From The Desk Of Clarence Bass
“Not all saturated fatty acids are alike.” Reuters Health News, August 22, 2014
Rethinking Saturated Fats
One Form of Saturated Fat Adds Dangerous Belly Fat, While Another Lowers Diabetes Risk
Thinking on saturated fat is changing. Guidelines that treat saturated fats as a whole are being questioned: researchers are finding that some forms of saturated fat are beneficial and others are harmful. While the science is far from settled, new directions are beginning to emerge from worldwide studies: one from Sweden and the other from the United Kingdom are important harbingers of what’s to come. (A third study was announced as this was being written; see below)
Researchers from Uppsala University in Stockholm found that overeating polyunsaturated fat—think plant oils, nuts, and fatty fish—resulted in less accumulation of belly and liver fat than the same amount of saturated fat, found in red meat, butter, and palm oil. Somewhat surprisingly, overeating polyunsaturated fat also resulted in more muscle.
On the other hand, UK researchers from Cambridge University found that saturated fats found primarily in dairy products (yogurt, cheese, milk) lowered the risk of type 2 diabetes, while saturated fats formed as a result of consuming alcohol, soft drinks, potatoes, and margarine increased the risk. “Different individual [blood] plasma…saturated fatty acids (SFAs) were associated with incident type 2 diabetes in opposite directions, which suggests that SFAs are not homogeneous in their effects,” the researchers wrote.
Let’s examine the studies and look for take away messages. We’ll start with the study from Sweden.
Animal studies had previously shown that overfeeding polyunsaturated fats caused less fat accumulation than overfeeding saturated fats. The Swedish study was the first study done on humans to show that the type of fat in your diet can not only influence cholesterol levels and cardiovascular disease, but may also determine where fat will be stored on your body. Senior researcher Dr. Ulf Riserus and colleagues found that overeating saturated fat (palm oil) caused participants to gain visceral fat, a dangerous type of fat around abdominal organs such as the liver. Subjects eating the same amount of polyunsaturated fat (sunflower oil), on the other hand, gained less fat and more muscle.
“If a high-caloric diet contains large amounts of saturated fats it seems to switch on some genes that may promote abdominal fat storage and insulin resistance, and thereby result in a more unfavorable fat storage,” Dr. Riserus told MedicalResearch.com. “In contrast, such effects were not seen if the diet was lower in saturated fats but higher in polyunsaturated fats from non-tropical vegetable oils.” Riserus added.
Previous research has shown that stored fat doesn’t just sit around your waist as an unattractive nuisance. It actually functions more like a toxic organ system that wields a powerful negative influence over the rest of the body. For more details, see our article # 378, “Healthy Obesity a Pipe Dream.”
In the Swedish study, participants were asked to gain 3% of their starting weight by overeating either saturated fat or polyunsaturated fat, keeping calories, protein, and carbohydrate the same. As intended, both groups gained a comparable amount of weight. The difference was that the group that ate saturated fat ended up with more visceral fat and three times less muscle than the group eating polyunsaturated fats.
MRI scans before and after the weight gains were used to measure changes in body fat and muscle mass distribution. Gene activity was measured using a gene chip that studies several thousand genes at a time.
The researcher concluded that the type of fat you eat has important “anabolic effects” in the body. “The fate of saturated fats appears to be ectopic [misplaced] fat accumulation, whereas polyunsaturated fats instead promote lean tissue in healthy subjects,” they wrote.
Asked for the take away from the report, Dr. Riserus recommended replacing some saturated fat—red meats, butter, and palm oil, for example—with unsaturated fats from plant oils, nuts, and fatty fish.
Mark A. Rosenberg, MD, a specialist in healthy aging not involved in the study, added an important corollary: “This is an especially significant finding for people over 50 who, with the hormonal imbalances of menopause and andropause, tend to gain a lot of fat around their belly….Adding more polyunsaturated fats in your diet, as you get older, could actually help you retain, and even build, muscle mass.” Muscle mass is, of course, important for independent living. (www.foodtrients.com )
The statistics in this study are voluminous and mind numbing—and impressive; you can read the full report in the February 18, 2014, Diabetes. The study is also summarized in the February 24, 2014, Science Daily.
The second study makes a powerful statement on the diversity of saturated fats; some are good and some are bad.
* * *
The Cambridge University researchers found that people with high levels of odd-chain saturated fatty acids in their blood—coming primarily from dairy fats—have a lower risk of type 2 diabetes. People with high levels of even-chain fatty acids—coming indirectly from alcohol, soft drinks, potatoes, and margarine—are just the opposite. They have a higher risk of type 2 diabetes. Let’s take it one step at a time.
Nita Forouhi, MD, and her team reported their results online August 6, 2014, in Lancet Diabetes Endocrinology. They identified 12,403 verified cases of type 2 diabetes and 16,154 other representative people from across eight European countries. They then examined their blood plasma for saturated fatty acids (SFAs) with 9 different configurations of carbon atoms, grouping their findings into three groups: even chain, odd chain, and longer chain. Unlike food questionnaires, blood plasma is an objective measure and a strength of the Forouhi study. Notably, the fatty acid groups were also found to correlate with self-reported food intake.
The study was accompanied by an enlightening editorial by Dariush Mozaffarian, MD, DrPH. Mozaffarian explained that SFAs exist with chain lengths ranging from 6 to 22 or more carbon atoms. He added that SFAs are obtained from remarkably diverse foods (red meat, poultry, processed meats, yogurt, milk, cheese, butter, vegetable oils, and nuts, among others) that contain many other components that could modify their overall impact on health. Mozaffarian further explained that some SFAs are formed inside the body in response to outsized carbohydrate or calories intake.
With that background, here are the bottom line findings on saturated fatty acids and diabetes risk.
Forouhi and her team found that odd chain (15 & 17 carbon atoms) and longer chain SFAs (20, 22, 23 & 24 carbon atoms) were both associated with a 30% lower diabetes risk, while even chain SFAs (14, 16 & 18 atoms) were associated with 43% greater risk of diabetes. Importantly, the results were robust and consistent across all eight countries.
As Dr. Mozaffarian alluded to in his editorial, even-chain SFAs correlates are a two-step process. Their formation is driven internally by consumption of alcohol, soft drink, potatoes and margarine, rather than direct dietary sources. Even-chain SFAs were, as noted, associated with greater diabetes risk.
Finally, longer chain SFAs had weaker associations with diet (the strongest association was with nuts/seeds) than the other SFAs, which suggests that internal mechanisms could be especially important for longer chain SFAs.
Forouhi and her colleagues concluded: The fact that two groups of SFAs were associated with less diabetes and the other group with more diabetes provides clear evidence that SFAs are not a single homogeneous group.
While observing that some of the findings are more clear-cut than others, Dr. Mozaffarian is clear on one thing: “Whatever the mechanism, these results add further challenges to prevailing dietary guidelines that recommend low-fat dairy products on the basis of calcium and theorize harms of total saturated fat content.” That's a key point; please read it again. (Dr. Mozaffarian is a high profile researcher. As you may remember, he was an out-spoken co-author of the much debated study which found no link between saturated fat and heart disease; see our article # 383. Mozaffarian recently left the Harvard School of Public Health to become dean of the highly-regarded Friedman School of Nutrition Science and Policy at Tufts University in Boston.)
Mozaffarian called for US dietary guidelines to move away from “over simplistic” groupings, such as total saturated fat, and toward food based guidelines.
My Take Away
Saturated fat is neither all bad nor all good; that's the "big picture" take away.
The third study mentioned above, the one that just came out (9-16-14), nailed down the most important finding--for me.
Researchers from Lund University Diabetes Center, Malmo, Sweden, found that a large intake of full-fat dairy products was associated with a reduced risk of type 2 diabetes. Low-fat dairy did not have the same effect. The study was presented by epidemiologist Ulrika Ericson, PhD, at the European Association for the Study of Diabetes 2014 Meeting. Ericson and her colleagues found that people who consume over 8 portions per day of full-fat dairy products (yogurt, cheese, and milk) have a 23% lower risk of developing type 2 diabetes than those who consume one or fewer portions a day. Again, low-fat dairy did not have the same effect.
That, along with the Forouhi study from Cambridge, reinforces my decision, announced several months ago, to go back to drinking full-fat milk after three decades of skimmed milk consumption; see “Organic Whole Milk Is Better,” our article # 382.
A super healthy HDL "good" cholesterol report was the first indication that my switch was well advised. (See article # 388, “About HDL Cholesterol.” )
The new findings that full-fat dairy lowered the risk of T2D are especially welcome in view of my familial propensity to develop T2D.
On the other hand, the finding from Uppsala University that overeating polyunsaturated fat resulted in less accumulation of belly and liver fat than the same amount of saturated fat strengthens my long established liking for nuts, fatty fish, and canola oil—and my avoidance of processed red meat and butter. (I can’t remember ever having palm oil.) Carol and I do enjoy range-fed bison or beef occasionally.
The complex findings in the Forouhi study, taken as a whole, also lend credence to a Mediterranean style diet. So I will hold the course there as well.
The Mediterranean diet appears to have the best of everything: fruits, vegetables, whole grains, fish, plant oils, and nuts, with lower intakes of sugar, processed meat, and animal fats. (We rarely have alcoholic beverages.) Add whole-fat dairy and we’re there.
You’ll find many articles about the Mediterranean style diet in our Diet & Nutrition category; don’t overlook my piece on the Grain Brain: http://www.cbass.com/carbs_brain.htm
Taken by Wayne Gallasch in 1983, this photo shows me buying whole milk at a local dairy. I switched to skimmed milk a short time later.
Here I'm doing HeavyHands. Taken by Wayne Gallasch at the same time, it suggests that whole milk was agreeing with me.
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