To illustrate the meaning of food, a simple example will suffice. Take onions, for instance, a very nutritious food, that is eaten by millions of people every day. Now, this does not mean you should start eating tons of onions and start being fatter than you already are. What we are talking about is simply showing that food has many different uses, not just for humans but also other creatures. A good example of food is water, which is used up by our bodies almost all the time. This is what we call food; food is anything consumed to give body support, and therefore, nutrition.

Food is normally of animal, plant or fungal source, and has all the necessary nutrients, like proteins, carbohydrates, vitamins, or other minerals. That is why if we talk about human nutrition, we must also talk about what the food sources are. The major food sources are meat, vegetables, nuts, and fruits. Other than these food sources, food could be cooked, and in some cases, even drunk.

There are people who believe that only animal products are beneficial to health, but research shows otherwise. In fact, there are certain foods, which when eaten in ample amounts can actually have health-improvement effects. Some examples of these sources are certain kinds of vegetables, nuts and fruits. The best way to find out what your own sources are, and to choose the right kinds of food to add to your diet, is to get a complete picture of your diet from a reliable food guide.