Whenever I give a talk about nutrition and healthy eating to groups, or during my cookery demonstrations I am always getting asked about fats, which are safe to use and which ones to avoid. I think most of us appreciate through all the media interest and numerous articles that are published that some fats are hugely beneficial and in fact essential and some are to be avoided because of their negative effect on our health.
Whether a fat is good for you or not depends on its chemical structure and whether it has been heated or processed in any way. The main groups of fats that we have are :
- Saturated fats
- Poly unsaturated fats
- Mono unsaturated fats
You may also have heard of fats that are hydrogenated and ‘trans’ fats (for those who are interested I will explain a bit more about these below).
So what are the differences between these and which are the beneficial ones and the ones to be avoided?
Well, the first thing I would say is basically, a fat that is in its natural form without any tampering from the food industry will do no harm. Even the saturated fats that get all the bad press are fine in moderation.
The reason people are advised to eat saturated fats in moderation is because they can contain high levels of cholesterol which is well reported as being bad for our health particularly for blood pressure and heart health. There are however authors writing research journals who believe that high cholesterol leading to cardiovascular problems is contentious, but that aside, generally we are told to keep the amount of these fats that we eat to a minimum.
Then of course we have all the mono unsaturated fats and polyunsaturated fats. Understanding which to choose and why can be a bit of a minefield.
Guide to choosing fats
To help with the understanding of this I created a guide to choosing fats, clearly showing which are beneficial and can be used freely and those which are best avoided if possible. I have had positive feedback about this and how useful it has been so thought that I would share this with you. It is a little bit formal but I think the best way to explain things.
Focus on eating the following types of fats.
- Coconut oil, Rapeseed oil and Olive oil are the best for cooking because their chemical structure makes them more heat stable, they do not become damaged when heated as other fats and oils do.
- Nut and seed oils that have been cold pressed i.e. no heat has been applied when manufacturing so no damage to the fat has occurred, are suitable for using cold as salad dressings. These are usually sold in dark green glass bottles. Examples are sesame seed oil, pumpkin seed oil, hemp oil, walnut oil and flaxseed oil. These fats are rich in the essential fatty acids omega 3 and omega 6 that I mentioned in our first blog. They should not be heated because heat destroys their nutritional value and causes the natural structure of the fat to become distorted and therefore a potential health risk.
- Eat a mixture of unsalted nuts and seeds as a snack as these are rich in the essential fatty acids omega 3 and 6. These essential fatty acids are absolutely essential because we do not make them in our bodies ourselves. They are transformed in the body into prostaglandins which are hormone like substances. These carry out important tasks in the body including hormone regulation, have shown to be anti inflammatory and are said to be disease protective. (more on this in our next blog)
- Oily fish (salmon, tuna, mackerel, trout, sardines, pilchards) are rich in omega 3. It is a good idea if you can manage it, to eat these oily type of fish 2-3 times a week to gain the health benefits.
- Always try and buy oils in glass not plastic bottles. Plastics are made from chemicals (e.g. PCB’s) that migrate into the oil which we then consume. The plastics have been shown to be hormone disrupting and could be cancer forming. (this is a whole new blog).
These fats are probably best avoided if possible.
- It is best to try and reduce or avoid eating processed/damaged fats that come from convenience foods, fried foods, some tub margarines and commercial cooking fats. These fats are known as ‘Trans fats’ or ‘Hydrogenated fats’. I am sure that you have heard the words if not truly understood the meaning.
Now for the technical bit for those who want to know more…
For those of you who are interested I thought I would explain a bit about the chemical structure of fat to try and help explain how the wrong sources can be detrimental to the body. I think when someone understands the reasons behind recommendations, advice is easier to stick to.
Basically a fat is made up of a chain of carbon atoms linked together. To each carbon atom there are 2 hydrogen atoms. If a fat is saturated it means that all the carbon atoms have 2 hydrogen attached to each of them and there is no room for any more hydrogen. These fats are hard at room temperature. A bit like blotting paper and ink. The paper will soak up so much ink but after that it is not capable of soaking up any more. i.e. the paper is saturated.
Some fats have some Hydrogen missing on the carbon chain. If it is only one pair of hydrogen missing then these are known as ‘mono unsaturated fats’. Mono meaning one. If the carbon chain has many missing hydrogen pairs this is known as poly unsaturated. Poly meaning many.
The poly unsaturated fats are the ones used by the food industry .They are runny at room temperature. In order to make them harder and therefore spread straight from the fridge etc. the manufacturers add hydrogen artificially. The more hydrogen they add the harder the fat. A process known as hydrogenation. Hence the word ‘Hydrogenated’. When the hydrogen is added heat is applied.
As I have said heat disrupts the natural chemical balance of a fat. When these type of fats are eaten they can cause problems because they are processed and no longer natural. Our bodies do not have the correct enzymes to recognise processed fats so they can become a toxic burden. They can create what is known as’ Free Radicals’. Another term that some of you may have heard. These free radicals have the ability to disrupt the normal functioning of the cells, which may encourage disease to develop.
Phew!!!!! that is a lot to take in I hope that it makes sense.
I will carry on the fat theme next week and add a recipe.
Blog originally written by Caroline May 2012