Fat is a nutrient that many people are afraid of. However, fat is essential to health as it provides energy for physical activity, is necessary for transport of fat-soluble vitamins, helps maintain proper cell function, provides cushioning and protection for the body and helps us to feel full. Not only that, fat gives food a pleasant taste and texture. What is important to understand is that not all fats are equal and that the type of fat you consume can drastically affect your health and longevity. 

What is fat?

Fat is made up of long chains of carbon atoms connected by hydrogen bonds. Both the presence of double or single hydrogen bonds and the position of the double bonds determine the type of fat.

If the chain of carbon consists of all single hydrogen bonds, then it is considered a saturated fat.  A fat molecule with one double bond is called monounsaturated fat and two or more double bonds creates a polyunsaturated fat. Two types of polyunsaturated fats that are essential (i.e. we must obtain them through our diet) are omega-3 and omega-6. Double bonds create kinks in the fat molecule, and the more double bonds the fat contains, the less tightly together it can pack, and the more fluid the fat. Saturated fats are the least fluid (they are solid at room temperature, such as lard) and polyunsaturated fats are the most fluid (liquid at room temperature, such as canola oil). Trans fat contains double bonds, but instead of the double bond creating a kink in the carbon chain, the chain remains straight. This allows the carbon chains to pack tightly together, similar to saturated fat. Trans fats exist naturally in small amounts in cow’s milk, beef and lamb, but the majority of trans fats in our food are added during the process of hydrogenation (ex. hydrogenated margarine).

Oils are made up of a combination of types of fat:

What types of fat are healthier?

Diets high in saturated fat can increase the risk of cardiovascular disease because high intakes of saturated fat can raise LDL levels. LDL, often referred to as “bad cholesterol,” is a molecule that carries cholesterol around in your blood. High levels of LDL increase the chances that cholesterol will deposit on arterial walls (thus narrowing arteries and restricting blood flow).

High dietary intakes of trans fat can raise LDL and lower HDL. HDL, referred to as “good cholesterol,” is a molecule that removes cholesterol from your blood and delivers it to the liver for uses such as the production of bile.  High levels of HDL reduce the chance of cholesterol being deposited on arterial walls, which lowers the risk of cardiovascular disease.

High intakes of omega-3 fat and monounsaturated fat are associated with a decreased risk of cardiovascular disease.  There is some evidence that a diet high in omega-3 can increase HDL levels. Monounsaturated fat reduces LDL levels.

Adequate intakes of omega-3 and omega-6 are important for many processes, including blood clotting, inflammation, and development of the eyes and brain. An imbalance between omega-6 and omega-3 intakes (not enough omega-3 and too much omega-6) is suspected to be associated with many diseases. For more information on omega-3 and omega-6 fats, read my post on omega-3 and disease.

Generally accepted recommendations for fat are: Eat more: monounsaturated and polyunsaturated fats (especially omega-3). Eat less: saturated fat. Avoid: trans fat.

Written by Deanna Ibbitson, M.Sc., CPT

Summary of the nutrition and appropriate uses for common cooking oils and fats: