Fat is a word that is viewed negatively and is often associated with poor nutrition. Some people believe that eating fat means getting fat, that all saturated fats are bad, and polyunsaturated fats are good. The real picture is a lot different. Here, we’ve unravelled some of the issues that have been made unnecessarily over-complicated.
We need good sources of healthy fats for a number of body functions. Put simply, without fat, we die. Some fatty acids are also essential as our bodies can’t make them, so we must eat them instead.
Fats are triglycerides (TGs). Once you’ve eaten or drank, any calories your body doesn’t need in the short-term get converted to triglycerides. They’re made up of three fatty acids with a glycerol backbone. Each type of fatty acid differs by the number and position of double bonds in their structure, and it’s the type of fatty acid present in the TG that denotes the type of fat.
There are six main groups of fats:
Saturated fatty acids (SFAs) have no double bonds in their structure. They’re most commonly found in meat and dairy products, but are also in some plant fats. SFAs have been given a bad reputation in the past due to observational studies that have linked their intake to an increased risk of cardiovascular disease (CVD) by increasing blood cholesterol levels. However, there’s more recent information which may indicate that this isn’t the case.
Monounsaturated fatty acids (MUFAs), or omega-9 fats as they’re sometimes known, have one double bond in their structure. You can find high amounts in olive, rapeseed and flaxseed oils. Having more of these fats as a proportion of our total fat intake may help to reduce our blood LDL levels (bad cholesterol), whilst keeping our HDL levels (good cholesterol) high[2, 3], reducing the risk of heart disease[4, 5].
Polyunsaturated fatty acids (PUFAs) have more than one double bond in their structure. There are two types; omega-6 and omega-3 PUFAs. As a general rule, increasing levels of PUFAs in our diet has been shown to help reduce total blood cholesterol[6, 7]. However, this also means the good HDLs may be reduced.
Omega-6 fatty acids are found in a wide range of nut and seed oils, and in foods of plant origin. Due to their cheap cost of production, many heavily processed junk foods are also high in omega-6s.
Omega-3 fatty acids are found in oily fish such as salmon, mackerel, sardines, pilchards, and trout. They can also be found in flaxseed and flaxseed oil, which is a great source for vegetarians and vegans. Read our Guide to EPA and DHA for more information. Eating a good intake of omega-3s can improve cardiovascular health[8-10], reduce some cancer risk, improve brain function, and possibly enhance athletic performance.
Fatty acids can also differ in structure at the point of the double bond, making them a trans fat. This changes the molecule’s appearance and behaviour. Trans fats are formed when liquid oils are converted into a semi-solid fat (hydrogenation). Often, they’re used in confectionery, margarines, and some heavily processed foods. These are the bad fats and we should limit their consumption.
The fats listed above are known as long chain triglycerides (LCTs). There’s another group known as medium chain triglycerides (MCTs). These are a lot rarer in nature, but are present in a few popular fats, such as coconut oil. MCTs are absorbed and metabolised differently to LCTs and are treated like an energy-dense carbohydrate source rather than a fat. MCTs are a type of saturated fat and you’ll find them under saturated on food labels.
There are two essential fatty acids (EFAs) that we need to include in our diet. These are linoleic acid (LA), an omega-6, and alpha-linolenic acid (ALA), an omega-3. There are also four conditionally EFAs. These are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both are omega-3s, and arachidonic acid (AA) and gamma-linolenic acid (GLA), omega-6s. If we don't consume enough LA and ALA, they also become essential.
|Fatty Acid||Type of PUFA||Rich dietary source|
|Linoleic acid (LA)||Omega-6||Corn, safflower, sunflower, soyabean, peanut oils|
|α-linolenic acid (ALA)||Omega-3||Flaxseed, soya, rapeseed oils|
|Arachidonic acid (AA)||Omega-6||Small amounts in animal fats|
|γ-linolenic acid (GLA)||Omega-6||Hemp seed, borage seed, evening primrose oils|
|Eicosapentaenoic acid (EPA)||Omega-3||Oily fish|
|Docosahexaenoic acid (DHA)||Omega-3||Oily fish|
So we can understand both good and bad fats, we need to understand oxidation. Oxidation is a naturally occurring process where a molecule reacts with oxygen and forms free radicals - this is where the molecule becomes potentially damaging to tissues.
Free radical formation through oxidation is involved in the process of some diseases including CVD, and some cancers, as well as aging. Although free radical formation is natural and inevitable, we can help minimise their formation and slow the damage they do.
Antioxidants are substances which help stop oxidation. These include vitamins C and E, some types of vitamin A, selenium, and phytonutrients like carotenoids and flavonoids. Eating a healthy diet rich in these substances will go a long way to help slow down oxidation.
CVD is the term that covers heart disease, stroke, and peripheral vascular disease. The process of CVD is where fatty deposits build up on artery walls, making them narrower until a blood clot gets stuck and cuts off the blood supply to that area.
If we have a diet high in saturated fat, it’s been shown to be linked to a high blood cholesterol level, in particular, LDL cholesterol[1, 7]. These high levels have been linked to an increased CVD risk. Cholesterol in the blood is harmless enough, until it oxidises. This makes it sticky and it attaches to the artery walls, forming a plaque by a process known as atherosclerosis. This is how the theory came about where diets high in saturated fats were linked to heart disease. However, there is one very important point - saturated fats cannot be oxidised, whereas unsaturated fats can.
The modern Western diet is high in overly processed junk food that are full of saturated fats, and contain large amounts of cheap vegetable oils. Some of these vegetable oils have been hydrogenated and are high in trans fats that have the plaque forming capabilities mentioned above. These vegetable oils are also high in processed omega-6s which have been damaged by oxidation. By consuming these, you’re consuming oxidised fats with a high risk of their fate being plaque formation. However, not all processed foods are bad, read our article to find out more.
The healthy eating guidelines suggest that less than 35% of our energy intake should be from fats. From this, no more than 11% should be from saturated fats. None of the saturated fatty acids are essential, so we don't need them but they’re an excellent source of energy and shouldn’t be shunned.
The optimal ratio of omega-6:omega-3 is thought to be around 1-2:1. However, Western diets have been shown to be as high as 6-20:1. Areas where the ratio is high, CVD rates are also high, and in regions where the ratio is nearer to 1-2:1 the incidence of CVD are significantly lower. An omega-6:omega-3 ratio of 1-2:1 is suggested with total polyunsaturates being 10-12% of total energy. Monounsaturates should make up the remainder of total energy.
It’s quite rare to be consuming insufficient omega-6s, but it’s not uncommon for low intakes of omega-3s. If you don’t eat oily fish or flaxseed, then supplementing with flaxseed oil or a specifically formulated oil blend might be a good idea. Cod liver oil supplements have been available for decades but offer little benefit in respect of fatty acid supplementation, as the doses of EFA are low. If you prefer to take a capsule fish oil supplement, check that it’s from a reputable brand first, as some cheaper, low quality brands haven't been treated properly and they may even be rancid (a term for an oxidised fat). Oils are very prone to oxidation and must be stored in cool, dark conditions. If they taste bad, they’re rancid.
Marine algae supplements also provide EPA and DHA, and ALA supplements are available, but don’t overdo these. Exceptionally high intakes of supplementary ALA have been linked to a higher incidence of prostate cancer in men.
Huel provides 30% of total energy from good sources of fat. The fats are from the natural ingredients; ground flaxseed, sunflower oil, MCTs from coconut, and even from the oats. Huel has been formulated to provide the optimum amounts of all the fats.
The level of polyunsaturated fats in Huel Powder provides an ideal ratio of omega-3s:omega-6s (just under 1:1). The total polyunsaturates level is higher than some sources recommend, for example, the Nordic Nutrition Recommendations suggest polyunsaturates should be below 10% of total energy intake. These recommendations are based on data collected from people who consume high-fat junk foods where the polyunsaturates have been exposed to oxidative damage. The polyunsaturates in Huel Powder are from natural ingredients that have been protected from oxidation. The higher level of polyunsaturates in Huel Powder is necessary to provide sufficient ALA conversion to EPA and DHA, as well as ample LA. At 10% of the total energy intake, there wouldn’t be sufficient amounts at 2,000kcal for the optimal intakes of the fatty acids discussed above.
Saturated fats in Huel Powder provide 5.2-5.5% (varies between flavour) of total energy intake. MCTs make up a large amount of this as they provide an efficient source of energy.
Similar to Huel Powder, Huel Ready-to-drink provides an ideal omega-3:omega-6 ratio of 1:2. Again, polyunsaturates make up over 10% of the total energy intake to ensure adequate ALA conversion MCTs make up a significant proportion of the saturated fats.
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