Review of the paper itself:

it is a RCT (Randomized control trial) which is the highest level of evidence we can get.

Unhealthy patient confounders - the diet of the school children was poor and not balanced, so conclusions of this study are limited to undernourished populations, and should not be extended to "well-nourished" populations.

Notes on the paper:

Diets tend to be of low energy density, and protein of poor quality

The area covered ;60 km2 in a drought-prone area with serious food shortages every 3–5 y

Findings persisted even after statistically controlling for a number of important covariates.

Its interesting that they randomized the intervention by school, I wonder if there would be geographic biases inherit in different schools? (unless we also did a cross over intervention - i.e. switch schools after some time)

Each Control family received a milk goat at the end of data collection, a gift of the parent’s choice

That is quite the detail.

The snacks for all 3 intervention groups were based on githeri, a local dish composed of maize, beans, and greens. For the Meat group, finely ground beef (Farmer’s Choice, Nairobi, Kenya) with 10–12% fat was added to githeri. The Milk group was given a glass of Ultra Heat Treated whole cow’s milk in addition to the basic githeri. The Plain Githeri (Energy) group received githeri with extra oil added to equalize the energy content of the 3 snacks.

This is a great paper, easy to read, I do wish they had included a egg in the intervention cohort, or liver for the meat cohort, as the nutritional needs of the children in the study were only partially completed (still room for improvement).