Oils are liquid fats. Most commercial oils come from plant sources, such as nuts and seeds. Oils are an important part of a balanced diet because, besides being a rich source of energy, they provide essential fatty acids which are the building blocks for cell membranes, especially cells in growing brains. Oils help the body absorb certain vitamins, such as A, D, E, and K, and contribute to healthier skin. And oils carry and intensify flavors in food and give it a pleasurable feel in the mouth.

Most oils come from the seeds of plants, which are crushed and pressed to remove the oil. Heat can damage oils and alter the fatty acids, creating harmful substances, so the best oils are produced with minimal heat. This is called cold pressing. However, when you see the term "cold-pressed" on a label, don't assume that the oil in the bottle was not heated during manufacturing. "Cold-pressed" is a little fib that appeals to consumers who are savvy enough to equate heating with damage to oils. The problem is that the term has no chemical, legal, or technological definition, and it means something different to a manufacturer than it does to the consumer. To a manufacturer, cold-pressed simply means that no external heat was applied during the pressing of the oil, yet the press itself, which comes in contact with the oil, may become quite hot anyway and damage the oil. A more informative label would state the temperature at which the oil was processed, which ideally should be below 110 degrees. The words "omegaflow process" on a label means that the oil has been protected from reaching high temperatures during processing.