What's That Rash? - Is 'old person smell' a thing?

0:00ABC Listen. Podcasts, radio, news, music, and more. Before Knives Out. Before True Crime Podcasts, there was Agatha Christie. Clarenicles here, and I'd love you to join me on the book show as we investigate the life and books of Dame Agatha Christie, the so-called Queen of Crime. This was definitely my deep, weird drug, if you like. Yeah, I wish I had my little Miss Marple mug that I could show you right now.

0:29Search for the Agatha Christie Murder Club on ABC Listen, or wherever you get your podcasts. So Norman, thinking back to your grandparents, what smells come to mind? Chicken soup. OK. Matt's balls. Roast chicken. Those are the smells. Yeah, food smells. Me too. I'm thinking about my grandma's cooking and more the smell of her house than the smell of her.

0:55What are you, like, do you associate any, like, particular old person-ness to the smell? Not really. I mean, the house was pervaded by cooking smells. But my grandparents did smell tobacco because in those days, people smoked. So that was the pervading order. Fair enough. Well, the idea of old person smell is what we are tackling today here on What's That Rash? That's the show where we answer the health questions that everyone's asking.

1:29So Norman, we say everyone's asking, this is one of these questions that we have gotten again and again from multiple people and I'm so curious to get into it. So Leanne, Judith.

1:40Suzette and Jane have all written in along a similar theme. And the theme is the idea of old person smell. Leanne says, I'm 64. So imagine my horror when I read this headline. Do people really smell different as they get older? The truth behind quote unquote old person smell. Leanne says, I know we all smell differently as we grow, but it was in no way comforting to read. Can you really smell someone's age?

2:09Judith says recently on my social media feeds, I've seen several interviews quoting Japanese research about kareshu or aging body odor, aka old person smell. Is this a real thing or just a scam to get mature age folks like me to buy some product to solve this supposed problem? Suzette says there's a lot of hype at the moment around persimmon soap to get rid of old person smell. Is this a real thing?

2:37Do you need a special soap to get rid of the smell or is washing daily in regular soap enough? And Jane has also seen advertisements for this soap, which she says is $20 for a bar. She wants to know if it works. So I feel like we've sort of got like a pipeline with these messages from, this is the thing to feel insecure about and surprise as a product that perhaps works to cure it, which is just the age old marketing.

3:06playbook really. It is. So what is an old person's smell? Well, this is okay. Is it real? That's got to be the first question. So when they've done research, which is the sniff test, and it's fascinating how they do these various sniff tests. So there's been some very elaborate tests where people wear a carefully washed shirt for three days, then part of it's cut out and put into a sealed bag, and then the vapors that come off the shirt and that sealed bag are put through an analysis. Or quite simply, they actually get people to sniff the clothes of people of varying ages and told to guess the age of the person that they're sniffing or who's been wearing this. And people are actually not bad at discriminating age according to the orders that they perceive.

3:54That is interesting. And at first I wanted to reject this, but then do you know what I remembered, Norman? I don't know what you remember. Tell me what you remembered. Babies. Babies heads. That's a lovely smell. If someone hands me a baby, the first thing I do is sniff its head. Baby head smell is so beautiful. So we know that babies smell great. I think we can mostly agree that teenagers in their natural form don't smell great. So I guess it's... Particularly when they're being in a sealed bedroom.

4:24So I think it stands to reason that there could be something to do with your age and your scent, although I think, especially if you feel a little weird about the idea of getting older, the idea of maybe secretly giving off some kind of old person odor, maybe strikes fear into your heart. It's incredibly complex. And I'd refer people back to a recent, a previous Watch That Ratch where we discussed body order and deodorant and things like that. But it's incredibly complicated body order. It's an interaction between what you secrete, Some people believe, and there's a little bit of evidence that the immune system's involved, and there's a little question that your diet's involved, that you can change your body odor by changing your diet. And there's been some interesting research along those lines, and we'll come back to that later about what you can run by in a $20 bar or so. What could you eat that might make you smell more pleasantly?

5:13You know, babies do smell nice. Although babies don't smell nice if you haven't washed them for a while. That's true. You've got to wash your babies. You've got to bath them or bathe them, so we would say in Australia, rather than bath them. But you know what I'm saying? And people talk about this gas that we put off, that we excrete if you like, or get. I'm not putting off gas, how dare you, sir. Emily's.

5:34It's called the volatiloam or volatiloam. Volatiloam? Volatiloam, that's the word. I love this word. This is a word that I only encountered very, very recently, i.e. while doing research for this discussion. So we have like a microbiome, like this idea of a kind of ecosystem of things to do with the body. And the volatiloam is like the volatile compounds, the sorts of things that give off an odor across our whole body. Yeah. And it's a complex phenomenon.

6:03So we should really take a dive. Now that we've said that maybe people can discriminate older age groups from younger age groups by the smell without necessarily being too sure about what they're smelling. There's an interesting research history in this area. Well, it's interesting in the fact that the studies are minuscule. But like, yeah, let's talk about it. There have been studies into this. They have identified a compound, but it does seem like when you start to look into this the same.

6:30two studies crop up again and again. There's not a huge body of research around this. Yes. This is Japanese research, tiny numbers. And you find journalists referring back to these two studies and they were not done well. And they reckon they found this compound from this, the gas in the bag from the shirts called two non and all. So two non and all is a real thing. It's an actual compound. The question is whether it is the secret ingredient in old person smell.

6:58And that study, those studies have not been replicated in other populations. So it's quite likely or it's quite possible that to not know is a body order in older people in Japan, but it may well be related to a diet that's heavy in marine foods.

7:13I think that's an interesting point in general for scientific research is there's a lot of criticism that a lot of research is very skewed towards Western populations and white populations. And this is sort of maybe a potential indicator of, yeah, population groups differences. And again, in such a small study in one particular population, you don't know what kind of potential confounders might be at play here. Correct. And where the study has been done in non-Japanese populations, they didn't find two non-inorm.

7:43So to none and all, for those of us who don't have like a chemistry degree, what is it? It's called a non-saturated aldehyde. Ah yes, that clears it up. Which is 9 carbons long and thought to be the result of breakdown of omega 7 fatty acid.

7:58Okay. On the skin. I guess I still maybe need a chemistry degree to understand what that means. But basically it's a chemical compound that has a particular odor and the implication from these small, small studies. Like the first one was like 22 subjects in it, ranging from people in their 20s to people in their 70s. So quite small, quite a big range. But the idea was that perhaps they found this compound in only the older half of that age group. So when you look at these other studies that have been done, They do find substances that seem to be related to aging. One's called dimethylsulfone, another one's called benzothiazole, and the other one looks like non and all, but it's actually spelled non anal. You got a real kick out of that, didn't you? I did. I've been waiting to do that since we began this episode. But I don't think it's got anything to do with the anus at all. It's just the name of the compound. So it makes sense that we excrete fat onto our skin.

8:58that fat content can be driven by all sorts of things like our immune system, like our microbiome, like what we eat. And there have been fascinating studies into what sort of diet makes you more sweet-smelling than others. Well, I have to know. Tell me. Well, you'd guess it. It's the... Lollies? Oh.

9:21Of course it is, the Mediterranean diet. The only diet in the whole world. That's right. So rub that under your arms rather than press them on the stalk. Like a capsicum. That's right. So it is a diet with fruit and vegetables and not too much meat. What a surprise. But I think Japanese traditional... I mean, if we're going to talk about the Japanese diet, these two main studies in Japanese participants, the Japanese traditional diet is a very Mediterranean-like diet in that it's very...

9:50high in vegetables, fruit and fish? Yeah, not quite as high as, say, the Vietnamese diet, but it is up there. It's certainly a very strong pescaterian diet. So what I'm hearing is a healthier diet is perhaps going to lead to a smell that we might consider to be more pleasant. But the truth is, Norman, most listeners of What's That Rash shower semi-regularly.

10:14We know this because we did a story on whether you need to bathe every day, and people told us about their showering habit, so I actually do have data here. And there were one or two who didn't, and were proud of it, but nonetheless. As I said before, I'm not ashamed to say I love skipping a shower if I can get away with it, which isn't very often, but every now and again I do.

10:34But what I'm saying is, if people are following normal hygiene practices, are these compounds building up to a point where people are going to be able to sniff you out as being a certain age? The answer is unclear. When you actually put people in a research context, they seem to be able to discriminate between young and older people. But here's the thing. When we say an old person's smell, it sounds pejorative that it's yucky. Actually, this study found that the pleasantness of the smell increased.

11:04as people aged. That is interesting. Okay, because this is the thing. So Norman, I don't have any official qualifications in health or science, but I do have a degree in marketing. And this is such a marketing coded story for me. Like I said before... It's got everything. It's got anxiety, social...

11:25rejection. Yes, exactly. And ageism. And ageism. You sort of got, marketing is all about creating a problem and then selling a solution, like I said before. And in terms of insecurities, it's a pretty potent one. It's the fear of being smelly, married with the fear of aging. And I'm actually surprised that this hasn't been like a bigger marketing sell before now. I mean, I'd never heard of two non-enull before.

11:53We started looking into it. Had you heard of it before? No, and I haven't even heard of non-enol either. Not a single enol to be found. No, but if you start looking, it is everywhere. And because it's chemistry and because there's like a chemical diagram you can draw of this thing, it feels very scientific. But in fact, it's largely illusory. Illusory. So I do want to talk about the persimmon soap that a couple of our correspondents referenced and just how we've managed to create an anxiety and then this particular product has been marketed as the solution. Well, this goes back to the Japanese research. So first thing to say about the study, there's only one, is that it's into two non and all, which is the Japanese research. And we've already shown that that's not what's causing a smell and odor of people outside of Japan. Well, it's not rock solid yet. And even in Japan, when you say it's not rock solid. And then it wasn't into person itself. It was person with

12:51various teas like Oolong tea and green tea because they have bioactive, most teas have bioactive compounds. So it's like taking bioactive compounds that in theory would break down this unsaturated aldehyde 2 nonanol. And when you do the mix, it does look as though it does, but there's no evidence that person by itself breaks down the 2 nonanol, which is what they're flogging at 20 bucks a bar. Right. So what I'm hearing you say is there were like the compounds that they've taken out of these teas and the persimmon. They've tested that in a single study. Okay, maybe it worked there, but the line between that and a soap is pretty shaky. And even then it's based on pretty shaky evidence to start with. Yeah, the evidence is dirty. You'd have to see really dirty adherence. Okay, so just sort of step through the process here. Is old person smell a thing? Maybe, but some studies found that it might actually be a more

13:47pleasantly received smell to participants. This particular compound maybe is associated with old person smell but it's only really been shown in Japanese people in two small studies and hasn't been replicated elsewhere. The persimmon soap itself probably doesn't have the ingredients in it that the persimmon study looked at anyway and possibly just showering is enough to get rid of any smells that you might be concerned about if you're concerned about them.

14:16And if you want to change your body order more fundamentally, then your diet should be looked at and have a diet that's less focused on red meat, more focused on vegetables and fruits. And it's quite likely that will wash through to your body order. This just feels like a really elaborate way for us to say, chill out and eat your vegetables. Yeah. And don't necessarily have to rub them under your arm.

14:41Okay, so we did get this question from four different people. It's obviously in a lot of people's minds, Norman. Well, it's in a lot of people's algorithms, clearly. It's coming up. True, true, exactly. Which I think, again, plays to this idea of predatory marketing. Correct. So you don't need to buy a $20 bar of persimmon, so unless you like the smell of persimmon. And I mean, if you like the smell of persimmon, go for it, I guess. What does persimmon smell like, by the way? I can sort of see it in my mind. I don't know if I can taste it. It's not as strong of a flavor as you think it's going to be based on the color. No.

15:09Well, Leanne, Judith, Suzette, Jane, thank you for your emails. We love getting your emails. We love attempting to answer your questions. You can send them to thatrashatabc.net.au. And I've been sitting in this muggy studio, and all I want to do is sniff my shirt, but I've actually pulled myself back, hurt myself back. I'm trying to smell. But I didn't decide what my own body smell smells like. OK, I'm going to have a smell. Smells just like a person. I smell OK, I think.

15:38But can you smell yourself? I don't know. That's a story for another Watch That Rich. It must be. It must be. So a fair bit in Malbec today, Norman. Georgie says, just a note after listening to Norman Swan saying, one should venture out occasionally to shop for nourishing food and not sit alone at home when one is aging, not just tuck into a cheese sandwich. I was actually doing just that as I was listening to your show. The said vegan cheese sandwich half eaten now sits in the fridge. No one in the house dares touch it as if it is cursed. I did go to the shops though and bought a chocolate bar. I hope it was dark chocolate.

16:11This is a health-promoting show, Norman. Look at us doing all this good in the world. And just show us. We don't edit our letters. We tell it how it is. And Mike in Albany in response to our mouthwash episode says Norman says that he does not or tries not to rinse toothpaste to retain fluoride. But listening to the science show last weekend, a gut biologist says you should rinse thoroughly as gut bacteria are killed off by fluoride. Oh no, Norman, we've been pitted against our sister show. I know, I know.

16:43But Shelby, trainer or producer, has dug deep into this. And we should say Shelby does often moonlight on the science show. And so she is an unbiased party. So it turns out that, in fact, a low dose of fluoride can actually boost a healthy microbiome, but a high dose of fluoride could increase the ratio of some unhealthy microorganisms.

17:07But it's about 10 milligrams a day, which is really right at the maximum fluoride intake for an average adult. And remember, you're getting lots of benefits from the fluoride as well. And a single tooth brushing episode would expose you to just over a milligram of fluoride. And just to be clear on my habits, since we're in an awkward habits-laden episode, I actually floss and interdent with the toothpaste still in my mouth. And then I wash it out. Sounds messy. I don't swallow it. It's disgusting.

17:37Can I just say it's disgusting? You don't want your partner or anybody else nearby while you're doing it. It's disgusting. The things we do for hygiene. So Norman, I know that you are a big fan of diseases in general and the fascinating stories that surround them. Absolutely fascinated in new diseases and particularly infectious ones. Well...

17:57Our colleagues at Science FriXion have a new series out right now, which is absolutely up yours and my alley. And anyone who maybe enjoyed this feed when it was still coronacast, it's called Outbreaks. It's on Science FriXion. Our brilliant colleague, Belle Smith, has been digging into Australian disease outbreaks. And the first one, which I listened to the other day, is all about an outbreak at the Melbourne Aquarium. So very homegrown and very, very interesting. It's just like true crime without the crime.

18:25The criminal is a microbe, but you don't always know which one it is. No spoilers. No spoilers. No spoilers. Anyway, search for science fiction in ABC Listen or wherever you get your podcasts to listen to this whole series. It's mint. See you next week. See you then.