The Omega-3 factor
by Rebecca N. Schiller, MSc
This article was originally published in February 2005
(February 2005) — Today’s industrialized food system has left many Americans very deficient in one essential fat. Why foods such as flax, walnuts and fish matter.
On my flight home last week, I found myself staring at my individually wrapped airplane meal, contemplating just how removed society has become from the food we consume. My seatmate had already torn into his hermetically sealed roast beef sandwich and was slathering margarine on either side of his white dinner roll.
I picked up my oversized chocolate chip cookie and examined the ingredients: enriched flour (bleached), sugar, partially hydrogenated soybean and cottonseed oil and high fructose corn syrup. I put the cookie down. My seatmate glanced over at me as if to inquire whether I was going to ‘dig in.’ I offered him my cookie saying, “Go ahead, I’ve had my fill of nonessential fat for the day.”
Many people are now familiar with the terms partially hydrogenated vegetable oil, saturated fat and trans-fat and the negative impact these fats have on health. Specifically, saturated and trans-fats have been shown to increase both cholesterol levels and the risk of developing coronary heart disease.
Fewer, however, may be aware that some fats are essential for human growth and development. They’re called essential fatty acids (EFAs) for this reason — we can’t live without them. Our bodies are able to produce most of the fat we need; however, we lack an enzyme necessary to make the omega-6 fat, linoleic acid (LA), and the omega-3 fat, alpha-linolenic acid (ALA). These essential fats can be obtained only from dietary sources, just as we must get vitamins, minerals and essential proteins from our diet. Research now indicates that consuming omega-3 and omega-6 fats in proper balance is critical in the prevention of various chronic diseases.
Fat deficiency?
With the abundance of fat found in the average American diet, it’s hard to imagine illness resulting from a fat imbalance or deficiency. But the evidence shows the typical American diet is unbalanced.
Omega-3 and omega-6 fats are the building blocks for substances within the body that help regulate normal immune function, skin integrity, blood-clotting and the body’s inflammatory response. Once ingested, these fats follow two distinctly different paths. Our bodies convert omega-6 fats into substances that promote blood clotting, inflammation and overall allergic response. Omega-3 fats, on the other hand, are converted into substances that reduce blood-clotting, inflammation and tend to subdue allergic responses.
In a healthy state, the body is able to maintain the proper balance between these substances, thus maintaining healthy metabolism. Problems arise when this careful balance is upset.
Current research suggests that a diet rich in omega-6 fat and lacking in omega-3 fat promotes inflammation. Inflammation, in turn, has been linked to a variety of chronic diseases including heart disease, cancer, Alzheimer’s disease and other inflammatory conditions. Unfortunately, many health practitioners fail to address the potential role of essential fats in promoting health and preventing disease.
Historically, humans have consumed a healthy one-to-one (1:1) or two-to-one (2:1) ratio of omega-6 to omega-3 fats. In recent times, this ratio has changed dramatically. Studies show the current Western diet is overly abundant in omega-6 fat and low in omega-3 fat; the current estimated ratio being roughly 20- or 30-to-1. This dietary shift towards excessive omega-6 fat intake may be attributed to several modern developments: industrialized ranching and agriculture, current Western food processing practices and a lack of essential fat dietary guidelines.
Think back through the generations. People historically got a greater variety of fats and oils from their meat, specifically from wild game. That’s because animals in the wild eat grasses, which in turn increase their omega-3 fat content. Today, cattle, chicken and hogs raised as livestock are routinely fed corn, which is inexpensive, abundant and can pack the pounds on an animal in no time.
Although corn-fed livestock is considerably cheaper to raise and Americans have grown accustomed to the taste and texture of grain-fed meat, there’s a hidden price to be paid. Research shows that corn-fed livestock are considerably lower in omega-3 fat, thus people aren’t getting the same nutrients from meat they once did.
Studies have shown, however, that the fat content of grass-fed livestock (such as grass-fed beef and lamb, both available at PCC) is similar to that of game meat and may provide a more optimal essential fat balance than grain-fed meat.
At the same time, Americans have shifted to eating more processed foods, which typically include refined vegetable oils high in omega-6 fat. Compared to whole, fresh foods, processed foods further throw off a healthy balance of fats.
Lack of dietary guidance
When it comes to fat intake, current dietary guidelines recommend reducing both saturated and trans-fat. This recommendation translates into the reduction of solid fats such as animal fat and processed margarines, which is generally a good thing.
Every five years the U.S. Department of Health and Human Services and the U.S. Department of Agriculture jointly publish Dietary Guidelines for Americans. Traditionally, these guidelines recommend consuming a variety of vegetable oils including soybean, corn and cottonseed. Unfortunately, past recommendations have neglected to distinguish between sources of omega-6 and omega-3 fats and, equally important, the quality of oils available to consumers.
Similarly, the American Heart Association’s current recommendations include incorporating “vegetable oils and margarines … (such as) canola, corn, olive, safflower, sesame, soybean or sunflower (oils)” into the diet. Here too, this recommendation implies that each of these oils is equal in quality and equally healthful; this is not true. Corn, safflower, sunflower and sesame oil all are high in omega-6 fats and contain little or no omega-3 fats, while canola and soybean oil are relatively high in omega-3 fats and lower in omega-6 fats.
As is often the case, published dietary guidelines lag well behind current scientific findings. This occurrence causes a disconnect between what scientific research shows to be healthful and the general public’s understanding of a healthful diet.
The sixth edition of Dietary Guidelines for Americans, published last month, now includes sources of omega-6 and omega-3 fats. While there are still no clear recommendations for a proper balance of these fats, this publication does suggest a link between the fats found in fish and a “reduced risk of mortality from cardiovascular disease.” Also, it suggests that consumption of “approximately two servings of fish per week (approximately eight ounces total) may reduce the risk of mortality from coronary heart disease.”
Research shows the average American must eat four times today’s average amount of dietary omega-3 fats for optimal health. So it’s up to us, the consumers, to get smart about what we eat. Learn what contains omega-3 and omega-6 fats and make your choices wisely. It’s important to know how much of these fats you’re taking in, what the food sources are, and how your diet can be modified to get the proper balance of these essential fatty acids. Omega-3 supplements also may help ensure an adequate balance of essential fat.
Rebecca N. Schiller received her Masters of Science degree in Nutritional Sciences from Bastyr University. She was the recipient of a Cancer Research Fellowship Award from the National Cancer Institute and has contributed to research conducted at both the National Cancer Institute’s Department of Cancer Epidemiology and Genetics, and the Fred Hutchinson Cancer Research Center. She has an extensive background in nutrition and health writing. Please contact Rebecca through her company, WriteNutrition, www.writenutrition.com (email rebecca@writenutrition.com).
References
1. Simopoulos AP. Essential fatty acids in health and chronic disease. Am J Clin Nutr. 2004 Mar; 79(3):523-4.
2. Cordain L, Watkins BA, Florant GL, Kelher M, Rogers L, Li Y. Fatty acid analysis of wild ruminant tissues: evolutionary implications for reducing diet-related chronic disease. Eur J Clin Nutr. 2002 Mar;56(3):181-91.
3. Nutrition and Your Health: Dietary Guidelines for Americans, fifth edition, USDA, 2000. www.health.gov/dietaryguidelines/dga2000/document/frontcover.htm
4. American Heart Association Dietary Guidelines. www.americanheart.org/presenter.jhtml?identifier=6735
5. Nutrition and Your Health: Dietary Guidelines for Americans. 2005 Dietary Guidelines Advisory Committee Report. www.health.gov/dietaryguidelines/dga2005/report/PDF/D4_Fats.pdf
Polyunsaturated fatty acids in the food chain in the United States