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Interviewer: Older adults are at a higher risk for death if they have low levels of bicarbonate in their blood. Bicarbonate, it's the main ingredient in baking soda. We'll talk about that next on The Scope.

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Interviewer: I'm talking with Dr. Kalani Raphael, a nephrologist and Associate Professor of Internal Medicine at the University of Utah and at the Salt Lake City VA. Dr. Raphael, tell me about the main finding of your study. It's pretty interesting.

Dr. Raphael: In this study, we were looking at the association between serum bicarbonate levels and mortality in a generally healthy older population. The basic finding from our study was that in people with low bicarbonate levels, they had a higher risk of death and their risk of death was about 24%, 25% higher over a mean follow-up period of about 10 years or so.

Interviewer: So that's pretty significant. What is bicarbonate?

Dr. Raphael: Bicarbonate is very important in the body for maintaining your pH levels in a normal range. In order for our cells and our organs to work normally, the pH needs to be kept at a range of about 7.40.

Interviewer: So people with low bicarbonate would have blood that's more acidic. Why might that be unhealthy?

Dr. Raphael: The bicarbonate levels could be low for two main reasons. One is it could be because the kidneys are holding on to too much acid and your bicarbonate levels fall. That's something we call metabolic acidosis. Or the reason the bicarbonate level could be low is because the lungs are breathing off too much carbon dioxide and your bicarbonate levels fall as a compensatory response is what we call that.

So we're not exactly sure why the bicarbonate levels were low in these people. If I had to guess, I would say that the most likely reason the bicarbonate levels are low is because of an impaired ability of the kidney to get rid of the acid that we need to on a daily basis. The main reason why I say that is because our diets are really high in acid content in these western diets that we have now. We don't consume enough fruits and vegetables in relation to the amount of acid that we intake.

So if I had to guess, I would say that the most likely reason that the bicarbonate levels were low is because of an impaired ability to get rid of acid by the kidneys.

Interviewer: So what caused you to even take a look at that in the first place?

Dr. Raphael: Well, in people with kidney disease, we know that low bicarbonate levels occur quite commonly. It occurs in about 15% of people with kidney disease who aren't yet on dialysis. What we know is that in people with kidney disease who have low bicarbonate levels, they have a higher risk of death and they have a higher risk of progression of their kidney disease to end-stage renal disease or needing dialysis or a transplant in order to survive.

But much less was really known about generally healthy people and so I was interested in whether or not low bicarbonate levels have any association with poor outcomes in people who are otherwise healthy. So that was really the driving force behind this research study.

Interviewer: So do you think measuring bicarbonate levels could be some sort of test or indicator that someone could do to evaluate the healthiness of somebody?

Dr. Raphael: Absolutely. I mean, bicarbonate levels are very commonly measured in clinical practice these days. Bicarbonate levels are measured usually when a physician wants to check on somebody's kidney function. They'll order a chemistry panel or a renal panel. In primary care, I'm not exactly sure how well people look at these levels and I think that one of the things that maybe doesn't attract their attention is they don't really know what it means for that person.

So if you had a healthy person sitting in your clinic who had a bicarbonate value that was low, I think most physicians would say, "Okay. It's low. I'm not sure what to do with that." But I think what this research is showing is that it's probably something we should be paying attention to. But I don't really know quite yet what we should do about that.

Interviewer: Right. Maybe it would be a signal that it's worth taking a second look at this patient to see . . .

Dr. Raphael: Absolutely.

Interviewer: . . . if something else is going on.

Dr. Raphael: Right. So, I think you said it correctly that it's a signal for potentially bad things. That might trigger the physician to look into their kidney function a little bit more or maybe consider underlying lung disease or heart problems in that person.

Interviewer: So do you think more research needs to be done to figure out exactly what this could mean?

Dr. Raphael: Absolutely. The key thing about this research is that these were really healthy people. I mean, they were older folks. They could have had diabetes. They could have had some cardiovascular disease. But they were independently living. They could take care of themselves. They could walk a quarter-mile. They could climb up stairs. These were pretty healthy, older folks.

Interviewer: Right. So not necessarily any other indication that something was wrong, right?

Dr. Raphael: Exactly.

Interviewer: Interesting.

Dr. Raphael: Yep. So I think the next steps are to kind of look into why this cohort had low bicarbonate levels in the first place. Is it an undiagnosed or yet to be determined type of kidney disease or some other underlying lung disease, potentially? Then, I think the next thing also to consider is can we raise the bicarbonate levels in these people with various types of interventions and perhaps improve their outcomes, make them live longer, those sorts of things?

Interviewer: Is there anything else you'd like to add?

Dr. Raphael: The takeaway from this type of research is that we can say that there are associations between bicarbonate levels and outcomes. We can't really say quite yet whether or not people should be changing their diets or taking baking soda. I think that's something that needs to be cautioned against at this point, pending further clinical trials.

But I think if somebody is interested in keeping their bicarbonate levels at a normal range, I think that the safest way to do that is to look at how much fruits and vegetables they eat because fruits and vegetables are a source of bicarbonate, that bicarbonate largely comes from citric acid in fruits and vegetables, which gets converted by the liver into bicarbonate. We all know that fruits and vegetables have great health benefits for lots of other reasons.

One of the cautions about increasing fruits and vegetables in your diet is in people with kidney disease because those have high levels of potassium and that could cause potassium buildup in people with kidney disease. So I think if somebody is thinking about increasing their fruits and vegetables in their diet to keep their bicarbonate levels in a normal range that they should probably check with their doctor to make sure that it's safe.

Announcer: Interesting, informative, and all in the name of better health. This is The Scope ÐÇ¿Õ´«Ã½ Sciences Radio.