Final answer:
Non-essential nutrients are substances that the body can make for itself and thus do not need to be consumed in the diet, with glucose being an example. Essential nutrients, on the other hand, must be ingested as the body cannot produce them.
Step-by-step explanation:
Non-essential nutrients are nutrients that the body can synthesize on its own in sufficient quantities for normal functioning, so they do not need to be obtained through the diet. An example of a non-essential nutrient is glucose, which the body can produce from other carbohydrates, proteins, and fats.
Contrary to non-essential nutrients, essential nutrients cannot be synthesized by the body and must be obtained from food. These include certain amino acids, fatty acids, vitamins, and minerals. For instance, vitamin C is an essential nutrient that humans must obtain from their diet.