A New Way of Looking at Fats

What are Fats?

Fats are probably the most complex of the macromolecules in foods because there are so many different types of fats. Unfortunately, fats have been given a bad reputation, in part because fat is the way we store excess calories, and in part because saturated fats, trans-fatty acids, and cholesterol have been asociated with health conditions like cardiovascular disease and obesity. The facts are, however, that not only are all fats not bad, but some fats have been shown to be health-promoting, and some fats are absolutely essential for your health. So, when you think about fats, the quality of the fat, and therefore the quality of the food from which you are getting the fat, really matters.

Fats, which are also referred to as lipids, are composed of carbon, hydrogen, and oxygen like the other macromolecules, but fats are designed in a structure that makes them insoluble in water. We call this hydrophobic (hydro=water; phobic=hating). Fats are chemically described as either unsaturated, monounsaturated or polyunsaturated. The saturated fats are straight molecules that form solids at room temperature, such as butter and the fats found in meat. Monounsaturated fats, like olive oil, are liquids at room temperature but form solids in the refrigerator. Polyunsaturated fats, which are found in high amounts in oils from grains and seeds, such as flaxseed oil, are liquid at room temperature and remain liquid even when cooled.

This different physical property of fats is one reason your body uses so many different types. One extremely important role of fats is as a major component of all the membranes in your cells. You cell membranes contain all of these different kinds of fats -- unsaturated, monounsaturated, and polyunsaturated -- however, they are needed in different amounts. Your cells primarily need polyunsaturated fats along with some monounsaturated fat to keep your membranes, and therefore your cells, flexible and moveable. When levels of saturated fat are too high, cell membranes become inflexible and don't function well, so they can't protect the internal parts of the cell, such as its DNA, as well.

Saturated Fats and the Controversy of the "Bad" Fat

More than 50 years ago, data linking consumption of saturated fats to elevated blood cholesterol levels, atherosclerosis, and then to a higher risk of heart disease first became apparent in the literature. As regulatory agencies and scientists continually found this association, food companies became prompted to come up with no-saturated fat alternatives. No-fat foods, low-fat foods, and foods with substituted fats have appeared in ample quantities on grocery store shelves. In fact, over 15,000 such products have been promoted over the past several decades.

Excessive consumption of saturated fats can negatively affect your health since the fat you eat in your diet gets directly into your cell membranes. This valid concern about saturated fats has been generalized to all fats, however, and your body needs other fats. Saturated fats are primarily found in high amounts in processed foods and meat products, in particular the meats that have white, solid fat on them. In addition, the fats found in meat fats also include cholesterol, so diets high in fatty meat are also high in cholesterol.

Minimizing the consumption of saturated fats is a good idea, but minimizing the consumption of all fats is not. Consider that your brain is approximately 70 percent fat. In addition, diets low in all types of fats have been associated with increased risk of hormone abnormalities, cardiovascular disease, and decreased brain and immune function. So, the real question is not how to indiscriminately avoid all fats, but which fats, in which amounts are good for you?

The Health Promoting Fats: Monounsaturated and Polyunsaturated Fats

Monounsaturated Fats

Monounsaturated fats caught the attention of research scientists after they first notcied that people who eat a traditional Mediterranean diet have a lower risk of developing cardiovascular disese, certain types of cancer, and rheumatoid arthritis. Traditional Mediterranean diets contain high amounts of olive oil, which is high in oleic acid, a monounsaturated fatty acid. Other monounsaturated fats include myristoleic and palmitoleic acids. In addition to olive oil, other food sources for monounsaturated fatty acids include canola oil, avocadoes, almonds, and cashews.

Research continues to support the theory that diets high in monounsaturated fats are health-promoting; however, the most exciting latest research revolves around the polyunsaturated fats, in particular, the omega-3 fatty acids.

The Health Promoting Polyunsaturated Fats

The polyunsaturated fats (PUFA) are molecules that contain many unsaturated bonds, a characteristic which distinguishes them chemically from the other fats. In practical terms, this chemical structure is the reason these fats are liquid even when cold. Many different polyunsaturated fats exist, but the ones getting the most attention from research scientists are the essential fats, linolenic acid and alpha-linoleic acid, and the omega-3 fatty acids.

The Essential PUFA Fats

Your body can make all the different fats it needs from two starting molecules, the two essential fats: linoleic acid (an omega-6 fatty acid) and alpha-linolenic acid (an omega-3 fatty acid). Because these are essential fats, meaning your body can't make them, you must get them from your diet. All other PUFAs can be made from these fats. The omega-6 PUFAs, such as arachidonic acid, one of the major fats in your cell membranes, are made from linoleic acid. The omega-3 fats, such as docosahexaenoic acid, the main fat in your brain, are made from alpha-linolenic acid.

Linoleic acid is an omega-6 fatty acid which is plentiful in the diet of most Americans. This fat is found in at high levels in oils from grains, nuts and legumes, and is often provided in your diet by sunflower, safflower, sesame, corn, soy, and peanut oils. In the body, linoleic acid is first converted to another omega-6 fat called gamma-linolenic acid, which is also found in evening primrose oil and borage oil.

As mentioned, few people are deficient in the omega-6 essential fat, linoleic acid; this is, in part, because arachidonic acid, which is made from linoleic acid, is found at high levels in animal tissue, such as beef and poultry. Since the average Western diet contains a lot of meat, most people get high quantities of arachionic acid.

The omega-3 fats, which are produced in your body from the essential omega-3 fat -- alpha linolenic acid -- have generated much interest since studies continue to show that diets low in omega-3 fats are associated with many health diseases including chronic inflammatory conditions like rheumatoid arthritis, inflammatory bowel disease, and cardiovascular disease, and behavioral syndromes like ADHD (attention deficit hyperactivity disorder). Alpha-linolenic acid is found in high quantities in flax oil, canola oil, and some leafy vegetables. Some of the most important omega-3 fats, which are synthesized from alpha-linolenic acid, are docosahaenoic acid (DHA) and eicosapentaenoic acid (EPA), and these can be obtained directly from the diet as well. Excellent sources for EPA and DHA are fish and algae.

Although omega-6 fats, like arachidonic acid, play important roles in your body, consuming too many of these in comparison to the amount of omega-3 fats you consume can cause problems. This is because the fluidity, or flexibility of cell membranes is so dependent on having a variety of fats present. Since omega-6 fats are in such high quantities in most people's diets, they occupy places where omega-3 fats should be. For good health, it is vital to consider the ratio of omega-6 to omega-3 fats in your diet.

The proper balance of omega-3 to omega-6 is extremely important not only for healthy cell membranes, but also because omega-6 fats are the precursors for pro-inflammatory molecules--the molecules that promote and maintain inflammatory reactions. Omega-3 fats, in contrast, are the precursors for anti-inflammatory molecules. Inflammatory reactions are an integral part of they way your body protects you against infections and promotes healing, but the body must be able to turn off its inflammatory defenses when their work is done. This is one of the primary roles of the omega-3 fats. When you lack a balance of omega-3 to omega-6 fats, your body can't turn off these inflammatory reactions, which promotes conditions of chronic inflammation. Current research continues to support that diseases such as atherosclerosis, arthritis, inflammatory bowel disese, and asthma are perpetuated by a heightened inflammatory state, and that in individuals with these conditions, the pro-inflammatory omega-6 essential fats are not balanced by adequate amounts of the anti-inflammatory omega-3s.

The ideal ratio of omega-3 to omega-6 is not known, but is estimated to be around 1:2; whereas, the current ratio in the typical American diet is more like 1:25. In order to achieve a more beneficial ratio, it is important to decrease the amount of omega-6 fatty acids in your diet, while increasing the amount of omega-3 fatty acids like EPA, DHA, and alpha-linolenic acid. This can be accomplished by reducing your comsumption of meats, dairy products, and refined foods, while increasing consumption of the omega-3 rich foods such as wild-caught cold-water fish like salmon, flaxseed oil, walnuts, and leafy green vegetables.

This page was updated on: 2004-11-07 14:55:31
© 2002 The George Mateljan Foundation