Only recently have we developed an understanding of the role of dietary fats in health. Fats are a source of energy (or calories too many in most cases) and provide structural protection around organs. As we'll see, they are also important components of cell membranes and precursors of important regulatory molecules.
Types of Fats
There are different kinds of fats, including animal fats, vegetable fats, saturated and unsaturated fats, liquid fats (oils) and solid fats. Some saturated fats have been artificially hydrogenated. This refers to the addition of hydrogen atoms to carbon atoms that are linked in a chain.
Fats that occur naturally as saturated fats and those that are artificially hydrogenated are solid at room temperature. The artificially saturated fats contain damaging substances called trans fats, which do not occur naturally. More about them later. Both animal fat and partially hydrogenated oils can increase inflammation and elevate the amount of cholesterol and fat in the blood. Vegetarian diets generally contain very little saturated fat, although coconut oil and palm oil are vegetarian sources of saturated fat, and some vegetarians do eat dairy products or eggs. (Vegans are strict vegetarians who eat no animal products.)
Essential Fatty Acids
Some unsaturated fats are required in the diet and are therefore called essential fatty acids or EFAs. These fats are essential for many reasons. They are an important component of cell membranes. These membranes allow passage of molecules in and out of cells and maintain receptors for hormones. Fats are also the building blocks for hormones. EFAs may also be converted into derivatives called prostaglandins, important hormone-like regulatory substances.
Good health is also dependent on a proper balance of the different types of fats. Linoleic acid is an omega-6 unsaturated fat, with its first double bond at the sixth position along the carbon chain. It is found in corn and beans. Linoleic acid is converted through a series of steps to a regulatory substance called prostaglandin E1. Prostaglandins regulate many metabolic functions. Minute amounts can cause significant changes in blood pressure, blood clotting, cholesterol levels, inflammatory responses, allergies, hormone activity, immune function, neurologic function and more. Prostaglandin E1 decreases the tendency of platelets to clump together, decreases inflammation, stabilizes blood sugar and decreases cholesterol. It decreases spasms in arterial and other involuntary muscle.
A deficiency of omega-6 EFA may result in eczema, premenstrual syndrome, breast pain and lumpiness, inflammation and autoimmune problems, hyperactivity in children and hypertension. Many people have adequate intake of these oils but inefficient conversion to the active prostaglandins. Specifically, individuals with a history of allergy, high cholesterol, diabetes, high alcohol intake, trans fat intake, chemical exposures, or specific nutrient deficiencies (particularly of magnesium and vitamin B6) may have difficulty with conversion. In these cases the metabolic block can be bypassed by taking supplements of GLA (gamma-linolenic acid), which helps the problems listed above.
The other EFA is called alpha-linolenic acid, which is an omega-3 oil. This oil is even more unsaturated (has more double bonds), with the first double bond at the third position in the carbon chain. This molecular structure gives the oil different properties. Omega-3 oils predominate in fish oils, flax seeds (linseeds) and some nuts, particularly walnuts. Omega-3 oils play a significant role in reducing the risk of coronary heart disease. Scientists have confirmed that populations with higher fish intake have a lower incidence of heart disease. These oils decrease the tendency of platelets to clump together, a reaction involved in the development of atherosclerosis as well as the precipitation of heart attacks. Omega-3 oils also decrease triglycerides, cholesterol and inflammatory reactions.