Welcome to Mayo Clinic's podcast. This month's topic is prehypertension. I'm your host, Rich Dietman.

The number of people in the United States estimated to have high blood pressure is around 65 million. That's up from about 50 million just a decade ago.

An increase in blood pressure brings with it a higher risk of heart disease and stroke, and because blood pressure tends to increase with age, all of this has doctors concerned that as increasing numbers of Americans get older, they will develop high blood pressure and the serious conditions that go along with it.

Just what is high blood pressure, what doctors call hypertension? High blood pressure is consistent readings of 140 millimeters of mercury over 90 millimeters of mercury or, more simply put, 140/90.

Here to talk about high blood pressure, and a new category called prehypertension, is Dr. Sheldon Sheps. Dr. Sheps is a Mayo Clinic cardiologist and senior editor for MayoClinic.com. He has devoted much of his career to studying and treating high blood pressure, and he played a key role in developing national guidelines for the diagnosis and treatment of hypertension, including serving on several working groups of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, often referred to as JNC.

Dietman: Dr. Sheps, welcome.

Dr. Sheps: Thank you, Rich.

Dietman: Talk a little bit about this new category that's been out there for just a few years, called prehypertension — what it means and why we should be concerned about it if our doctor tells us we have it.

Dr. Sheps: Well, there's interesting data that has come out in the last few years from the Framingham Heart Study and also from some international work that shows that at levels below 140/90, there's an increased risk of having heart disease and stroke, and actually the best blood pressure is 115/75, and so the new normal from the last JNC is less than 120/80. We know now that between 120 and 140 and between 80 and 90 on the diastolic side, there's an increasing risk of having heart disease, stroke and kidney disease as your blood pressure goes higher.

Dietman: So it's a real warning flag for someone whose doctor tells him or her that they have this prehypertension, that it could likely progress into full-blown hypertension, or high blood pressure.

Dr. Sheps: That's right. And we've known, for example, again from Framingham, that people who are at age 55, for example — men and women — if you have normal blood pressure at age 55 and you live long enough, you have an over 90 percent chance of developing high blood pressure as you age.

Dietman: So my doctor has told me that I have prehypertension. It's not high blood pressure. He or she is saying that I probably don't need medication, but I wonder about that because I see there are blood pressure medications available, and if a pill will take care of it, why shouldn't I do that? That's what I might wonder. What might I expect? What would I be thinking about as a patient with prehypertension going into those first days and weeks after the diagnosis?

Dr. Sheps: Unless you have two major complicating illnesses, such as kidney disease or diabetes, we are not recommending initiating treatment with blood pressure lowering drugs when you have a diagnosis of prehypertension. That's because the goal for blood pressure for those people — that is with diabetes or kidney disease — is less than 130/80, and it's hard to get there without medication for those people. But for the rest of us, we don't know yet that treatment with drugs is safer than treatment with lifestyle. We do know that changes in your behavior — what you eat and how you exercise — do lower blood pressure, and it does it safely, without side effects, and that is the recommendation at the present time for people with uncomplicated prehypertension at any age, lifestyle changes. And indeed, even if you have definite hypertension, making those changes in your lifestyle will assist the medication that you may have to take to work better, to need less medication, less strong medication, in order to achieve your blood pressure goal if you are also doing lifestyle at the same time.

Dietman: So my doctor is not likely, unless I have diabetes or — was it heart disease was the other general condition?

Dr. Sheps: Kidney disease.

Dietman: Kidney disease … diabetes or kidney disease, that I'm not likely to be prescribed a medication, that more than likely, he or she is going to say that I have to get more active, lose some weight, do those kinds of things?

Dr. Sheps: Yeah, that's what it is. You know, we all would prefer a quick fix and like prescription rather than proscription. But I think you have to think about lifestyle changes as a healthy life. And it's not a temporary fix for something, but it's the way you should be leading your life, because we have good data that if you follow these things, you live longer and better.

Dietman: So if I have to choose — and I hear you talking about lifestyle so that presumably covers something of a range of things — but if I'm telling myself I'm a busy guy, you know, and I have to choose between paying attention to my diet and exercising regularly and watching my sodium and my salt intake, if there's one thing that I could do to help manage that prehypertension, what would it be?

Dr. Sheps: Well, the one thing that I would recommend that you do, if you smoke now, is to stop smoking. That is the one factor that we know of that will help your blood pressure get controlled and will also reduce your risk of heart disease, as well as many other things. If you're a nonsmoker, the next thing that you should be doing is looking at your alcohol intake, because excessive alcohol — that is over two drinks a day for men, one drink for women — is a blood pressure elevator and also increases risks of other diseases. As you know, there's a lot of literature that says having alcohol moderately — like between one and two drinks a day — actually lowers your risk of heart disease, and that's true, but we're not asking people who are teetotalers to start drinking to do that. We're saying that people who do like alcohol should be using it in that kind of average daily amount of about two drinks a day for men and one for women.

Dietman: OK, so I'm not a smoker, so I don't have to stop, and I use alcohol in moderation. What's the next best thing that I can do?

Dr. Sheps: The best recommendation we have at the present time is called the DASH eating plan, which is a dietary approach to stop hypertension. It's basically a food plan which has an emphasis on fruits and vegetables, the low-fat dairy foods, fish, chicken, and de-emphasizes things like steak. You control your fat intake, in particular no trans-fats, and reduce the amount of cholesterol that you take in. So there's a good amount of protein in this diet. There are good nuts, such as walnuts, which you can consume regularly, and it's a healthy diet for more than heart disease, but we know that if you follow this diet, this eating plan, that you will lower your blood pressure. Whether you already have high blood pressure, or you're prehypertensive, your blood pressure levels will go down.

In addition to that, if you control the mineral content of that diet by reducing the amount of sodium you consume and putting an emphasis on potassium, you will have additional benefit in lowering your blood pressure. So, if we want to take numbers — for example, if you just took the DASH eating plan, you would probably get your blood pressure down, maybe eight to 10 points, over several weeks of eating on that plan. If you added some dietary sodium control, you'd get a few more points beyond that, and again with the moderate alcohol you might get two or four points. Now they're not all necessarily additive, but you would get some benefit from doing each of these things.

We can't talk about this without talking about weight. The population as a whole is increasing in weight — children as well as adults — and we need to do something about that for our population as a whole and for ourselves as individuals, and aim for normal body mass index, which is less than 25, and having a waist size less than 40 if you're a male and 35 if you're a female. And weight loss, you don't have to get down four dress sizes or lose five inches on your waist. Ten pounds will make a difference in your blood pressure and get you on the way to getting blood pressure control. Ideally you should get down to a body mass index of 25, for example, but you don't have to get there tomorrow. It's a process. You have to learn to eat differently. Your body accommodates to the taste of food with reduced sodium. It accommodates to having less calories in your body during the day, so give yourself the time to do that.

Dietman: Now, when you say that the body accommodates to less sodium, if I like to load up my mashed potatoes with lots of salt at the dinner meal, you're saying that I can get over that?

Dr. Sheps: You can. Using a saltshaker is kind of next to being evil, I think. Most of the sodium that we have is already in the food. Eighty percent of the sodium that we ingest is already in the food before the saltshaker appears, so you're just adding a lot of extra that you don't really need. And we don't need a lot of the sodium that's in the prepared foods. Slow reduction in that amount of sodium, down to the amounts that are necessary for preservation of food and some of the other reasons … chemical reasons that sodium is in our food products is OK, but we have loads more than we need in there, which has been to facilitate so-called taste, and taste is personal.

You can change the flavor by many other compounds and enjoy food without having the sodium in there. And if you reduce sodium, it takes maybe six to eight weeks and your taste buds change, so what once tasted great now tastes like poison, when it's so highly filled with sodium. There are compounds now that can help you do that. There are salt substitutes, and there are some salt substitutes which have reduced amounts of sodium in them and have other chemicals, other minerals in the compound to have taste, and yet you're reducing your sodium content in your diet. You can cook with those things as well as use them at the table if you have to.

Dietman: Do you mean it tastes like salt, or just adds a different sort of seasoning?

Dr. Sheps: There is nothing that's salt, other than salt. But it adds a different kind of flavor that enhances flavor. To taste good, it doesn't have to be salt.

Dietman: Let's talk a little bit about exercise. I'm assuming that aerobic exercise is what you would recommend if I had prehypertension, as part of a plan to get my blood pressure down. On the face of it, running for 30 minutes on a treadmill, I would imagine that would get my blood pressure up. Maybe not, but what is it about physical activity and exercise — aerobic exercise, if that's what's recommended — that would, over time, help me to keep my blood pressure under control?

Dr. Sheps: Regular physical exercise, of course, helps you lose weight because you're consuming calories, but it also, by itself, even if your weight doesn't change, will help lower your blood pressure, and regular exercise will maybe get you five to 10 points on the systolic blood pressure. But it has to be fairly regular — every day, every other day — so you accumulate the number of minutes that you need.

If you're a busy guy, like you told me you were, it's kind of hard to carve out an hour every day or every other day, but if you do those things as part of your daily activities — go up and down the stairs, park further away at the ramp — you can accumulate time, and that all counts. So it doesn't have to be a focused 35- to 45-minute time when you're on a treadmill.

Dietman: And what about that activity? Is there anything to the idea that my blood pressure would actually be elevated if I was exercising, doing a lot of aerobic exercise?

Dr. Sheps: During the time you exercise, your systolic pressure goes up, and your diastolic pressure is the pumping …

Dietman: That's the bigger number …

Dr. Sheps: Right, that's the first number — the higher number — and that goes up with your heart pumping the blood around to be able to allow you to exercise, but the diastolic goes down because the diastolic is the pressure between beats and it goes down because your blood vessels open up to get all the blood out to the muscles that are exercising, so you have a high systolic and low diastolic during the time you're exercising, and then it comes right back down as soon as you stop.

Dietman: So this condition called prehypertension, which I've learned I have, is serious. It's something I need to pay attention to, but if I manage it correctly, it doesn't have to lead to high blood pressure, and it's a condition but not necessarily a disease, it sounds like, that is going to radically change my health forever.

Dr. Sheps: You're quite correct. The way to think about prehypertension is a warning. If you have prehypertension and you're overweight and you have a bad family history of strokes and heart attacks and diabetes, and you smoke and you drink a lot — these are all warning signs that you're going to get clobbered in the near future if you don't take care of yourself. And as we've said, taking care of yourself is just following healthy behaviors.

Dietman: We've been talking with Dr. Sheldon Sheps, Mayo Clinic cardiologist and an expert in the diagnosis and treatment of high blood pressure. Dr. Sheps is also senior medical editor at MayoClinic.com.

Thanks very much, Dr. Sheps.