Instant Genius - Busting testosterone myths

Episode Date: August 27, 2023

Mere mention of the word ‘testosterone’ is likely to bring to mind images of bodybuilders with bulging muscles or angry, aggressive men that are constantly spoiling for a fight. But what does the science really say? In this episode we catch up with Dr Channa Jayasena, an endocrinologist based at Imperial College London. He helps us to break down some of the myths surrounding this often-misunderstood hormone. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Hello and welcome to Instant Genius, a bite-sized masclas in podcast form. I'm Jason Goodyear, commissioning editor of BBC Science Focus magazine. Mea mention of the word testosterone is likely to bring to mind images of bodybuilders with bulging muscles or angry, aggressive men that are constantly spoiling for a fight.

But what does the science really say? In this episode, we catch up with Dr. Chana Jayasina, an endocrinologist based at Imperial College London. He helps us to break down some of the myths surrounding this often misunderstood hormone. So we're talking about testosterone today. So this is something that a lot of people will have heard on. I think a lot of people will be unclear of exactly what it is.

So by way of starting, can we just say exactly what is testosterone sort of scientifically? What's its definition? What is it chemically? No, thank you. Testosterone is a hormone, so a signalling molecule that is made in mostly in the testes of men, but it can be made in smaller amounts in the ovaries of women and the adrenal glands of both men and women. And what it does is whizz around the body

and act on tissues to do specific things such as affecting behaviour, giving rise to reproductive function and changes such as growing armpit hair, facial hair, and allowing particularly boys to go through puberty and to look like men. So yeah, you mentioned there about it also being produced

in ovaries and females, So I think a lot of people, if you were to stop them on the street and say, oh, hello, may I ask you a question, what's testosterone? They'd say, well, it's the male sex hormone, isn't it? But it also plays a critical role in females' bodies, doesn't it? It does. And in fact, not to say that it's coming into vogue, but there's an increasing realization for women, particularly after menopause, that in some cases, giving them small amounts of testosterone, not enough to what we call virilize or create masculine appearances can be useful for improving women with low libido and interest in sex. So it clearly plays an important role in behaviour, just as estrogen, the female hormone, plays an important role in male sexual behaviour. So it's almost like we have this assumption that this very binary relationship between hormones, and sexual behaviour and gender, but in fact, they cooperate. So you mentioned there another hormone estrogen.

Is testosterone a typical hormone, or does it differ from other hormones that we have in the body? So it's part of a sort of superfamily of what we call steroid hormones. And steroid means they're fat soluble and are munched up by the liver, whereas peptide and estrogen is also, and adrenal hormones as well in general, are steroid hormones. another group of hormones called peptides. So steroid hormones like testosterone, estrogen, and related hormones have overlapping functions so that it may not just bind to one receptor, but multiple receptors and therefore have multiple actions. So it's almost like they're overlapping, like a bird might like feeding off one tree, but it might occasionally feed off another tree.

So a lot of time when we talk about testosterone these days, people talk about levels of testosterone. So I thought that would be an interesting area to explore. I guess by way of starting there then, is there even such a thing as a normal level of testosterone? There is, and this is a real topic of debate. So we know statistically when we look at levels of any hormone in the body, 95% of the population are by definition called the reference population. We try to with the word normal because if you're outside that range, then you might automatically assume you're unhealthy,

whereas in fact you simply have statistically an abnormal results. But you could be healthy. And I think the problem is defining when is a low testosterone, a problem, when is it abnormal? So there is still a topic of debate about how, so I can tell you statistically what is a normal level, whereas there's a lot of debate still about health-wise, what is a normal level.

Having said that then, How do we test testosterone levels? Is it a blood test, something like that? It's a simple blood test. It has to be done in the morning, and it has to be done before breakfast, because if you eat big meal, then you get a 20% drop in testosterone as a reflex.

And that will be, when it's analysed, give you a results. And that in someone, a man who is experiencing problems with low libido, loss of erections, that can be a very useful test. But as I said, there are complications with interpreting the results and that's something that I work on myself. Great. So let's have a look at some common ideas or tropes that are thrown around about testosterone and testosterone levels. So I think the first one that will come to most people's minds is that it's often banded around that people with higher levels of testosterone are more aggressive. I mean, is there any truth to that? No, I'm afraid not. We've got

If you look at the male population, there is no relationship whatsoever in the healthy range of testosterone levels for a man, that there's any variation at all or association with aggression. Now, once you go beyond that, and this is where we enter the world of what we call anabolic steroids, where men take enormous amounts of testosterone that are orders of magnitude bigger, that induces aggression. But that is very different to the natural effects of testosterone. And I think that's where some confusion lies. So that's probably where this idea has come from, is it? Exactly. Okay, so you mentioned there libido. So how strong is the link between testosterone and libido?

There's an exquisite link between low testosterone and a loss of libido erections. And in fact, a particular type of erection, which is waking up in the morning, with an erection, and that's actually a reflex to bladder filling. And it is healthy and a young man in particular to, on most days, to experience this. Now, that naturally will subside with time as men get older, but that's a key reflex that is lost. And that's why we use these symptoms, and they're very useful for identifying men who may be at risk. Now, there are other symptoms as well, such as tiredness and feeding low, but we sometimes all feel these in everyday life. but the sexual symptoms are highly specific.

How about the connection between testosterone levels and fertility? What do we know about that? That's a great question. So we know that testosterone, when it's made in the testes, is best thought of as heat escaping from a big oven. So you actually, your body experiences very low amounts of testosterone that escape perhaps into the room around the oven. But the oven is a furnace,

with very high levels of testosterone, and those high levels of testosterone are needed to bake sperm. And when sperm are produced, they're sort of not quite, you know, there's half-cooked croissants, and that final process is needed for somatogenesis. Now, it's complex to explain, but if you start giving someone testosterone when they don't need it, perhaps if they're taking analytic steroids, for example,

you actually switch off the oven and actually paradoxically you can create infidelity. So testosterone from the testes, good for sperm, testosterone outside switches off the testes. No one goes to Hank's for his spreadsheets. They go for a darn good pizza. Lately though, the shop's been quiet. So Hank decides to bring back the $1 slice. He asks co-pilot in Microsoft Excel to look at his sales and costs to help him see if he can afford it. Co-pilot shows Hank where the money's going and which little extras make the dollar slice work.

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name audio creates systems that deliver exceptional sound and unforgettable listening experiences at home. Try it for yourself at a focal powered by name boutique. Visit focal powered by name.com for more information. So I think another common thing that a lot of people will have heard is that elite athletes have naturally higher levels of testosterone. So what's the current thinking on that? idea. No, again, I think it's interesting that I think, let's put it this way, I think if you are born

with very low levels of testosterone such that it might, now, athletics, competitive athletics might be a way in which there would be a small detrimental effect on your performance. But by and large, there isn't a linear, straightforward relationship between testosterone and physical performance. Now, There is a debate when you look between the sexes about physical performance, particularly when you deal with those who take and say masculizing HRT. And there are clear differences between men and women in physical performance and trans athletes. And testosterone does contribute. So to answer your question, within the sexes, I don't think there's an effect,

but it does contribute to difference in performance between sexes. So I think this is perhaps the wildest idea that I've heard related to testosterone when I was reading about this. So one thing that often comes up is that men with higher levels of testosterone are more successful and they make better leaders and better business people. I'm afraid that's completely wrong. I'm afraid. I could probably make a lot of money by using your idea and putting it on the internet and probably get into jail quite soon after.

No. We do know that when men have a problem such as having loss of testers for cancer, so when you've got abnormally low levels and you replace it back into where everyone else in a population lies, then yeah, you feel more optimistic, you feel happier, your mood rises. But if you're already there and in population, more does not. help you further. So another slightly unusual claim that I've read is that high levels of testosterone somehow reduce your empathy. Ah, right. I don't think that there is, again, a relationship between

increased levels of testosterone in men and a lack of empathy. But we know that there are clear behavioral and psychological differences between men and women. And some of those different are underpinned by testosterone affecting cognition in ways that we don't fully understand. So I think reading into that, it may be a manifestation of sex differences that we all know. So you mentioned right at the start that eating a meal can affect testosterone level when we're having a blood test. So what else? What other factors can affect our testosterone levels? The biggest thing is that testosterone is a marker of. of your, it reflects how healthy you are as a man. So we know that contemporary societal problems such

as obesity, diabetes, inactivity physically, particularly in men over the age of 40 are associated undoubtedly with lower levels of testosterone. And that's one of the biggest messages we get, we try to get across in clinic that actually one of the greatest things you can do to optimize your health and your testosterone is by improving your metabolic health. So what happens then? Say I am a person who's got maybe on the low side of testosterone. How does that manifest physically? So as we talked about the behavioral effects in terms of your mood and that may translate into how you relate to people. You may become more withdrawn. And there are physical manifest. stations, you may lose some muscle bulk and get more fat in relation to muscle. And, you know,

despite exercising, you may not be able to put on physical bulk. And, you know, there is the sexual dysfunction as well. Those are the three key things. There are other things. It may thin your bones and may make you later life susceptible to osteoporosis and fractures. And you may get anemia, which is unusual in a man. You may start to feel puffy and breathless when you're exercising. So those are the things that you could present with. So are there any sort of underlying health conditions that can influence our testosterone levels? Yeah.

Obesity, diabetes, and anything that makes you chronically unwell, cancer treatment, anything serious that affects your health is going to affect your reproductive health and that will lower your testosterone. And huge studies, in fact, it's a very large study done. in Europe, across many countries and over 3,000 men showed this beautifully. The men who had higher levels of what we call comorbidity, so essentially a surrogate of how many medications you're on, how many times you see doctors, there's a very clear relationship between that and low testosterone.

So what role does age play? We know that until you're 40, levels of testosterone are very stable. then after 40 this European study showed that there's on average a 1% year-on-year reduction in the population such that in men who are 80 it's relatively common quite a high proportion of them will have lower than normal testosterone levels however only actually most of those men feel fine and actually even in 80-year-olds it's still only a small minority of men who are ill from feeling low testosterone. But there is inevitably an increased risk with increasing age. So sort of coming off the back of that, I think one thing that's been doing the rounds for quite a while now in men over 40, particularly in the States, is the idea of

TRT or testosterone replacement therapies. And there are some commentators saying that any man over 40 would benefit from TRT to stave off what they call the andro pores, like the male equivalent of the menopause. So first off, what is the theory behind testosterone replacement therapy? And then who really does benefit from it? And can it even be harmful for those who don't really need it? Well, I think you've just asked a central question which is fiercely debated. And I think there are a number of things.

First of all, unlike menopause in women, where you have an absolute complete cessation of ovarian activity, that does not exist in men. So I want to say loud and clear, there is no andriples. A small minority of men would benefit from testosterone over the age of 40, and we think that's 2% of the population, so very few. Therefore, I think there's a great danger in trying to sell to men, you know, who may be desperate to improve their hair.

health. And, you know, we all want to, inverse commas, live forever. And I think that there is a big marketing movement to try to monetise and normalize TRT, just like HRT for women. And it's not the same. So in a small minority of men, they would benefit from it. But the first thing is to look at whether your health can be optimized. If you can optimize your health, and I get men coming in who are overweight, sedentary jobs, maybe in an office. If you give them testosterone because they can't make adjustments to their life, then they will feel better, but not as better as actually if they could make those adjustments themselves. And no one has ever shown that testosterone can make you live longer. And in fact, all drugs have associated with side effects. But if you actually get out on

exercise and these weights, there's a mountain. of evidence that you can low your cholesterol, your blood pressure, well-being, etc. So I like to say to men who are older who don't have perfect health, who are thinking about TRT, we could give you testosterone, but actually the Rolls-Royce treatment, if you can do it, is actually overhauling your lifestyle. Sometimes that's not possible, and that's when TRT has a role. So what is the theory behind TRT? You know, how does it work? So we've had for a number of years the ability to synthesize artificial versions of testosterone. So it has exactly the same chemical structure.

And in general, you can give it by rubbing it onto your skin as a gel, or you can give it as an injection. And interestingly, as I said, you know, these are steroid hormones. They're not water soluble. So they have to be injected in oil. and that sits either under your skin or in your muscle. And that gets released over time and tries to replicate the Passanoff testosterone release from the testes. And in general, it's pretty good. And that's been widely available for quite a few decades.

So can this sort of therapy ever be harmful? Very good question. So we know that if you have clearly a problem of severe testosterone deficiency, see, the best example is having lost one or both testes because of testicular cancer. By actually being deprived of testosterone, you have increased risk of osteoporosis, anemia, and maybe heart disease. So testosterone replacement therapy for these men is clearly important. Where a man is taking testosterone and perhaps they don't need to, and I think we're talking

about middle-aged older men who might be very keen and eager to take testosterone because they want to feel better. I think that is probably going to result in them having an increased risk of heart problems, maybe increased risk of cholesterol, and might predict that those men are not helping themselves in the long term and it might lead to their demise prematurely, even though in the short term it might help them feel a bit better. Is there something you'd like to say to sort of sum up? You know, is there any sort of final message that you'd like the listeners to take away about what we've just talked about for the last 20 odd minutes?

Yeah, I just want to say that testosterone is really a window into your health. And I think when you look on the internet, there's, I think, an increasing commercial pressure for men to feel that they should have a perfect testosterone. There's no such thing as a perfect testosterone. If your testosterone is in the normal range, it's fine and giving you testosterone will not help you. And I think the thing that we all are challenged in today's society is maintaining a good metabolic health through diet and lifestyle. And that's the key message.

I think focusing on testosterone replacement therapy in older age, unless you're one of those two percent of men who has a real problem, is not going to help you. That was Dr. Chana Jayasina, an endocrinologist based at Imperial College London. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus magazine. The current issue of BBC Science Focus is out now. Pick up a copy wherever you buy your favourite magazines, or download a digital copy from your preferred app store. You can, of course, also find us online at ScienceFocus.com. This podcast is sponsored by Name, Audio and Focal.

The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analogue warmth. Alongside French acoustic specialist focal, Name creates high-end audio systems, combining innovation with craftsmanship, so you can listen to music, just as the artist intended. Discover more at Name Audio.com. Thank you.