HEART OF THE MATTER"
a special program of the National Emergency Medicine Association (NEMA)
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Guest: Martha Howell, PhD. Nutrition, Assoc. Prof. Nutritional Sciences, University of Arizona, Tucson
Topic: Cholesterol is OK
Host/Producer: Steve Girard
NEMA: For years, I've been throwing out the yolks. Yep...whether hard boiled, scrambled or in baking...I've been eating just the whites of my eggs. You know the reason? Right...because of the large amount of cholesterol contained in nature's otherwise perfect food. Well, my bubble's burst...because a new study corralled by my guest today indicates that there is not as strong a correlation between the cholesterol we eat, and the cholesterol our body makes. Dr. Wanda Howell is an Associate Professor of Nutritional Sciences at the University of Arizona...
HOWELL: The issue of diet, cholesterol and blood cholesterol actually started many years ago, around the turn of the century, when researchers were studying animals to see how the diet affected their blood cholesterol levels. And in animals, it is true that the cholesterol in their diets will influence the cholesterol in their blood. In humans however, it has been shown consistently that this is not the case. And to that end, we were interested in looking at all of the human studies that had been done which involved feeding human subjects a diet and then looking at how the blood cholesterol changed in response to the diet. And when we looked back through all the studies... about 225 studies actually, involving over 8 thousand subjects...we found that in humans, the case of diet cholesterol affecting blood cholesterol did not hold up. So, what we found was that not cholesterol...but saturated fat, would influence blood cholesterol levels. So the culprit all these years has been misnamed, and the actual problem in the diet is saturated fat, not dietary cholesterol. We were interested in how the American population might react to changes in their diet, and came up with, through a process called meta analysis, models that allow us to predict how much cholesterol in the diet, saturated fat in the diet, would influence blood cholesterol...and that's what we've reported. Essentially, the bottom line is...for the American population...one to two eggs a day really will not have much effect at all on blood cholesterol, so your point about the lack of an association between diet cholesterol and blood cholesterol is extremely important. They are not the same, nor does the cholesterol that we eat in our diet have much effect on our blood cholesterol.
NEMA: Well, why? It seems logical that there should be a relationship...why isn't there a correlation when there is one in animals. What happens to the cholesterol we eat...is it a different makeup than the cholesterol our bodies make?
HOWELL: I think that's an important question...and one that the public needs clarification on. Our bodies produce cholesterol, regardless of what we eat, because the body needs cholesterol...it's a very important part of building of cell walls and tissues. So, our bodies will produce cholesterol regardless of what take in in the diet. That's the first important message. The second is that most of us will regulate, quite nicely, our blood cholesterol based on what we take in in the diet. By that I mean most of us are not sensitive to dietary cholesterol. If we eat dietary cholesterol, our bodies make less, so that our blood cholesterol levels stay relatively the same. On the other hand, saturated fat does not trigger that mechanism to stop making cholesterol. So, saturated fat will contribute much more to increasing blood cholesterol. But cholesterol in the diet will shut off some production of internal cholesterol, so we maintain a reasonable level of blood cholesterol. That happens in about 85% of the adult population. The other 15%, that regulatory mechanism doesn't work quite the way it should. And those are the people that you may have heard say that they have a genetic form, or family history of very high blood cholesterol. Those people are diet sensitive. Their diets will affect how their blood cholesterol moves up and down. And those are the people who are usually on medication to control their blood cholesterol. So, what we'd like to tell folks is: find out if you're sensitive. If you have a family history of this problem, you really need to monitor it. We all, as adults, need to know our number...our cholesterol. And to the extent that our blood cholesterol may be elevated, we need to find out if we are sensitive to diet. Most of us will not be...that is, we self-regulate. About 15% will be sensitive...and that 15% really does need close medical management.
NEMA: What's the feed back been like from those who have spent the last 10 years or so advising people...packaging products...to tell people to stay away from cholesterol?
HOWELL: I have not personally gotten feedback...I suppose I will. There are always folks in one camp or another. I think the important thing is that the groups that have issued dietary guidelines...it's our hope anyway...that they will look at this scientific evidence, and base their recommendations on the science, rather than tradition. And we're very confident based on our research, and the quality of our research, that the limitation of eggs, for instance, in the diet to two to four per week...is not really based on the science, and our view is that one to two eggs a day will not influence blood cholesterol, and there's no reason that public health guidelines need to issue limitations on a single food product. It just clearly is not supported by the scientific evidence.
NEMA: There are some people, perhaps the elderly, who don't get great amounts of protein from meat anymore...but who didn't eat eggs because of the advisory against raising blood cholesterol....and they miss the really pure protein content in the egg whites.
HOWELL: The quality of protein in egg is, as you say, close to what we call perfect...or reference protein. Many other protein sources in the diet are compared to egg protein, so that's exactly correct. Very high quality protein. The other issue is that, in that yolk that you're avoiding, loaded with vitamins and minerals. That yolk has very little saturated fat - about a gram - the rest of it's the good, monounsaturated fat. So when you look at that little package, that pretty package that is the egg...you see a great source of protein, vitamins and minerals, including iron...which of course to women becomes an issue often...as well as the fact that it is an inexpensive nutrient package, and one that is readily available. So, I think that we've been missing the boat excluding, unnecessarily, such a good nutritional package, when the evidence clearly doesn't support that. One thing that I do want to point out, however, is that we're not recommending to folks that they can eat a dozen eggs a day. Of course not. You exceed that ability to regulate that cholesterol level if you eat too much dietary cholesterol. But one to two eggs a day simply will not influence blood cholesterol, and that message I think is important for those who depend on inexpensive, very high quality food source.
NEMA: There aren't many other foods that carry low fat, high cholesterol....?
HOWELL: Some of the foods that are high in saturated fat are also good sources of dietary cholesterol...so what we generally recommend in moderation of saturated fat intake will also decrease cholesterol from other sources. So, when we focus, as myself as a dietitian...I focus on, when I counsel people, to take in less saturated fat...which will also take care of reducing other sources of dietary cholesterol...I don't focus on dietary cholesterol at all. One of the issues that we're all concerned with, in terms of public health, is weight control...and reducing saturated fat in the diet hopefully will also reduce calorie intake, and subsequently promote weight loss.
NEMA: I guess I'll have to change my ways...of the two dozen eggs I eat each week, I can treat myself to a few of the yolks I've been avoiding all this time. Our thanks to Dr. Wanda Howell, Associate Professor of Nutritional Science at the University of Arizona.
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...for a look at transcripts of this or past programs, or to find out more about the National Emergency Medicine Association. I'm Steve Girard at The Heart of the Matter.