Should you aim for an alkaline lifestyle?

Summary

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Podcast Summary: "Should you aim for an alkaline lifestyle?"

What's That Rash? – ABC News
Date: November 18, 2025
Hosts: Norman Swan, Sam, Ting
Main Theme:
This episode examines the popularity and scientific validity of alkaline diets and lifestyles. The hosts respond to listener questions about whether modern diets are too acidic, the physiological basis for alkaline diets, and the health claims associated with such diets—especially in relation to cancer and chronic disease.

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1. Introduction to Alkaline Diets

• Listener questions (Brett and Annie) prompt a discussion:
  • Are modern diets too acidic?
  • Should we be aiming to eat more ‘alkaline’ foods?
• Popular trends noted: Alkaline water, low-acid diets, and commercial products to “balance pH”.
• Funny opening exchange:
  • Ting jokes that Norman has a “Live Laugh Love” sticker, leading to:

    "I'm probably less basic than I used to be.... Cause I'm more acid."
    — Norman Swan [01:19]

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2. pH, the Body, and Acid-Base Balance

[02:59 - 05:50]

• What is pH?

  • pH = measure of hydrogen ion concentration (acidic below 7, neutral at 7, alkaline above 7).
  • Litmus paper memories:

    “I think I even made my own litmus paper using red cabbage.”
    — Sam [03:29]

• How does the body control pH?

  • Blood pH is tightly regulated (7.35 – 7.45).
  • Extreme deviations are life-threatening—critical for oxygen transport and enzyme function.
  • Regulation mechanisms: via lungs (CO₂ removal raises pH) and kidneys (excrete or retain acid/alkali in urine).

• Quote:

  “Our bodies do not work well... in life-threatening situations when we're too alkaline or too acidic, particularly too acidic.”
  — Norman Swan [03:51]

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3. The Origins of the Alkaline Diet Trend

[05:50 - 10:48]

• Historical context:

  • 19th-century interest in acids and bases led to early research on diet and body pH.
  • 1933: Study with ammonium chloride/phosphoric acid—body adjusted, except under extreme conditions (like diabetic acidosis).
  • Research used “acid-ash” and “alkaline-ash” (burning foods to ash, measuring pH post-metabolism).

    “[Citrus fruits] are acidic, but really it's about what's left over from those foods once your body's metabolized them.”
    — Sam [08:20]

• Early observations:

  • Meat-heavy (acidic) diets vs. plant-heavy (alkaline) diets
  • Short-term, extreme diets caused nausea (1930s study lasted "two and two-thirds of a day" before stopping).
  • 1960s: Vegetarians had more alkaline urine, but this was about the diet, not their blood pH.

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4. What Alkaline Diets Really Do

[10:48 - 13:38]

• Correlation vs. Causation:

  • Alkaline diets are healthier not because they change your blood pH, but due to increased intake of fruits, vegetables, and fewer processed foods/meat.
  • The "Mediterranean diet" theme arises:

    “It was the Mediterranean diet.”
    — Norman Swan [10:31]

• Practical upshot:

  • “Alkaline diet” = high-fruit and veg, low-meat diet.
  • Consuming alkaline water or “alkaline products”? Not necessary or impactful.
  • Risks of acid diets?
    Slight evidence of increased calcium in urine (potential osteoporosis or kidney stone risk), but overall, calcium balance is tightly controlled in the body.

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5. Acidosis, Chronic Disease, and Diet

[12:27 - 15:24]

• Serious acidosis: Only occurs with conditions like untreated type 1 diabetes; otherwise, body self-regulates.
• Is “low-grade metabolic acidosis” a chronic risk?
  • Not well established in research; possible, but hard to separate from the general harms of poor diets.
• Quote:

  "A simple solution being, just have more alkali in your life—one is that you think, well, I'll just drink alkaline water. That's not going to cut it...what's going to benefit you is more alkaline foods which happen to benefit you independent of their alkaline activity."
  — Norman Swan [13:57]

• Homeostasis: Body rigorously corrects disruptions to pH; diet cannot meaningfully change blood pH in healthy people.

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6. Fad Diets, Claims, and the Cancer Controversy

[15:24 - 16:27]

• Cancer claim: Some say alkaline diets “fight cancer” by altering tumor environments.
  • Reality: Healthier diets may improve immunological resilience, but diet does not alter tumor pH directly.
  • Quote:

    “It probably does [help], but not because of being alkaline...it'll make the immune system more active, your microbiome more active, and in general you'll be healthier... but it won't influence necessarily the immediate PH environment around a tumour.”
    — Norman Swan [15:32]

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7. Alkaline Diet vs. Low-Acid Diet: Is There a Difference?

[16:14 - 16:55]

• No meaningful difference; low-acid diet = alkaline diet in popular understanding.

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8. Bottom Line & Health Guidance

[16:34 - 17:03]

• Best practice:
  • Don’t obsess about “alkaline” products.
  • Eat more fruits and vegetables, less meat, and limit processed foods.
• Quote:

  “If you like the idea of an alkaline diet, go for it. But don't assume that if you take an alkaline product such as alkaline water, that's going to cut it.”
  — Norman Swan [16:39] “Foods to eat: basically fruit and vegetables, less meat and avoiding ultra processed foods.”
  — Sam [16:55]

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9. Notable Quotes & Memorable Moments

• Humorous banter and asides:
  • “Could that interfere with the results? …I don't know if eating a lot of red cabbage causes you to be alkaline or acidic.”
    — Ting [03:39]
  • “It’s an extreme keto diet, isn’t it?”
    — Norman Swan on meat-only study [09:29]
• On homeostasis and “simple solutions for complicated problems”:
  • “Simple solutions for complicated problems…are almost always wrong.”
    — Norman Swan [13:57]

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10. Key Timestamps

• [01:06] – Show proper begins, listener questions introduced
• [02:59] – Explanation of pH and acid-base balance
• [05:50] – Origins and early research of acid and alkaline diets
• [08:20] – Acid-ash vs. alkaline-ash explanation
• [10:31] – Mediterranean/plant-heavy diet discussion
• [13:38] – Fad-diet critique, homeostasis, and marketing commentary
• [15:24] – Alkaline diet and cancer claims
• [16:55] – Bottom line and recommendations

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Summary for New Listeners

In this approachable, witty discussion, the hosts debunk the myth that alkaline diets alter blood pH and deliver health benefits that way. Instead, the benefits arise from the core advice repeated by health authorities: eat more plants, avoid processed foods, and reduce meat intake. The body's acid-base balance is robustly self-regulated; you cannot shift it meaningfully by dietary tweaks. While eating well supports general health—and may indirectly support cancer resistance—it is not because of an "alkaline" effect. The allure of "simple solutions to complicated problems" can mislead, but following dietary guidelines will serve you best.

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Transcript

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[Claire Nicholls]

It is a truth universally acknowledged that on one's 250th birthday, there should be a celebration. I'm Claire Nicholls, and on the bookshow we're raising our teacups to Jane Austen.

[Norman Swan]

Why Austen?

[Sam]

What is it about her?

[Claire Nicholls]

Authors Colm Toveen, Karen Joy Fowler, and more will explain why in 2025 the Austen effect is bigger than ever.

[Ting]

That's quite incredible.

[Claire Nicholls]

Search for the bookshow and look for Dear Jane wherever you get your podcasts or hear it now on the ABC Listen app.

[Sam]

Norman, would you describe yourself as a basic?

[Norman Swan]

I'm kind of basic.

[Ting]

You got a live Laugh Love sticker on your lounge room wall.

[Norman Swan]

That's right. I'm probably less basic than I used to be.

[Ting]

Why do you say that?

[Norman Swan]

Cause I'm more acid.

[Ting]

Incredible science pun. Which actually is the perfect segue into today's episode of what's that Rash?

[Norman Swan]

Where we answer the health questions that simply everyone's asking.

[Sam]

So today's questions come from? Well, a couple of people. Brett and Annie are both asking about alkaline diets or low acid diets. So Brett says, I just read an interesting story in New Scientists about low acid diets. I've even seen an Australian company that sells information and products to help maintain an alkaline lifestyle. And Annie says, is there any evidence that our diets today are too acidic and therefore need to be balanced by consuming more alkaline foods? I don't remember much from high school biology these days, but I'm pretty sure our stomach has its own version of acid that is very much required for digestion. So claims about balancing the body's ph doesn't sound right to me. Mm. Alkaline and acid diets, Norman. I've seen alkaline water sold, and I've definitely heard the alkaline diet promoted over the past few years.

[Norman Swan]

Well, going back to my comment there about me being acid, I need to be a little bit acid about this. But, you know, we couldn't survive. You've written about this as well. You wrote a piece on this five or six years ago.

[Sam]

It's funny.

[Ting]

Yeah, we did dig up an article that I wrote on this very thing from 2018, which I had completely forgotten I'd written about. And also I wrote it for.

[Sam]

For Life Matters.

[Ting]

I wrote it for a segment that.

[Sam]

I'd done on Life Matters before I came to be hosting it.

[Norman Swan]

Yeah, before you abandoned us.

[Sam]

I didn't abandon you. I'm here with you right now. It's okay. We've talked about this, all right?

[Norman Swan]

I'll get over it. So the thing is. Well, we should really just talk about the technical stuff. We're talking about ph, the level of hydrogen ions in our body. Cause hydrogen ions are what creates acid. And there's a way of measuring the acid in your body. And a pH of seven is neutral. Lesson seven, you're heading towards acidic. And above seven, it's alkaline or basic.

[Sam]

I remember being in high school and using those, the coloured paper. The paper that would change colour depending on.

[Norman Swan]

Litmus paper.

[Sam]

Yes, litmus paper. And I think I even made my own litmus paper using red cabbage. I can't remember how I did it, but it was pretty cool.

[Norman Swan]

Could that interfere with the results or.

[Sam]

I don't know.

[Ting]

I don't know if eating a lot of red cabbage causes you to be alkaline or acidic, but.

[Norman Swan]

Well, from memory it went red when it was acidic. And Correct from that memory, or vice.

[Ting]

Versa, I can't remember.

[Norman Swan]

The fact of the matter is one of the things that is exquisitely controlled in our bodies is our acid base balance, our acid alkali balance. Because our bodies do not work well when, and I'm talking about life here, life threatening situations when we're too alkaline or too acidic, particularly too acidic. Oxygen doesn't separate, doesn't get taken up by haemoglobin as well and doesn't separate into our tissues. So you end up with low oxygen levels if you're too acidic. And enzymes and all sorts of activities in our body require a very narrow range of ph. And that narrow range of ph is like 7.3, 7.4 or so. And we really, unless there's something wrong with you, we really don't budge from that number.

[Sam]

And that's particularly your blood pH, if I'm not mistaken. Because there's parts of our body that are very acidic, like our stomach.

[Norman Swan]

That's right. And ph, you know, there's hydrochloric acid in your stomach. So the ph gets very low indeed. And also your urine. Urine can be acidic because the two ways that. Two main ways that your body regulates acid and alkali in your body is through the lungs. If you excrete carbon dioxide, you actually raise the pH. Complicated story. But there's this acid in your body that's related to carbon called carbonic acid. And when that goes into carbon dioxide and you breathe it out, you lose carbonic acid, and your ph rises in your kidneys. Your kidneys can transfer hydrogen ions and. And bicarbonate in and out of your urine. So if your blood is too acidic, you will actually pee out acid. And if it's not acidic enough, it will hold back on the hydrogen ion. So this is very tightly regulated. And if it gets out of control a little bit, there are other chemicals, substances in the blood like phosphate and others that can buffer it, can absorb hydrogen and carbon and hold the fort until the lungs and kidneys can take over. So it's really finely balanced.

[Sam]

Okay, so what I'm hearing is our bodies do this work for us already, but it is work that it's doing. And so I think it'd be interesting to talk about the claims of the alkaline diet or the low acid diet, and maybe where some of these came from, because I could imagine that even though our body's really good at managing the ph of its systems, that maybe it takes a toll while it's doing that. Or maybe theoretically it does. So shall we take a little bit of a trip down memory lane here?

[Norman Swan]

Well, you're the memory lane person.

[Sam]

Why don't you miss memory lane? Well, so Basically, in the 19th century, we first described acids and bases, and then as soon as we sort of knew that they existed and we could measure them, it's like, well, let's measure them. And one of the things that they did was measure urine and that sort of thing. And then you kind of go, well, all right, how can we adjust this? How malleable is this feature of our bodies? And so there's a paper from 1933 where they basically got people to take either ammonium chloride or phosphoric acid. What would you say to someone who was going to take one of these substances? Norman Dawn.

[Ting]

I mean, what is ammonium chloride? Sounds toxic to me.

[Norman Swan]

Yeah, you smelled ammonium. Oh, God. I mean. I mean, it's amazing what they got people to do in the old days. So here you are taking deliberately an alkali or an acid and seeing what's going to happen. And what would happen is Your body would adjust to it. I mean, there are certain situations where your body finds it very hard to adjust. So for example, if you've got diabetes and you are short of insulin, type 1 diabetes, you're short of insulin, your body can't metabolize glucose, you metabolize energy in a different way, which produces acid. And you have this metabolic acidosis where your body is running too acid and so acid that it finds it very difficult to adjust, Your oxygen levels drop. And this is a life threatening condition. You become seriously dehydrated and you don't treat it by pouring in alkali, you treat it by rehydrating the person and giving them insulin, so you restore the metabolism. But when they first looked at this, they found an association between a high acid diet. So they looked at it very simply. They, they burnt these foods, turned into ash, and they had what was called acid ash and alkali ash.

[Sam]

Yeah, so basically one of the things, just to skip ahead a little bit, one of the features of an alkaline diet is a diet high in fruit and vegetables, including citrus fruit, which doesn't really make sense. If you go, well, hang on, citrus fruit, citric acid, I think of those fruits as being acidic, but really it's about what's left over from those foods once your body's metabolized them. And so, yeah, if you burn them and then you measure the ph of the ash, that's where you get this idea of acid ash and alkaline ash.

[Norman Swan]

So there is, in an epidemiological sense, if you want to look at things in the light of your ph and your diet, the acid diet has more meat in it. It's a less healthy diet than an alkaline diet, which is richer in vegetables.

[Sam]

So can I tell you about the rest of this study? From the 1930s, they got people to change their diet. So like you say, an acid diet is very heavy in meat. And so these people were given almost entirely meat. The exception was 20 grams of rice, brains, ham, chicken, veal, beef and eggs. Guess how long the study lasted?

[Norman Swan]

I don't know, but it's an extreme keto diet, isn't it?

[Sam]

Two and two thirds of a day.

[Ting]

The subject became nauseated and they had to stop the experiment.

[Sam]

So that one was a bit of a bust. And then a few decades later, in the 1960s, doctors discovered that even though human urine is usually acidic, vegetarians seem to have slightly alkaline whe. Which really tracks with this idea of this vegetable diet maybe being slightly more likely to produce an Alkaline urine at least, whereas meat was more likely to produce an acidic urine.

[Norman Swan]

But really what they were doing was looking at the wrong thing in the wrong place.

[Sam]

Where should they have been looking?

[Norman Swan]

Not in their bladders, at the actual food. Because the next correlation they made was that when you look at alkaline foods, it was associated with less chronic disease than acid foods. So they made an assumption that your blood needed to be alkaline to improve your health and well being. But the reality is it was nothing to do with the ph, it's to.

[Ting]

Do with the fact that it was fruit and vegetables.

[Norman Swan]

It was the Mediterranean diet.

[Sam]

I knew that was gonna come up today. I brought my bell.

[Norman Swan]

Well, maybe not the Mediterranean diet, but certainly a diet that was higher.

[Sam]

A plant heavy diet.

[Norman Swan]

That's right. And we know for all sorts of reasons why that's good for you. But one of them is not whether or not it's acid or alkaline.

[Sam]

Okay, so let's talk about the diet itself. We've got on one hand a so called alkaline diet, which is high in fruit and vegetables, low in processed foods, low in meat. And then the converse is this acidic diet. If you're following that diet and no one is profiting off it unnecessarily, is it a problem?

[Norman Swan]

It doesn't look as though it is. Although people are selling things like alkaline water and that's not necessarily a natural product. But if you are eating a diet which is biased towards vegetarianism, then that's going to be good for you. But people do wonder whether or not there is a risk in an acid diet.

[Sam]

What kind of risk?

[Norman Swan]

So when you have more acid in your blood and the kidneys are actually responding by switching to excreting acid in the urine, calcium goes out in your urine as well. So there's a little bit of evidence that maybe that increases the risk of stone osteoporosis. Well, loss of calcium and osteoporosis and maybe renal stones. And there's a little bit of evidence that if you eat a meat rich diet, you are at increased risk of kidney stones, a very painful condition. There have been studies though of calcium balance in the body relative to acid balance. And there is no evidence that you actually depleting the calcium in your bones when the kidneys are excreting acid, because calcium is very tightly controlled as well in the body, because your heart and electrical systems work in calcium in large part. And if your calcium is being excreted more, you absorb more from your diet.

[Sam]

Okay, so you talked before about like really serious acidosis. The body is properly out of whack, it's a life threatening thing. But there's also this idea that there's a condition called low grade metabolism metabolic acidosis that could potentially be a driver of chronic disease.

[Norman Swan]

I just don't think it's been well enough studied. I mean, anything is possible. And it's possible that one of the additional complications of a bad diet is a mild acidosis. So whether or not the acidosis is cause and effect or a side effect is another matter. But if you're going to change it by improving your diet, then both problems are solved at the same time.

[Sam]

So I feel like whenever we're talking about fad diets, I'm thinking about the alkaline diet here. I'm thinking about like detoxes and that sort of thing. And often what the narrative is from people in the health space, the research based health space is your body's really good at doing this, don't worry about it. But then on the other hand, we also have things like your diet's really important for your health, Mediterranean diet, blah, blah, all that sort of thing. Like how much of it is trust your body, trust your body to do what it needs to do to keep your body healthy and how much of it is watch what you eat, be careful about what you eat, prioritise healthy foods.

[Norman Swan]

Well, it's the latter. So I think that the good thing that this acid base discussion has had in the general community is that it's biased people towards a much healthier diet. It's just not necessarily working the way they thought. Where we get things wrong sometimes in a debate about simple solutions for complicated problems. So a simple solution being just have more alkali in your life. One is that you think, well, I'll just drink alkaline water. That's not going to cut it because actually what's gonna benefit you is more alkaline foods which happen to benefit you independent of their alkaline activity, their PH effect on the body. So in that sense, if you follow the dietary guidelines, if you follow the dietary advice, you're actually gonna be okay. But there's this, I mean, just in general, when people are offering simple solutions for complicated problems which are almost always wrong, is a phenomenon known as homeostasis in the body. And homeostasis is this incredibly powerful force in our bodies which aims to keep the body in balance. So you push, it pulls, blood pressure goes up, it'll try to get the blood pressure down, heart rate goes up, It'll try to get it down, more alkali in your body. It will try to get that down so that you get a better acid base balance. Too little oxygen, you'll breathe faster to try and get more oxygen into your body. So homeostatic mechanisms are very powerful and it's very hard to disrupt them. And you can if you've got something like type 1 diabetes, but you can eat a Mediterranean diet until the cows come home, but your PH won't shift. What will shift are the bioactive compounds, your microbiome and all sorts of other things in your body which create a new homeostasis.

[Sam]

The other thing around the alkaline diet that I wanted to call out was claims around it fighting cancer. Can we talk to that?

[Norman Swan]

The answer is it probably does, but not because of being alkaline. The theory is that when you look at the tumour environment of a malignant tumour, it tends to be an acid environment around the tumour, which is part of its survival. But eating an alkaline diet isn't necessarily going to affect the immediate tumour environment around the cancer. What it will do, because it's a healthier diet and it's got more bioactive compounds, is that it'll make the immune system more active, your microbiome more active, and in general you'll be healthier and more able to resist the cancer or fight it, but it won't influence necessarily the immediate PH environment around a tumour.

[Sam]

So we had our beautiful question askers asking about both the alkaline diet and a low acid diet, which to me sounds like the same thing. Is there any difference with this low acid versus what was called the alkaline diet a few years ago?

[Norman Swan]

Not that I'm aware of, no. If you're eating a lower acid diet, you're eating a high alkaline diet. That's the flip side of it.

[Sam]

So what's our bottom line for Brett and Annie and anyone else who's seen this around and wondered about it?

[Norman Swan]

Well, if you like the idea of an alkaline diet, go for it. But don't assume that if you take an alkaline product such as alkaline water, that that's going to cut it. It's eating alkaline producing foods that's going to be good for you, not because of the alkali, but because they're good.

[Sam]

Foods to eat, basically fruit and vegetables, less meat and avoiding ultra processed foods.

[Norman Swan]

And you know what that means.

[Ting]

What does it mean, Ting? You'd think I would have guessed by now. Well, Brett, Andy, thank you both so much for sending in your questions.

[Sam]

We love getting your questions. You can email us that rashbc.net au.

[Norman Swan]

What have we got in the mailbag?

[Sam]

So we have a lot of letters today about people falling asleep in front of the tv. John has emailed saying love your show. Have listened since the inception of coronacast.

[Ting]

Also, enjoy the health report. Lots of excellent information.

[Sam]

John just said I wanted to give some feedback regarding this most recent episode about falling asleep in front of the T. As a physician, sometimes when I hear patients mention these symptoms in my clinical practice, it can be an indication of the presence of obstructive sleep apnoea. We didn't talk about that. Norman.

[Norman Swan]

No, we didn't. So excessive daytime sleepiness but also sleepiness in front of the telly would qualify. So yep, don't ignore it.

[Sam]

And Renee has also emailed in, also.

[Ting]

A listener since the early days of coronacast makes the point of saying I.

[Sam]

Never fall asleep during your shows.

[Ting]

But Renee does say I do, however.

[Sam]

Fall asleep during Gardening Australia daily. Intentionally.

[Ting]

That is, Falling asleep to Gardening Australia is not only for septuagenarians but also for 33 year olds.

[Norman Swan]

We're going to have to get Costa onto the program to tell us what he does to make this so magical for people.

[Ting]

Oh, sorry, Renee continues, There's more to this. I use iview to put on old episodes of Gardening Australia to help me go to sleep. I put the sleep timer on for 30 or 45 minutes, but I often fall asleep within five to 15 minutes. My husband, who normally falls asleep later than me, is getting a very thorough gardening education.

[Norman Swan]

Well done.

[Ting]

Renee Lynn has said she's got to listen to she had to listen to WhatsApp rash on the app because she fell asleep listening to us on the radio on Saturday morning. The irony.

[Norman Swan]

Saturday morning. How do you fall asleep on a Saturday morning? You might know.

[Sam]

Maybe she had a big weekend, big Friday night.

[Norman Swan]

Yeah, maybe you got sleep out.

[Sam]

And Jonathan says, listening to your episode.

[Ting]

About falling asleep in front of the.

[Sam]

Tv, I wondered how can I keep my students awake in lectures? I fell asleep in almost every lecture in undergrad and still drift off in.

[Ting]

Seminars, so I am sympathetic.

[Sam]

Aside from making my lectures more like.

[Ting]

The Wire, what else can I do.

[Sam]

To help my students?

[Norman Swan]

I mentioned that I fall asleep on the second slide if I'm watching a PowerPoint presentation. It's really embarrassing, particularly if I'm chairing it and I'm on stage. It's really difficult. I think. Start off in a very quiet voice, then raise your voice and keep going. Raise your voice. You know, just make sure you surprise them.

[Ting]

I just also think that falling asleep in lectures is a critical undergraduate experience and just part of being a uni student.

[Norman Swan]

It's a rite of passage.

[Sam]

Oh, well, thank you all very much for your emails. You can email us anytime. That email address again, thatrashbc.netau See you next week.

[Norman Swan]

See you then, Sam.