Find the cheapest combination of raw foods that fulfill nutritional requirements I am starting a raw food diet and would like to properly plan it, and thus, would like to create a program that takes a list of available raw food, and finds the best combination of foods (multiples allowed) with the lowest total price.

Does anyone have any advice as to how to approach this problem? Is there a certain algorithm that exists that takes in a list of possible items, and finds a permutation that minimizes one property of the item(s), in this case the price, and also makes sure that the sum of each property meets a certain range, in this case nutritional properties like carbs and protein? Any advice is greatly appreciated. Thanks!
Use integer linear programming.  Suppose you have $n$ foods.  Let $x_1,\dots,x_n$ be zero-or-one variables, with the intention that $x_i=1$ means you include food $i$ in the combination.  Then the price is a linear function of these $x$'s, so that's your objective function you are minimizing.  If you want the total carbs to be within a range, you can express that as a linear inequality (e.g., $\ell \le c_1 x_1 + \dots + c_n x_n \le u$, where $\ell,u$ are the lower and upper bounds of the range and $c_i$ is the amount of carbs in food $i$).  Feed this to an off-the-shelf ILP solver, and it should give you the optimal answer.