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http://www.cholesterol-and-health.com/Does-Cholesterol-Cause-Heart-Disease-Myth.html#6
EDITOR’S NOTE – This conversation with Ron Krauss took place in late March 2012. It focuses on the health questions involving saturated fat and red meat that have been in the news of late. Ron is a Senior Scientist and Director of Atherosclerosis Research at Children’s Hospital Oakland Research Institute, Adjunct Professor in the Department of Medicine at UCSF and in the Department of Nutritional Sciences at UC Berkeley, and Guest Senior Scientist in the Department of Genome Sciences of Lawrence Berkeley National Laboratory.
So that was an interesting study which showed that eating more saturated fat does not increase heart disease risk. But then, there’s that newer study you’ve done that involves saturated fat and red meat. And it’s a fascinating study because of some clues it gives about how health may be affected by both saturated fat and red meat. Right now there’s a great deal of concern that eating red meat may be dangerous for people’s health. But the question is why. In your recent study, you hint at a reason why.
RON KRAUSS
We published a paper this past fall in the Journal of Nutrition, in which we reported the results of the study that we carried out as a followup to the one we just discussed. Now, in the interest of full disclosure, I have to say that the first study was funded the National Dairy Council, and we used fairy fat and dairy products liberally in that study, since they’re high in saturated fats. The second, more recent study was funded by the National Cattleman’s Beef Association because they felt, and frankly we felt at the time, based on the evidence we had, that feeding a high saturated fat and low carbohydrate intake would have the same benefit on a high beef diet as as on a mixed protein diet, and bottom line is that when we did the study, we found out that was not the case.
So using what you learned from your 2006 study of a mixed-protein diet and high saturated fats, in this new study, you kept carbohydrates somewhat low, and fats somewhat higher, just as you did in 2006. Really, the main difference was that this time, you didn’t feed a variety of protein sources. Your test subjects just ate lots and lots of beef. And this time, you found that “healthy” blood work depended not only on what kind of protein people ate, but what kind of fat the people WITH the protein. So if you get out your Sherlock Holmes hat and pipe, what were the clues and what did they mean?
RON KRAUSS
To begin with, keep in mind, this was a very high beef diet. People were eating beef breakfast lunch and dinner. So this is really way outside of what we would ever consider to be a usual health practice. Maybe some people do it. But not many. We were really interested in the metabolic impact of this diet. To get as many clues as possible, we fed people in either the context of lean beef alone, or with extra saturated fat, mostly from diary products. Again, that’s because most of the saturated fat we get in our diet comes from dairy products. There’s some saturated fat in beef, but more in dairy fat. To make things as clear-cut as possible, in this study, we fed the same beef product to two groups. Lean beef, low in fat, without any added saturated fat. For one group, we added lots of dairy fat, to increase saturated fat. For the other group, we kept saturated fat low, but kept total fat basically the same by using an unsaturated fat–basically olive oil. So between the two groups, let’s say the difference was the equivalent of a cheeseburger versus a lean hamburger dressed with olive oil. That sort of describes, in a nutshell the kind of differences we were looking for. When we did blood work on the groups, the group who ate lots of beef with low saturated fat, meaning the olive oil, didn’t seem to have any adverse effects.
Meaning the blood work you did on that group didn’t reveal an increase in the LDL particles and other biomarkers that indicated heart disease risk.
RON KRAUSS
We didn’t see any adverse effect if we just fed a high beef diet in the absence of saturated fat.
So, in your study, a lean burger without cheese looked on the surface as the one to do.
RON KRAUSS
That’s true from our study. However, keep in mind, there may be other effects from eating red meat that still might mean it’s something to limit in the diet. After all, there are studies from the epidemiology world that are very convincing pointing to red meat itself as associated with many disease outcomes ranging form cancer to heart disease to diabetes. In our study, our measurements were strictly focussed on the metabolic risk factors for heart disease and diabetes. In that setting we couldn’t detect a real significant signal. That doesn’t mean there aren’t other adverse effects being revealed by other techniques. But in our case, we analyzed total cholesterol and the number of LDL particles and blood sugar measurements and inflammation measurements, and we didn’t see anything particularly dangerous occurring when people ate lots of red meat but kept the saturated fat very low.
What’s interesting is what the punchline is going be be. So keep going!
RON KRAUSS
The punchline is that we expected that because these diets have low carbohydrate, when we fed the high saturated fat level along with the red meat, we would see a pretty benign metabolic risk profile. Just as we did with low saturated fat and red meat.
But that’s not what happened!
RON KRAUSS
This is one of the surprises that keep life interesting for us for us as researchers and also for the world out there who happens to be looking over our shoulder. In this case, the surprise was that the combination of the high beef diet and the high saturated fat diet caused very serious increases in all of the cholesterol related risk factors we had been measuring, including total particle numbers, small LDL, total LDL cholesterol, inflammation, whatever we looked at, we saw an adverse effect.
Everything went wrong.
RON KRAUSS
This was in contrast with our earlier studies where the same amount of saturated fat and very similar carbohydrate intake but a diet not loaded up with red meat, had no adverse effect even if it had lots of saturated fat in it.
So if you put on your Sherlock Holmes hat and get our your magnifying glass, what is it you found was the likely smoking gun here?
RON KRAUSS
I wish I could give you a definite answer to the question. But fortunately, the fact that we had these two very different results with two different kinds of protein led us to propose to the National Institutes of Health, one of the nation’s leading funders of health research, which hopefully will stay that way, a new study. We are glad that it’s being funded by the National Institutes of Health, as a neutral ground if you will, between the world of sponsors from the food industry. NIH is allowing us now to investigate in a detective-like matter what is going on, and also test directly in a head to head manner, three different diets. All the diets will have the same amounts of saturated fat. But one is high in red meat, one is a non-meat, vegetarian diet where the protein comes from vegetable sources, and one is an intermediate diet, with meat from chicken, primarily. We’re doing this study to determine whether the source of protein influences the response to saturated fat in the way we suspect it will from these earlier results, and we’ll do some blood work that will allow us to investigate possible underlying mechanisms.
You think there are clues in the beef.
RON KRAUSS
Perhaps some other component of beef, not necessarily the protein, but something that comes along with it, such as iron would be one example, that may have an adverse effect in conjunction with saturated fat.
In a detective novel, the writer often throws in a red herring, and a red herring is designed to take someone off the track. But in your case, the color red, which is caused by the iron in meat may actually be the smoking gun.
RON KRAUSS
That’s one possibility.
Why would the iron in red meat, when coupled with saturated fat, increase risk factors for inflammation, for small particle LDL, for higher blood sugars, and all the rest?
RON KRAUSS
This is just an idea. This is in our whole discussion the one area where we do’t have data . . . yet. But it’s an intriguing hypothesis. Because it’s known from genetic, metabolic and population studies that the iron content of the liver, which stores most of our iron for our needs for red blood cell production and many other metabolic processes . . . if that amount of iron within the liver is excessive, it can lead to impaired sugar metabolism and predispose even to diabetes in the extreme case. High levels of iron in the liver also can be associated with abnormal lipid profiles, with higher amounts of small particle LDL. So we already have evidence that high iron levels in the liver are a potential determinant of things that can influence risk for diabetes and heart disease. And since iron comes from what we eat, it could be related to the dietary response that we studied. Why beef should have a particularly high effect on hepatic iron is a possibility we’re interested in, along with the question of why beef would create this risk for us, in particular, when we consume saturated fat. So while we don’t have data yet, we do have an intriguing collection of clues that maybe would lead to definitive conclusions from Sherlock Holmes.
You’re still awaiting the results from your study, though you have some suspicions.
RON KRAUSS
It turns out that heme iron, the form of iron in red meat, is absorbed pretty efficiently into the body. That’s why red meat is considered a good, or maybe in this case, we should just say, an abundant, source of dietary iron. But even though it’s more bioavailable, heme iron still requires certain factors for absorption. In checking to see why saturated fat could potentially increase the amount of iron coming in from beef, what I discovered buried in the literature is that certain kinds of saturated fat, beef tallow being one of them, and the saturated fat called stearic acid being another, both promote the absorption of heme iron. And both saturated fat and stearic acid are found in dairy products and in the fat that comes with red meat. So it’s our hunch that the combination of eating both an abundant source of iron and the fat that helps the body absorb that iron, might be what converts this style of eating into a dangerous risk profile that raises small particle LDL, blood sugars, inflammatory markers, and so on.
And that risk might also be a consequence of modern day living. Looking back in time, people used to be in wars and accidents more often, and during those times, they had more parasites in their blood that would be going after the iron in the body. They might have been bleeding out more of their iron stores, and more vulnerable for iron deficiencies. So we may have evolved to conserve iron, and way back then, it may be that eating foods that promoted iron uptake was actually protective. But these days we don’t have the parasites to sip on our iron stores, and we don’t have the blood bleeding out of us as much. So Ron Krauss, to make up for our cleaner, more peaceable times, if someone likes cheeseburgers and they like them nice and juicy and covered with high saturated fat cheese, should they reduce their iron stores by giving blood more often?
RON KRAUSS
(LAUGHS) You’ve asked a question that has come up in other contexts as well. Does keeping people’s iron level low reduce risk of heart disease? For instance, there are people who claim that women who have a natural protection from heart disease when they’re menstruating lose that protection after they go through menopause, because without that monthly release of blood, their iron levels can build up.
So, does giving blood and reducing your iron stores that way reduce heart disease risk?
RON KRAUSS
We don’t know. The real way to check this would be to not focus on the iron in someone’s diet, but instead, do blood work to reveal how much of the potentially dangerous iron you have in your system. That would be an interesting study to do sometime. As for now, there’s absolutely no basis yet for therapeutically reducing iron stores, for instance, by giving blood, as a means of reducing heart disease risk. The best way to reduce your risk, right now, is to stay away from the cheeseburger diet.
But to get the answer through blood work might be challenging. It’s very hard to measure with any accuracy what the heme level of iron is in the liver. It’s a different measurement than the standard “annual checkup” measure of iron in the blood. Getting a good measurement of the liver’s iron . . . . It’s a very very hard bit of data to get.
RON KRAUSS
There are markers . . . and we haven’t measured all of them yet. Part of the funding we’re getting from the new NIH grant will allow us to measure some of these more accurate markers. So it may be possible for us to tease out more information. The standard iron tests in the blood are not sufficient. That’s where we need more information, and why we’re doing this new study.
http://www.zuivelengezondheid.nl/PDF..._AJCN_2012.pdf
Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis
Results:
After adjustment for demographics, lifestyle, and dietary confounders, a higher intake of dairy SF was associated with lower CVD risk [HR (95% CI) for +5 g/d and +5% of energy from dairy SF: 0.79 (0.68, 0.92) and 0.62 (0.47, 0.82), respectively]. In contrast, a higher intake of meat SF was associated with greater CVD risk [HR (95% CI) for +5 g/d and a +5% of energy from meat SF: 1.26 (1.02, 1.54) and 1.48 (0.98, 2.23), respectively]. The substitution of 2% of energy from meat SF with energy from dairy SF was associated with a 25% lower CVD risk [HR (95% CI): 0.75 (0.63, 0.91)]. No associations were observed between plant or butter SF and CVD risk, but ranges of intakes were narrow.
Conclusion:
Associations of SF with health may depend on foodspecific
fatty acids or other nutrient constituents in foods that contain SF, in addition to SF
EDITOR’S NOTE – This conversation with Ron Krauss took place in late March 2012. It focuses on the health questions involving saturated fat and red meat that have been in the news of late. Ron is a Senior Scientist and Director of Atherosclerosis Research at Children’s Hospital Oakland Research Institute, Adjunct Professor in the Department of Medicine at UCSF and in the Department of Nutritional Sciences at UC Berkeley, and Guest Senior Scientist in the Department of Genome Sciences of Lawrence Berkeley National Laboratory.
So that was an interesting study which showed that eating more saturated fat does not increase heart disease risk. But then, there’s that newer study you’ve done that involves saturated fat and red meat. And it’s a fascinating study because of some clues it gives about how health may be affected by both saturated fat and red meat. Right now there’s a great deal of concern that eating red meat may be dangerous for people’s health. But the question is why. In your recent study, you hint at a reason why.
RON KRAUSS
We published a paper this past fall in the Journal of Nutrition, in which we reported the results of the study that we carried out as a followup to the one we just discussed. Now, in the interest of full disclosure, I have to say that the first study was funded the National Dairy Council, and we used fairy fat and dairy products liberally in that study, since they’re high in saturated fats. The second, more recent study was funded by the National Cattleman’s Beef Association because they felt, and frankly we felt at the time, based on the evidence we had, that feeding a high saturated fat and low carbohydrate intake would have the same benefit on a high beef diet as as on a mixed protein diet, and bottom line is that when we did the study, we found out that was not the case.
So using what you learned from your 2006 study of a mixed-protein diet and high saturated fats, in this new study, you kept carbohydrates somewhat low, and fats somewhat higher, just as you did in 2006. Really, the main difference was that this time, you didn’t feed a variety of protein sources. Your test subjects just ate lots and lots of beef. And this time, you found that “healthy” blood work depended not only on what kind of protein people ate, but what kind of fat the people WITH the protein. So if you get out your Sherlock Holmes hat and pipe, what were the clues and what did they mean?
RON KRAUSS
To begin with, keep in mind, this was a very high beef diet. People were eating beef breakfast lunch and dinner. So this is really way outside of what we would ever consider to be a usual health practice. Maybe some people do it. But not many. We were really interested in the metabolic impact of this diet. To get as many clues as possible, we fed people in either the context of lean beef alone, or with extra saturated fat, mostly from diary products. Again, that’s because most of the saturated fat we get in our diet comes from dairy products. There’s some saturated fat in beef, but more in dairy fat. To make things as clear-cut as possible, in this study, we fed the same beef product to two groups. Lean beef, low in fat, without any added saturated fat. For one group, we added lots of dairy fat, to increase saturated fat. For the other group, we kept saturated fat low, but kept total fat basically the same by using an unsaturated fat–basically olive oil. So between the two groups, let’s say the difference was the equivalent of a cheeseburger versus a lean hamburger dressed with olive oil. That sort of describes, in a nutshell the kind of differences we were looking for. When we did blood work on the groups, the group who ate lots of beef with low saturated fat, meaning the olive oil, didn’t seem to have any adverse effects.
Meaning the blood work you did on that group didn’t reveal an increase in the LDL particles and other biomarkers that indicated heart disease risk.
RON KRAUSS
We didn’t see any adverse effect if we just fed a high beef diet in the absence of saturated fat.
So, in your study, a lean burger without cheese looked on the surface as the one to do.
RON KRAUSS
That’s true from our study. However, keep in mind, there may be other effects from eating red meat that still might mean it’s something to limit in the diet. After all, there are studies from the epidemiology world that are very convincing pointing to red meat itself as associated with many disease outcomes ranging form cancer to heart disease to diabetes. In our study, our measurements were strictly focussed on the metabolic risk factors for heart disease and diabetes. In that setting we couldn’t detect a real significant signal. That doesn’t mean there aren’t other adverse effects being revealed by other techniques. But in our case, we analyzed total cholesterol and the number of LDL particles and blood sugar measurements and inflammation measurements, and we didn’t see anything particularly dangerous occurring when people ate lots of red meat but kept the saturated fat very low.
What’s interesting is what the punchline is going be be. So keep going!
RON KRAUSS
The punchline is that we expected that because these diets have low carbohydrate, when we fed the high saturated fat level along with the red meat, we would see a pretty benign metabolic risk profile. Just as we did with low saturated fat and red meat.
But that’s not what happened!
RON KRAUSS
This is one of the surprises that keep life interesting for us for us as researchers and also for the world out there who happens to be looking over our shoulder. In this case, the surprise was that the combination of the high beef diet and the high saturated fat diet caused very serious increases in all of the cholesterol related risk factors we had been measuring, including total particle numbers, small LDL, total LDL cholesterol, inflammation, whatever we looked at, we saw an adverse effect.
Everything went wrong.
RON KRAUSS
This was in contrast with our earlier studies where the same amount of saturated fat and very similar carbohydrate intake but a diet not loaded up with red meat, had no adverse effect even if it had lots of saturated fat in it.
So if you put on your Sherlock Holmes hat and get our your magnifying glass, what is it you found was the likely smoking gun here?
RON KRAUSS
I wish I could give you a definite answer to the question. But fortunately, the fact that we had these two very different results with two different kinds of protein led us to propose to the National Institutes of Health, one of the nation’s leading funders of health research, which hopefully will stay that way, a new study. We are glad that it’s being funded by the National Institutes of Health, as a neutral ground if you will, between the world of sponsors from the food industry. NIH is allowing us now to investigate in a detective-like matter what is going on, and also test directly in a head to head manner, three different diets. All the diets will have the same amounts of saturated fat. But one is high in red meat, one is a non-meat, vegetarian diet where the protein comes from vegetable sources, and one is an intermediate diet, with meat from chicken, primarily. We’re doing this study to determine whether the source of protein influences the response to saturated fat in the way we suspect it will from these earlier results, and we’ll do some blood work that will allow us to investigate possible underlying mechanisms.
You think there are clues in the beef.
RON KRAUSS
Perhaps some other component of beef, not necessarily the protein, but something that comes along with it, such as iron would be one example, that may have an adverse effect in conjunction with saturated fat.
In a detective novel, the writer often throws in a red herring, and a red herring is designed to take someone off the track. But in your case, the color red, which is caused by the iron in meat may actually be the smoking gun.
RON KRAUSS
That’s one possibility.
Why would the iron in red meat, when coupled with saturated fat, increase risk factors for inflammation, for small particle LDL, for higher blood sugars, and all the rest?
RON KRAUSS
This is just an idea. This is in our whole discussion the one area where we do’t have data . . . yet. But it’s an intriguing hypothesis. Because it’s known from genetic, metabolic and population studies that the iron content of the liver, which stores most of our iron for our needs for red blood cell production and many other metabolic processes . . . if that amount of iron within the liver is excessive, it can lead to impaired sugar metabolism and predispose even to diabetes in the extreme case. High levels of iron in the liver also can be associated with abnormal lipid profiles, with higher amounts of small particle LDL. So we already have evidence that high iron levels in the liver are a potential determinant of things that can influence risk for diabetes and heart disease. And since iron comes from what we eat, it could be related to the dietary response that we studied. Why beef should have a particularly high effect on hepatic iron is a possibility we’re interested in, along with the question of why beef would create this risk for us, in particular, when we consume saturated fat. So while we don’t have data yet, we do have an intriguing collection of clues that maybe would lead to definitive conclusions from Sherlock Holmes.
You’re still awaiting the results from your study, though you have some suspicions.
RON KRAUSS
It turns out that heme iron, the form of iron in red meat, is absorbed pretty efficiently into the body. That’s why red meat is considered a good, or maybe in this case, we should just say, an abundant, source of dietary iron. But even though it’s more bioavailable, heme iron still requires certain factors for absorption. In checking to see why saturated fat could potentially increase the amount of iron coming in from beef, what I discovered buried in the literature is that certain kinds of saturated fat, beef tallow being one of them, and the saturated fat called stearic acid being another, both promote the absorption of heme iron. And both saturated fat and stearic acid are found in dairy products and in the fat that comes with red meat. So it’s our hunch that the combination of eating both an abundant source of iron and the fat that helps the body absorb that iron, might be what converts this style of eating into a dangerous risk profile that raises small particle LDL, blood sugars, inflammatory markers, and so on.
And that risk might also be a consequence of modern day living. Looking back in time, people used to be in wars and accidents more often, and during those times, they had more parasites in their blood that would be going after the iron in the body. They might have been bleeding out more of their iron stores, and more vulnerable for iron deficiencies. So we may have evolved to conserve iron, and way back then, it may be that eating foods that promoted iron uptake was actually protective. But these days we don’t have the parasites to sip on our iron stores, and we don’t have the blood bleeding out of us as much. So Ron Krauss, to make up for our cleaner, more peaceable times, if someone likes cheeseburgers and they like them nice and juicy and covered with high saturated fat cheese, should they reduce their iron stores by giving blood more often?
RON KRAUSS
(LAUGHS) You’ve asked a question that has come up in other contexts as well. Does keeping people’s iron level low reduce risk of heart disease? For instance, there are people who claim that women who have a natural protection from heart disease when they’re menstruating lose that protection after they go through menopause, because without that monthly release of blood, their iron levels can build up.
So, does giving blood and reducing your iron stores that way reduce heart disease risk?
RON KRAUSS
We don’t know. The real way to check this would be to not focus on the iron in someone’s diet, but instead, do blood work to reveal how much of the potentially dangerous iron you have in your system. That would be an interesting study to do sometime. As for now, there’s absolutely no basis yet for therapeutically reducing iron stores, for instance, by giving blood, as a means of reducing heart disease risk. The best way to reduce your risk, right now, is to stay away from the cheeseburger diet.
But to get the answer through blood work might be challenging. It’s very hard to measure with any accuracy what the heme level of iron is in the liver. It’s a different measurement than the standard “annual checkup” measure of iron in the blood. Getting a good measurement of the liver’s iron . . . . It’s a very very hard bit of data to get.
RON KRAUSS
There are markers . . . and we haven’t measured all of them yet. Part of the funding we’re getting from the new NIH grant will allow us to measure some of these more accurate markers. So it may be possible for us to tease out more information. The standard iron tests in the blood are not sufficient. That’s where we need more information, and why we’re doing this new study.
http://www.zuivelengezondheid.nl/PDF..._AJCN_2012.pdf
Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis
Results:
After adjustment for demographics, lifestyle, and dietary confounders, a higher intake of dairy SF was associated with lower CVD risk [HR (95% CI) for +5 g/d and +5% of energy from dairy SF: 0.79 (0.68, 0.92) and 0.62 (0.47, 0.82), respectively]. In contrast, a higher intake of meat SF was associated with greater CVD risk [HR (95% CI) for +5 g/d and a +5% of energy from meat SF: 1.26 (1.02, 1.54) and 1.48 (0.98, 2.23), respectively]. The substitution of 2% of energy from meat SF with energy from dairy SF was associated with a 25% lower CVD risk [HR (95% CI): 0.75 (0.63, 0.91)]. No associations were observed between plant or butter SF and CVD risk, but ranges of intakes were narrow.
Conclusion:
Associations of SF with health may depend on foodspecific
fatty acids or other nutrient constituents in foods that contain SF, in addition to SF
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