There are many a many a many different sources of fat we’re told to cook with, take in dietary supplement, add to our prepared foods or just plain avoid like the plague. The aims of this post are to try and debunk some of the myths and help you make positive choices about your daily eating.
Fat is a really important part of our daily diets as it helps the body absorb vitamins A, D and E. These vitamins are fat-soluble; meaning that they can only be absorbed by the body with the help of fats. Any fat not used by your body’s cells or to create energy is converted into body fat. Likewise, unused carbohydrate and protein are also converted into body fat.
The fat you eat is broken down during digestion into smaller units of fat called fatty acids. There are some you may have heard referred to as essential fatty acids, such as omega-3. This is termed “essential” because the body can’t make these fatty acids itself. I’ll return to these essential fats later in the post.
All types of fat are high in energy. A gram of fat, whether saturated or unsaturated, provides 9kcal (37kJ) of energy compared with 4kcal (17kJ) for carbohydrate and protein. This is one reason why high fat diets are being given attention by top athletes.
The main types of fat found in food are saturated fats and unsaturated fats. Most fats and oils contain both saturated and unsaturated fats in different proportions. Lets have a little look at what these fats are and how they effect you;
Monounsaturated fatty acids (MUFAs) are found in avocados, olive oil, and many types of nuts. MUFAs are often popularised as good and healthy fats, they are liquid at room temperature and turn solid when they are chilled.
Biochemically speaking, these fatty acids have a single double bond in their fatty acid chain. The more double bonds a fatty acid boasts, the more “fluid” it is.
MUFAs have been thought to help decrease risk of breast cancer, aid in weight loss in comparison to diets heavy in trans fats and polyunsaturated fats and even reduce belly fat! Furthermore, they have been linked to reducing less severe pain and stiffness for sufferers of rheumatoid arthritis.
Some of the populations that have been identified as having the longest, healthiest life spans, (such as the famed Mediterranean diets) have diets high in monounsaturated fats.
Polyunsaturated fatty acids (PUFAs) are found in grain products, soybeans, peanuts, seeds and fish oil. PUFAs have more than one double bond in their fatty acid chain. They tend to be liquid even when refrigerated.
As with MUFAs, PUFAs also tend to go rancid easily, particularly when heated, which in turn causes oxidisation and plenty of free radical damage in the body. The free radical damage to the body can result in cell membrane damage causing issues from wrinkles to arterial plaque build up.
Polyunsaturated fats can help lower the level of LDL cholesterol, which we’ll go into some more detail on later. Polyunsaturated fats are also thought to protect against cardiovascular disease by providing more membrane fluidity to cells than that provided by monounsaturated fats.
PUFAs have also been shown to aid towards reducing insulin resistance as opposed to the insulin resistance promoting monounsaturated fats.
Omega-3 & Omega-6
There are two types of polyunsaturated fats: omega-3 and omega-6. Some types of omega-3 and omega-6 fats cannot be made by the body and, as highlighted earlier in the post, are classed as essential fats.
Omega-3 fats are found in oily fish such as mackerel, kippers, herring, trout, sardines, salmon and fresh tuna. Omega-3 appears to decrease the risk of coronary artery disease. There are plant sources of omega-3 fatty acids. However, it hasn’t yet been determined whether replacements for fish oil, plant-based or krill, have the same health effects as omega-3 fatty acid from fish.
Omega-6 fats are found in vegetable oils such as rapeseed, corn, sunflower and some nuts. Omega 6 fats are often painted as the enemy of those trying to achieve a healthy lifestyle. This is because a diet heavy in theses oils can cause significant inflammation in the body which in turn causes a breeding ground for conditions such as heart disease, cancer and diabetes.
Although it is true that many of the unhealthy sources of processed and inflammatory foods contain omega-6, so do healthy foods including nuts and seeds. What is being seen now though with the established nature of mass, industrialised farming, is that livestock, (including farmed fish), are being fed a diet heavy in grain. Grain is of course laden with omega-6 fatty acids. This in turn alters the fat profile of the animal’s digesting them, to have a high pro-inflammatory omega-6 presence.
Once upon of time these animals would have fed upon grass or, in the case of fish, other water based organisms, making their fat profiles far more omega 3/6 neutral. This is of course not even taking into account the impact of antibiotics and growth hormones often found in factory farmed animals.
While most of us get sufficient omega-6 from healthy sources in our diet, what is needed is balance. Omega-3 and omega-6 ratio is the term used to discuss the balance of these essential fatty acids in the body. Both omega-3 and omega-6 compete for this space, so diet is all-important.
Many people who eat a lot of processed foods will have higher Omega 6 levels in their body in comparison to the omega 3. This in part will be the types of oil in our foods. The most common source of omega 6s is linoleic acid, found in corn oil, soybean oil, safflower oil, cottonseed oil, sunflower oil, poultry, and some nuts and seeds. These oils are cheap to produce, so many companies use them in processed foods like chocolate, cookies, crackers, popcorn, granola, dairy creamer, margarine, frozen pizza, and other snacks.
Estimates vary, but experts generally characterise Western diets as anywhere between 10-30 parts omega-6 to 1 part omega-3 (10-30:1). Although many experts will to tell you that 4:1 is good enough, striving for 1:1 is optimal.
So, what about the other oils? What about olive oil? The ratio for olive oil is 3:1. Olive oil is 75% monounsaturated and 14% saturated, which means that only 11% of it has the polyunsaturated ratio to begin with. In these relatively small amounts, ratio isn’t as much of a concern, particularly when the oil contains so many other good compounds like polyphenols that fight inflammation damage caused, in part, by the problematic ratio. Corn oil, on the other hand, contains only about 25% monounsaturated fat (and 13% saturated). The ratio matters big time here.
A saturated fat is one which is mainly the product of animal fats (barring coconut and palm oil). These are fats such as those found in dairy, cuts of meat and meat cooking fats such as lard, talo and goose fat. Saturated fats tend to be solid at room temperature.
The fatty acids that comprise saturated fats all have single bonds. Saturated fats have all available carbon bonds paired with hydrogen atom which long story short makes them highly stable. They don’t have the same tendency toward rancidness as polyunsaturated fats, even if heated. This is a good thing, especially in the context of cooking.
Saturated fats serve critical roles in the human body. They make up 1/2 of cell membrane structure. They enhance calcium absorption and immune function. They aid in body’s synthesis of the essential fatty acids and provide a rich source of fat-soluble vitamins.
Cholesterol is a molecule that is absolutely vital to life. Every cell membrane in our bodies is loaded with it. It is used to make hormones like cortisol, testosterone and estradiol. Without cholesterol, we would die. The human body does make its own, but it needs some support. Saturated fats provide cholesterol.
Saturated Fats Increase The Size of LDL Cholesterol. However, a protein that carries cholesterol in the blood, low-density lipoprotein (LDL), has been associated with an elevated risk of heart disease. New data however shows that there are subtypes of LDL:
- Small, Dense LDL: Particles that are small, dense and can easily penetrate the arterial wall.
- Large LDL: Particles that are large and fluffy like cotton balls. These particles are not as well associated with an elevated risk of heart disease.
Saturated fats raise the large subtype of LDL — which means that the cholesterol-raising effects of saturated fats (which are mild) are mostly irrelevant.
Saturated Fats Raise HDL Cholesterol. HDL (high density lipoprotein) is also known as the “good” cholesterol. It transports cholesterol away from the arteries and towards the liver, where it may be either excreted or reused. The higher your HDL levels, the lower your risk of heart disease, and saturated fats raise blood levels of HDL
Artificial trans fat
Ok, so these nasties are the scourge of any would be health conscious individuals shopping list. They can be found in biscuits, cakes and margarines. Trans fats (or trans fatty acids) are created in an industrial process that adds hydrogen to liquid vegetable oils to make them more solid. The primary dietary source for trans fats in processed food is “partially hydrogenated oils.” Look for them on the ingredient list on food packages
Artificial trans fats can be formed when oil goes through a process called hydrogenation, which makes the oil more solid (known as hardening). This type of fat, known as hydrogenated fat, can be used for frying or as an ingredient in processed foods. (Quick fact: the hydrogenation process changes the position of hydrogen atoms in the fatty acid chain.)
Artificial trans fats can be found in some processed foods such as biscuits and cakes, where they are sometimes used to help give products a longer shelf life. However, in recent years many food manufacturers have removed trans fats from their products.
The unnatural chemical modification process that created trans fats made products more shelf stable but has wreaked havoc in the bodies of those who ingest them. Trans fats, have been associated with inflammation, associated atherosclerosis, diabetes, obesity and immune system dysfunction.
So, as we’ve seen on the big fat journey, things are not clear as they seem, or as we’re told. I think untimely the take away is that fat is an essential part of everyone’s diet and as is already being observed in the food industry with organic, etc, the quality does matter.
Unsaturated fat is an important addition from natural food sources but not when used for cooking. The balance of omega-3 and omega-6 are essential by name and essential by nature. What is needed is the right balance, so look to supplement but more importantly, up your oily seafood intake and lower your grain based oils, processed foods and products such as margarine.
Lastly, saturated fats, the long time bad guy. Saturated fats are not just ok, but actually really important in your diet to ensure longevity. Not only are saturated fats crucial in our diets through food but they are also they only fats we should be using when cooking. We can see now the importance of cholesterol and how saturated fats are not the enemy of promoting this vital molecule.
Ok, well I’ve banged on a fair old bit now. Thanks for staying with me for what’s been a pretty long read. As ever, please share the article and give me some feedback!