It is commonly known that too much fat can lead to disease, however our bodies require a certain amount of healthy fats through dietary sources to function effectively. These fats are considered the building blocks of the body as they are involved in a variety of physiological processes. These include:
Provision of energy, particularly during exercise. During exercise, stored fat in the body is broken down into fatty acids. These fatty acids are then transported through the blood to the muscles for fuel.
The production of cell membranes. Cholesterol, the soft waxy fat found in our bloodstream and within every cell in our body plays a major role in not only the production of cell membranes but also the production of hormones including testosterone and oestrogen. It also helps create fat-soluble vitamins such as vitamin A and E which are required for skin integrity, brain function and eye health.
Cholesterol also plays a major role in the synthesis of Vitamin D. Recent studies have shown that low levels of vitamin D have been associated with increased cardiovascular risk (Wang et al. 2012, p 11-42).
What are bad fats?
A majority of the trans fats we ingest are through commercially available foods that go through a manufacturing processes and have hydrogenated vegetable oils added to enhance their flavour and increase their shelf-life. However, trans fats also naturally occur in animal products such as milk, butter, cheese and meat products. Trans fats have been shown to increase the amount of harmful LDL Cholesterol in the blood stream and reduce beneficial HDL cholesterol. A quantitative review that was conducted in 2010 looked at 39 intervention trials reporting the effects of trans fats on cholesterol. The published data was conclusive that all trans fatty acids raise the ratio of plasma LDL to HDL cholesterol (Brouwer et al. 2012).
When high levels of harmful cholesterol build up in the blood stream, an inflammatory response is triggered which in turn speeds up the accumulation of cholesterol within the arteries. Eventually this build of cholesterol hardens into plaque causing blockages, often resulting in cardiovascular attacks (Fritsche 2010, p 293-301).
There has been research demonstrating an association of high saturated fat and increased incidences of cardiovascular disease. These recent studies are now suggesting that we lower our intake of saturated fats but do not eradicate them completely. Small amounts of saturated fats have been proven to assist with healthy brain function and nerve signalling, immune support and healthy bone formation (Ryan et.al, 2012, p 137-149). Good fats are typically sourced from vegetables, nuts, seeds and fish. There are two main categories of beneficial fats: Mono and Polyunsaturated fats.
It was discovered in the 1960’s that Monounsaturated fats or MUFAS were beneficial to health when people residing within the Mediterranean region had a very low rate of heart disease despite having a high fat intake. To this day, the ‘Mediterranean Diet’ is a style of eating regarded as a healthy choice particularly for cardiovascular health. The most common MUFA’S within this diet comes from vegetables and animal oils, particularly olive oil. MUFA’s are also found in nuts, avocados and whole milk.
Polyunsaturated fats or PUFAS are essential fatty acids that are required for normal body functioning. As our bodies cannot make them naturally, we must source them through food. PUFA’s are necessary for blood clotting, muscle contractions and reducing bad cholesterol levels. PUFAs also play a key role in reducing inflammation by downregulating pro-inflammatory molecules within the body (Lee et al. 2014, p 12). There are two types of PUFAs: omega 3 fatty acids and omega 6 fatty acids, both offering a variety of health benefits.
Sources of omega 3 fatty acids include fatty wild caught salmon, sardines, flax seeds and walnuts. Foods rich in omega 6 fatty acids include safflower, sunflower and hempseed oil, pumpkin seeds and sunflower seeds.
How much fat do we need?
Nutrient Reference Values Australia recommend that women aged 19+ years consume 8g/day of Omega 6 fat, 0.8g/day of omega 3 fat and 90mg/day of total fats and fatty acids.
- Avoid products marketed as ‘Low fat’ as they typically contain high amounts of sugar.
- To find out if a fat is saturated, leave it out in room temperature for a while. If it turns from a liquid to a solid or remains solid, it is a saturated fat. If its liquid at room temperature, then it is a mono or polyunsaturated fat.
- Eat everything in moderation!
Wang, H., Xia, N., Yang, Y., & Peng, D.-Q. (2012). Influence of vitamin D supplementation on plasma lipid profiles: A meta-analysis of randomized controlled trials. Lipids in Health and Disease, 11(1), 42. https://doi.org/10.1186/1476-511X-11-42
Brouwer, I. A., Wanders, A. J., & Katan, M. B. (2010). Effect of animal and industrial Trans fatty acids on HDL and LDL cholesterol levels in humans - A quantitative review. PLoS ONE, 5(3), https://doi.org/10.1371/journal.pone.0009434
Fritsche, K. L. (2015). The Science of Fatty Acids and Inflammation. Advances in Nutrition: An International Review Journal, 6(3), 293S–301S. https://doi.org/10.3945/an.114.006940
Ryan, K. K., Woods, S. C., & Seeley, R. J. (2012). Central nervous system mechanisms linking the consumption of palatable high-fat diets to the defence of greater adiposity. Cell Metabolism, 15(2), 137–149. https://doi.org/10.1016/j.cmet.2011.12.013
Healthy fats VS Bad Fats