by Bonnie Bruce, DrPH, MPH, RD
Have you ever considered the way your ancestors lived? Not your grandparents, but relatives who lived way back in time — such as 10,000 years ago, when humans were hunter-gatherers. Imagine what it must have been like to subsist only on what you could hunt, fish, or forage. The human diet consisted primarily of plant foods, with some wild meats when the hunting was good. Limited though it may seem to us, our ancestors’ diet met their bodies’ needs and allowed them to survive.
That kind of life is far from today’s reality. Most of us have easy access to all the food we want, and a wide variety at that. And we live much longer, on average, than our ancestors did. But we also have high rates of chronic diseases such as heart disease and diabetes, health problems that researchers think most of our ancestors didn’t have to contend with.
What accounts for the rise in these diseases? Some scientists and nutrition experts believe that we have essentially the same genetic makeup as when we were living in caves and off the land, so changes in our genes don’t seem to be the culprit. Our longer lifespan may have something to do with it, since many chronic diseases are associated with age. But many clues point to today’s Western diet and lifestyle. We exercise far less than our ancestors did, we eat far more refined, sugary, salty, and high-fat processed foods, and too many of us are overweight or obese. All this makes some researchers wonder if our lifestyles have changed too fast for our genes to keep up — and whether a diet closer to that of our ancestors might be better for our bodies.
For too many of us, the great majority of our calories come from processed meats and other foods, added sugar, and refined grains, none of which existed during our hunter-gatherer years. Today, many of us are becoming more aware of the ill effects of eating too many processed foods and are trying to make better choices. Those of us concerned about heart health may be aware of the need to cut down on foods high in saturated and trans fats, but few of us are aware of a dietary issue that some scientists believe may be a contributor to many of our current health problems: an imbalance in our dietary intake of certain types of fatty acids. This article explains what fatty acids are, what foods they are found in, and how you can achieve a better balance.
Fatty acids are the basic building blocks of the kind of fat that is found in food and that makes up our body fat. Three fatty acid molecules attach to a three-slot chemical backbone to form larger fat molecules called triglycerides. During digestion, the body splits up the triglyceride molecule and then absorbs the parts. The body uses the fatty acids as they are, or when it is able to, it changes some of them into different metabolic substances that perform a wide variety of functions.
Since the early days of nutrition research, chemists have identified a few hundred different fatty acids. In the early 20th century, scientists discovered that a few fatty acids are essential for life and normal growth and development. They found that the body is unable to manufacture these fatty acids, and thus we can get them only by eating foods that contain them. Originally, scientists called these essential fatty acids “vitamin F,” but they later reclassified them as fats rather than vitamins. (To this day, however, some companies sell fatty acid supplements erroneously promoted as “vitamin F.”)
Essential fatty acids are indispensable for numerous biological activities that affect growth, development, and overall health, and they are also a source of the body’s energy. They are used to produce hormonelike substances that regulate several body functions, including blood pressure, blood clotting, brain development, and immune system responses, including inflammation. They influence cell behavior, participate in genetic activities, and are a component of cell membranes. Simply put, we could not live without them.
There are two main fatty acids that are considered essential. These are linoleic acid and linolenic acid, both of which belong to a class of fats called polyunsaturated fats. Linoleic acid is the primary member of a family of polyunsaturated fats called omega-6 fatty acids. Linolenic acid is the primary member of the omega-3 fatty acid family. These two essential fatty acids are used to make other fatty acids important for health and growth. Without them, the body would be unable to manufacture certain other fatty acids and compounds. Examples of these beneficial products include other members of the omega-3 family called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are best known for being found in fish oils.
Because our bodies cannot make linoleic acid or linolenic acid, we need to get both omega-6 and omega-3 fatty acids through foods that contain them.
Last Reviewed on March 7, 2013
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