The Effects of Adult Offspring Migration on Nutrient Intake of Rural Elderly People in China

16 Sufficient and Reasonable nutrient intake is essential for guaranteeing elderly people’s health, especially in rural China where elderly people are the main labor inputs in agricultural sector. 18 Using the 2011 wave data of China Health and Nutrition Survey, this study has empirical 19 analyzed the impact of adult ch ildren’s migration on nutrient intake of their elderly parents in 20 rural areas. The results show that dietary energy and protein intake of rural elderly parents are 21 inadequate where it is less than the Chinese RNI value significantly. Adult offspring migration 22 positively relates with rural elderly parents’ protein intake as well as the dietary energy intake. In 23 the families that partly adult offspring have out-migrated or in the one-child families, elderly 24 parents benefit more from children migration. And for male, younger and low education elders, 25 their nutrient intake is more likely to be improved by offspring migration. 26


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China has stepped into the era of rapid population aging, where the proportion of people aged 65 34 and over has increased from 8.87% in 2010 to 13.50% in 2020. In rural areas, since the majority 35 of the young adults have out-migrated to work in cities or take on off-farm jobs, the aging degree 36 is more serious than it in urban areas. 1 At the same time, due to the "separation of family Some studies have investigated the effects of adult offspring migration on the health of their 49 elderly parents. 6,7,8 In China, these are even the facts. 7,9,10,11,12,13 Generally, the existing literatures 50 adopted self-report health status, physical health (such as illness, physical ability level), mental 51 health (such as life satisfaction, depression, cognition) and BMI to denote individual's health and 52 then explore the influence of adult children migration on the health of their elderly parents. 53 However, as the key input for producing heath, nutrient intake is the material basis of  Labor migration is widespread in developing world, and many studies have demonstrated that 78 migration is closely related to the health of left-behind household members. 6,8,14,15 But, their  Although health is an important indicator for individuals' welfare, it depends more on nutrition 88 and nutrients intake. For elderly people, nutrition is especially important, is a vital factor of 89 health. 21 As we know, malnutrition is very common in older. 22,23,24 In China, the prevalence of 90 inadequate intake of nutrients is considerably higher among elderly people, especially for those 91 rural elders. 25,26,27 However, analyzing the impact of labor migration on nutrition of rural elders 92 is scarcely. 13

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Even migration can affect the nutrition of left-behind family members through a multiple 94 channels, 28 this effect in the present studies can be divided into two parts regularly: the negative 95 care-loss effect, that is, the labor migrants would spend less time taking care of their family 96 members and the positive income-increasing effect, which means the migrants would transfer 97 their income to their family, therefore the food consumption budget would be enlarged and then 98 reduce their food insecurity. 29,30,31 And the overall effect is mixed with these opposite effects.

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Therefore, the effect of adult offspring migration on elders' nutrients intake is supposed as 100 ambiguous in this study.

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Furthermore, under the traditional Confucian culture, which is deeply rooted in rural areas, 102 family care is dominant to the elders' care in rural China, and the intergenerational supports from 103 adult offspring are essential for elderly people's food consumption and health. And in 104 accordance with customary customs, the adult offspring who live with their parents together have 105 the responsibility to take care their parents, while the offspring who have separated from their 106 parents as a results of marriage or economic independent don't need to take on this duty. This  Moreover, the age of elders may also relate with the effect heterogeneity. For those elderly 121 parents who are relatively young, they have more work capacity and could earn income through 122 on/off-farm employment to achieve self-caring. But for those elders that are relatively old, their 123 work ability has deteriorated so they mainly depend on the offspring's support to live. Therefore, 124 the nutrition of latter may be affected significantly by offspring migration than the former. 125 Besides of these, the existing studies have found that migration may enhance the migrant 126 household's knowledge of health and nutrition and then potentially shift the elders' nutritional 127 habits. But we consider the incidence of this shifting depends on the elders' education degree.

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The older people who have high education are expected to improve their health and dietary 129 information from migrants. Hence, we even compare the effect heterogeneity by elders'   In the nutrition theories, malnutrition refers to deficiencies, excesses or imbalances in a person's 146 intake of energy and/or nutrients, where it means not only an adequate quantity requirement for 147 nutrients but also an appropriate structure for nutrients. 32 Where (⋅)is a nonlinear function which is set as follows: Where, 1 and −1 are cut points, and satisfy 1 < 2 <. . . < −1 . * is the latent outcome 162 variable defined as:     Baseline results

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The baseline outcomes are listed in Table 4. On the absolute level, the OLS estimates show that

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In PSM estimation, balance test should be applied firstly to confirm whether there are systematic 299 differences of concomitant variables between samples without and with migrant adult offspring.

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After matching, absolute value of the standard deviation of all variables is smaller than 20%, and 301 the standard deviation declines significantly (Table A1). Meanwhile, T-test value of the 302 difference between these two groups indicates that most variables are not significant after 303 matching, so the matching effect is good and the self-selection bias of samples can be weakened 304 with the PSM method.

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Considering there are similar effects of adult offspring's migration on nutrient intake in baseline 306 estimation, using k-nearest-neighbor matching (k=4), caliper matching (caliper=0.05) and kernel 307 matching respectively, we re-estimate these effects on relative intake level (Table 5) we apply PSM model to analyze the heterogeneity of migration effects.

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From the results shown in Table 6, we find children migration has insignificant impact on energy

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Heterogeneity with family structure 342 In here, the sample is grouped into two subsamples by family structure that one-child families 343 and multi-child families. The estimated results are shown in Table 7. Children migration has a 344 similar positive impact on energy intake of rural elderly parents in these two types of families, 345 and this effect in one-child families is greater than it in multi-child families.

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However, on protein intake, the effect of children migration in one-child families is unobvious, 347 while it is significant in multi-child families. And also we notice this positive effect is just 348 significant at a low statistical level.

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Heterogeneity with individual characteristics of elders 354 We investigate the effect's heterogeneity on gender, education and age of rural elderly parents in 355 this section. First, the results in Table 8 show energy intake of both male and female rural elders

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Generally, the work capacity of elders would worsen rapidly with age growing. This lead older 370 elders to contribute less than the younger counterpart for household production and income.

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Therefore, we consider, since the elders lost their work capacity due to aging, they are more 372 likely ignored in caring from family. In terms of this, we divide the whole samples into two 373 groups by age: 60-70 years old and over 70 years old and then compare the migration effect by 374 age. The estimated results in Table 9  quality of nutrition of rural elders whose age is 60-70 are both improved by adult offspring 379 migration, while for the elders whose age is over 70, only the quantity of nutrition is obviously 380 increased.

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Education is an important determinate of personal healthy knowledge (Liu et.al., 2017) and so it 386 may influence the migration effect on rural elders' dietary intake structure and nutrition. The 387 estimated results are listed in Table 10. According to the education distribution of rural elders, 388 we split the entire samples into low level group whose educational level is less than primary 389 school diploma and high level group whose education level is above primary school diploma 390 group. As we can see from Table 10, the effect of offspring migration is significant both on the 391 energy and protein intake in the low educational level group, but it is insignificant in higher level 392 group. These results suggest that, for less-educated elders in rural families, offspring migration 393 could not only improve their nutrient quantity but also their nutrient quality. For its reason, we 394 consider it may be related with the relative high level of healthy awareness and dietary 395 knowledge of rural more-educated elders and they pay more attention to their health and 396 balanced diet in daily life. Therefore, adult offspring's migration hardly has obvious effects on 397 their nutrient intake.
398   In one-child and multi-child families, these effects on dietary energy and protein are both 420 significant, but stronger in one-child families. In terms of gender, age, and education, energy and 421 protein intake of male elders or elders younger than 70 years old would both benefit from 422 migration, but only energy would benefit for female elders or elders aged over 70; For those 423 elders whose educational level is less than primary school, this effect on energy and protein is 424 significant, but insignificant for elders whose educational level is above primary school diploma.

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In general, the effect of adult offspring migration on rural elders' nutrition status has been 426 investigated carefully in this paper and its findings have important implications for policy, given 427 that adequate nutrition is essential to elders' health and well-being. Despite there has a positive 428 role of offspring migration played on elderly parents' nutrient intake apparently, malnutrition of