Twenty-two children died after eating poisoned school meals this week in Bihar state, India. Postmortems indicate the cause may have been adulterated cooking oil. This is a terrible tragedy – awful, avoidable, unconscionable. It should, and has, provoked much outrage and some soul-searching about the neglect of basic services in India. And for once, the political establishment seems to be taking note.

But what does this mean for the midday meals scheme? If your knowledge of the scheme comes from Kishwar Desai's article in the Guardian, you probably believe it is a giant hogwash, a policy meant to improve nutrition and school attendance gone badly wrong with "little evidence to suggest that schoolchildren are actually getting any nutritional value from it at all".

As the headline in another Guardian article pithily captured it: "Free school meals kill Indian children". No sign whether it does anything good at all anywhere.

This impression is wrong and by now a lot of evidence exists to back it up. Farzana Afridi at the Indian Statistical Institute, has found large benefits to the scheme: in a paper (pdf) in the Journal of Development Economics, she says: "At a cost of between 1.44 cents to 3.04 cents per child per school day the scheme improved nutritional intakes by reducing the daily protein deficiency of a primary school student by 100%, the calorie deficiency by almost 30% and the daily iron deficiency by nearly 10%."

In a paper (pdf) in the Journal of Development Studies, she found that the attendance rate of girls in grade 1 rose by 12 percentage points because of the meals. Rajshri Jayaraman and Dora Simroth at the European School of Management and Technology in Berlin said enrolment went up substantially as a result of the introduction of school meals, similar to evidence reported in other studies (such as these papers (pdf) by Jean Dreze).

In a recent paper (pdf), co-authored with Stefan Dercon and Albert Park, forthcoming in Economic Development and Cultural Change, I used panel data on 2,000 children collected by the Young Lives study at Oxford University to investigate the impact of the scheme on nutritional outcomes. Specifically, we were interested in whether school meals might serve as a safety net for children who were malnourished as a result of droughts in early childhood.

We found that children whose households experienced droughts when they were very young (under two years) had higher levels of malnourishment, but if they had since been enrolled in a government school, the meals compensated for the early nutritional deficits – put simply, there was no physical evidence of worse nutrition by the time they were aged five to six years compared with children who had not experienced drought. In a country with high child malnutrition, and with agriculture often at the mercy of the monsoon rains, these are encouraging results.

There are other effects possible that are less easily quantified: on every school day, millions of schoolchildren, from different castes and religions, eat meals from the same pot together – in a socially stratified society, this cannot be seen as being anything but good for social equity. These are not trivial results. Taken together, they mean that the midday meals, which reach about 120 million children on every school day, are probably the most successful of all interventions in education that the Indian state has delivered in the past decade. On any school day, a quarter of teachers are absent from government schools (pdf), only 45% of those in school are teaching, but in 87% of schools, a hot meal is served (pdf).

The death of 22 children is not a trivial matter. And it is not enough to point out that, for the vast majority of 120 million children who are fed every school day, the meals are a good thing. But it is possible to report about this feelingly, without undermining the scale of the tragedy, with some perspective on what this case means for the scheme as a whole (see here and here). Do we need better storage to make sure food does not get mixed with insecticides? Of course! Beyond school meals, we also need to deal with adulteration in Indian food (including adulteration in cooking oil, which has caused dropsy and death). Let's not, however, use the death of these children as an excuse to declare open season on the one thing that does seem to get delivered to kids in India's government schools.

• Abhijeet Singh is a research officer at Oxford University's Department of International Development and a doctoral student in economics. More on his research can be found on his website