In reply to your letter in which you describe the health of your children, and conclude with a question regarding whether the children should receive a type of food whose kashrus is somewhat in doubt, in order that this food enhance their appetites:
Scrupulous observance of kashrut (Jewish dietary laws) is important not only for the proper observance of the mitzvah of kashrut, but also because each morsel of food that a person eats is transformed into his flesh and blood, thereby binding the soul and the body.
The kashrut and refinement of foods have an effect on the character and moral fiber of the person who eats them. Thus, every enhancement in the degree of a food's kashrut, refinement and purity, must also be recognised as an added enhancement to the quality, calibre and refinement of the individual's character and moral fibre.
If this is so regarding adults, how much more so with regard to children whose characters are in the process of being formed. The direction one takes in their formative process is thus of utmost importance.
In light of the above, my opinion and reply to your question is obvious: Since we are not dealing with a life-threatening situation - G-d forbid - and it is only a matter of increasing your children's appetites and strengthening them, you should not diminish the level of kashrus of their foods.
Surely other means and methods can be found to strengthen their appetites and make them healthier - and not to the detriment of proper observance of kashrut.
