The Effect of Fat In Our Diet

Fats form a very important part of our diet with roles as energy sources and in forming cell membranes. The four main types of fats include monosaturated fats, polyunsaturated fats, saturated fats and trans fats. So what is the purpose of each and do they have health benefits?

There are increasing amounts of evidence to support that the intake of certain types of nutrients positively influences health and promotes the prevention of common non-infectious diseases.

Of all the types of dietary fats, unsaturated fats, found in a variety of foods such as plant-derived oils, seeds and fish, are most clearly associated with health benefits such as decreased cardiovascular and mortality risks.

From the 1990s onwards studies began revealing potential negative health effects of trans fats. A decade later abundant research identified that trans fats increase the risk of coronary heart disease. Further studies have shown that trans fats and saturated fats can be associated with increased mortality risk and overall decreased health.

Trans fats found in our diets are most commonly the result of processing vegetable oils, such as frying food. They are however still present in small quantities in animal products from sheep, goats and cows. The main sources of saturated fats are animal products, including butter, salmon, meat and egg yolks, and some plant products such as chocolate and coconut.

There has been an increased incidence of non-infectious diseases such as cardiovascular disease, obesity and diabetes, specifically in the Western world, due to diets consisting of high levels of processed meats, saturated fats, salt, and sugars accompanied by a lack of fresh fruits and vegetables. It is believed excess intake of foods required in the diet, such as fats, protein and carbohydrates, may be an important risk factor in the development of obesity and insulin resistance.

This is because high intakes of fat and sugar may contribute to excess energy intake. There is however limited evidence that saturated fat in moderate amounts has negative effects on health or the risk of insulin resistance and Type 2 Diabetes as they are a necessary part of our diet. Nevertheless, a saturated fat intake greater than 15% of total energy intake is discouraged as in excess there can be detrimental health consequences.


Milad Rouf Final Year Medical Student, Cardiff University.

Cena, H. & Calder, P.C. 2020. Defining a Healthy Diet: Evidence for the Role of Contemporary Dietary Patterns in Health and Disease. Nutrients. 12(2), pp. 334.

De Souza et al.. 2015. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ, 351, h3978.

Brownell, K.D & Pomeranz, J.L. 2014. The Trans-Fat Ban — Food Regulation and Long-Term Health diabetes: systematic review and meta-analysis of observational studies. New England Journal Of Medicine. 370, pp. 1773-1775.

Morio et al.. 2016. Involvement of dietary saturated fats, from all sources or of dairy origin only, in insulin resistance and type 2 diabetes. Nutrition Reviews. 74(1), pp. 33-47