Energy not used is stored, leading to weight gain. As such, the body mass index may be interpreted as a measure of net nutrition, which is defined as the excess of calories ingested over calories claimed for maintenance and discretionary use. Figure 2.1 documents the secular increase in body mass index for white men between 1864 and 1991.

The self-reinforcing cycle of greater body size and higher productivity

2.14

                                      Modern Norwegian males

                                                                                                                    Union Army veterans

0.88

                       17                             19 21 23 25 27 29 31 33 35

BMI

Figure 2.2 Relative mortality risk by BMI among men 50 years of age, Union Army veterans around 1900 and modern Norwegians (from Costa and Steckel, 1997). In the Norwegian data BMI for 79084 men was measured at ages 45–49 and the period of risk was 7 years. BMI of Union Army veterans was measured at ages 45–64 and the observation period was 25 years. Costa and Steckel (1997). Reproduced with kind permission from The University of Chicago Press. © 1997 by the National Bureau of Economic Research.

It has been shown that eliminating chronic hunger will strengthen the body’s defenses against infectious diseases, thus lowering the risk of contracting diseases and premature death. The relationship between weight, as measured by the Body Mass Index, and mortality was established empirically by Hans Waaler (1984) for Norwegian men aged 45–49 and confirmed for a sample of Union Army veterans measured at ages 45–64 and followed for 25 years. Figure 2.2 shows a U-shaped relationship between BMI and the relative risk of death for both samples. Among both modern Norwegians and Union Army veterans the curve is quite  at within the range 22–28, with the relative risk of mortality hovering close to 1.0, which represents the average risk of death in the population. However, at BMIs of less than 22 and over 28, the risk of death rises sharply as BMI moves away from its mean value.

The gain in height

A larger and better survival diet allowed adult members of the generation that first witnessed the rise in agricultural efficiency to increase weight, and, consequently, to improve health and extend life. Better nutrition of pregnant women also improved the nutritional status of fetuses and infants. Access to sufficient amounts of calories and other vital nutrients in utero and developmental ages has been shown to affect the off-spring’s final height. Thus, whereas the immediate effect of the improvements in food

Economic and technological development and their relationships to body size and productivity

1.5

1.0

0.5

              62                   64 66 68 70 72 74 76 78 80

Height (inches)

Figure 2.3

Relative mortality risk among Union Army veterans and among Norwegian males. Author’s

Calculations

Supply was to raise the amount of energy spent at work and to boost body weight, the long-run impact over the course of several generations has been an increase instature. This conclusion is supported by the time series on mean final heights for various European populations, shown in Table 2.2. Waaler (1984) also identified the role of body height as a factor in uencing morbidity and mortality. Figure 2.3 plots the relationship between relative mortality risk and height found among Norwegian men aged 40–59 measured in the 1960s and among Union Army veterans measured at ages 23–49 and at risk between ages 55 and 75. Short men, whether modern Norwegians or nineteenth-century Americans, were much more likely to die early than tall men. Height has also been found to be an important predictor of the relative likelihood that men aged 23–49 would be rejected from the Union Army between 1861 and 1865 because of chronic diseases. Despite significant differences in ethnicity, environmental circumstances, the array and severity of diseases, and time, the functional relationship between height and relative risk are strikingly similar in the two cases. To gauge the relative importance of height and weight for an individual’s risk of mortality, an isomortality surface that relates the risk of death to both height and weight simultaneously is needed. Such a surface, presented in Fig. 2.4, was fitted to Waaler’s data. Transecting the isomortality map are iso-BMI lines that give the locus of BMI between 16 and 34. The heavy line transecting the minimum point of each iso-mortality curve represents the weight that minimizes mortality risk at each height. Since an individual’s height cannot be varied by changes in nutrition after maturity, adults can move to a more desirable BMI only by changing their weight. Therefore, the x-axis is interpreted as a measure of the effect of the current nutritional status of mature males on adult mortality rates. Moreover, since most stunting takes place before age three, the y-axis is interpreted as a measure of the effect of nutritional.

The self-reinforcing cycle of greater body size and higher productivity

                     Isomortality-risk curves                            Iso-BMI curves Minimum-risk curve

                             (0.7–2.2)                                                              (16–34)

1.95

1.90

1.85

1.80

1.75

                                                                                             1975

1.70

1.65                                                          1870

                                          1785

1.60

                          1705

1.55

40 50 60 70 80 90 110                                                                           100

Weight (kg)

Figure 2.4

Isomortality curves of relative risk for height and weight among Norwegian males aged 50–64 years, with a plot of the estimated French height and weight at four dates. Author’s calculations.

Deprivation during developmental ages (including in utero) on the risk of mortality at middle and late ages. Superimposed on Fig. 2.4 are rough estimates of heights and weights in France at four dates. In 1705 the French probably achieved equilibrium with their food supply at an average height of about 161 cm and BMI of about 18. Over the next 270 years the food supply expanded fast enough to permit both the height and the weight of adult males to increase. Figure 2.4 shows that the increase in available food per per-son translated mostly into weight gain during the eighteenth and nineteenth centuries. During the twentieth century the gains in calories per capita served mainly to increase height. Between 1870 and 1975 height increased at more than twice the rate that it did during the previous 165 years. Figure 2.4 implies that although factors associated with height and weight jointly explain about 90% of the estimated decline in French mortality rates over the period between 1785 and c. 1870, they only explain about 50% of the decline in mortality rates during the past century.

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