Oh so many questions arise when we start to consider this topic! To complicate it, you will receive different advice and opinion depending who you ask!
My suggestion is to ask widely and work out what makes sense to you. It’s your body after all!!
On that note, here’s my opinion, garnished from a great deal of reading and blended with common sense. Several references are included at the end of the article.
For any reader who is familiar with my approach to food and health, you will know that my by-line is to ‘let nature be the doctor’. Our bodies are intended to function without artificial intervention and without artificial foods. When we feed our bodies appropriately, health and healing are a continuous, renewing process.
Now, to the topic, which fats and why?
There are three main categories of fats that we consume – saturated fats, monounsaturated fats and polyunsaturated fats.
Most fats that we eat actually contain all three categories, but in different ratios. What differentiates them is the structure of their carbon-hydrogen atom linkages.
Saturated fats have a molecular structure that has all available carbon atoms surrounded by hydrogen atoms. In this stylized diagram, the carbon atoms are the black connection points and the hydrogen atoms are the white ones that hang from the black points.
This gives saturated fats two particular characteristics that are important to understand. Due to this molecular structure that has carbon atoms ‘saturated’ by hydrogen atoms, (a) the shape of these fat molecules is very straight so that they can pack tightly together and remain firm even at room temperature; (b) when they are heated, the ‘saturation’ by the hydrogen atoms means that the fat molecules remain stable under the stress of heat, and free radicals will not be formed under normal heating conditions.
The firmness of the fat is demonstrated when you think of animal fat left at room temperature, it does not melt or turn to clear liquid. It will soften but that’s all. These two characteristics mean that saturated fats are the ideal choice for cooking such as roasting, stir frying and deep frying. Animal fats such as ghee, lard, tallow and butter are saturated fats. Coconut oil is also a saturated fat.
Monounsaturated fats have one double-carbon bond that does not have hydrogen protecting it – hence the word ‘mono’ meaning one bond that is not protected by hydrogen.
This one unprotected bond means that the fatty acid will have a slightly bent molecular structure at the position of this double carbon bond. This bent shape means they cannot stack together as tightly and will therefore be liquid at room temperature but become solid in the fridge. As the carbon atoms of the fatty acid are not fully protected, slight oxidation can occur under high heat, creating free radicals that can then harm the body. Oil from fruits and nuts such as avocado, macadamia and olive oil are monounsaturated fats.
They are ideal for all salad dressings and to be poured over food after cooking. They can also be used for mild sautéing such as mushrooms when the heat is moderate.
Polyunsaturated fats, as the name suggests, have many (‘poly’) carbon bonds that are not surrounded (‘unsaturated’) by hydrogen.
As a result these fatty acids have ‘many’ bends in the fatty acid chain, which means they do not stack closely together, so are always liquid at both room temperature and in the fridge. This is why they are called ‘oils’ rather than ‘fats’. The unpaired electrons at the double bonds makes these oils highly reactive and therefore very vulnerable to oxidation, so should never be heated. Fish oils and vegetable oils such as sunflower, flaxseed, corn, soybean and canola oil are all polyunsaturated fats. Margarine also falls into this category. There’s a very important caveat to the use of PUF’s (poly-unsaturated fats) that I cover later in the article.
What Else Should You Know?
All these types of fat are important in our diets. However, there are two additional points to keep in mind when you choose your fats to ensure the healthiest results. We need to consider (1) what we are using the fat for, and (2) how it has been sourced and processed, to really determine its worth to our health.
- What are you using the fat for?
If you would like a simple approach, here is a practical guide:
- Use saturated fats for cooking at higher temperatures such as stir fry and roasting
- Use monounsaturated fats for low temperature cooking such as sautés, and use liberally for salad dressings
- Use polyunsaturated fats very sparingly, only for salad dressings and never for heating. Never eat margarine. (To help understand why you should only use them sparingly, read the section below about the processing of most vegetable oils.)
If you follow that guide, you will be doing pretty well for your health. If you would like to understand more, please read on.
- How has it been sourced and processed?
The origin of the fat and the way it has been processed are also important considerations.
(a) Saturated Fats
Saturated fats are virtually unprocessed. They are naturally acquired without industrial activity. Animal fat is ‘rendered’ to clean and purify it and then allowed to solidify. Rendering is simply using a low heat and filtering process which does not impact on the structure of the saturated fat at all, it’s just been cleaned. The healthiest form of animal fat is from grass fed animals that are exposed to open pastures. This contrasts with fat from grain fed animals that have generally spent at least three months in an intensive animal feeding facility, fed a grain mix that often consists of genetically modified grains and soy products, as well as the frequent use of growth-promotants and antibiotics. These animals are producing a more manufactured fat with a different makeup than fat from pasture-raised animals, and it is much less healthy for the human body.
(b) Mono-unsaturated Fats
The most common mono-unsaturated fat is olive oil. It has always been a favourite and is widely utilised. The important point here is to always choose extra-virgin, cold pressed olive oil. These words tell you a lot. When the label contains the words ‘extra virgin’ this means it is the oil acquired from the first (‘virgin’) press of the olives. All subsequent processes probably use heat and/or chemicals to draw out more oil. The words ‘cold pressed’ means exactly that. The oil has been acquired using a cold press process without any heat or chemicals.
There is a cautionary warning for buying olive oil. When you read that the olive oil is a ‘blend’, this means that it is probably only partially pure, healthy olive oil and also contains some that has been processed with heat and chemicals, thus destroying the health qualities of the oil.
When it comes to cooking, remember to only use your extra-virgin, cold pressed olive oil for low heat sautéing. You can use it liberally for salad dressings and pouring over food after it has been cooked.
There is an exception to this cooking rule with olive oil. Sometimes you can use it for high heat cooking! When you mix it with saturated fats, they protect the molecular structure of the olive oil. This means you can rub olive oil over your roast lamb or chicken prior to roasting because it is being rubbed directly onto the animal fat that is naturally present on the outside of the meat. However, if you are roasting vegetables, it is not advised to use olive oil on its own as there is no animal fat to combine with. If you really want to use olive oil in your roast vegetables, you can overcome this by mixing it with ghee, lard or beef tallow. You can also tip the olive oil on once you are seated at the table to obtain that flavour as this is not heating the olive oil.
Other monounsaturated fats that can be used for salads as well as mild heating include macadamia oil, avocado oil, peanut oil (to be used infrequently) and sesame oil.
(c) Poly-unsaturated Fats
And now to polyunsaturated fats. These are generally deeply corrosive to the human body. Just as metal oxidises or rusts when it is exposed to the atmosphere, so too do vegetable oils when they are heated. This is because they have kinks in their molecular structure where there are double carbon bonds that do not contain hydrogen atoms to surround and protect them. For most vegetable oils, this heating begins when it is being extracted from the seed, along with chemical processes as well. This means that when you bring them home from the supermarket they are already a flawed food!
Most people buy vegetable oils for cooking. Our bodies cannot digest these vegetable oils due to their damage at the point of extraction and manufacture, as well as due to the heating at cooking time. Thus, we exhibit an inflammatory response. Margarine is a very manufactured product that is dyed to make it look like butter but our bodies know better!
I mentioned earlier that vegetable oils can be used for salad dressings. Here’s the caveat that I referred to in the first part of the article. Using polyunsaturated fats at any time should only be done with oils that have not undergone any heat and chemical extraction processes. Because the source of the oil is from seeds that are not very oily, most vegetable oils have undergone this industrial process in order to obtain the oil from the seed. One more common exception is sunflower oil that can be bought with a label that says ‘expeller expressed’. This will not have undergone heat and chemical processing. It’s hard to find but it does exist. If you do find it, this should still never be heated but can be used for salad dressings.
If this level of detail is all too confusing, then for simplicity, I recommend that you throw out all vegetable oils, eat butter, and use only olive oil for salads.
There is alot more to know about fats and oils. Please go to the recommended readings at the end of this article for further personal research. I will be writing a second article shortly looking at the health benefits of saturated fats.
In the meantime, I encourage you to do a pantry inspection and throw out all vegetable oils. These are most likely to be labelled as margarine, refined vegetable oil and canola oil, but you may also have safflower and sunflower oil in the mix.
Until next time, remember … let nature be the doctor!
References and recommended reading
“Nourishing Fats” by Sally Fallon-Morell
“The Big Fat Surprise”, by Nina Teicholz
“Know your Fats”, by Dr Mary G Enig
“Big Fat Lies”, by David Gillespie