What is food "security"?

If you mean nutritionally balanced, I assume that it would be possible but it's a round about way doing it when you can simply analyze the food commonly consumed by the children in the region of your interest. 

I think that 5 is a very small population, at least 30 becaus a lot of factors can generate abnormal distribution

Food security is the availability, accessibility, affordability, sustainability, safety of food sources and under five nutritional status is just one indicator of food security

Under 5 is good for such, but you have to mind deficiencies during parturition which have effects on the growth and survival of the infants. However, in the rural areas where more attention is needed, accessing under 5 is difficult because of parents' unco-operative attitude.

Undernutrition among U5 children is only a very very distant proxy of food INsecurity (which is not necessarily the opposite of food security, since we can have different thresholds of various indicators to characterize one or the other).

Indeed, there are several dimensions of food insecurity and there is no single indicator to measure it. On the other hand, there are also two types of undernutrition among U5 children (stunting and wasting) which have not the same relationship with various indicators of food insecurity.

In any case, there is only a small intersection between food insecurity and undernutrition (i.e. many food insecure households don't have children suffering undernutrition; and many children suffering undernutrition don't live in a food insecure household).  

Finally, your question can't be answered simply. The most important is to know what you are interested to measure in the end and for what purpose. Are you interested in characterizing food insecurity in an area? If so to do what? Or are you interested in undernutrition and to relate it to food insecurity?

Depending on your objective(s) the answer can vary (or there might even be no answer...) 

Dear Dr.Yves, 

Paul Howe and Stephen Devereux (2004)  proposed Famine Intensity and Magnitude Scales using nutritional indicators of under five children. Can we use only prevalence of wasting  to classify a region/area as a food insecured region. 

or suggest me how to estimate the stages of food insecurity/security using some development indicators of the area, (whenever there is no data available on food security (since it is multidimensional). 

Thanks

I suggest you have a look at http://www.ipcinfo.org/ 

Yes, nutritional indicators would indicate the type of undernutrition in terms of protein- energy malnutrition or specific deficiencies and you can relate that to non-availability or insufficient intake of specific foods. As for example, growth retardation would mean  a food gap itself, vitamin A deficiency would indicate less of green and yellow vegetables and fruits and milk intake. Iron deficiency would mean lower level of ion rich foods, You can find an association between both. 

Thanks Dr. Jamuna Prakash.

Greetings:

Definitively, food security in a region can be evaluated based on the nutritional status of children. To evaluate the nutritional status of children less than 5 years of age and to link this with food security, a nutritional assessment is crucial. However, the sources and types of data evaluated in the nutritional assessment depend on the setting. In United States we use the following groups of data: food/nutrition history; biochemical data, medical tests, and procedures; anthropometric measurements; physical examination findings; and client/patient history. Since food security is a multidimensional concept it must be estimated using data from each of the aforementioned categories. Mixed methods will be a good research approach. Also, critical thinking is needed to separate out irrelevant data and to identify the appropriate norms or standards for evaluation of relevant data.

Carmen María Pérez