Complex and Risky
Delving deeper into the world of fats and oils.
By Isla Burgess
...They divided fats into two groups, ‘Everyday fats' and ‘Fats to watch – reduce or avoid'. The advice given in this article would have me believe all vegetable oils are the ‘goodies' such as sunflower, soybean, corn and safflower , polyunsaturated margarines, canola oil, flaxseed oil and walnut oil, while saturated fats and with trans-fats are the ‘baddies'.
Complex and Risky
Delving deeper into the world of fats and oils.
By Isla Burgess
I read the July 17 Bulletin article by the Tairawhiti Dieticians on ‘Heart health: focus on fats' with much interest.
They divided fats into two groups, ‘Everyday fats' and ‘Fats to watch – reduce or avoid'. The advice given in this article would have me believe all vegetable oils are the ‘goodies' such as sunflower, soybean, corn and safflower , polyunsaturated margarines, canola oil, flaxseed oil and walnut oil, while saturated fats and with trans-fats are the ‘baddies'.
Let's delve deeper into what really is a healthy fat or oil, and what the best choices are when you look at the array of different oils on the supermarket shelf, including the more recent phenomenon of rice bran oil.
Basics
Why are fats and oils so important?
They provide a concentrated source of energy, are found in every cell membrane ( as fatty acids) and form a part of our hormones.
They also slow the absorption of digested food so the body feels more satisfied and act as carriers for the important fat soluble vitamins A, D, E and K. They take part in converting carotene (the orange pigment in vegetables) to Vitamin A, they are also involved in mineral absorption and a number of other biochemical processes.
This means our choice of oils is pretty important to our overall health and wellbeing. The method used to extract the oil can help us in our choice, and a knowledge of the fatty acids present can give us an idea of how many additives are added to keep them from going rancid.
As soon as we extract an oil from its whole part (seed or fruit) rancidity is a problem, and when the oil is then put into a plastic container the problem gets worse.
Butter or Margarine?
Margarines are a highly processed substance. They begin with a vegetable oil such as canola or soybean and the processing can involve any or all of the following – de-gumming, refining, bleaching, deodorizing, preservative addition, and de-foaming. This is all before they are hydrogenated.
All margarine has gone through some degree of hydrogenation to solidify the oil. The trans-fatty acids produced as a result of this, range from 0.4% to 5% -- the cheaper the margarine, the higher the trans-fat.
Minerals, proteins, fibers, fatty acids, beta carotene and Vitamin E are all lost in this process and what we have remaining is a non nourishing, plasticised substance with solvent residues from the oil extraction, and some hydro-peroxides are also produced when the essential fatty acids were oxidized during processing.
Is it food? No. Is it harmful? Likely.
To quote the Tairawhiti dieticians article, “….trans-fats raise blood cholesterol and increase the chance of heart disease.” Not really much different from butter.
Butter in comparison is not a highly processed food, contains linoleic acid, Vitamins A,D and K. How has it got such bad press? Well, we just ate too much of it.
It is a concentrated food, high in saturated fats which will make the cell membrane stiffer, and it can increase cholesterol if used in excess. When you weigh everything up though, it comes out on top, but the critical factor is how much is okay?
Depending on who you are, your age, health, and how much you exercise you do, somewhere between a teaspoon and a dessertspoon daily is a good guide, but if you do not want to use either read on…
Canola, Polyunsaturates or Olive oil?
Most oils on the supermarket shelf are made from seeds, the exception is olive oil, which is from a fruit.
Oils from seeds require an extracting solvent and of course they all say that the solvent is removed. We will look at that in the section on rice bran oil. Often the claims are ‘cold-extracted' – well what does that mean?
It takes around 65-70 degrees C to ‘burn off' a solvent – although some residue invariably remains. The ‘cold extracted' claim then only relates to part of the process. Now these oils are polyunsaturated, which means they have many double bonds that are vulnerable to oxidation by exposure to heat and light, and so need a lot of added compounds to stabilize them.
Extra virgin olive oil does not require a solvent – it is ‘cold pressed', is not exposed to any heat and has all of its nutritional constituents intact. It is a monounsaturated oil – which means is that it has only one double bond in its chemistry per molecule to potentially be oxidized and therefore produce free radicals. We can overcome this by sautéing olive oil in onions and garlic, use a powder of Rosemary, Sage and Thyme and the problem is solved. The onions and garlic have anti-oxidant actions and so ‘mop up' the tiny number of free radicals produced by heating. The herb powder has a plethora of strong antioxidant plant chemicals which gives further protection. This, I believe, is the secret of the ‘Mediterranean diet'. If you are heating oil in sweeter dishes then add some finely grated citrus peel to the dish for a similar effect.
Rice bran oil, friend or foe?
Rice bran oil has been boosted by an intensive marketing campaign focusing on stability at high temperatures.
Rice bran is one of the most fragile oils there is, and it becomes rancid within minutes of extraction – and this tells us a lot about what is needed to stabilize it at high temperatures. It cannot be cold pressed but requires hexane, a petrochemical by-product, to extract it. This means that it is then heated to 70 degrees C to remove the hexane, although I am not convinced residues don't remain.
Why would you use it?
Gisborne's finest
In addition to my last article on using ‘local not global', I discovered that we have our very own Gisborne extra virgin olive oil. This is made by Repongaere Estate and I have used it for both salad dressings and in sautéing.
It is light, slightly greenish tasting and quite delicious. It does not overpower the tastes of other food to which it is added. You can even buy a soap made from the same.
Summary- making sense of it all.
• Don't buy ANY oil in a plastic container – they will leak endocrine (hormone) disrupters into the oil.
• Choose a LITTLE butter (1 teasp to a dsp) over margarine.
• OR use avocado or tahini or almond butter instead of butter as a spread. Tahini with honey on bread is delicious.
• Use only extra virgin olive oil in a coloured glass bottle to reduce damage by light – best if produced locally and add onions, garlic and herbs if heated. Store in a cool place away from light. Note the use by date.
• Read all labels – most processed foods contain soy and/or margarine.
• If you really do have to have a fried egg, use a little olive oil and a little butter (1 teaspoon), the butter will burn (turns brownish) at a temperature at which the constituents of the olive oil are likely to be damaged, so you know if you have overheated the oil.
Do plants contain essential fatty acids?
This question was asked of me recently and the answer is yes they do, but only in minute amounts, not enough to cover your daily needs. The exception to this is a herb/weed that you all pull out of your gardens in the summer. It is Portulacca oleracea or purslane and for a plant it has substantial levels of omega 3 fatty acids.
Further reading.
If you really want to get to grips with the complexity of the world of fats and oils I suggest reading ‘Fats that Heal and Fats that Kill' by Udo Erasmus.
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