What can we do to reduce stunting?

What can we do to reduce stunting? Technical Meeting on the Long-term Consequences of Chronic Undernutrition in Early Life UNICEF, New York, August 15...
Author: Stanley Malone
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What can we do to reduce stunting? Technical Meeting on the Long-term Consequences of Chronic Undernutrition in Early Life UNICEF, New York, August 15 2012 Kathryn G. Dewey, PhD Program in International and Community Nutrition University of California, Davis PICN 2008

Outline What rates of stunting reduction are achievable?  The role of nutrition within a broader framework for reducing stunting  Impact of prenatal nutrition interventions  Impact of postnatal nutrition interventions  The need for combined approaches  Conclusions 

What rates of stunting reduction are achievable? 

Global stunting rate decreased from 39.7% in 1990 to 26.7% in 2010 – 1.6% reduction per year over 20 years – Very little decline in Africa (from 40% to 38%) – Large decline in Asia (from 49% to 28%)  = 2.9% reduction per year

What rates of stunting reduction are achievable? Global target: 40% reduction in stunting by 2025 (65th WHA, Apr 2012)  Would require 3.9% reduction per year  Higher than the rate of reduction seen in Mexico (2.9% per year, 1988 to 2006) or Asia (2.9% per year, 1990 to 2010)  Less than the rate of reduction seen in Brazil (5.2% per year, 1974-75 to 2006-07) 

What rates of stunting reduction are achievable? Examples of “success” stories:  Brazil [Victora et al. 2011] – Stunting decreased from 37% in 1974-75 to 7% in 2006-07  IMCI evaluation in Bangladesh [Arifeen et al. 2009] – Stunting decreased from 63.1% to 50.4% between 2000 and 2007 in areas where Integrated Management of Childhood Illness (IMCI) was implemented

Prevalence of stunting by family income, Brazil. Victora CG, et al. Lancet 2011;377:1863-76.

Distal factors responsible for stunting reduction in Brazil Increased maternal education  Reduced disparity in socio-economic status – increased purchasing power among the poor (e.g. via conditional cash transfer program)  Expansion in coverage of maternal & child health services  Expansion of public water supply & sewage services 

Likely proximal factors: improved diets, reduced infections & better child care

IMCI Evaluation in Bangladesh Arifeen SE, et al. Lancet 2009;374:393-403.

Factors likely to be responsible for stunting reduction in Bangladesh IMCI evaluation project Better case-management of infections  Increased complementary feeding frequency  Possibly improved dietary quality 

Impact of nutrition may have been underestimated because components of national nutrition program delivered in both areas However, proportion of caregivers reporting that they received feeding advice was low in both IMCI (~33%) and control (~20%) areas

The role of nutrition in a broader framework for reducing stunting

UNICEF framework for causes of undernutrition

Clinical infection (“disease”) - the tip of the iceberg? Sub-clinical conditions probably far more common and may have profound effect on growth Environmental enteropathy  Inflammation and impaired physiological/immune responses due to other environmental insults, e.g. household air pollution, mycotoxins 

Proposed causal pathway linking enteropathy with adverse health outcomes [Prendergast & Kelly 2012]

How nutrition can reduce the negative impact of infections on child growth 1. Strengthening the immune system, thereby reducing the severity and duration of infections 2. Providing extra amounts of nutrients to compensate for poor absorption during infection, losses during diarrhoea, reallocation due to immune system activation or reduced appetite during infection 3. Providing nutrients for catch-up growth following infection, particularly those needed to build lean body tissue such as protein, potassium, magnesium, phosphorus, zinc and sodium 4. Preventing poor appetite caused by micronutrient deficiencies, thereby facilitating catch-up growth 5. Favoring the growth of beneficial bacteria in the gut that enhance gut function and immune defenses

Timing of interventions is important

Key Window of Opportunity Preconception through pregnancy

0-6 mo: Exclusive breastfeeding

6-24 mo: Complementary feeding

Guiding principles for complementary feeding (2003; 2005)

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Impact of prenatal nutrition interventions

How much of childhood stunting is attributable to malnutrition in utero?

Cumulative difference in stature (cm length or height) between Malawi children (both sexes) and the median of the WHO Child Growth Standard (for girls) Of the total 10-cm deficit at 3 years of age: •20% already present at birth •20% occurs 0-6 mo •50% occurs 6-24 mo •10% occurs 24-36 mo


2 cm difference

Source: Maleta et al., World Health Organization

Nutritional status and linear growth of Indonesian infants in West Java are determined more by prenatal environment than postnatal factors. Schmidt MK, et al. J Nutr 2002;132(8):2202-07. [β-coefficients for predictors of height-for-age z-scores at 12 mo of age.]

Can prenatal nutrition interventions reduce stunting? A.

Multiple micronutrient supplements

Meta-analyses:  Small but significant increase in birth weight (+22 g) but not birth length(+0.06 cm) – Measurement issues?  11-17% reduction in low birth weight  Impact only evident in mothers with higher BMI

Impact of prenatal multiple micronutrient vs. iron+folic acid supplements on birth weight varies by maternal BMI. Fall et al. Food Nutr Bull 2009;30(4 suppl):S533-46.

Long-term impact of prenatal MMN supplements on stunting? 

Roberfroid et al. 2012 (Burkina Faso) – 27% reduction in postnatal stunting – Effect significant during infancy, but no longer significant at 30 mo of age

Wang et al. 2012 (China) – No effect on stunting at 30 mo of age of prenatal MMN vs. iron/folic acid

Can prenatal nutrition interventions reduce stunting? B. Balanced protein-energy supplementation Meta-analysis (Kramer & Kakuma 2003):  Increase in mean birth weight (+38 g) but not birth length (+0.1 cm)  32% reduction in small-for-gestational-age births  Larger effect of supplementation on birth weight in hungry season and in undernourished women

Greater impact of food supplementation during hungry season in the Gambia [Ceesay et al. 1997]

Prenatal supplementation with lipid-based nutrient supplement (LNS) in Burkina Faso [Huybregts et al. Am J Clin Nutr 2009]

RCT of LNS vs. multiple micronutrient tablets (MMN), n=1296  LNS provided 373 kcal/d & similar micronutrients as MMN tablets  LNS group: 

– Birth weight +31 g (p=0.2) – Birth length +0.46 cm (p=0.001) 

Same research group previously showed that MMN (vs. control) increased birth length by 0.36 cm; thus predicted impact of LNS vs. control would be 0.46 + 0.36 = 0.82 cm (effect size 0.33)

Prenatal supplementation with LNS in Burkina Faso [Huybregts et al. Am J Clin Nutr 2009]

Effects on birth length greater in higher risk subgroups: – Mothers with BMI < 18.5: +1.2 cm in LNS vs MMN group – Anemic mothers: +0.7 cm in LNS vs MMN group

Impact of postnatal nutrition interventions

Exclusive Breastfeeding 0-6 mo 0-6 mo: Exclusive breastfeeding (0-6 mo)

Large impact on infant survival Little evidence of impact on stunting

Preconception through pregnancy

6-24 mo: Complementary feeding CF guiding principles

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Complementary feeding 6-24 mo 6-24 mo: Complementary feeding Guiding principles

Potential for major impact on stunting but evidence is mixed

Preconception through pregnancy

for complementary feeding (2003; 2005)

0-6 mo: Exclusive breastfeeding

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Conceptual model of proximal factors affecting linear growth during the period of complementary feeding Linear growth




Morbidity -

Quality of complementary foods

Quantity of complementary foods


Breast milk intake -



Complementary Feeding Interventions [Systematic review: Dewey & Adu-Afarwuah 2008]   

 

Education about complementary feeding as the main intervention Increased energy density and/or nutrient bioavailability of complementary foods Provision of complementary foods or a food product offering extra energy (with or without added micronutrients) as the only intervention Provision of food combined with some other strategy, usually education for mothers Fortification of complementary foods (centrally processed, or home fortification including MNPs)

Complementary Feeding - 1 

Educational approaches – mixed results – Most showed little or no impact – Peru study illustrated substantial potential to improve linear growth (Effect size=0.5): emphasized consumption of nutrient-rich animal-source foods & was conducted in a population where animal-source foods were available & affordable – Two recent studies (Shi et al.; Vazir et al.) show modest impact (Effect size ~0.2): both emphasized key messages including dietary diversity and animal-source foods

Effectiveness of an educational intervention delivered through the health services to improve nutrition in young children: a cluster-randomised controlled trial. Penny et al., Lancet 2005;365:1863-72

Complementary Feeding - 2 

Interventions to increase energy density – mixed results – Of 5 studies, 2 had positive impact but 3 had no impact on energy intake or growth – May be effective when traditional complementary food has low energy density & infant unable to compensate by increasing volume of food consumed or feeding frequency

Complementary Feeding - 3 

Provision of food – mixed results – Average effect size ~0.2-0.3, but wide range  May depend on food security of target population  May depend on nutrient quality of food provided

– Two studies directly compared food + education vs. education only (both in S Asia): somewhat greater impact when food included

Complementary Feeding - 4 Fortification (or improved bioavailability) alone has little effect on linear growth  Combination of macro- and micronutrients in “complementary food supplements” may have a larger impact  Nutrient quality of fortified products is likely to be important 

Nutrient quality of fortified products may influence efficacy 

Amount and bioavailability of nutrients essential for growth – Inhibitors of zinc absorption (e.g. phytate in cereallegume blends) – Quantities of “neglected” type II nutrients e.g. phosphorus, potassium, magnesium

Inclusion of milk – Potential growth-stimulating effect

Essential fatty acids – May play a key role in growth

The need for combined interventions Nutrition, infection control & care  Prenatal + postnatal (and possibly preconception)  Macronutrients + micronutrients: Adequate supply 

of macronutrients may be needed to ensure growth response to micronutrients

Potential impact of prenatal infection control Lungwena Antenatal Intervention Study (Malawi)

[standard care vs. monthly anti-malarial (SP) vs. monthly SP + 2 doses of antibiotic (azithromycin); n=1320] 20.0 % with outcome


Monthly SP


15.0 10.0 5.0 17.9 15.4 11.8

15.7 12.4 9.2

0.0 Preterm delivery LBW Luntamo et al, Am J Trop Med Hyg, 2010

Lungwena Antenatal Intervention Study Stunting & Underweight at 4 wk 30.0 % with outcome


Monthly SP


25.0 20.0 15.0 10.0 5.0 24.2 24.9 14.8

11.7 10




Stunting Underweight Luntamo et al, Arch Ped Adol Med, submitted

Little evidence on impact of combined pre- and postnatal nutrition interventions Key trials conducted in 1970’s  INCAP trial in Guatemala 

– Fortified food (atole) with high milk content

Intervention trial with fortified food supplements provided both pre- and postnatally not attempted since  Why not? 

– Need for low-cost options (e.g. small-quantity lipid-based nutrient supplements)

Trials with combined nutrition + infection control are underway WASH Benefits (water, sanitation and hygiene interventions: singly, combined or in combination with nutrition intervention)  SHINE (independent and combined effects of improved water, sanitation and hygiene and improved infant feeding) 

Both target only the postnatal period

Conclusions - 1 Large reductions in stunting are possible, but probably not with nutrition interventions alone  Effect size of successful nutrition interventions generally modest (0.2-0.5) 

– Need to be realistic about expected impact of nutrition interventions on stunting 

However, impact on lower tail of the distribution may be larger than effect on mean height

Hypothetical impact on stunting if whole curve shifted to the right, mean change in HAZ 0.2

Number of children

Change in mean z-score: 0.2


Proportion stunted: 37% to 31%





Height-for-age z-scores





Hypothetical impact on stunting if greater impact on those with lower HAZ at baseline, mean change in HAZ 0.2

Number of children

Change in mean z-score: 0.2


Proportion stunted: 37% to 28%





Height-for-age z-scores





Conclusions - 2 Need to include the entire “window of opportunity”  Must pay attention to dietary quality, not just quantity  Integrate nutrition interventions within a comprehensive approach to reduction of stunting 