Nutrition expert Dr. Eric Berg says consumers may not be getting what they think when buying avocados, avocado oil, or guacamole -- and in some cases, they may be paying for products with little or no real avocado. Buying locally sourced products is usually a better option.Berg said many avocados sold in grocery stores are artificially ripened with ethylene gas, a process that can hinder the development of natural flavor chemicals and phytonutrients. "Anytime you force something to ripen, it's very unnatural," he said.A study of 22 avocado oil samples found widespread problems, including oxidation, contamination with other oils such as soy or canola, and even bottles with no avocado oil at all. Berg said oxidation -- the same process that turns cut apples brown -- can make