Many years ago a Chinese gentleman said, "food should be our first medicine." Depending on what is wrong food may not be enough but food should always be involved in healing.
What the ailment is decides; what foods will have to be reduced or eliminated, what must be added, and in what combination. Knowing how to adjust your nutrition can make a great difference on the recovery.
Using high cholesterol as an example a person has to add oatmeal (not instant), walnuts, almonds, black beans and lentils to their diet. They must also reduce all fats and eliminate processed (e.g. hydrogenated) fats and fried foods. This is not a complete list but a great start.
While there are herbs and prescription drugs that can lower cholesterol using food first or with treatment improves the results.