FATS

Dietary fat can often be something that is demonised or that people are afraid of. While eating too much of the wrong types of fat can certainly be bad for our health, it is important to know that having some fat in our diet is essential as it is much more than just a source of energy. It is involved in many vital processes.

There are also different types of fats, these have different effects on our health and so type as well as amount is important.

Fat has had a bad reputation for over 40 years now. Since the 1980s we've been conditioned to avoid fat in fear that it will make put us on weight or clog our arteries. As a result, many of us now naturally choose low fat or no-fat versions of our favourite food.

The truth is, that our bodies need fat to thrive and work properly. The problem is that there are many types of fat that have been all grouped into the same ‘bad-for-you’ category. The fact is, that not all fats are made equally.

To help us sort out the good fat from the bad fat, our dietician Ro explains below which fats we should embrace and which we should avoid, and most importantly - why.

Dietary fat can often be something that is demonised or that people are afraid of. While eating too much of the wrong types of fat can certainly be bad for our health, it is important to know that having some fat in our diet is essential as it is much more than just a source of energy. It is involved in many vital processes.

There are also different types of fats, these have different effects on our health and so type as well as the amount is important.

The role of fat in our bodies

Alongside protein and carbohydrates, fat is one of the 3 macronutrients that provide us with the energy we require to function effectively. Alongside this, fat also plays an important role in many other vital bodily processes.

· Help with the absorption of fat soluble nutrients such as vitamin D

· Fat is involved in production of hormones vital for reproduction and appetite control

· They are good sources of certain nutrients such as vitamin E

· Required to build cell membranes and for cell signalling

· Important for healthy skin and hair

· Protects our vital organs and provides insulation

· Contribute to the smell and taste of food

Types of fat

The main types of fat found in foods are saturated, unsaturated fats and trans fats. While all having a similar structure, the slight differences between them translate into very different effects in our bodies.

Saturated fats are typically found in animal products, such as red meat and full fat dairy/dairy products, coconut and its oils, as well as fried, fast and processed foods as well as baked goods. Eating too much saturated fat can raise our level of LDL cholesterol, which has been linked to an increased risk of heart disease (1). Therefore it is recommended that men should eat no more than 30g of saturated fat a day and women no more than 20g a day.

Unsaturated fats include monounsaturated and polyunsaturated fats and are often termed as ‘good’ or ‘healthy’ fats. Monounsaturated fats are one of the main components of a Mediterranean-style diet and which is linked to a lower risk of cardiovascular disease (2). Unsaturated oils include extra virgin olive oil, rapeseed oil and their spreads. Nuts and seeds and avocados are also good sources.

Polyunsaturated fats are essential fats found in many cooking oils such as sunflower oil, safflower oil and corn oil. They are required for important functions and are termed essential as they can only be gained from our diet. The two main types are omega-6 and omega 3 polyunsaturated fats, most people get enough omega 6 fats. Oily fish are the best sources of omega 3 fatty acids but they can also be found in flaxseeds, chia seeds, walnuts, flaxseed oil, soybean oil and canola oil. Omega 3 fatty acids possess anti-inflammatory properties and may be beneficial for a range of anti-inflammatory conditions such as rheumatoid arthritis and asthma (3) as well as reducing risk of heart disease (4). It is recommended to have 2 portions of fish per week one of which being oily, alternatively omega 3 fatty acids can be found in supplement form. Total diet replacement products are designed to be nutritionally complete and so will contain omega 3.

Trans fats are fats that we should be avoiding, or at least reducing. They occur as a by product of a process called hydrogenation, where oils are turned into solid form and are used in the manufacture of margarines as well as fast and processed foods. They raise our levels of LDL cholesterol levels increasing risk of heart disease, stroke, and other health conditions (5). Manufacturers are reducing their use in food products however it is recommended to check out food labels and limit consumption of hydrogenated or partially hydrogenated fats to avoid trans fats.

Amount of fat

Fat carries a higher number of calories per gram than carbohydrates or proteins and so reducing fat intake can help to reduce your overall calorie intake. Fat cells can expand to an unlimited size to store fat, it is when a surplus of fat occurs that we can start to see harmful effects on our health.

The bottom line is that we do need some fat in our diet but we should aim to consume mainly unsaturated fats and cut down on foods and drinks high in saturated and trans fats. Looking at nutrition labels can help you choose products lower in both saturated as well as total fat. Those high in saturated fat contain more than 5g saturates/100g, products low in saturates contain 1.5g or less/100g. Products sold as part of a total food or total diet replacement program will generally be low in both total fat as well as saturated fat.

References

1. Saturated fats and health: SACN report - GOV.UK . . Available from: https://www.gov.uk/government/publications/saturated-fats-and-health-sacn-report

2. Estruch R, Ros E, Salas-Salvadó J, Covas M-I, Corella D, Arós F, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. N Engl J Med . 2018 Jun 21 ;378(25):e34. Available from: https://pubmed.ncbi.nlm.nih.gov/29897866/

3. Calder PC. Marine omega-3 fatty acids and inflammatory processes: Effects, mechanisms and clinical relevance. Vol. 1851, Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. Elsevier; 2015. p. 469–84.

4. Harris WS, Zotor FB. N-3 Fatty acids and risk for fatal coronary disease. In: Proceedings of the Nutrition Society . Cambridge University Press; 2019 . p. 526–31. Available from: https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/n3-fatty-acids-and-risk-for-fatal-coronary-disease/DD36DED15EA4022ABF37F46A9DF03004

5. Kim Y, Je Y, Giovannucci EL. Association between dietary fat intake and mortality from all-causes, cardiovascular disease, and cancer: A systematic review and meta-analysis of prospective cohort studies. Clin Nutr . 2020 ; Available from: https://pubmed.ncbi.nlm.nih.gov/32723506/