Patrick Webb, Tufts University, Keynote Presentation: "Agriculture and nutrition. what do we know, and what do we still need to know?"
Science Forum 2013
Agriculture and Nutrition: What do we know,
and what do we still need to know?
23 September 2013,
The tines, they are a changin’….
Copyright 2013 by S. Karger AG
“Higher calorie intake has improved nutrition and health.”
CGIAR (1996) Annual Report 1995-96
“Merely producing more food does not ensure food
security or improved nutrition.” (Herforth (2012) World Bank)
“Agriculture interventions do not always contribute to
positive nutritional outcomes.” (FAO 2012)
Starting at the end…
1. Effective agriculture-nutrition research needs honesty
(about feasible contribution to nutrition), engagement
across sectors, and rigor (outcome-appropriate methods).
2. Only possible with agriculture researcher involvement in
public health dialogue, priority-setting, integrated research.
3. Expanded research agenda: highest impact may be in
‘novel’ domains (food system hygiene, agriculture
programmes as platforms for delivery of other services).
a) Discussion of potential for
agriculture to contribute to,
accelerate, and enhance coverage
of improved nutrition outcomes
b) Search for evidence that it can…
All forms of undernutrition combined responsible
for 45% of avoidable child deaths.
165 million children stunted in 2011.
20% stunting ascribed to in utero conditions
(small for gestational age) – which means reaching
pregnant women and pre-pregnant girls is priority.
10 targeted interventions implemented at 90%
coverage cuts stunting by 20%, mortality by 15%.
But…“coverage rates for [many] interventions are
either poor or non-existent.”
Cost: US$9.6 billion per annum.
Even at 90% coverage, 80% of stunting remains!!!
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
height-for-age z-score (stunting)
Mountains Hills Terai
Source: DHS 2006
Children below 5 years (n=5,237)
by agroecological zone
(from left to right, means = -2.27, -2.02, -1.89)
Height-for-age Z-scores (stunting) Nepal, 2006
and Shively (2013)
Masset et. al. (2011)
7,000 studies considered.
Only 23 qualified for final inclusion (i.e. having
credible counterfactuals and rigor in methods).
Masset et al. (2011/12):
a) Positive impacts on farm output/productivity.
b) “Poor evidence of impact on households’ net income.”
c) “Little evidence…on changes in diets of the poor.”
d) No studies assessed quality of whole diet (substitutions).
e) 9 studies tested impact on Vitamin A (only 4 were positive).
f) “No evidence of impact on stunting, wasting.”
1. Productivity 2. Empowerment
Source of food
Source of income
Stability of food
A doubling of per capita income from agriculture is
associated with 15-21% point decline in stunting.
Transfer of labor
Net return/day of
Net rise in real
10% income rise
= 4.8% rise in
Child nutrition improved
(but less than expected)
10% rise in calories =
2.4% fall in children
Source: von Braun et al. (1989)
1. Productivity 3. Diet Quality2. Empowerment
4. Food system safety 5. Delivery platforms
Source of food
Source of income
Stability of food
Sources of anti-
Source of human and
Integration with multi-
Value chain foundations
Lancet Paper 3 (Ruel and Alderman 2013)
“Poor-quality evaluations prevent firm conclusions
on the impact of agriculture programs on nutrition.”
“Evidence of the effectiveness of … agricultural
programmes on maternal and child nutrition, with
the exception of vitamin A, is limited.”
Source: Masset et al. 2011
costs of time
Diet quality (animal
source foods, whole
diet diversity; anti-
nutrients in meals)
(gut microbiota; shared
Do no harm
(malaria, bird flu,
Nutrition and Health
What do we still need to know? - Lancet
1. Rigorous cost-effectiveness assessment of large scale
nutrition-sensitive programmes (not just gardens).
2. Careful assessment of intermediary outcomes along
3. Programme entry/technology adoption barriers.
4. Feasibility and desirability of integrating interventions
from several sectors, versus co-location.
5. Documented scalability of biofortified crops.
What do we still need to know? - Hawkes/DFID review
1. Complete links in chain (from ag. to nutrition outcomes).
2. Cost-effectiveness of interventions/investments.
3. Population sub-groups (incl. the poorest, rural non-farm).
4. Indirect effects on nutrition (pathogens, agric. safety).
5. Value chain roles in linking agriculture and nutrition.
6. Agriculture/food/trade policy effects on nutrition.
7. Incentives for effective nutrition-sensitive policies.
What do we still need to know? - Food Security Learning Framework
1. Cost-effective approaches that result in demonstrated
improvements in diets and nutrition.
2. Effect mediators of those approaches by context.
3. What combinations of sector actions most effective.
4. Value chain and agriculture policy impacts on nutrition.
5. Assessment of actual mechanisms to having impacts on
diets and nutrition.
6. Incentives for effective governance of nutrition sensitive
actions to impact nutrition nationally.
CGIAR Independent Science and Partnership Council (2012)
Strengthening Strategy and Results Framework
As stewards of scarce resources, we must understand and
document investment impacts (and explain how and why).
Much more high quality research needed (beyond agronomy,
ag. econ., resource management); requires evidence-capture
that passes the bar of future meta-analyses (but not just RCTs!)
Need less claiming/modeling of “potential” impact, more
demonstration of actual net impacts.
Must link agriculture with public health research to fill
knowledge gaps on ‘dose-response’, effect modifiers, cost-
effectiveness, inter-sectoral processes, etc.