Well it's not clear there is one optimal level for most nutrients. You should hit all the Recommended Dietary Allowances and stay under the Tolerable Upper Intake Levels (links to both given in the grandparent), but in between that large range (often a factor of ten), who knows, it doesn't seem to make any difference (which is why the ULs are so high).

Given most usual Western diets, the problem isn't malnourishment (although it does exist, Vitamin D deficiencies in general, and problems with low SES populations subsisting on soda and chips come to mind). The problem is simply too many calories (and salts) consumed. Fast food is actually quite healthy ... if consumed in the appropriate amounts.

In other words, as long as you stay in the range, there's probably little difference between a formula designed specifically for adults, and a formula designed for kids which when scaled up is also in the correct ranges.