The 8 Least Healthy Vegetable Oils, According To An MD

During a mindbodygreen podcast episode, Shanahan says, "I think vegetable oils are the No. 1 cause of health problems in this country." Now, before anyone starts throwing away their cooking oils, Shanahan is only referring to eight specific types of vegetable oils. 

Eight of the most unhealthy vegetable oils, according to Shanahan, include:

Though polyunsaturated fats are actually healthier than saturated and trans fats, (and have been shown to reduce "bad" or LDL1 cholesterol), Shanahan says they're highly unstable. Meaning, when they're exposed to chemicals in the refining process, they're stripped of their antioxidants, vitamins, and minerals. Over time, PUFA becomes stored in the body fat, which may lead to inflammation2.

The same can be said of olive oil, coconut oil, and avocado oil when they're cold-pressed and unrefined. Traditionally, these oils are squeezed straight from the fruit, or the seed of the fruit, and are not stripped of their antioxidants and minerals. 

Not all fats or cooking oils are unhealthy. In fact, in their natural and unrefined state, fats can be healthy. When possible, Shanahan recommends avoiding or limiting these eight oils: corn, canola, cottonseed, soy, safflower, sunflower, grapeseed, and rice bran oils, which may lead to inflammation over time.