Dear Karleen, Indeed you can read everywhere that stunting is irreversible after 2 y, but this statement is debatable as it is based mainly on observation of children who remain in nutritionally deprived settings. FYI, this was discussed in detail in a special issue of Eur J CLin Nutr a few years ago. See in particular the following articles. Martorell R, Khan LK, Schroeder DG. Reversibility of stunting: epidemiological findings in children from developing countries. Eur J Clin Nutr. 1994 Feb;48 Suppl 1:S45-57. Golden MH. Is complete catch-up possible for stunted malnourished children? Eur J Clin Nutr. 1994 Feb;48 Suppl 1:S58-70 I hope this helps.

Yes, that is very helpful. Thankyou very much. Karleen

The emerging evidence on reversal of stunting is indeed interesting and may even change the way we programme nutrition activities in future. However, is the reversibility just about linear growth? What about the cognitive implications due to stunting before two years?

I don't know about stunting due to nutritional deprivation but interventions to deal with psychosocial stunting require therapeutic parenting to build the areas of the brain where development has also been stunted and remediation work on areas where maladaptive pathways have developed as a result of deprivation....I doubt whether there is ever complete catch up (though those with an interest in brain plasticity might disagree) It may be of interest that catch up growth following psychosocial stunting has been associated with precocious puberty. From what I understand of the proposed mechanisms behind this, the same might occur with catch up as a result of nutritional deprivation.

Dear Sophiya, You make a very good point by questioning the reversibility of cognitive effects of stunting. To make a long story short, I am afraid we don't have the answer to your question, mainly because we even don't know whether the association between stunting and delayed cognitive development is causal or not. Several mechanisms can explain this reported association: i) It is possible that some nutrients needed for bone growth are also needed for brain growth. Zn is a good candidate for this. ii) It is also possible that nutrients needed for cognitive development are often also missing in diets also poor in nutrients needed for bone growth. For instance, it is quite possible that diets poor in absorbable Ca, P, Mg, Zn are also poor in essential fatty acids, presumably not needed for bone developments but needed for cognitive development. iii) Stunting usually occurs in deprived social groups in which stimulation is limited for different reasons and this limits cognitive development independently of the diet. These mechanisms can also be associated. It is clear that if mechanism ii) and iii) are mainly involved, a nutritional intervention can have an effect on stunting without an effect on cognitive development. For this reason, it is important that a possible effect on cognitive development should be assessed to judge the success of interventions on stunting. Also, if mechanism ii) is predominant, it is conceivable that some nutritional interventions may have an effect on cognitive development without an effect on linear growth. And if mechanism iii) is predominant, stimulation programmes can in theory have an effect on cognitive development without an effect on linear growth.

Dear Andre, Thank you very much for your reply. Very interesting theories and they certainly deserve further research. You are saying that the nutrition community is not sure whether the association between stunting and delayed cognitive development is causal or not. However, in all our nutrition trainings, we have been passing the message that stunting is directly related to mental development and cognitive abilities of children. Also, aren't there studies (one for sure from the Phillipines) that have demonstrated lowered IQ in children later on who were stunted at two years of age compared to children who weren't?

Dear Sophyia, There are many statements in textbooks which are not really supported by hard data. The most important thing to teach students is that association does not mean causality. Indeed stunting is often associated with delayed cognitive development, but this does not mean that just being tall makes you smarter, or that being tall is a prerequisite to have a good brain. We all know small people who are bright and tall people not so much. Indeed, there is some overlap between nutrients needed for bone and brain growth, but bones and brain are still rather different organs with very different nutrient content and conceivably different specific requirements. To show that reversing stunting improves cognitive development, you need to have an intervention with an impact on both, ideally with a comparison group. I am not aware this has often been done.

Dear Sophia and Andre, indeed this is an interesting topic-that has been under-looked. Under-looked, in the sense that there is still paucity of vivid data to explain and hence an indicator that the larger nutrition community is yet to take a bold step to critically unveil, if any, and pre-package a suitable model to make stunting a 'myth!' in the future! For general consensus, please permit me make the following observations: 1) Stunting and Cognitive impairment due to under-nutrition (Macro- and Micro-nutrients) is largely irreversible after the first two years of life; and that preference is being placed on preventing rather than incur huge economic costs towards reversing either effects. 2) In the larger 'sense' one would expect stunting to result from either of emotional or nutritional deprivation (or both) especially on food (nutrient) intake and utilization. Remember the COMPLEX Malnutrition-Infection cycle! In conclusion, I suggest "That stunting beyond two years is largely irreversible. Perhaps the "proportion' that may be reversible thereafter is a trade off between the larger contributor of (emotional vs nutrient deprivation) during the first two years! Indeed this would depend on the extent to which emotional deprivation and nutritional deprivation can be assessed for contribution to stunting!! Some one please suggest a design for this study! Sorry, a hard nut to crack! Feel like rotating along the same pivot with no means to end!! Good luck and thank you for the collective observations.