If you’re like most health-conscious people, you know that a healthy diet should include plenty of healthy fats. But what exactly are “healthy” fats? How do they vary from their “unhealthy” counterparts?
One major clue to use as a guideline is how fats behave in various temperatures. They range from always being a solid at room temperature and stable in heat to only becoming a solid in the freezer and very unstable in heat.
Processed, fabricated fats like Crisco®️ and saturated margarines remain solid at almost any room temperature and almost never go bad....
Lard, butter, ghee and coconut oil stay solid at cooler room temperatures, but will soften when it’s warmer; coconut oil will turn into a liquid when it gets really warm inside the house (above 76). All of these naturally-occurring fats remain stable, making them safe for high-heat cooking.
Olive, avocado, and peanut oils will stay liquid at room temperatures but turn solid in the refrigerator. The integrity of these natural fats will be compromised by heat, however. So they should not be used for high-heat cooking and should be stored in a cabinet, where they can be kept away from exposure to the stove or other sources of direct heat.
Safflower, corn, soy and sesame oil stay liquid, even in the refrigerator. These vegetable-derived oils are natural, but highly-unstable and easily damaged by heat. As a result, they should not be used for cooking.
Heat-sensitive oils like those from flax, hemp, and fish should be kept refrigerated to preserve and protect them. They should never be exposed to heat and will solidify only when frozen.
See the trend?
The more solid at room temperature a fat is the more resistant it is from going rancid with heat as well as to light and oxygen.
Do you know why?
It all has to do with how these fats are structured. From a chemical standpoint, it becomes important to evaluate how many double bonds each type of fat contains. This is when the terms polyunsaturated, monounsaturated, and saturated all come into play.
I won’t get into the specific organic chemistry of fats other than to remind you that all fats are a long, carbon-linked (bonded) chain with hydrogen and oxygen attached.
Here’s your cheat sheet:
- A saturated fat has double bonds between all the carbon chains.
- When a fat is missing a double bond, it’s called unsaturated.
- If it’s missing only one double bond, it’s called monounsaturated.
- If it’s missing more than one double bond, it’s called polyunsaturated. These type of fats can be missing usually anywhere from 2 up to 6 double bonds.
So why is this important?
The more double bonds a fat is missing, the more flexible it becomes but the trade-off comes at making it more susceptible to heat, light and oxygen damage. (This is where our bodies antioxidant protection comes into play.)
And these different fat structures are the result of nature’s grand plan for protecting naturally-occurring oils from heat, oxygen, and light while accommodating their varying needs for structural flexibility in variety of environments.
For example, in high-temperature, tropical climates, there is no need for structural flexibility but a great need for heat protection. Saturated fats including coconut and palm kernel oils as well as animal fats (which are produced by warm-blooded animals) are nature’s solution in this environment. Conversely, fats sourced from cold-temperature organisms (like fish, algae, and krill) or crops grown in cold temperatures (such as flax, chia, and hemp) are highly polyunsaturated because they need to stay flexible; in their natural environment, they would not be exposed to heat.
However, Crisco®️ and hard margarines stay hard forever as they are artificially-created saturated fats. For decades now, food manufacturers have been implementing a chemical process to turn cheap, polyunsaturated oils into a processed, fat-like substance that will stay “fresh” for months (or even years) at room temperature. While this is good for manufacturers and merchants, it’s bad for you—the end consumer; this profitable, chemical process is the reason for the ever-increasing incidence of trans-fat related disease.
Your take home message:
Because of their high heat stability, saturated fats (and some mono-unsaturated oils such as avocado and macadamia oils) are the best choice for cooking—as they can withstand higher temperatures without being damaged.
On the other hand, polyunsaturated fats such as corn, soy, sesame and canola, because they are susceptible to heat damage, should never be used for cooking. And highly polyunsaturated oils (like those from flax, hemp, and fish) are so susceptible to damage, they should not only be protected from heat but from oxygen and light as well. They should be kept refrigerated in an opaque container, and used within 45 days after opening.