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“Today we eat oils that did not exist 100 years ago, like cottonseed and soybean oils, which are among the top sources of omega-6 fat. Prior to industrialization, no population has eaten the current levels of omega-6 fat. While omega-6 fat is an essential nutrient (especially linoleic acid), eating just two slices of whole wheat bread will provide for your body needs.” Evelyn Tribole, MS, RD
The Problem with Omega-6 Fat
Fat Making Fats
Our article on food combinations and Alzheimer’s risk discouraged consumption of omega-6, an essential fatty acid: http://www.cbass.com/Mediterranean_BrainandHeart.htm.
If omega 6 is essential for good health, what's the problem?
This is an opportune time to talk about it, thanks to a recent experiment by Susan Allport, the author of The Queen of Fats (University of California Press, 2006). (We discussed Allport’s book earlier; see “Harvard Study Says, Eat Fish” http://www.cbass.com/EatFish.htm )
Our bodies can’t manufacture omega 3 or 6; they must be supplied in the food we eat. “The problem [is] that the tissues of Western populations [are] awash in omega-6s, fats that compete with the omega-3s,” Susan Allport wrote in her book
She used herself as a case study to observe what happens in the body after 30 days on a diet high in omega-6 fatty acids. A single study on a single subject is hardly definitive, but it is a remarkable demonstration of what happens when omega 6s overwhelm omega 3s. It’s especially noteworthy when we realize that the typical Western diet is overloaded with omega 6s (and relatively deficient in omega 3s).
Allport’s experiment is reported online by Evelyn Tribole, a registered dietician; see link below. What follows is an overview and commentary.
The Allport Experiment
Tribole begins with the bottom line: 30 days on a high omega-6 diet stiffened Allport’s arteries, slowed her metabolism, and increased her belly fat.
Interestingly, Allport sold her story to Oprah magazine, which for unspecified reasons decided not to publish it. Allport then contacted Tribole, who enthusiastically reported it on her blog.
The first thing I wanted to know was how Allport changed her diet; next was how the results were measured.
Allport was of course consuming a desirable balance of omega 3s and 6s. She switched to high omega-6 spreads and oils. For example, canola-based mayonnaise was replaced with mayo made with soybean oil. Olive oil-based salad dressings were replaced with a mixture of safflower, sunflower, corn, and soybean oils.
She also replaced grass-fed dairy products with traditional dairy foods. (Explained below)
Importantly, Allport continued to eat fish twice a week, as recommended by the American Heart Association.
Allport’s documentation was based on state-of-the-art tests. We've discussed most of them previously:
●The new Omega-3 Index of fatty acids in the blood
● Dual-energy X-ray (DEXA) to determine body composition throughout the body
● Resting Metabolic Rate (RMR)
● Flow-Mediated Vasodilation (FMD) http://www.cbass.com/Everymealcounts and ultrasound scan, both measures of arterial function and stiffness.
The changes after only 30 days were remarkable.
As noted here previously, the Omega-3 (blood) Index protective level is 8% or higher; under 4% indicates high risk for heart disease. Susan Allport’s Omega-3 Index dropped from 8.3% to 4.7%. Amazingly, her heart disease risk went from low to borderline high in only 30 days.
Her body weight remained the same, but the composition changed. “[Her] body fat increased in the abdominal area by nearly one-half pound,” Tribole reported. “Fat was also increased in the trunk region, where notably, lean body mass decreased.” (Total fat gain is not specified.)
Her resting metabolic rate dropped, lowering her daily calorie burn at rest from 1367 to 1291. (A pound of fat contains 3500 calories, suggesting that total fat gain was about .65 pounds.)
Finally, flow-mediated vasodilation (FMD) showed that her brachial artery dilation decreased by 22%. As explained in our earlier articles, FMD measures blood flow after the release of a blood pressure cuff around the upper arm. Her arteries were also stiffer, based on the ultrasound scan. Taken together, these reading indicate that her blood vessels were less able to expand and contract.
It’s telling that these changes took place even though Susan Allport complied with the standard advice to eat fish twice a week.
“This reinforces the notion that merely gobbling fish oil, or eating fish, will not overcome the problem of eating a high omega-6 diet,” Tribole observed.
Tribole compared it to “Omega-6 Syndrome” occurring in Okinawans experiencing a marked rise in chronic disease rates. “The answer, the [Japanese] scientists discovered, was Okinawans had inadvertently tripled their omega-6 intake,” she wrote. “Like Susan, the Okinawans were still eating fish, but it did not protect them from health problems, when eating a higher omega-6 fat diet.” (The fat in processed foods is usually saturated or omega 6.)
This is analogous to the recent finding that reducing saturated fat consumption is not enough; to reduce heart disease risk, saturated fat must be replaced with “good” fats. For more details, see our article: http://www.cbass.com/CuttingSatFat.htm
The point being made in Susan Allport’s case is that eating more omega-3 fats alone is not enough; we must also cut back on omega-6 fats.
Exploring the changes Allport made in her diet helped me understand what happened.
I assume that she was already eating fish, the best source of useable omega-3 fatty acids. So that didn't change.
Canola oil and olive oil, which she was having previously, are largely monounsaturated oils. Most of the fat calories in a healthy diet come from monounsaturated fatty acids. Canola oil and olive oil also have a favorable omega 6 to 3 polyunsaturated fatty acid ratio. The omega-3, however, is not easily converted to a form humans can use. (Less than 5% is converted to EPA and DHA.)
Canola oil and olive oil are “good” fats, because they are relatively low in omega-6 and do not crowd out the amount of omega-3 taken up by the cells. (For more details on the conversion of vegetable-oil omega 3s by humans, see http://www.cbass.com/FishOil.htm )
The oils Susan switched to—safflower, sunflower, corn, and soybean—are all high in omega-6 fatty acids, with little or no omega-3. They wreak havoc with the omega 6 to3 ratio.
Evelyn Tribole added this historical perspective: “Today we eat oils that did not exist 100 years ago, like cottonseed and soybean oils, which are among the top sources of omega-6 fat. Prior to industrialization, no population has eaten the current levels of omega-6 fat. While omega-6 fat is an essential nutrient (especially linoleic acid), eating just two slices of whole wheat bread will provide for your body needs.”
We cannot close without commenting on Susan Allport’s change in body composition.
Fat Making Bomb
After only 30 days on a high omega-6 diet, her metabolism slowed, and a portion of her muscle mass morphed into tummy fat. As you will recall, her weight remained stable. Her calories in and out were apparently in balance. The only change was in the type of fat she was eating.
Tribole speculates that the connection between omega-6 and fat gain may raise public consciousness of omega-6 intake like nothing else has.
“Perhaps, awareness and change will come from public health’s ‘war on obesity,’” she wrote. “Earlier this month, the global news agency AFP, warned that eating the wrong mix of fats can cause obesity, and quoted the lead scientist, ‘Omega six is like a fat-producing bomb.’” (My emphasis)
“In…experiments, four generations of mice were fed a 35-percent fat diet with the omega imbalance now found in much of the developed world,” AFP reported. “The result was progressively fatter mice at birth, generation after generation.”
“Over the last four decades, the ratio of omega-6 to omega-3 in a typical Western diet has shifted from a healthy five-to-one to 15-to-one in much of Europe, and up to 40-to-one in the United States,” AFP reported.
The generational weight gain can be partly explained by the change from grass-fed to grain-fed livestock, according to the researcher. (Grass is rich in omega-3.) "But to increase productivity, feed was shifted to grain meal, especially corn, which contains a high concentration of omega-6,” the researcher said.
(That explains why Susan Allport replaced grass-fed dairy products with traditional dairy foods.)
* * *
The idea that omega imbalance can promote obesity is not new. We wrote about it in Challenge Yourself and again in Great Expectations.
The concept began with the report of a Japanese study reported in the December 1996 issue of the journal Metabolism.
That study parallels Susan Allport’s experiment of one.
The Japanese researchers raised mice prone to diabetes and obesity on a variety of diets containing 60% fat, and then recorded the change in body weight. All of the diets contained the same number of calories; the only difference was the type of fat consumed. (Again, note the parallel to the Allport experiment.)
The resulting variation in weight gain was astonishing.
The difference in weight between the mice fed soybean oil and those fed fish oil was “comparable to the difference in weight between a 225- and a 150-pound man,” according to Artemis P. Simopoulos, MD, author of The Omega Plan (Harper Collins, 1998). A lard/fish oil comparison produced a weight gain disparity almost as great.
Soybean oil and lard are high in omega-6 and fish oil is high in omega-3.
Susan Allport, in her book The Queen of Fats, developed this concept further and provided a plausible explanation. I summarized her explanation in Great Expectations. The basic idea isn’t hard to grasp.
“There are profound differences between diets and tissues full of omega-6s and omega-3s, differences that slow our bodies down and speed them up,” Allport wrote.
Analyzing the tissues of animals with different metabolic rates, researchers found that “the fat of large, slow mammals were more saturated and contained more omega-6 fatty acids than the fats of small, fast mammals like the mouse, which contains more [omega-3],” Allport wrote. “The fats of high-speed animals like the hummingbird were loaded with [omega-3].”
Zooming back to present day, Allport has walked her talk. By switching from omega-3 fats to omega-6 for just 30 days, she demonstrated a slowing of her own metabolism and a change in body composition from lean mass to fat.
The slowing of resting metabolic rate was only 100 calories and the change in body fat was only ½ pound or so, but it is remarkable nonetheless. She has made a very impressive start on proving the concept in humans.
Eat fish—and watch your omega-6s.
As promised, here are the links to Evelyn Tribole’s blog: www.evelyntribole.com (Omega-6 Fat Research News) and to Susan Allport’s website www.susanallport.com (Omega-6 Me). Both are valuable repositories of cutting-edge information on the omega fats.
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