New Evaluation to Build Evidence on the Usefulness of Nutritional Supplements for Later-life Outcomes

Behind the Scenes: Researchers talk about their work

It is well-documented that prenatal nutritional supplements can give children the right start in life by supporting development in-utero and improving birth-weight, which reduces infant mortality. But can a case be made that good nutrition early on will give children a measureable earnings boost years later? 

A research team that has received preliminary SIEF funding is planning to update and evaluate a rare find of 20 years of data tracking Gambian children whose mothers received nutritionally-fortified snacks during either the last 20 weeks of pregnancy or the first 20 weeks after giving birth. The study will help policymakers understand when nutritional supplements are most effective – and whether there’s an argument to be made that good nutrition is measurable investment in a child’s economic future. 

The study’s project leader, Mattias Lundberg, of the World Bank, talks about the research and its relevance. 

1. How did your team decide on this study?
   
   We were very lucky because Harold Alderman, a former World Bank staffer who will be joining the research team, ran into one of the study’s original researchers at a conference. His interest was piqued when he realized there was ongoing data collection on the children whose mothers received supplements and he started thinking about how to use this. For those engaged in this issue of nutrition and early childhood development, longitudinal material of such a magnitude isn’t common and we all realized this was an incredible opportunity to look at the long-term effects of nutritional supplements.
   
   
2. How much do we know already about the effects of nutrition on later childhood development?
   
   We probably think we know more than we actually have evidence for. We know good nutrition helps physical development. And we know that good physical development raises economic productivity, which is another way of saying higher incomes. But we actually have very little evidence that good nutrition leads to higher incomes. In other words, we’re inferring that because A results in B and B results in C, then A leads to C, but we don’t have much evidence for this. We also don’t necessarily know when the best time is to boost nutritional intake. Is it during pregnancy when the baby’s brain and body is developing? Or is it more important to support children after they are born, either through supplements to lactating women or to the children directly?
   
   There was one very well-known evaluation in Guatemala that followed children and that makes this link explicitly. But in that case, both the children and their mothers received nutritional supplements, so it’s not possible to separate the effect of each intervention on its own. Also, the study was conducted in only two villages, so it was a very small sample. In Gambia, on the other hand, 28 villages were included in the original study and only mothers received the supplements.
   
   
3. Can you tell me a little more about the original study and what your work hopes to show?
   
   The original study, a randomized trial in the West Kiang region of Gambia between 1989 and 1994, compared the birth weight of babies whose mothers received nutritionally-fortified biscuits with a control group that received iron and folate supplements and, after giving birth, received the nutritionally-fortified biscuits. The evaluation showed that nutritional supplements during pregnancy reduced low birth-weight by six percentage points and cut the probability of perinatal mortality. What we now want to look at are the long-term effects of supplements on key developments such as education and jobs and on the likelihood of engaging in self-destructive behaviors, like smoking and alcohol abuse.
   
   
4. Why hasn’t more research like this been done already?
   
   It’s very hard to do longitudinal studies. For one thing, they are expensive because you have to track people over decades, often following them from very remote areas as they move to dense cities or even other countries. It’s not always easy to find people. Also, researchers move on, both to other projects or other areas of interest. So the fact that these beneficiaries were still being tracked was really a great chance for us.
   
   
5. Isn’t it enough to know that good nutrition helps cut down on infant mortality and gives people a developmental boost at the start of life? Why not just focus on getting more countries to ensure proper nutrition in what is called the first 1000 days of life?
   
   Of course, that’s important, and certainly it’s something that we are trying to encourage and support. But what we want to understand is whether there are measurable benefits later in life, particularly when it comes to economic productivity. Let’s say the data shows that there are real gains for children whose mothers received the supplements. Imagine how much stronger an argument you will have if you can go to a government and say if you put money into these fortified snacks for pregnant women, you’re doing more than helping the poor, you are making an investment in your country’s future. 

Interviewed by Aliza Marcus, January 2013