Demystifying fats and oils

The subject of fat – how much is good for you, which fats are good for you and what happens when you don’t get enough or the right balance of the different kinds of fats seems to baffle most people. That’s not really surprising when you realize that most of what you read in the media is either:

• people quoting other people without bothering to check the truth of what they are saying, or
• disinformation distributed by companies and organizations with a financial gain in changing people’s behavior

What most often gets forgotten in this often emotive issue is basic biochemistry, so here I attempt to go back to that as I describe the different types of fats and oils, collectively called lipids, and how our body uses them on a chemical level. I apologize if some of the information is a little technical but I did want to give as full and complete a picture as possible.

All lipids are composed of chains of carbon atoms with hydrogen attached, which in food are most usually found joined together in 3s.  The different names that we give the fatty acid chains – saturated, mono-unsaturated, poly-unsaturated and trans are simply ways of categorizing the different ways in which the carbon and hydrogen atoms are arranged along the chains;

Saturated fatty acids have two hydrogen atoms for every carbon atom (in other words the carbon chain is saturated with hydrogen). The carbon chains in these fats pack together very tightly and so they are solid at room temperature. These types of fatty acid chains are often found in animal fats, but cocoa butter, coconut oil and palm oil are also rich in saturated fatty acids. SFAs don’t go rancid easily because chemically they are quite stable, so they are less likely to contribute to systemic inflammation than other fatty acids, and are great for cooking.

Over the past 50 years SFAs have wrongly received a lot of bad press, having been linked incorrectly with heart disease, high blood pressure and even cancer but the truth is that they are of critical importance to health and perform many important functions including protecting our internal organs, providing fuel for our bodies, transporting the fat soluble vitamins A, D, E and K, strengthening our cell membranes and our immune systems, and even enabling minerals to be absorbed into our bones.

Mono-unsaturated fatty acids (mono = 1) have one double bond between 2 of the carbon atoms and the chain is missing a pair of hydrogen atoms. This means that there is a ‘kink’ in the chain at the point of the double bond, and so these fatty acids don’t pack together quite as tightly as the saturated ones. This means that they are liquid at room temperature and for this reason they are commonly called oils. Monounsaturated fatty acids are found throughout nature, most often in nut or fruit oils in combination with powerful antioxidants such as vitamin E or polyphenols such as those found in extra virgin, cold pressed olive oil, which is why they have been linked with heart health.

Because they are chemically more unstable then saturated fats, oils with a high proportion of monounsaturated fatty acids in need to be treated with care i.e. kept in dark glass and not exposed to extremes of temperatures, light or air, or they will oxidize and form free radicals which can damage cell walls. When these oils are processed they lose much of their health benefits, so when purchasing always choose cold pressed, unrefined oils, and try and use them either raw, or heated to moderate temperatures only.

Poly-unsaturated fatty acids (poly = more than 1) have 2 or 3 double bonds along the chain and are therefore missing 2 or 3 pairs of hydrogen atoms. These types of fatty acids have several kinks at the points of the double bonds and are also liquid at room temperature, but they are very chemically unstable because of all of the double bonds and form free radicals very easily. Oils containing high proportions of polyunsaturated fatty acids should NEVER be heated, exposed to light / air and have a short shelf life – interesting when you think that all of the common vegetable oils used by the processed food industry fall into this category – corn oil, soy oil, canola oil, safflower oil, sunflower oil etc. The body uses polyunsaturated fatty acids for cell membrane flexibility, for brain development, immune function and the production of localized tissue hormones so it is critical to good health that these fatty acids should not have been damaged in any way.

Polyunsaturates can be classified by where the first double bond is along the carbon chain; omega 3 fatty acids have their first double bond 3 carbons from the (methyl) end, and omega 6s have their first double bond 6 carbons from the methyl end.

Essential fatty acids

There are two essential polyunsaturated fatty acids that the body cannot make, and which have to be obtained through diet. The first is an omega 3 fatty acid called alpha linolenic acid, which is a significant component of flax seed oil and the ‘parent’ omega 3 fatty acid (all the other omega 3s e.g EPA and DHA are derivatives). The second essential fatty acid is an omega 6 fatty acid called linoleic acid, which is the parent omega 6 fatty acid and found in large quantities in most vegetable oils. In the body one of the functions of essential fatty acids is to form localized tissue hormones which in general (there are some exceptions) are anti-inflammatory when they are made from omega 3s and pro-inflammatory when they are made from omega 6s. The body needs both in about equal proportions, but because of increased vegetable oil consumption most people these days consume far more omega 6s than omega 3s. This significantly contributes to health problems associated with increased inflammation over time – not only because it disrupts the balance of essential fatty acids but also because of the large numbers of free radicals found in the processed oils.

Artificial trans-fats are man made fats which started out as naturally unsaturated but which have had extra hydrogen forced into their structure using a process called hydrogenation, so that they look (but they don’t act in the body) similar to naturally occurring saturated fats. These fats are VERY unhealthful and should form no part of a healthy diet – they have been linked to cancer, diabetes, heart disease, vascular problems and obesity. Unfortunately for people who eat a lot of processed foods, trans fats are EVERYWHERE as they allow cheap oils like soy oil which are usually liquid at room temperature to be used in place of more expensive fats like butter or coconut oil. They are also created during the refining process of many vegetable oils, where they don’t have to be listed on the label; try and find a pre-prepared meal or snack that doesn’t contain vegetable oil and you will see how common these adulterated fats are in most people’s diets.

Natural, unprocessed fats have important health benefits

As you can see from the descriptions above, each different type of naturally occurring fatty acid has different functions to perform in the body, and so they are all important to a balanced diet. Sadly, many of the early studies that linked saturated fats to heart disease and cancer included man made trans fats in their calculations; later studies and epidemiological evidence which excluded trans fats did not produce the same negative results. Unhappily for most people (but happily for the vegetable oil industry!) the damage had been done though, and saturated fats started to be known as ‘bad fats’ - this is now just being repeated over and over by a media which has never looked at the science behind what they are saying. Ironically once people started to eat LESS saturated fat, and MORE processed, refined unsaturated oil, rates of degenerative disease began to rise. We are told that we eat too much fat, but the truth is that we don’t get the right balance of fat, particularly of the essential fatty acids, and the quality of the fats and oils we eat is poor.

But what about cholesterol?

Here we encounter probably the biggest health myth circulating today, which is the myth that foods high in cholesterol, which by definition are foods also high in saturated fat, are the cause of arterial plaque formation and heart disease. Nothing could be further from the truth but sadly millions of people worldwide have replaced many of the healthy, natural foods that nourished our ancestors for thousands of years with low fat and / or man made alternatives, doing themselves a disservice in the process.

Rather than being the villain that it is made out to be, cholesterol is in fact vital to your health, and your body will simply make what it needs if it doesn’t get enough from your diet. Some of the many functions of cholesterol include the manufacture of vitamin D, providing the raw materials for the steroid hormones, boosting the immune system and repairing arterial walls which have been damaged by systemic inflammation. If your LDL cholesterol levels are high your body is simply responding to damage already done, and trying to repair itself; blaming the LDL cholesterol for the damaged arteries is a little like blaming a sticking plaster for a wound – it’s not the sticking plaster’s fault, and instead of focusing on the repair substance we need to be focusing on what caused the problem in the first place.

So how much fat do we actually need?

The bottom line is this - we are all different and need different amounts of fat to stay healthy, but apart from man-made trans fats, the concept of ‘bad’ fats and ‘good’ fats is just plain wrong and not supported by either basic biochemistry or good science. Some people like me, with a slow burning metabolism, do very well on a diet with a moderate amount of fat but others need more. You can usually tell whether you are getting enough fat in your diet by how you look and feel, with a big indicator being the health of your skin and how much energy you have.

Instead of obsessing about the amount of fat in our diet, we should be focused on the quality of the fats that we consume, as oxidized fatty acids are so strongly linked to systemic inflammation. We should also be making an effort to balance our intake of the 2 essential fatty acids – omega 3s and omega 6s.

If you would like to ask a question about this topic, which has only been very briefly covered here, please contact Flourish.