Things started to go downhill about 60 years ago when health organizations began suggesting folks replace animal fats rich in saturated fats with “heart healthy” vegetable oils packed with polyunsaturated omega-6 fats. A classic example is the recommendations to swap margarine (and vegetable shortening) for butter.

Ironically, there’s now pretty darn good evidence that saturated fat is not the devil it was once thought to be. In fact, it’s now well-established and widely accepted that saturated fat is not associated with heart-related issues and other adverse health outcomes. Even more, some have speculated that ramping up the consumption of vegetable oils may have increased the rates of death from all causes, as well as coronary heart disease, and cardiovascular disease—the exact opposite of the desired outcome!

While there’s some debate about that, there’s no question this recommendation has resulted in the majority of people consuming way too many omega-6 fats. Why is this important? Overconsumption of omega-6 fats promotes inflammation, particularly when they are consumed in excess of omega-3 fats, which are truly heart healthy and have anti-inflammatory effects.

Believe it or not, research shows the average person consumes between 10 and 20 TIMES more omega-6 than omega-3 fats. Ideally, this ratio should be closer to 2 to 1. That means most people aren’t even close!

This unhealthy consumption of omega-6 fats has been tied to virtually every negative health outcome you can imagine—even accelerated aging. While there are several reasons for this health-derailing imbalance, it’s due, in large part, to the ubiquity of the following refined vegetable oils, which we recommend avoiding at all costs:

• Soybean oil
• Canola oil
• Corn oil
• Vegetable oil

“Vegetable oils” sound oh-so-healthy though, don’t they? Au contraire. Vegetable oil is a catch-all term, and it may include one or more of the above oils along with any/all of the following, which we also suggest avoiding like the plague:

• Safflower oil
• Sunflower oil
• Cottonseed oil

In addition to being primary contributors to excess omega-6 fat intake, which drives inflammation, these vegetable oils are heavily processed. In fact, those in the industry call them “RBD” oils, which refers to the refining, bleaching, and deodorizing processes they go through during manufacturing.

The refinement process strips the oils of potentially healthy nutrients and antioxidants. For example, extra-virgin olive oil contains nearly 40 times more health-promoting antioxidant polyphenols than refined (“light”) olive oil.

But there’s more. Because consumers prefer bland-tasting oils, these oils go through a deodorization process, which subjects the delicate oils to very high heats for prolonged periods of time. While it’s remarkably effective at removing the natural taste and smell of the oils, deodorization creates artificial trans fatty acids, arguably the worst fat you could possibly consume.

While the amount of trans fats present (~4%) is substantially lower than partially hydrogenated oils (~50%), the fact is industrial-produced trans fats like these are not healthy in ANY amount. In fact, the Institute of Medicine says that any intake of artificial trans fats above zero increases your risk of heart disease, and the FDA has recently taken steps to ensure all artificial trans fats are removed from the food supply.

And don’t let the labels fool you. Manufacturers can list the amount artificial trans fats as ZERO if they contain less than 0.5 grams per serving. Remember, artificial trans fats are toxic to your body in ANY amount.

But hang on, there’s still more. These vegetable oils are rich in polyunsaturated fats, which are very unstable. When heated, these fats are very susceptible to oxidation, which results in the production of free radicals and harmful compounds, and rancidification, which results in an unpleasant smell and taste.

Now that you know what cooking oils you should never use, let’s talk about what you should be using. Here are our top choices, listed in alphabetical order to avoid showing favorites (BUTTER!):

• Butter from grass-fed cows
• Cold-pressed macadamia nut oil
• Extra-virgin olive oil
• Extra-virgin avocado oil
• Extra-virgin coconut oil
• Ghee (also known as clarified butter) from grass-fed cows