This document summarizes research on chronic undernutrition (stunting) in children. It discusses four main factors associated with stunting: wealth, health care access, sanitation, and maternal education. While these contribute to reductions in stunting, the major deterioration in children's height between 6-24 months is not fully explained. New research highlights the importance of diet quality, particularly consumption of animal source foods and nutrients like amino acids and choline that are critical for growth. Interventions providing cash plus nutrition education were most effective at improving diets and reducing stunting. Future research should further examine how diets, not just calories, impact growth to inform improved social and agricultural interventions.

1. Chronic undernutrition: Retrospect and prospects
John Hoddinott
Cornell University
Department for International Development
London
June 2017

2. Introduction
• Historically, in developing country contexts, discussions of undernutrition
focused on conditions of marasmus and kwashiorkor
• Starting in the 1970s, attention switched to:
– Micronutrient deficiency (not the focus of this presentation)
– Using anthropometry, the measurement of body size and gross body composition, to
assess nutritional status
• The core idea underpinning anthropometry is that prolonged or severe
nutrient depletion eventually leads to retardation of linear (skeletal)
growth in children and to loss of, or failure to accumulate, muscle mass.
• This presentation focuses on chronic undernutrition (stunting) as
measured by height for age (HAZ). Globally, ~165 million children are
stunted

3. Introduction
• Reducing chronic undernutrition has intrinsic value
• It also has instrumental value – that is, it contributes to the attainment of other
development objectives
• Chronic undernutrition is associated with neurological impairments that persist
into adulthood. Poorer cognitive function reduces earnings; individuals
undernourished at age 2 are more likely to be poor in adulthood (Hoddinott et al,
2013a)
• This implies a “business case” for reducing chronic undernutrition; early Transform
Nutrition work showed that doing so has high benefit: cost ratios (Hoddinott et al,
2012; 2013b) (TN)
– The business case resonates beyond the nutrition sector; see David Cameron’s use of these results to
justify the inclusion of the reduction of chronic undernutrition as a Sustainable Development Goal

4. Introduction
• Two objectives:
– Review current thinking and knowledge gaps regarding aspects of chronic
undernutrition and the contribution of Transform Nutrition to addressing these
– Outline areas for future research and intervention design, with particular reference to
nutrition sensitive interventions in social protection and in agriculture

5. Stylized facts and knowledge gaps:
Wealth, health care, sanitation and maternal schooling
• Wealth is associated with improved HAZ (Black et al, 2013).
• Using DHS data from 2000 and 2014, Headey, Hoddinott and Park (2017)
find that increases in assets account for about 20 percent of the reduction
in stunting across six countries (TN)
– Improvements in health care (% mothers receiving 4+ ANC visits; child being
born in a health center) also contribute
– Improvements in maternal schooling and reductions in open defecation play a
role but the magnitudes of these effects are small

6. Stylized facts and knowledge gaps:
Age profile of chronic undernutrition, Bangladesh 1997 and 2011
-2.5
-2
-1.5
-1-.5
PredictedHAZscore
0 20 40 60
Age of child (months)
95% CI 1997 2011
Headey et al, 2015 (TN)

7. Stylized facts and knowledge gaps:
Four stories
• But this stylized fact raises a critical issue; why does HAZ deteriorate so
badly between 6 and 24 months
• Story #1: “It is all about food availability.” Energy is needed for growth;
when energy is lacking growth faltering occurs
– This is consistent with another component of the 1970s revision. “The great
protein fiasco” (McLaren, the Lancet 1974). Protein deficiency is over-rated as
a source of nutrition deficiency. “Lack of energy rather than protein is the crux
of the matter”
• But Headey and Hoddinott (2016) combine DHS and agricultural
productivity data to look at the association between rice yield growth and
HAZ in Bangladesh between 1996 and 2011. They find no effect. (TN)

8. Stylized facts and knowledge gaps:
Four stories
• Story #2: “Its all about income.”
• 2011 DFID Evidence Paper on Cash Transfers describes several social
protection interventions that improved anthropometric status
• Manley, Gitter and Slavchevska (2013) report a meta-analysis of the
impact on HAZ of 17 social protection interventions. Across all programs
they consider, the average impact is:
Scots Gaelic: Dad
Welsh: Dim byd
Cornish: Traveth
English: Nothing

9. Stylized facts and knowledge gaps:
Four stories
• Story #3: But Headey and Hoddinott is associational (though with lots of
controls), Manley et al is built out of a heterogeneous set of studies
• So consider an RCT in southern Bangladesh (Khulna and Barisal) reported
in Ahmed et al (2016) (TN):
– Multiple treatment arms: Monthly cash transfers equivalent to 25% of hh income; Food
basket (rice, pulses, fortified vegetable oil) of equivalent value; ½ food, ½ cash payment;
Food plus nutrition behavior change communication (BCC)
– RCT runs for 24 months
– All payments made to mothers of children <2y at baseline
– High quality BCC; ~95 meetings over two years

10. Stylized facts and knowledge gaps:
Four stories
• Impact on children’s diets:
– Small effects of food+BCC on consumption of eggs and animal source foods
– Small effect of cash on egg consumption
• Impact on nutritional status:
– Dad, Dim byd, Traveth, Nothing

11. Stylized facts and knowledge gaps:
Four stories
• Story #4: Surely the nutritionists have a good idea what to do
• Bhutta et al (2013) identify the 10 best bet direct nutrition interventions:
– These have a powerful effect in terms of reducing acute undernutrition (and therefore
infant and child mortality); reduction of severe wasting is estimated to be 61%
– These have only a limited effect on chronic undernutrition, reducing it by around 20%

12. Chronic undernutriton: Prospects
• One starting point may be to re-focus attention on the biological
processes underlying linear growth
• Both in nutrition and economics, the “food” component of this is often
thought of in terms of energy (and micronutrients)
• The logic is that energy (think “calories”) is needed for cellular growth;
absent sufficient energy over protracted periods of time during the first
two years of life, growth falters
• But this view might be incomplete

13. Prospects: Advances in metabolomics
• Rapid advances are occurring in metabolomics – the study of small
molecule chemicals that are the consequence of metabolic processes.
• Improvements in our understanding of mTORs (mechanistic target of
rapamycin) is an example
• mTORs are catalytic proteins. They signal (or regulate) cellular processes
such as growth and differentiation (anabolic processes). This signaling
process integrates information about the availability of nutrients (food
sources, oxygen, and growth factors).
• When activated, one type of mTOR, MTORC1 (mechanistic target of
rapamycin complex 1) regulates growth in:
– Chondral plates (ie part of the bone where growth takes place)
– Skeletal muscle growth
– Myelination of nervous system

14. Prospects: Advances in metabolomics
• Metabolomic work has also focused attention on choline, an essential nutrient
• Choline is needed for the synthesis of phosphatidycholines; this synthesis is
needed for bone formation and cell membrane formation.
• Choline also appears to play a role in neurotransmitter synthesis, needed for the
transmission of chemicals across synapses in the brain
• In addition, cow’s milk (an important source of amino acids, calcium, iron, and
vitamin B-12) stimulates the secretion of insulin-like growth factor I (IGF-I), the
hormone that stimulates bone and tissue growth

15. Prospects: Advances in metabolomics
• A review by Semba et al (2016a) shows that amino acids are essential for
the activation of mTORC1. So when these are absent:
– The body represses protein and lipid synthesis and cellular growth
– Bone growth is restricted
• Essential amino acids cannot be synthesized from scratch within the
human body; these must be obtained via diet. The best sources are animal
source foods (meat, poultry, fish, eggs). Plant sources also contain these,
but typically in much lower concentrations.
• Eggs are an excellent source of choline. Flesh foods (beef, chicken) are
another source as are groundnuts, though the latter contain much less
choline than eggs

16. Prospects: Three examples consistent with advances in
metabolomics
• Example #1: Biochemical analysis
• Semba et al (2016b) analyze serum blood samples from Malawi. These
show that stunted children lack all essential amino acids.
• Semba (2016c) find that in Malawi, children with low serum choline
concentrations are more likely to have experienced linear growth failure

17. Prospects: Three examples
• Example #2: Consider a second RCT (in north Bangladesh, Rangpur)
reported in Ahmed et al (2016) (TN):
– Multiple treatment arms: Monthly cash transfers equivalent to 25% of hh income; Food
basket (rice, pulses, fortified vegetable oil) of equivalent value; ½ food, ½ cash payment;
Cash plus nutrition BCC
– RCT runs for 24 months
– All payments made to mothers of children <2y at baseline
– High quality BCC; ~95 meetings over two years
• Impact of the cash, food and cash&food treatment arms on child diet:
– Some small effects of cash on improving diet quality
• Impact of the cash, food and cash&food treatment arms on child
anthropometry:
– Dad, Dim byd, Traveth, Nothing

18. Prospects: Three examples
• Impact of cash+BCC on child diet:
– 10.9 percent ↑ in consumption of dairy products
– 22.8 percent ↑ for flesh foods (meats, poultry, fish)
– 24.6 percent ↑ for legumes and nuts
– 36.0 percent ↑ for eggs
• Impact on chronic undernutrition:
– ↑ HAZ by 0.25SD
– ↓ Stunting by 7.3 percentage points

19. Prospects: Three examples
• Example #3: Hoddinott, Headey and Dereje (2015) use observational data
from Ethiopia to look at associations between dairy cow ownership and
chronic undernutrition (TN)
• Ownership is associated with higher milk consumption and with a
reduction in stunting of 6 to 13 percentage points, even after controlling
for household wealth and other confounding factors.
• But effect disappears for households living close to a food market
• Results are consistent with Hirvonen and Hoddinott (forthcoming) who
find that in Ethiopia, the diversity of pre-school diets (children 6-24m) is
associated with diversity of household agricultural production but only
when access to food markets is poor (TN)

20. Future Prospects
• Given that chronic undernutrition “matters”, what should future research and
intervention design focus on?
• In general, shift towards focusing on:
– What children eat, not just how much they eat, with particular attention to animal source foods
– As well as .. Hygiene and sanitation (Dean Spears work, work on environmental enteropathy etc)
• On social protection and nutrition:
– Are TMRI-type benefits sustainable
– Are TMRI-type results scale-able
• On agriculture and nutrition:
– Think more about market access and value chains
– At least for chronic undernutrition, re-think when it makes sense to encourage smallholders to
diversify production

21. References
Ahmed, A. et al 2016. Which kinds of social safety net transfers work best for the ultra poor in Bangladesh? Operation and Impacts of the
Transfer Modality Research Initiative. IFPRI: Dhaka. (TN)
Bhutta, Z. et al, 2013. Evidence-based interventions for improvement of maternal and child nutrition: what can be done and at what cost? The
Lancet
Black, R. et al, 2013. Maternal and child undernutrition and overweight in low-income and middle-income countries. The Lancet
Headey, D. and J. Hoddinott, 2016. Agriculture, nutrition and the Green Revolution in Bangladesh, Agricultural Systems. (TN)
Headey, D., J. Hoddinott and S. Park, 2017. Accounting for nutritional changes in six success stories: A regression-decomposition approach,
Global Food Security. (TN)
Headey, D. J. Hoddinott, D. Ali, R. Tesfaye and M. Dereje, 2015. “The other Asian enigma: Explaining the rapid reduction of malnutrition in
Bangladesh”, World Development, (TN)
Hirvonen, K. and J. Hoddinott, forthcoming “Agricultural production and children’s diets: Evidence from rural Ethiopia”, Agricultural
Economics. (TN)
Hoddinott, J., et al. 2013a. Adult consequences of growth failure in early childhood, American Journal of Clinical Nutrition.
Hoddinott,J. et al. 2013b. The economic rationale for investing in stunting reduction, Maternal and Child Nutrition (TN)
Hoddinott, J. et al. 2012. “Investments to reduce hunger and undernutrition, in Global Problems, Smart Solutions (TN)
Hoddinott, J., D. Headey and M. Dereje. 2015. Cows, missing milk markets, and nutrition in rural Ethiopia. Journal of Development Studies.
(TN)
Manley, J. et al. 2013. How effective are cash transfers at improving nutritional status. World Development.
Semba, R., et al, 2016a. Perspective: The potential role of essential amino acids and the mechanistic target of rapamycin complex 1 pathway
in the pathogenesis of child stunting. Nutritional Reviews.
Semba, R., et al, 2016b. Child stunting is associated with low circulating amino acids, EBioMedicine
Semba. R., et al, 2016c. The association of serum choline with linear growth failure in young children from rural Malawi, American Journal of
Clinical Nutrition.