MensHealth.com
Saturated Fat
Stop Blaming Saturated Fat
The research is clear: Carbohydrates, not fats, are the foe in America's battle against heart disease and obesity
By: Adam Campbell & Jeff Volek, Ph.D., R.D.
The recent news that the Atkins low-carb diet works well and improves health has some people scratching their heads.
--We typically eat more than a dozen kinds of saturated fat. Some have zero effect on cholesterol. Some raise bad (LDL) cholesterol, but all of them raise good (HDL) cholesterol to a greater extent. That’s a net gain in heart health.
--The nation's top health organizations have for decades called saturated fat one of the main culprits for diet-related diseases, including obesity, diabetes, heart disease, and cancer. Problem is, this blame stems from research that is now seen as incomplete. For instance, a famous 1953 study took data from six countries, overlooking 16 countries whose numbers provide contradictory evidence. (Like France, for instance, or native cultures in Africa and Canada where high amounts of fat and saturated fat are eaten but heart disease is practically unknown.)
--Since the 1970s, American men have decreased their saturated fat intake by 14 percent and increased their carbohydrate intake by 23 percent--yet rates of obesity and heart disease are increasing. You might say that carbohydrates make people fat, which leads to heart disease. Or that more carbohydrates you eat, the greater your risk for a heart attack.
--But these simple numbers only suggest a cause. To prove something, you need a controlled experiment. There have been many such clinical trials, and not one has shown has shown that cutting back on saturated fat reduces heart disease risk.
--When you look at the effect of saturated fat on health, you must also look at the intake of carbohydrates. Many studies have shown that if you replace carbs with fat, your triglycerides levels go down and your good cholesterol goes up. And your bad (LDL) cholesterol particles get bigger, which means they're less harmful.
--Here's a paradox for you: A high saturated fat intake decreases blood levels of saturated fat. How can this be? Here's how: The saturated fat in your blood comes from both the food you eat and from your liver, which produces saturated fat. The more carbs you eat, the higher your insulin levels climb, which signals your liver to produce saturated fat. If you go on a low-carb diet, your insulin levels drop, and so does production of saturated fat.
--A bonus: with low insulin levels, your body can burn more fat for energy, decreasing your sat-fat levels even more.
http://www.menshealth.com/cda/article.do
?site=MensHealth&channel=nutrition&category=food.for.fitness
&conitem=b675909829731110VgnVCM10000013281eac____&page=0
2007 RODALE INC. ALL rights reserved
Showing posts with label nutrition. Show all posts
Showing posts with label nutrition. Show all posts
Wednesday, December 12, 2007
Tuesday, November 6, 2007
Extremely Fascinating Article
Men's Health
Saturated Fat
What if Bad Fat is Actually Good for You?
For decades, Americans have been told that saturated fat clogs arteries and causes heart disease. But there's just one problem: No one's ever proved it
By: Nina Teicholz, Photographs by: Nikolai Golovanoff
Suppose you were forced to live on a diet of red meat and whole milk. A diet that, all told, was at least 60 percent fat -- about half of it saturated. If your first thoughts are of statins and stents, you may want to consider the curious case of the
Masai, a nomadic tribe in Kenya and Tanzania.
In the 1960s, a Vanderbilt University scientist named George Mann, M.D., found that Masai men consumed this very diet (supplemented with blood from the cattle they herded). Yet these nomads, who were also very lean, had some of the lowest levels of cholesterol ever measured and were virtually free of heart disease.
Scientists, confused by the finding, argued that the tribe must have certain genetic protections against developing high cholesterol. But when British researchers monitored a group of Masai men who moved to Nairobi and began consuming a more modern diet, they discovered that the men's cholesterol subsequently skyrocketed.
Similar observations were made of the Samburu -- another Kenyan tribe -- as well as the Fulani of Nigeria. While the findings from these cultures seem to contradict the fact that eating saturated fat leads to heart disease, it may surprise you to know that this "fact" isn't a fact at all. It is, more accurately, a hypothesis from the 1950s that's never been proved.
The first scientific indictment of saturated fat came in 1953. That's the year a physiologist named Ancel Keys, Ph.D., published a highly influential paper titled "Atherosclerosis, a Problem in Newer Public Health." Keys wrote that while the total death rate in the United States was declining, the number of deaths due to heart disease was steadily climbing. And to explain why, he presented a comparison of fat intake and heart disease mortality in six countries: the United States, Canada, Australia, England, Italy, and Japan.
The Americans ate the most fat and had the greatest number of deaths from heart disease; the Japanese ate the least fat and had the fewest deaths from heart disease. The other countries fell neatly in between. The higher the fat intake, according to national diet surveys, the higher the rate of heart disease. And vice versa. Keys called this correlation a "remarkable relationship" and began to publicly hypothesize that consumption of fat- causes heart disease. This became known as the diet-heart hypothesis.
At the time, plenty of scientists were skeptical of Keys's assertions. One such critic was Jacob Yerushalmy, Ph.D., founder of the biostatistics graduate program at the University of California at Berkeley. In a 1957 paper, Yerushalmy pointed out that while data from the six countries Keys examined seemed to support the diet-heart hypothesis, statistics were actually available for 22 countries. And when all 22 were analyzed, the apparent link between fat consumption and heart disease disappeared. For example, the death rate from heart disease in Finland was 24 times that of Mexico, even though fat-consumption rates in the two nations were similar.
The other salient criticism of Keys's study was that he had observed only a correlation between two phenomena, not a clear causative link. So this left open the possibility that something else -- unmeasured or unimagined -- was leading to heart disease. After all, Americans did eat more fat than the Japanese, but perhaps they also consumed more sugar and white bread, and watched more television.
Despite the apparent flaws in Keys's argument, the diet-heart hypothesis was compelling, and it was soon heavily promoted by the American Heart Association (AHA) and the media. It offered the worried public a highly educated guess as to why the country was in the midst of a heart-disease epidemic. "People should know the facts," Keys said in a 1961 interview with Time magazine, for which he appeared on the cover. "Then if they want to eat themselves to death, let them."
The seven-countries study, published in 1970, is considered Ancel Keys's landmark achievement. It seemed to lend further credence to the diet-heart hypothesis. In this study, Keys reported that in the seven countries he selected -- the United States, Japan, Italy, Greece, Yugoslavia, Finland, and the Netherlands -- animal-fat intake was a strong predictor of heart attacks over a 5-year period. Just as important, he noted an association between total cholesterol and heart-disease mortality. This prompted him to conclude that the saturated fats in animal foods -- and not other types of fat -- raise cholesterol and ultimately lead to heart disease.
Naturally, proponents of the diet-heart hypothesis hailed the study as proof that eating saturated fat leads to heart attacks. But the data was far from rock solid. That's because in three countries (Finland, Greece, and Yugoslavia), the correlation wasn't seen. For example, eastern Finland had five times as many heart-attack fatalities and twice as much heart disease as western Finland, despite only small differences between the two regions in animal-fat intake and cholesterol levels. And while Keys provided that raw data in his report, he glossed over it as a finding. Perhaps a larger problem, though, was his assumption that saturated fat has an unhealthy effect on cholesterol levels.
Although more than a dozen types of saturated fat exist, humans predominantly consume three: stearic acid, palmitic acid, and lauric acid. This trio comprises almost 95 percent of the saturated fat in a hunk of prime rib, a slice of bacon, or a piece of chicken skin, and nearly 70 percent of that in butter and whole milk.
Today, it's well established that stearic acid has no effect on cholesterol levels. In fact, stearic acid -- which is found in high amounts in cocoa as well as animal fat --i s converted to a monounsaturated fat called oleic acid in your liver. This is the same heart-healthy fat found in olive oil. As a result, scientists generally regard this saturated fatty acid as either benign or potentially beneficial to your health.
Palmitic and lauric acid, however, are known to raise total cholesterol. But here's what's rarely reported: Research shows that although both of these saturated fatty acids increase LDL ("bad") cholesterol, they raise HDL ("good") cholesterol just as much, if not more. And this lowers your risk of heart disease. That's because it's commonly believed that LDL cholesterol lays down plaque on your artery walls, while HDL removes it. So increasing both actually reduces the proportion of bad cholesterol in your blood to the good kind. This may explain why numerous studies have reported that this HDL/LDL ratio is a better predictor of future heart disease than LDL alone.
All of this muddies Keys's claim of a clear connection between saturated-fat intake, cholesterol, and heart disease. If saturated fat doesn't raise cholesterol in such a way that it increases heart-disease risk, then according to the scientific method, the diet-heart hypothesis must be rejected. However, in 1977 it was still a promising idea.
That was the year Congress made it government policy to recommend a low-fat diet, based primarily on the opinions of health experts who supported the diet-heart hypothesis. It was a decision met with much criticism from the scientific community, including the American Medical Association. After all, officially endorsing a low-fat diet could change the eating habits of millions of Americans, and the potential effects of this strategy were widely debated and certainly unproved.
We've spent billions of our tax dollars trying to prove the diet-heart hypothesis. Yet study after study has failed to provide definitive evidence that saturated-fat intake leads to heart disease. The most recent example is the Women's Health Initiative, the government's largest and most expensive ($725 million) diet study yet. The results, published last year, show that a diet low in total fat and saturated fat had no impact in reducing heart-disease and stroke rates in some 20,000 women who had adhered to the regimen for an average of 8 years.
But this paper, like many others, plays down its own findings and instead points to four studies that, many years ago, apparently did find a link between saturated fat and heart disease. Because of this, it's worth taking a closer look at each.
The Los Angeles VA Hospital Study (1969) This UCLA study of 850 men reported that those who replaced saturated fats with polyunsaturated fats were less likely to die of heart disease and stroke over a 5-year period than were men who didn't alter their diets. However, more of those who changed their diets died of cancer, and the average age of death was the same in both groups. What's more, "through an oversight," the study authors neglected to collect crucial data on smoking habits from about 100 men. They also reported that the men successfully adhered to the diet only half the time.
The Oslo Diet-Heart Study (1970) Two hundred men followed a diet low in saturated fat for 5 years while another group ate as they pleased. The dieters had fewer heart attacks, but there was no difference in total deaths between the two groups.
The Finnish Mental Hospital Study (1979) This trial took place from 1959 to 1971 and appeared to document a reduction in heart disease in psychiatric patients following a "cholesterol-lowering" diet. But the experiment was poorly controlled: Almost half of the 700 participants joined or left the study over its 12-year duration.
The St. Thomas' Atherosclerosis Regression Study (1992) Only 74 men completed this 3-year study conducted at St. Thomas' Hospital, in London. It found a reduction in cardiac events among men with heart disease who adopted a low-fat diet. There's a major caveat, though: Their prescribed diets were also low in sugar.
These four studies, even though they have serious flaws and are tiny compared with the Women's Health Initiative, are often cited as definitive proof that saturated fats cause heart disease. Many other more recent trials cast doubt on the diet-heart hypothesis. These studies should be considered in the context of all the other research.
In 2000, a respected international group of scientists called the Cochrane Collaboration conducted a "meta-analysis" of the scientific literature on cholesterol-lowering diets. After applying rigorous selection criteria (219 trials were excluded), the group examined 27 studies involving more than 18,000 participants. Although the authors concluded that cutting back on dietary fat may help reduce heart disease, their published data actually shows that diets low in saturated fats have no significant effect on mortality, or even on deaths due to heart attacks.
"I was disappointed that we didn't find something more definitive," says Lee Hooper, Ph.D., who led the Cochrane review. If this exhaustive analysis didn't provide evidence of the dangers of saturated fat, says Hooper, it was probably because the studies reviewed didn't last long enough, or perhaps because the participants didn't lower their saturated-fat intake enough. Of course, there is a third possibility, which Hooper doesn't mention: The diet-heart hypothesis is incorrect.
Ronald Krauss, M.D., won't say saturated fats are good for you. "But," he concedes, "we don't have convincing evidence that they're bad, either."
For 30 years, Dr. Krauss -- an adjunct professor of nutritional sciences at the University of California at Berkeley -- has been studying the effect of diet and blood lipids on cardiovascular disease. He points out that while some studies show that replacing saturated fats with unsaturated fats lowers heart-disease risk, this doesn't mean that saturated fats lead to clogged arteries. "It may simply suggest that unsaturated fats are an even healthier option," he says.
But there's more to this story: In 1980, Dr. Krauss and his colleagues discovered that LDL cholesterol is far from the simple "bad" particle it's commonly thought to be. It actually comes in a series of different sizes, known as subfractions. Some LDL subfractions are large and fluffy. Others are small and dense. This distinction is important.
A decade ago, Canadian researchers reported that men with the highest number of small, dense LDL subfractions had four times the risk of developing clogged arteries than those with the fewest. Yet they found no such association for the large, fluffy particles. These findings were confirmed in subsequent studies.
Now here's the saturated-fat connection: Dr. Krauss found that when people replace the carbohydrates in their diet with fat--saturated or unsaturated -- the number of small, dense LDL particles decreases. This leads to the highly counterintuitive notion that replacing your breakfast cereal with eggs and bacon could actually reduce your risk of heart disease.
Men, more than women, are predisposed to having small, dense LDL. However, the propensity is highly flexible and, according to Dr. Krauss, can be switched on when people eat high-carb, low-fat diets or switched off when they reduce carbs and eat diets high in fat, including the saturated variety. "There's a subgroup of people at high risk of heart disease who may respond well to diets low in fat," says Dr. Krauss. "But the majority of healthy people seem to derive very little benefit from these low-fat diets, in terms of heart-disease risk factors, unless they also lose weight and exercise. And if a low-fat diet is also loaded with carbs, it can actually result in adverse changes in blood lipids."
While Dr. Krauss is much published and highly respected -- he has served twice as chairman of the writing committee of the AHA's dietary guidelines -- the far-reaching implications of his work have not been generally acknowledged. "Academic scientists believe saturated fat is bad for you," says Penny Kris-Etherton, Ph.D., a distinguished professor of nutritional studies at Penn State University, citing as evidence the "many studies" she believes show it to be true. But not everyone accepts those studies, and their proponents find it hard to be heard. Kris-Etherton acknowledges that "there's a good deal of reluctance toward accepting evidence suggesting the contrary."
Take, for example, a 2004 Harvard University study of older women with heart disease. Researchers found that the more saturated fat these women consumed, the less likely it was their condition would worsen. Lead study author Dariush Mozaffarian, Ph.D., an assistant professor at Harvard's school of public health, recalls that before the paper was published in the American Journal of Clinical Nutrition, he encountered formidable politics from other journals.
"In the nutrition field, it's very difficult to get something published that goes against established dogma," says Mozaffarian. "The dogma says that saturated fat is harmful, but that is not based, to me, on unequivocal evidence." Mozaffarian says he believes it's critical that scientists remain open minded. "Our finding was surprising to us. And when there's a discovery that goes against what's established, it shouldn't be suppressed but rather disseminated and explored as much as possible."
Perhaps the apparent bias against saturated fat is most evident in studies on low-carbohydrate diets. Many versions of this approach are controversial because they place no limitations on saturated-fat intake. As a result, supporters of the diet-heart hypothesis have argued that low-carb diets will increase the risk of heart disease. But published research doesn't show this to be the case. When people on low-carb diets have been compared head-to-head with those on low-fat diets, the low-carb dieters typically scored significantly better on markers of heart disease, including small, dense LDL cholesterol, HDL/LDL ratio, and triglycerides, which are a measure of the amount of fat circulating in your blood.
For example, in a new 12-week study, University of Connecticut scientists placed overweight men and women on either a low-carb or low-fat diet. Those who followed the low-carb diet consumed 36 grams of saturated fat per day (22 percent of total calories), which represented more than three times the amount in the low-fat diet. Yet despite this considerably greater intake of saturated fat, the low-carb dieters reduced both their number of small, dense LDL cholesterol and their HDL/LDL ratio to a greater degree than those who ate a low-fat diet. In addition, triglycerides decreased by 51 percent in the low-carb group--compared with 19 percent in the low-fat group.
This finding is worth noting, because even though cholesterol is the most commonly cited risk factor for heart disease, triglyceride levels may be equally relevant. In a 40-year study at the University of Hawaii, scientists found that low triglyceride levels at middle age best predicted "exceptional survival" -- defined as living until age 85 without suffering from a major disease.
According to lead study author Jeff Volek, Ph.D., R.D., two factors influence the amount of fat coursing through your veins. The first, of course, is the amount of fat you eat. But the more important factor is less obvious. Turns out, your body makes fat from carbohydrates. It works like this: The carbs you eat (particularly starches and sugar) are absorbed into your bloodstream as sugar. As your carb intake rises, so does your blood sugar. This causes your body to release the hormone insulin. Insulin's job is to return your blood sugar to normal, but it also signals your body to store fat. As a result, your liver starts converting excess blood sugar to triglycerides, or fat.
All of which helps explain why the low-carb dieters in Volek's study had a greater loss of fat in their blood. Restricting carbs keeps insulin levels low, which lowers your internal production of fat and allows more of the fat you do eat to be burned for energy.
Yet even with this emerging data and the lack of scientific support for the diet-heart hypothesis, the latest AHA dietary guidelines have reduced the recommended amount of saturated fat from 10 percent of daily calories to 7 percent or less. "The idea was to encourage people to decrease their saturated-fat intake even further, because there's a linear relationship between saturated-fat intake and LDL cholesterol," says Alice H. Lichtenstein, Ph.D., Sc.D., who led the AHA nutrition committee that wrote the recommendation.
What about Krauss's findings that not all LDL is equal? Lichtenstein says that her committee didn't address them, but that it might in the future.
It could be that it's not bad foods that cause heart disease, it's bad habits. After all, in Volek's study, participants who followed the low-fat diet -- which was high in carbs -- also decreased their triglycerides. "The key factor is that they weren't overeating," says Volek. "This allowed the carbohydrates to be used for energy rather than converted to fat." Perhaps this is the most important point of all. If you consistently consume more calories than you burn, and you gain weight, your risk of heart disease will increase -- whether you favor eating saturated fats, carbs, or both.
But if you're living a healthy lifestyle -- you aren't overweight, you don't smoke, you exercise regularly -- then the composition of your diet may matter much less. And, based on the research of Volek and Dr. Krauss, a weight-loss or maintenance diet in which some carbohydrates are replaced with fat -- even if it's saturated -- will reduce markers of heart-disease risk more than if you followed a low-fat, high-carb diet.
"The message isn't that you should gorge on butter, bacon, and cheese," says Volek. "It's that there's no scientific reason that natural foods containing saturated fat can't, or shouldn't, be part of a healthy diet."
For more on this topic and a guide to foods you shouldn't fear, check out "Fat Foods You Can Eat".
http://www.menshealth.com/cda/article.do
?site=MensHealth&channel=health&category=heart.disease
&conitem=a03ddd2eaab85110VgnVCM10000013281eac____&page=0
2007 RODALE INC. ALL rights reserved
Saturated Fat
What if Bad Fat is Actually Good for You?
For decades, Americans have been told that saturated fat clogs arteries and causes heart disease. But there's just one problem: No one's ever proved it
By: Nina Teicholz, Photographs by: Nikolai Golovanoff
Suppose you were forced to live on a diet of red meat and whole milk. A diet that, all told, was at least 60 percent fat -- about half of it saturated. If your first thoughts are of statins and stents, you may want to consider the curious case of the
Masai, a nomadic tribe in Kenya and Tanzania.
In the 1960s, a Vanderbilt University scientist named George Mann, M.D., found that Masai men consumed this very diet (supplemented with blood from the cattle they herded). Yet these nomads, who were also very lean, had some of the lowest levels of cholesterol ever measured and were virtually free of heart disease.
Scientists, confused by the finding, argued that the tribe must have certain genetic protections against developing high cholesterol. But when British researchers monitored a group of Masai men who moved to Nairobi and began consuming a more modern diet, they discovered that the men's cholesterol subsequently skyrocketed.
Similar observations were made of the Samburu -- another Kenyan tribe -- as well as the Fulani of Nigeria. While the findings from these cultures seem to contradict the fact that eating saturated fat leads to heart disease, it may surprise you to know that this "fact" isn't a fact at all. It is, more accurately, a hypothesis from the 1950s that's never been proved.
The first scientific indictment of saturated fat came in 1953. That's the year a physiologist named Ancel Keys, Ph.D., published a highly influential paper titled "Atherosclerosis, a Problem in Newer Public Health." Keys wrote that while the total death rate in the United States was declining, the number of deaths due to heart disease was steadily climbing. And to explain why, he presented a comparison of fat intake and heart disease mortality in six countries: the United States, Canada, Australia, England, Italy, and Japan.
The Americans ate the most fat and had the greatest number of deaths from heart disease; the Japanese ate the least fat and had the fewest deaths from heart disease. The other countries fell neatly in between. The higher the fat intake, according to national diet surveys, the higher the rate of heart disease. And vice versa. Keys called this correlation a "remarkable relationship" and began to publicly hypothesize that consumption of fat- causes heart disease. This became known as the diet-heart hypothesis.
At the time, plenty of scientists were skeptical of Keys's assertions. One such critic was Jacob Yerushalmy, Ph.D., founder of the biostatistics graduate program at the University of California at Berkeley. In a 1957 paper, Yerushalmy pointed out that while data from the six countries Keys examined seemed to support the diet-heart hypothesis, statistics were actually available for 22 countries. And when all 22 were analyzed, the apparent link between fat consumption and heart disease disappeared. For example, the death rate from heart disease in Finland was 24 times that of Mexico, even though fat-consumption rates in the two nations were similar.
The other salient criticism of Keys's study was that he had observed only a correlation between two phenomena, not a clear causative link. So this left open the possibility that something else -- unmeasured or unimagined -- was leading to heart disease. After all, Americans did eat more fat than the Japanese, but perhaps they also consumed more sugar and white bread, and watched more television.
Despite the apparent flaws in Keys's argument, the diet-heart hypothesis was compelling, and it was soon heavily promoted by the American Heart Association (AHA) and the media. It offered the worried public a highly educated guess as to why the country was in the midst of a heart-disease epidemic. "People should know the facts," Keys said in a 1961 interview with Time magazine, for which he appeared on the cover. "Then if they want to eat themselves to death, let them."
The seven-countries study, published in 1970, is considered Ancel Keys's landmark achievement. It seemed to lend further credence to the diet-heart hypothesis. In this study, Keys reported that in the seven countries he selected -- the United States, Japan, Italy, Greece, Yugoslavia, Finland, and the Netherlands -- animal-fat intake was a strong predictor of heart attacks over a 5-year period. Just as important, he noted an association between total cholesterol and heart-disease mortality. This prompted him to conclude that the saturated fats in animal foods -- and not other types of fat -- raise cholesterol and ultimately lead to heart disease.
Naturally, proponents of the diet-heart hypothesis hailed the study as proof that eating saturated fat leads to heart attacks. But the data was far from rock solid. That's because in three countries (Finland, Greece, and Yugoslavia), the correlation wasn't seen. For example, eastern Finland had five times as many heart-attack fatalities and twice as much heart disease as western Finland, despite only small differences between the two regions in animal-fat intake and cholesterol levels. And while Keys provided that raw data in his report, he glossed over it as a finding. Perhaps a larger problem, though, was his assumption that saturated fat has an unhealthy effect on cholesterol levels.
Although more than a dozen types of saturated fat exist, humans predominantly consume three: stearic acid, palmitic acid, and lauric acid. This trio comprises almost 95 percent of the saturated fat in a hunk of prime rib, a slice of bacon, or a piece of chicken skin, and nearly 70 percent of that in butter and whole milk.
Today, it's well established that stearic acid has no effect on cholesterol levels. In fact, stearic acid -- which is found in high amounts in cocoa as well as animal fat --i s converted to a monounsaturated fat called oleic acid in your liver. This is the same heart-healthy fat found in olive oil. As a result, scientists generally regard this saturated fatty acid as either benign or potentially beneficial to your health.
Palmitic and lauric acid, however, are known to raise total cholesterol. But here's what's rarely reported: Research shows that although both of these saturated fatty acids increase LDL ("bad") cholesterol, they raise HDL ("good") cholesterol just as much, if not more. And this lowers your risk of heart disease. That's because it's commonly believed that LDL cholesterol lays down plaque on your artery walls, while HDL removes it. So increasing both actually reduces the proportion of bad cholesterol in your blood to the good kind. This may explain why numerous studies have reported that this HDL/LDL ratio is a better predictor of future heart disease than LDL alone.
All of this muddies Keys's claim of a clear connection between saturated-fat intake, cholesterol, and heart disease. If saturated fat doesn't raise cholesterol in such a way that it increases heart-disease risk, then according to the scientific method, the diet-heart hypothesis must be rejected. However, in 1977 it was still a promising idea.
That was the year Congress made it government policy to recommend a low-fat diet, based primarily on the opinions of health experts who supported the diet-heart hypothesis. It was a decision met with much criticism from the scientific community, including the American Medical Association. After all, officially endorsing a low-fat diet could change the eating habits of millions of Americans, and the potential effects of this strategy were widely debated and certainly unproved.
We've spent billions of our tax dollars trying to prove the diet-heart hypothesis. Yet study after study has failed to provide definitive evidence that saturated-fat intake leads to heart disease. The most recent example is the Women's Health Initiative, the government's largest and most expensive ($725 million) diet study yet. The results, published last year, show that a diet low in total fat and saturated fat had no impact in reducing heart-disease and stroke rates in some 20,000 women who had adhered to the regimen for an average of 8 years.
But this paper, like many others, plays down its own findings and instead points to four studies that, many years ago, apparently did find a link between saturated fat and heart disease. Because of this, it's worth taking a closer look at each.
The Los Angeles VA Hospital Study (1969) This UCLA study of 850 men reported that those who replaced saturated fats with polyunsaturated fats were less likely to die of heart disease and stroke over a 5-year period than were men who didn't alter their diets. However, more of those who changed their diets died of cancer, and the average age of death was the same in both groups. What's more, "through an oversight," the study authors neglected to collect crucial data on smoking habits from about 100 men. They also reported that the men successfully adhered to the diet only half the time.
The Oslo Diet-Heart Study (1970) Two hundred men followed a diet low in saturated fat for 5 years while another group ate as they pleased. The dieters had fewer heart attacks, but there was no difference in total deaths between the two groups.
The Finnish Mental Hospital Study (1979) This trial took place from 1959 to 1971 and appeared to document a reduction in heart disease in psychiatric patients following a "cholesterol-lowering" diet. But the experiment was poorly controlled: Almost half of the 700 participants joined or left the study over its 12-year duration.
The St. Thomas' Atherosclerosis Regression Study (1992) Only 74 men completed this 3-year study conducted at St. Thomas' Hospital, in London. It found a reduction in cardiac events among men with heart disease who adopted a low-fat diet. There's a major caveat, though: Their prescribed diets were also low in sugar.
These four studies, even though they have serious flaws and are tiny compared with the Women's Health Initiative, are often cited as definitive proof that saturated fats cause heart disease. Many other more recent trials cast doubt on the diet-heart hypothesis. These studies should be considered in the context of all the other research.
In 2000, a respected international group of scientists called the Cochrane Collaboration conducted a "meta-analysis" of the scientific literature on cholesterol-lowering diets. After applying rigorous selection criteria (219 trials were excluded), the group examined 27 studies involving more than 18,000 participants. Although the authors concluded that cutting back on dietary fat may help reduce heart disease, their published data actually shows that diets low in saturated fats have no significant effect on mortality, or even on deaths due to heart attacks.
"I was disappointed that we didn't find something more definitive," says Lee Hooper, Ph.D., who led the Cochrane review. If this exhaustive analysis didn't provide evidence of the dangers of saturated fat, says Hooper, it was probably because the studies reviewed didn't last long enough, or perhaps because the participants didn't lower their saturated-fat intake enough. Of course, there is a third possibility, which Hooper doesn't mention: The diet-heart hypothesis is incorrect.
Ronald Krauss, M.D., won't say saturated fats are good for you. "But," he concedes, "we don't have convincing evidence that they're bad, either."
For 30 years, Dr. Krauss -- an adjunct professor of nutritional sciences at the University of California at Berkeley -- has been studying the effect of diet and blood lipids on cardiovascular disease. He points out that while some studies show that replacing saturated fats with unsaturated fats lowers heart-disease risk, this doesn't mean that saturated fats lead to clogged arteries. "It may simply suggest that unsaturated fats are an even healthier option," he says.
But there's more to this story: In 1980, Dr. Krauss and his colleagues discovered that LDL cholesterol is far from the simple "bad" particle it's commonly thought to be. It actually comes in a series of different sizes, known as subfractions. Some LDL subfractions are large and fluffy. Others are small and dense. This distinction is important.
A decade ago, Canadian researchers reported that men with the highest number of small, dense LDL subfractions had four times the risk of developing clogged arteries than those with the fewest. Yet they found no such association for the large, fluffy particles. These findings were confirmed in subsequent studies.
Now here's the saturated-fat connection: Dr. Krauss found that when people replace the carbohydrates in their diet with fat--saturated or unsaturated -- the number of small, dense LDL particles decreases. This leads to the highly counterintuitive notion that replacing your breakfast cereal with eggs and bacon could actually reduce your risk of heart disease.
Men, more than women, are predisposed to having small, dense LDL. However, the propensity is highly flexible and, according to Dr. Krauss, can be switched on when people eat high-carb, low-fat diets or switched off when they reduce carbs and eat diets high in fat, including the saturated variety. "There's a subgroup of people at high risk of heart disease who may respond well to diets low in fat," says Dr. Krauss. "But the majority of healthy people seem to derive very little benefit from these low-fat diets, in terms of heart-disease risk factors, unless they also lose weight and exercise. And if a low-fat diet is also loaded with carbs, it can actually result in adverse changes in blood lipids."
While Dr. Krauss is much published and highly respected -- he has served twice as chairman of the writing committee of the AHA's dietary guidelines -- the far-reaching implications of his work have not been generally acknowledged. "Academic scientists believe saturated fat is bad for you," says Penny Kris-Etherton, Ph.D., a distinguished professor of nutritional studies at Penn State University, citing as evidence the "many studies" she believes show it to be true. But not everyone accepts those studies, and their proponents find it hard to be heard. Kris-Etherton acknowledges that "there's a good deal of reluctance toward accepting evidence suggesting the contrary."
Take, for example, a 2004 Harvard University study of older women with heart disease. Researchers found that the more saturated fat these women consumed, the less likely it was their condition would worsen. Lead study author Dariush Mozaffarian, Ph.D., an assistant professor at Harvard's school of public health, recalls that before the paper was published in the American Journal of Clinical Nutrition, he encountered formidable politics from other journals.
"In the nutrition field, it's very difficult to get something published that goes against established dogma," says Mozaffarian. "The dogma says that saturated fat is harmful, but that is not based, to me, on unequivocal evidence." Mozaffarian says he believes it's critical that scientists remain open minded. "Our finding was surprising to us. And when there's a discovery that goes against what's established, it shouldn't be suppressed but rather disseminated and explored as much as possible."
Perhaps the apparent bias against saturated fat is most evident in studies on low-carbohydrate diets. Many versions of this approach are controversial because they place no limitations on saturated-fat intake. As a result, supporters of the diet-heart hypothesis have argued that low-carb diets will increase the risk of heart disease. But published research doesn't show this to be the case. When people on low-carb diets have been compared head-to-head with those on low-fat diets, the low-carb dieters typically scored significantly better on markers of heart disease, including small, dense LDL cholesterol, HDL/LDL ratio, and triglycerides, which are a measure of the amount of fat circulating in your blood.
For example, in a new 12-week study, University of Connecticut scientists placed overweight men and women on either a low-carb or low-fat diet. Those who followed the low-carb diet consumed 36 grams of saturated fat per day (22 percent of total calories), which represented more than three times the amount in the low-fat diet. Yet despite this considerably greater intake of saturated fat, the low-carb dieters reduced both their number of small, dense LDL cholesterol and their HDL/LDL ratio to a greater degree than those who ate a low-fat diet. In addition, triglycerides decreased by 51 percent in the low-carb group--compared with 19 percent in the low-fat group.
This finding is worth noting, because even though cholesterol is the most commonly cited risk factor for heart disease, triglyceride levels may be equally relevant. In a 40-year study at the University of Hawaii, scientists found that low triglyceride levels at middle age best predicted "exceptional survival" -- defined as living until age 85 without suffering from a major disease.
According to lead study author Jeff Volek, Ph.D., R.D., two factors influence the amount of fat coursing through your veins. The first, of course, is the amount of fat you eat. But the more important factor is less obvious. Turns out, your body makes fat from carbohydrates. It works like this: The carbs you eat (particularly starches and sugar) are absorbed into your bloodstream as sugar. As your carb intake rises, so does your blood sugar. This causes your body to release the hormone insulin. Insulin's job is to return your blood sugar to normal, but it also signals your body to store fat. As a result, your liver starts converting excess blood sugar to triglycerides, or fat.
All of which helps explain why the low-carb dieters in Volek's study had a greater loss of fat in their blood. Restricting carbs keeps insulin levels low, which lowers your internal production of fat and allows more of the fat you do eat to be burned for energy.
Yet even with this emerging data and the lack of scientific support for the diet-heart hypothesis, the latest AHA dietary guidelines have reduced the recommended amount of saturated fat from 10 percent of daily calories to 7 percent or less. "The idea was to encourage people to decrease their saturated-fat intake even further, because there's a linear relationship between saturated-fat intake and LDL cholesterol," says Alice H. Lichtenstein, Ph.D., Sc.D., who led the AHA nutrition committee that wrote the recommendation.
What about Krauss's findings that not all LDL is equal? Lichtenstein says that her committee didn't address them, but that it might in the future.
It could be that it's not bad foods that cause heart disease, it's bad habits. After all, in Volek's study, participants who followed the low-fat diet -- which was high in carbs -- also decreased their triglycerides. "The key factor is that they weren't overeating," says Volek. "This allowed the carbohydrates to be used for energy rather than converted to fat." Perhaps this is the most important point of all. If you consistently consume more calories than you burn, and you gain weight, your risk of heart disease will increase -- whether you favor eating saturated fats, carbs, or both.
But if you're living a healthy lifestyle -- you aren't overweight, you don't smoke, you exercise regularly -- then the composition of your diet may matter much less. And, based on the research of Volek and Dr. Krauss, a weight-loss or maintenance diet in which some carbohydrates are replaced with fat -- even if it's saturated -- will reduce markers of heart-disease risk more than if you followed a low-fat, high-carb diet.
"The message isn't that you should gorge on butter, bacon, and cheese," says Volek. "It's that there's no scientific reason that natural foods containing saturated fat can't, or shouldn't, be part of a healthy diet."
For more on this topic and a guide to foods you shouldn't fear, check out "Fat Foods You Can Eat".
http://www.menshealth.com/cda/article.do
?site=MensHealth&channel=health&category=heart.disease
&conitem=a03ddd2eaab85110VgnVCM10000013281eac____&page=0
2007 RODALE INC. ALL rights reserved
Wednesday, August 15, 2007
Nutitiondata Comparisons
Whenever I have food questions, I always go to www.nutritiondata.com. These are some things I learned this week...
Cooked frozen spinach is MUCH healthier for you than raw spinach. Just to show a few differences-
Fresh raw Cooked Frozen
Vit A 2813 IU 26534 IU
Vit K 145 mcg 1190 mcg
Folate 58.2 mcg 266 mcg
General mineral content for fresh, raw spinach is between 1% & 6% (although Mangenese is 13%) while the average mineral content for cooked, frozen spinach is 26.3%.
Cooked, fresh spinach is comparable to cooked frozen containing more vitamin C & E but less vitamin A and K. Spinach's anti-inflammatory index raises considerably after cooking it.
Baby carrots contain almost no vitamins and minerals, especially when compared to regular carrots. They do contain 2068 IU vitamin A but regular carrots contain 21520 IU.
Brown and white rice are surprisingly similar. Brown rice does have slightly more vitamin K, riboflavin, niacin, & vitamin B6 but white rice has more thiamin & folate.
Cooked frozen spinach is MUCH healthier for you than raw spinach. Just to show a few differences-
Fresh raw Cooked Frozen
Vit A 2813 IU 26534 IU
Vit K 145 mcg 1190 mcg
Folate 58.2 mcg 266 mcg
General mineral content for fresh, raw spinach is between 1% & 6% (although Mangenese is 13%) while the average mineral content for cooked, frozen spinach is 26.3%.
Cooked, fresh spinach is comparable to cooked frozen containing more vitamin C & E but less vitamin A and K. Spinach's anti-inflammatory index raises considerably after cooking it.
Baby carrots contain almost no vitamins and minerals, especially when compared to regular carrots. They do contain 2068 IU vitamin A but regular carrots contain 21520 IU.
Brown and white rice are surprisingly similar. Brown rice does have slightly more vitamin K, riboflavin, niacin, & vitamin B6 but white rice has more thiamin & folate.
Wheat
Wheat
Enjoying Wheat Without a Wheat Grinder–
Use cracked wheat instead of cracker crumbs, bread or rice in meatloaves and meatballs.
Substitute half of your hamburger in any recipe with processed berries.
Use cracked wheat in breads and cookies or on salads for a nutty flavor.
Pop bulgar wheat like popcorn.
Sprout wheat for salad greens.
More suggestions and recipes at-
Approximate Measurements–
1 cup uncooked wheat = 2 cups cooked wheat
2 cups whole wheat = 3 cups ground flour
1 lb whole wheat = 2 1/4 cups wheat berries
Getting the Most Nutrients Out of Your Wheat–
Pairing wheat with vitamin C rich foods will increase iron absorption (think strawberries, kiwis orange juice, peppers, spinach, broccoli &c) as well as neutralize the phytic acid which can inhibit nutrient absorption and cause allergies.
Pairing wheat with a healthy fat (as in not a trans fat) will help your body access the
Cooking Whole Wheat Berries-
Wash one cup of wheat and soak in 2 cups cool water for 12 hours. Place rehydrated wheat in a pan and bring to a boil. It may be necessary to add water. Simmer for about one hour until tender. Wheat need not be covered with water since cooking by steam is effective (use a lid). Water should be mostly absorbed after the hour. The plump, cooked wheat will keep in a covered container in the refrigerator for about two weeks or frozen for longer. So, make lots and save time!
Cooking Whole Wheat Berries Overnight–
Wash wheat thoroughly, place in pot with twice as much water as wheat. Bring wheat to a steady boil for 10-20 minutes. Turn off heat, cover & let stand over night By morning the berries should be full and plump with most of the liquid having been absorbed by the berries. Carefully scoop the drier berries form the top of the pot and place in a plastic bag for storage. Drain remaining liquid from pot and reserve the more moist berries for processing.
Processed Cooked Berries– Run moist berries through a food processor. This will resemble hamburger. Freeze unused processed berries in 1 c portions after a few days.
Bulgar Wheat– Spread a thin layer of cooked berries on a cookie sheet and place in a warm oven (200°F-300°F) stirring from time to time until the kernels are completely dry and hard (about 45-60 min).
Cracked Wheat– Coarsely crack bulgar wheat in a blender or grinder.
Storing Bulgar & Cracked Wheat– Place in a glass jar to be reconstituted or used (respectively).
Reconstituting Bulgar Wheat– Add 2 cups of boiling water to each cup of bulgar. Let stand until moisture is completely absorbed, about 30-60 minutes.
Beans
Beans
Storage- Store unopened bags of dry beans in a cool, dark cupboard for a maximum of one year; after that they will lose some of their natural moisture and need longer cooking times, although the nutrients will remain. Once the package is opened, either store the bag inside a zipped plastic bag or pour out the leftover beans into a canister with a tight seal.
1 lb. dry beans = 2 - 2 1/2 cups
1 cup dry beans = 2 - 3 cups cooked beans
About 3/4 c dry beans = 1 lb cooked beans
About 3/4 c dry beans cooked = 16 oz can beans
Cooking– Always sort and rinse beans before cooking. There are two ways to reduce the flatulence factor, both of which may be used on either cooking method. A couple carrots cut up into 2-3 in. chunks will absorb the enzyme that causes flatulence (discard carrots after cooking). You may also soak the beans overnight, discard water, rinse and cook in fresh water. Presoaking the beans will reduce the cooking time by about 30 minutes. To check beans, take a spoonful out of the pot and blow on them gently. The skins should split easily. If the "skin test" works, taste one or two to see if they are soft.
Stovetop Method– Bring cooking water to a rapid boil and add beans. Bring the water to a second boil, reduce heat to very low and cook covered (very important) until tender.
Crock Pot Method– This is best for older beans. Pour rinsed beans in crock pot with water and cover with lid. The water level should be 2 in. above the beans. Cook on high for one hour and then reduce to low and cook overnight or until tender.
Black & pinto beans can be used in any Southwest/Mexican recipe instead of meat (ie Enchiladas, Tacos, Southwestern pasta’s, salads, & pizzas). Southwest seasonings include chili powder & cumin.
Soups, chili’s & dips are bean classics as well as adding beans to a green salad.
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