Fats are a contentious issue and get a lot of bad press, however they are an essential part of our diet. Not all fats are created equal and it is important to understand the different types of fats as well as their effects on health – both positive and negative.
Did you know that eating fat does not make you fat? Shock! (Unless of course you’re eating lots of over-processed, heat-treated, rancid fat – that’s not going to help your cause one iota).
Fats have several important roles to play:
When talking about fats it’s not as simple as saying ‘this fat is good’ and ‘this fat is bad’. Unfortunately this is what the medical industry has been saying to us for several decades – saturated fats are bad, polyunsaturated fats are good. Rarely is nutrition as cut and dried as this. When discussing the benefits and risks of different foods, it is important to assess it in the context of the whole diet. Fats are no different. In order for us to get the best nutrition from our fats, we must consume them in the right ratio and as part of a healthy, balanced diet. We must also make sure that the fats we consume are of the highest quality and not over-processed and rancid.
Polyunsaturated fats are liquid at room temperature and are found mostly in vegetable oils such as soy, corn, sunflower and canola oils. They are not very heat stable and consequently go rancid very easily during storage, processing and cooking.
The mainstream consensus is that polyunsaturated fats are good for us and that they do not contribute to heart disease like saturated fats do.
Unfortunately, because polyunsaturated fats go rancid so easily, they actually do contribute to many health problems. Rancid oils contain free radicals that, as we know, rampage around the body causing inflammation, premature aging and cancers etc. When blood vessels become chronically inflamed, cholesterol sticks to them causing blocked arteries. Poor quality polyunsaturated oils contribute to cardiovascular disease far more than good quality saturated fats. Also eating polyunsaturated fats in the incorrect ratio causes inflammation as we shall see below.
The safest way to consume polyunsaturates oils is to only buy cold-pressed oils and not to heat them to a high temperature during cooking. Any oil that does not specify that it is cold-pressed has been extracted using a heat or chemical method and will contain free radicals.
Don’t buy margarine. Margarine, due to the manufacturing process, is full of rancid oils. The oils in margarine undergo several stages of processing to get to its semi-solid spreadable state. It is steam-cleaned, deodorised, bleached, hydrogenated and coloured to turn the original liquid oils into a product loosely resembling butter. Several of the stages involve the oils being subjected to very high temperatures which promotes the formation of free-radicals. The hydrogenation stage turns the liquid oil into a semi-solid substance but in doing so creates trans-fats. These have had a lot of press in the last few years as they become implicated in more and more health problems (including heart disease, which margarine was originally supposed to protect against). Margarine manufacturers must now label their products with the amount of trans-fats they contain and many are looking at different ways to turn liquid oils into semi-solid fats without creating trans-fats. This does not change the fact that margarine is very far removed from anything resembling a natural food. Repeat after me: Margarine is not a healthy alternative to butter!
These are the most common types of polyunsaturated fats found in our food and are termed ‘essential’ because they cannot be made in the body – we must obtain them from our diet. The problem is that our Western diet favours consumption of omega 6 over omega 3, leading to an imbalance of these fats.
The average Western diet contains a ratio of 15:1 omega 6 to omega 3 fatty acids. Some sources suggest that humans evolved consuming omega 3 and 6 fatty acids in equal parts, so you can see how out of balance we have become. It is recommended that a healthy balance is a maximum of 3:1 omega 6 to omega 3.
Omega 6 fatty acids have an inflammatory effect in the body when consumed in a high ratio compared to omega 3 fatty acids. They have been linked to cardiovascular disease, autoimmune diseases and cancers. In contrast, an increased amount of omega 3 fatty acids in the diet reduces the incidence of these diseases by exerting an anti-inflammatory effect in the body.
Examples of omega 6 fatty acids include GLA (gamma-linolenic acid) and linoleic acid. Sources include:
Omega 3 fatty acids include ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Sources include:
As you can see, both groups contain healthy whole foods that should be included in the diet. Many foods contain both omega 3 and omega 6 fatty acids (as well as saturated and monounsaturated fats). Omega 6 fatty acids are not bad, per se. The problem comes when they are consumed in large quantities in relation to omega 3 fatty acids.
Some suggestions of how to regain this balance are to increase consumption of fish and seafood, reduce consumption of polyunsaturated vegetable oils and make sure your meat comes from grass-fed animals.
These fats are liquid at room temperature, turning solid or semisolid when refrigerated.
Some sources include:
Monounsaturated fats have been associated with reduced risk of cardiovascular disease and neurological diseases such as Alzheimers. The Mediterranean Diet which also shows protective qualities against degenerative diseases, is high in monounsaturated fats (mostly in the form of olive oil). In fact, the Mediterranean Diet is considered to be a fairly high fat diet. However it is also high in fresh fruit, vegetables, fish and meat which all needs to be taken into account when assessing it’s health benefits.
Monounsaturated fats are more stable than polyunsaturated fats meaning they do not turn rancid as easily and can handle slightly higher cooking temperatures. However it is still important to choose cold-pressed monounsaturated oils as oils that are not cold-pressed will likely be rancid and contain free radicals.
Saturated fats are solid at room temperature and very heat stable meaning that they do not easily turn rancid, even when used for cooking. Examples of some saturated fats in our diet are:
All these fats are an important part of your Real Food diet.
Saturated fats have been blamed for clogging arteries, causing atherosclerotic plaques and contributing to cardiovascular disease. We have been taught that if we eat a high amount of saturated fat in our diet we will end up with high cholesterol and blocked arteries and increase our risk of having a heart attack.
Actually saturated fats are an important part of our diet and have several functions in the body:
As we have already seen, polyunsaturated oils actually carry a far greater risk to cardiovascular disease than saturated fats.
Despite all the warnings from government health organisations for the last few decades that saturated fats increase cholesterol in the blood, it was not until 2005 (!) that we discovered the actual mechanism in the body that causes this to happen. Up until this time we had observed the effect but did not know how or why it happened.
Science stuff: All our cells contain cholesterol – it is needed to provide structure to the cell walls as well as performing several other important functions. When our cells need more cholesterol they switch on genes that cause more cholesterol to be made inside the cell. They also switch on receptors on the outside of the cell which allows cholesterol in the blood to be pulled into the cell (with the help of LDL which attaches to the cholesterol molecule so it can be transported). Once the cells have enough cholesterol, these genes and receptors are switched off.
This is fairly straightforward and shows our body’s amazing capacity to regulate itself. What we have only just discovered is that when exposed to high amounts of saturated fats, the liver cell switches on the gene to make cholesterol inside the cell but switches off the receptor that pulls cholesterol in from the blood. This means that the LDL-cholesterol continues to circulate in the blood instead of being transported to the cells. A high blood LDL reading is considered to be one of the risk factors for cardiovascular disease. Remember, though, that circulating cholesterol does not stick to artery walls unless those arteries are already damaged by inflammation.
So now we know how dietary saturated fats cause an increase in LDL-cholesterol but we still don’t know why. The complicated biochemical chain of events that causes this to happen has evolved for a reason. Our ancestors ate a diet high in saturated fats and our bodies have evolved over thousands of years to deal with this. Are we really sure that the rise in LDL-cholesterol that is caused by saturated fats is a bad thing? The answer is no, we’re not sure. Scientists are only just starting to consider the possible benefits of this regulatory system. This system has evolved for a reason, we just don’t fully understand that reason yet.
Saturated fats alone are not a problem. When they are eaten as part of a traditional diet that also includes a rich variety of antioxidants in the form of fresh fruit and vegetables they show many health benefits (eg the Mediterranean Diet). The problems we see with saturated fats is when they are consumed with high amounts of sugar and processed foods and low amounts of fresh fruit and vegetables. When studies show a relationship between high quantities of dietary saturated fats and heart disease, they generally fail to take into account the rest of the diet. Another important distinction to make is the quality of the saturated fat that is consumed. Saturated fat that has been processed and refined and is rancid will have negative effects on your health, contributing to inflammatory diseases. Rancid fats behave very differently in the body to fresh, natural, high quality fats.
Sugary, refined foods and rancid vegetable oils cause inflammation in the body and we now know that inflammation is the root cause of cardiovascular disease. The answer, therefore, is not to reduce intake of saturated fats, but to reduce intake of refined and inflammatory foods that cause circulating cholesterol to stick to our artery walls. Without inflammation, cholesterol just carries on circulating happily without causing any problems.
Our diet is highly complex and the interplay between all the nutrients we consume and our body’s biochemistry is not something that can be broken down into simple hard and fast rules (too much of x is bad, eating more of y is good). Giving dietary advice without considering the whole of a person’s diet (and lifestyle) is meaningless. We also have different responses as individuals, so what is beneficial to one person may not be for the next.
This is what is important about eating a traditional diet. By eating a wide variety of natural, real food we are able to maintain health without counting calories and weighing our serving sizes.
For more information on consuming fats and cholesterol in the diet have a look at this Weston Price Foundation page. It provides very comprehensive, easy to read, referenced information.