What Is The Difference Between Unsaturated and Saturated Fats?

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Saturated fats and unsaturated fats are found in a variety of foods. Which types of fats to consume if you are following a lipid-lowering diet have been the subject of some controversy, as some studies suggest that these fats are not all created equally. The American Heart Association recommends that between 25 and 35% of your total daily calories should consist of fat, with most of this intake consisting of unsaturated fat.

However, recent studies suggest that unsaturated fats alone may not be as heart healthy, and consuming saturated fats may not be as dangerous as once thought. 

Saturated Fat

Saturated fats are a category of fats that have no double bonds in their chemical structure, and are therefore “saturated” with hydrogen atoms. Because of their chemical structure, they have a solid consistency at room temperature. Saturated fats can be found in a variety of foods, including:

  • Animal meat – including beef, poultry, pork
  • Certain plant oils – such as kernel or coconut oil
  • Dairy products – including cheese, butter, and milk
  • Processed meats – including bologna, sausages, hot dogs, and bacon
  • Pre-packaged snacks – including crackers, chips, cookies, and pastries

The American Heart Association currently recommends that less than 7% of your daily caloric intake should consist of saturated fat. Some studies have shown that consuming a high amount of saturated fats may increase your LDL and, therefore, your risk of heart disease.

However, there have been multiple recent studies that refute the detrimental effects of saturated fat. Although the amount of LDL appears to be increased by consuming saturated fats, studies have shown that the type of LDL that is increased is large, buoyant LDL. Larger LDL particles do not appear to increase your risk of heart disease.

 Small, dense LDL – the type of LDL cholesterol that has been shown to promote forming atherosclerosis in studies – appears to be not affected and, in a few cases, even reduced with saturated fat consumption.

Some studies also suggest that the type of saturated fat-containing foods can make a difference in your heart health. One large study suggested that consuming dairy products may actually lower your risk of cardiovascular disease while including processed meats in your diet could increase your risk of cardiovascular disease.

Unsaturated Fat

Unsaturated fats are typically liquid at room temperature and differ from saturated fats in that their chemical structure contains one or more double bonds. They can be further categorized as:

  • Monounsaturated fats – a type of unsaturated fat that contains only one double bond in its structure.
  • Polyunsaturated fats – another type of unsaturated fat that contains two or more double bonds in their structure.

Studies have shown that replacing saturated fats in the diet with foods containing polyunsaturated fats reduced LDL cholesterol levels and lowered cardiovascular disease risk.

The American Heart Association currently recommends that most of your daily fat intake should come from monounsaturated and polyunsaturated fats. Foods containing unsaturated fats include:

  • Nuts
  • Plant oils – such as canola, vegetable, or plant oil
  • Certain fish – such as salmon, tuna, and anchovy, which contain omega-3 unsaturated fatty acids
  • Olives
  • Avocados

Which Fats Should You Include in Your Lipid-Lowering Diet?

More research is needed surrounding the influence on unsaturated and saturated fats on cardiovascular disease. If you are watching your cholesterol and triglyceride levels, you should include a variety of healthy foods – including lean meats, vegetables, fruit, legumes, and whole grains. Although there has been recent research suggesting that saturated fats are not as bad for heart health as once thought, the current recommendations still remain in place.

Both unsaturated fat and saturated fat are equally energy-dense – so you should eat both in moderation as these can add calories to your meal and weight to your waistline – if you consume too much of either one.

Additionally, the type of fat-containing foods you consume can make a huge difference in your lipid levels. A handful of walnuts or a lean piece of beef is a better choice for your meals in comparison to a bag of chips or links of sausage. Both may contain fats, but the former choices also contain vitamins, minerals, and other healthy nutrients - whereas the latter choices may be higher in sugar, chemical preservatives, salt, and trans fats – all of which can have an adverse effect on your lipid levels and heart health.

Sources:

Rolfes SR, Whitney E. Understanding Nutrition, 13th ed 2013.

DiNicolantonio James J., Lucan Sean C., O’Keefe James H., The Evidence for Saturated Fat and for Sugar Related to Coronary Heart Disease, Progress in Cardiovascular Diseases (2015), doi: 10.1016/j.pcad.2015.11.006

de Oliveira Otto MC1, Mozaffarian D, Kromhout D et al. Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. Am J Clin Nutr. 2012;96:397-404.

 American Heart Association. Know Your Fats. Website: http://www.heart.org/HEARTORG/Conditions/Cholesterol/PreventionTreatmentofHighCholesterol/Know-Your-Fats_UCM_305628_Article.jsp#.VlueOvmrSM9. Accessed 25 November 2015.

Vafeiadou K, Weech M, Altowaijri H, et al. Replacement of saturated with unsaturated fats had no impact on vascular function but beneficial effects on lipid biomarkers, E-selectin, and blood pressure: results from the randomized controlled Dietary Intervention and VAScular function (DIVAS) study. Am J Clin Nutr. 2015 Jul;102(1):40-8.

De Souza RJ, Mente A, Maroleanu A, et al. 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 2015351:1-16.

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