But why do some fats and oils offer tremendous health benefits, while others are so incredibly destructive?

Commercial vegetable and seed oils in the shop are highly damaged for two reasons.  Firstly, they are processed using very high temperatures and sometimes chemical processes⁹.  Secondly, the types of oils used tend to be primarily polyunsaturated (as they are liquid at room temperature), but this makes them unstable and thus highly susceptible to damage from chemical processing and even routine exposure to light, heat, and oxygen.

So while polyunsaturated fats found in chia seeds, cod liver oil, fish (and fish oil), flaxseeds, grapeseed, hempseeds, pine nuts, sunflower seeds,  soy and sesame seeds are loaded with health benefits⁸ in their natural form, processing these fats into oils causes significant oxidative damage (we won’t go into oxidation here, but suffice to say a rusty old nail is another example of oxidation), which is made even worse if you use them for cooking.  Ingesting these fats promotes oxidative (free radical) damage to cell membranes and other tissue in the cardiovascular system, immune system, nervous system and brain. Over time, free radical damage and the ensuing inflammation causes premature aging, obesity, fatigue, burnout, compromised digestion, skin disease, hormonal imbalances, high blood pressure, heart disease, liver damage, sub-optimal neurological function, immune dysfunction and even cancer¹.

Total elimination of these damaged, highly reactive fats is critical to allow your body to repair at the cellular level.

On the other hand, the molecules of saturated fats, such as grass-fed animal fats (butter, lard), coconut oil and avocado are very stable, making them less prone to oxidation when exposed to heat, light or oxygen and thus good choices for cooking.

Contrary to conventional wisdom, there are actually little to no reliable studies that have shown that saturated fats, by themselves, are unhealthy.  In fact, saturated fats have been shown to be an excellent source of energy and provide enhanced nutrient absorption, immune function, hormone production and protection against oxidative damage.

Monounsaturated fats (in their natural form), such as nuts, avocado, olives, egg yolk, lard, chicken and duck fat are universally regarded as healthy, lauded for enhancing cardiovascular and immune function and offering protection against heart disease. They are more stable than polyunsaturated fats, but can oxidize at higher temperatures, making them suitable only for cooking at lower temperatures,

Extra-virgin olive oil is not processed using high temperatures, but is instead ‘cold-pressed’, making it a great option for fresh salad dressings and sauces and low temperature cooking.  Other oils can also be cold-pressed, making them a healthier option, but not always suitable for high temperature cooking.  These are not usually as easily available as extra virgin olive oil.

And the absolute worst of all the fats is Partially Hydrogenated Trans Fats, which occur through heating an unsaturated fat (typically a vegetable oil) to a high temperature under extreme pressure and mixing it with toxic chemical solvents to saturate the carbon bonds with hydrogen, rendering the fat solid at room temperature and increasing shelf life.  What could go wrong, right?

Chemically altered trans fats are easily oxidized to form free radical chain reactions that damage cell membranes, also promoting systemic inflammation, obesity, immune system dysfunction, the oxidation and inflammation process that characterizes heart disease and many other serious health problems.  Trans fats are considered to contribute to over half a million deaths every year and WHO aims to remove them from foods by 2023¹¹