Interview with Cooper Clinic head of cardiology Dr. Nina Radford about HDL Cholesterol
Todd Whitthorne recently sat down with Dr. Nina Radford, and discussed HDL Cholesterol. Click here if you would prefer to listen to the interview.
Todd: Hello, and welcome to another Healthy Living podcast from Cooper Aerobics Center. This is Todd Whitthorne, and I’m joined today by Dr. Nina Radford the head of cardiology at the Cooper Clinic, and Dr. Radford we have a topic today that I think is going to interest a lot of our listeners. Generally when it comes to health, we like to distill things down to takeaways, and when it comes to cholesterol we have a tendency to think that LDL is lousy and the HDL is healthy. There’s a recent study published in May of 2012 in the Lancet that says, well maybe raising HDL is not all that beneficial. What do we need to know about that?
Dr. Radford: Well Todd, that’s a great question. Historically, when we talk about cholesterol parameters, as you described, we look at LDL, and when it’s high it’s bad for us – it increases the risk of heart attack…, and when we look at HDL, if it’s too low, it increases our risk of heart attack. And those are associations – if we look at a group of people who’ve had heart attacks versus a group of people who haven’t, and you find that high LDL is associated with heart attacks and low HDL is associated with heart attack, but that doesn’t necessarily prove causation.
Now with LDL cholesterol, there have been a number of studies that have gone on from “association” to proving “causation,” and how do we do that? Well first we say “Gosh, if high LDL is associated with heart attack, if we lower it with drugs does that lower the risk?”, and in fact there have been many, many studies showing if you lower LDL cholesterol with diet or medication, you reduce the risk of subsequent heart attacks.
They can also look at from another angle, and that is the genetic angle. There are some people who are actually born with genes that cause their LDL to be low. So, they look in those families who have those genes that cause low LDL, and they ask the question “In those families, is there a reduced risk of having a heart attack?”, and in fact there is. So, whether or not your LDL is low because you take medicine, or you follow specific lifestyles, or it’s low because low LDL happens to run in your family…, either way, both of those situations are associated with a lower risk of heart attack. So you make the transition from “association” to “cause.”
Now investigators are trying to do the same thing with HDL. So we say “Gosh, having a low HDL is associated with heart attacks – having a high HDL must be good for you then!” So we look at studies: If I give you a drug that causes your HDL to increase – something like niacin, for example, will that reduce the risk of having heart? And in fact, there was a recent trial called the Aim-High Trial that took patients who already had a low LDL (so that is they were already on medicine to lower their LDL because they have heart disease), but their HDL was low. Researchers treated patients with a drug that causes the HDL to go and see if it would lower their risk of having another heart event even more! The study did not demonstrate any benefit from increasing the HDL with the medication. So, then all of a sudden, people started to wonder if raising HDL is a good thing, “Is high HDL really protective?” because we didn’t see it in this study. So, what these investigators did in the Lancet study was they looked at people who have a genetic cause of having high HDL – they had genes that ran in their family that actually blessed them with very HDL levels.
Todd: Dr. Cooper calls that the Methuselah factor. I’ve heard him say that many times.
Dr. Radford: They’re just lucky they were born with a high HDL. Investigators looked at 21,000 people in one study and 12,000 people in another group, so they combined those groups and were looking at over 30,000 individuals who had this gene, and they predicted that the risk of having a heart attack should be lower in these people because they have HDL, and in fact they did not see that the risk was lower.
So here we have this Genetic Study, right on the heels of this Drug Trial, and all a sudden people are saying “Hey, I thought having a high HDL was good for you! What’s going on here?” Well, you have to be careful about dismissing decades of historical data based on a couple of studies.
For example, in this study where they gave a drug to increase the HDL to see if it would reduce risk, well we know that LDL, the bad cholesterol, is a bigger driver of risk than HDL. So if I lower your LDL and get it super low with a drug, plus you’re on an aspirin, and an ACE inhibitor, and fish oil, and you’re meditating, and you’re doing all the right things…, and on top of all those really good things, I add another good thing, it may be that the effect is not big enough that you can see it. Because you’re doing six other good things, and when you add the seventh the benefit isn’t big enough. And so, that may be part of.
But then when you look at this Genetics Study, and you add it to the Drug Study, what’s the story? Well, the story is this: It may be that having a high HDL is a marker for some other thing that you’re doing that’s good. So, for example, we know that if you want to increase your HDL and you exercise, you can do it. But what if exercise causes another thing to happen? So, and I’m going to make it up….. Let’s say exercise increases your “Todd” factor. So, if you’re a regular exerciser, your “Todd” factor goes sky high. Now, your HDL also goes sky high, and we can measure the HDL, but we don’t know how to measure the “Todd” factor.
Todd: At least not yet!
Dr. Radford: So, it may be that HDL is kind of going along for the ride and the real benefit of exercise is the “Todd” factor that we’re not smart enough to measure yet. So, that’s what we’re not clear about.
Now, should you stop doing things we know will raise HDL? Like being at your ideal body weight, taking some fish oil, exercising regularly? Absolutely not! But whether or not you should take medications to raise your HDL, beyond the other good heart healthy things that you’re doing, is not clear, and what most physicians are doing is taking it on a case-by-case basis.
If you’re taking a medication to raise your HDL don’t stop it, because we’ve only got that one Trial that’s raised some questions…, but it’s a good thing to ask your doctor when you see them next. You’re reviewing all your meds – it’s a good thing to do every year – and say you’re taking this for your blood pressure, taking this for cholesterol, this for prostate, this to make your hair shiny, etc. Every year you’ll want to look at all those meds and talk with your doctor and say “Do I need to take each of these (medications)?” And, if you happen to be on a drug for raising HDL, it’s a good time to review (taking it) and decide if you still need it.
Todd: So, where are we from your perspective – historically, it’s the question that comes up all the time – “Is at HDL? Is it LDL? Is it the combination, that atherogenic index, of total cholesterol divided by HDL?” Dr. Nina Radford, head of cardiology at the Cooper Clinic, what you think is the most important component? Or, is there a magic number we need to be thinking about, as the average patient?
Dr. Radford: Well, that is a great question! It depends a little bit on what your other risk factors are; what your age is; and what your gender is. So, for example, compared to men, HDL is probably a bigger driver of risk in women. But that has to do with probably differences in our hormones. LDL is still a driver of risk in women – it doesn’t mean you can willy-nilly have your LDL be high and super size your fries, but it looks like some studies suggest in women before they’re had their first heart attack or heart disease HDL is a big driver of risk.
In men, LDL appears to be a bigger driver. When you talk about patients who already had their first heart attack; had a stent; have heart disease…, LDL is a very big driver of risk, and needs to be very specifically controlled.
Todd: In both men and women?
Dr. Radford: Absolutely! In both genders! So it depends a little bit on the age and the clinical background in terms of which factors I’ll be more concerned about.
Todd: So the takeaway is case-by-case, patient-by-patient, one size does not fit all?
Dr. Radford: Absolutely.
Todd: Very good. Dr. Nina Radford, the head of cardiology at Cooper Clinic, great information as always! We appreciate your time Dr. Radford.
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