Since the 1900s, China have entered a violently turbulent modern society. During this period, people's lives were generally difficult, and hunger caused a large number of deaths. After the establishment of the People's Republic of China in 1949, the country experienced a "three-year difficult period" from 1959 to 1961, which caused a nationwide "famine”. The number of deaths caused by starvation had risen, and the lack of nutrition greatly affected the health of the population. In recent years, some studies analyzed the impact of the "Great Famine" in childhood on the health and economic status of their adulthood, and found that infants and children who have grown up in the period had shorter life longevity and poorer health in old age [1]. The factors show that the health status of the elderly is not only affected by elements of the old stage, but also earlier life experiences especially childhood.
Life course theory has gradually become an important paradigm for the study of elderly health, emphasizing the long-term impact of life events in critical periods on the health outcomes of elderly. Existing research show that childhood is a critical period of growth and development[2]. At this time, negative nutrition and health shocks experienced may change the original development track of the individual and thus affect the health trajectory of their entire life course. The elderly who experienced starvation during childhood as a health disadvantaged group, have current disadvantages that may depend on the previous unfavorable socioeconomic status. From a policy perspective, it is necessary to understand the long-term effects of malnutrition in earlier life, because child malnutrition is not only common in developing countries, but also an important issue faced by developed countries. Data show that there are approximately 1 billion people in the world who are malnourished, including 140 million preschool children under the age of 5, which will lead to permanent damage to their physical and cognitive development and even death due to nutritional diseases[3].
In recent years, the economics has begun to pay attention to the long-term effects of life experiences in the fetus or early childhood on health, education, and labor market conditions, especially the health and nutritional status before the age of 5 [4]. These studies generally used negative external shocks as an identification event, such as war, famine, rainfall, flu, etc.[5–7]. Schellenberg J A, Victora C G and other studies of low-income or middle-income countries such as Brazil, India, and South Africa have found that malnourished children had shorter height in adulthood, fewer years of education, and diminished labor productivity[8]. Epidemiology and health economics in China are increasingly concerned about the impact of childhood health and developmental status on their health in adult period. Scholars such as Chen and Zhou[9] analyzed the long-term effects of China's "Great Famine" on the health of those who experienced famine. Studies found that babies and children born or raised during this period had a lower height, poorer health, and economic status in adulthood.
Despite there are many literatures on widely acknowledged links between childhood hunger and a range of adverse health outcomes late in life, the reliability of research results and research conclusions are different because of different measurement indicators. A comprehensive evaluation of long-term impacts of hunger on individual’s health capital is empirically difficult to conduct. Earlier investigation of this issue was hindered by several challenges including data restrictions. To determine the long-term consequences, we need both information about whether a person experienced hunger several decades ago as well as information about health status. Data tracking individual experiences for such a long period are not often available even in developed countries [10–11]. The most frequent method in the previous literature is to use exposure to shocks defined at a more aggregated level[12], taking famine as an indicator of having childhood starvation[13–15]. But the problem is exposure to famine and exposure to hunger are not equivalent. The famine and hunger belong to different levels of variables. Therefore, identification strategies that only exploit macro-level variations may obtain inconsistent estimates of the long-term effects of hunger.
We deal with this problem by exploiting retrospective data on individual-level occurrence of hunger episodes during childhood, collected by the survey of Chinese Longitudinal Healthy Longevity Survey (CLHLS). This kind of measurement method is more effective, which can conduct a micro-analysis of how the dilemma in the early life is transformed into the negative results in the later life. There is a growing literature taking advantage of this self-reported measure to examine long-term consequences of childhood hunger associated with World War II and several famines happened in European countries[16–18].
In summary, some researchers have done a lot of exploration in this field, but there are still many limitations. First, the above-mentioned studies have paid more attention to the lasting impact of severe nutrition and health shocks on the health of economically active people (people who have not yet reached the old age). Second, in most previous research literature, self-assessed health status of the elderly was used as the dependent variable, by which body function of the elderly cannot be reflected effectively due to stronger subjectivity. As for the measurement of healthy life expectancy, most international literature adopts the multi-state life table method based on cohort data, which can reflect the true health level of the study population, and the research conclusions are more reliable[19–20]. Third, Due to the lack of high-quality cohort data in China, most previous studies were based on cross-sectional data to measure the relationship between child hunger and health, and cannot make statistical inferences. Therefore, this paper takes life course theory as the analysis framework based on strict cohort data, whether to have the childhood starvation as independent variables, to measure healthy life expectancy of the elderly in China, trying to give answer to the question: to what extent does the accumulated disadvantage formed by childhood starvation affect the health of the elderly?