Program: Should you be avoiding nightshades?

Tegan Taylor: So, Norman, I just finished eating my lunch.

Norman Swan: What did you have?

Tegan Taylor: I had a chili bean thing with tomatoes and corn chips. It was delicious. 

Norman Swan: Sounds good. 

Tegan Taylor: It was, it was very good. But the thing about that particular meal, and the tomatoes in particular, is that I feel like tomatoes are so ubiquitous in so many cuisines around the world, and every now and again I think about the fact that they are native to the Americas and so were never found outside of those two continents until the 1500s.

Norman Swan: Yep. So we talk about the 'ting!' Mediterranean diet. 

[Bell rings]

Thank you. The Mediterranean diet did not have tomatoes in it for most of its life.

Tegan Taylor:  Yeah, and all of the other related foods that we think of as just being staples among European cuisines, potatoes, and then also, like I was saying before, chilies and things like that, all of which belong to one particular group of vegetables or fruits…

Norman Swan: The nightshades.

Tegan Taylor: The nightshades, it's such a good name, and there's a lot of claims around about their health effects, which we're going to talk about today.

Norman Swan: Yeah, do nightshades make your joints sore? That's the question we're going to be answering this week on What's That Rash?.

Tegan Taylor: A show where we answer the health questions everyone is asking.

So Kelly has written to us, Norman, this week, about her dad…

Norman Swan: This like asking for a friend, is it?

Tegan Taylor: My 'dad' wants to know. Kelly said her dad recently read something that said people should stop eating nightshade vegetables if they have arthritis, so he stopped eating his two favourite vegetables (fruits?); aubergine or eggplant and tomatoes. Kelly says, 'I'm not sure he needs to.'

Norman Swan: Well, Kelly, we are going to answer that question for you, because aubergine and tomatoes are part of the nightshade group. But the nightshade group isn't necessarily what you think.

Tegan Taylor: The nightshade group is very big, and I think because they're called nightshades, the first thing you think of if you have any passing interest in history is deadly nightshade. 

Norman Swan: Absolutely, the worst one of all.

Tegan Taylor: The coolest one, kind of. It's very…what era are we talking here? I've just got, like, ladies in big puffy dresses, and perhaps they're beautifying themselves with nightshade, or perhaps they are poisoning their husbands with it.

Norman Swan: Exactly, or putting the drops of deadly nightshade in their eyes to make their pupils dilate so that their eyes look more beguiling.

Tegan Taylor: There's nothing sexier than a big old dilated pupil, that's what I always say. 

Norman Swan: This is an ancient medicine, ancient poison, and it got this name 'deadly' because taken to excess it can in fact be deadly, but in fact it's still used to this day in medicine.

Tegan Taylor: What? What?

Norman Swan: Yeah, it's called Atropa belladonna, 'bella donna' meaning 'beautiful lady'. 

Tegan Taylor: And Atropa was one of the Three Fates in Greek mythology. So the Three Fates, one spins the thread of life, one measures it, and Atropos cuts it, i.e. that's when you die. We were talking before about the nightshade vegetables like aubergine and tomato, which come from the Americas. Deadly nightshade is kind of related but it's from Europe, if I'm right.

Norman Swan: Well, we should start by doing some botany here on What's That Rash?. While they're called the nightshades, they were called the nightshades originally because they had similarities in terms of their flowers and how they looked, but when you actually look at their genetics and what they are, there's very little relationship between them. Yeah, potatoes, tomatoes, aubergine, chili peppers, they probably do have some relationship to each other in terms of the chemicals that they have in them, but it was more of how they looked rather than what they actually were, and deadly nightshade was part of that group. And if Kelly's listening, as I hope you are, Kelly, this gives a secret to what the answer is to your question, but we will take our time getting to the answer of the question because we'll just jump so many wonderful stories.

Tegan Taylor: There really are a lot of cool stories, especially when it comes to deadly nightshade which is what we're talking about now. I was shocked to hear you say that it is still used in medicine, because it's one of those substances which you hear people…'oh the Romans had lead in their pipes, and they all killed themselves with their lead, and they're putting deadly nightshade in their eyes to dilate their pupils to try to make themselves look hotter, but they were actually putting poison in their eyes.' And it's crazy that it's actually used in medicine today.

Norman Swan: Yeah, atropine is very useful, and it's got a sister compound called scopolamine, which also comes from a nightshade group. They've been used in anaesthetics. What they do is they dry up secretions, they can give you a dry mouth, and that's quite useful sometimes in anaesthetics, although there are better and safer drugs being used now, but still sometimes it's used. Because of the way the drug works, it's called an anticholinergic, if your heart rate has slowed down dangerously, you can actually give atropine to speed up your heart rate, to salvage your heart rate while the doctors work out what's going on. 

Ophthalmologists can use atropine, or an atropine-like drug in your eye to dilate the pupils so they can see in the back of the eye more clearly, which is why you're told not to drive afterwards, not because you're going to get poisoned by the atropine, but because your vision is blurred and you can't focus that well. So atropine is very handy, but because of its effects, for example, on the heart, it can be incredibly toxic if used in too high a dose. Scopolamine is useful as an anti-nausea drug, and in fact some people have used it in pregnancy, although that's considered not terribly safe.

Tegan Taylor: Well, it was used as poison in a couple of historic murders back in the olden days. But like I said before, deadly nightshade is native to Europe and West Asia, and the nightshades that we eat like tomatoes and potatoes and chilies and that sort of thing are native to the Americas, so there's actually very little to do with them. Are these alkaloids that you're talking about actually found in tomatoes and potatoes at all? 

Norman Swan: You mean the atropine-like drugs? 

Tegan Taylor: Yeah.

Norman Swan: I'm not aware that they are, no. You do get these substances called alkaloids and all sorts of other substances that are really good for you in foods like tomatoes and aubergine and what have you, and some people believe that they are actually bad for you, they cause inflammation, they might increase the inflammation in the joints to make arthritis worse. So, first of all, there's no evidence of that. 

To the contrary, interestingly, these alkaloids…for instance, alpha-solanine in tomatoes, particularly in green tomatoes, which has been considered a toxin, and you get it when potatoes turn green, which is why you should always peel your potatoes to get all that green away, because they can be toxic. But people are talking about these as anti-inflammatory drugs, so that in fact the alkaloids that some people believe cause arthritis or make arthritis worse may actually help the arthritis, particularly the alpha-solanine in tomatoes. So it is a bit of a myth that these foods such as potatoes, aubergine and tomatoes make arthritis worse, and there have been studies to that effect.

Tegan Taylor: Well, obviously there's always a kernel of something beneath a myth like this, and it looks to us at least like the kernel that this is based on is two mouse studies looking at solanine and irritable bowel syndrome, one from 2002 (which to you and I, Norman, sounds like a couple of years ago but was 22 years ago), and one from 2010, and there doesn't really seem to be much else since.

Norman Swan: Well, there has been much else since but on the positive side. There was one just this year about how alpha-solanine, which is this substance that gives nightshades a bad rap, actually theoretically could help osteoarthritis by affecting one of the cell types in the joint.

Tegan Taylor: But it is one of those things that keeps coming up. So we were talking randomly about this as we were planning what to say today, and we're hearing stories of people saying, oh yeah, more than one doctor has told me I should avoid nightshades because I've got arthritis or it's an anti…you know, to reduce some sort of inflammatory disease. So even among the medical community there's still advice kicking around that you should be avoiding them, which I guess if the rest of your diet was amazing and lots of plant foods, that would be fine, but should we really be discouraging people from eating vegetables? 

Norman Swan: No, is the short answer. And if you look at the people who are expert in arthritis, and the groups that represent consumers in arthritis, they do not recommend that you stop these vegetables, remembering that, coming back to your original point, as soon as you say 'nightshade' you think poison…

Tegan Taylor: Deadly.

Norman Swan: The dark of the night, vampires, and in fact it's an accident of fates in some senses that Carl Linnaeus (who classified plants) lumped these 2,000 species all together, when in fact they are genetically often quite separate.

Tegan Taylor: So are there any other reasons why people might have a medical reason to avoid nightshades, either as a group, or certain vegetables or fruit within that category?

Norman Swan: What's been described rarely is an allergy to some of these alkaloids in some of these fruits. Some people will say 'when I eat tomatoes, I get migraine', which could be an effect of the alkaloids in there. Other people who get migraine are unaffected by tomatoes and might get it from oranges, which are not nightshade. So in other words, if you find a specific food causes a certain set of symptoms, then stop eating it. But without that sense that if you eat something, something gets worse, you're not doing yourself any good at all by withdrawing it.

Tegan Taylor: So your mileage may vary. If it doesn't work for you, then cut it out, that's fine. But in terms of Kelly and her dad, avoiding fruits that he loves just because he has arthritis is probably unnecessary. 

Norman Swan: Yes. Back on the aubergine, back on the tomatoes, and the chips.

Tegan Taylor: Potato chips. Outside of nightshades, what do we know about arthritis? It's not very useful for us to just be like 'eat your veggies, but sorry you're still in pain' to Kelly's dad.

Norman Swan: No, that's right. Well, first of all be sure that it's osteoarthritis that you've got, which is the commonest form of arthritis. Sometimes people who are older have rheumatoid arthritis, which is an autoimmune disease which requires different treatment. And the key here with arthritis is to stay active and to strengthen the muscles around your joints. You may require advice from an exercise physiologist or a physiotherapist to do that, but there are rehabilitative exercises that can actually mitigate the pain and discomfort from osteoarthritis. 

Losing weight is quite important, because for some reason being overweight can trigger…there's stronger evidence for this than there is for eliminating certain vegetables from your diet, that when you put on weight, inflammation goes up and your joints tend to be more tender, even the non-weight-bearing joints. So there's lots of things that you can do for arthritis. But not eating vegetables should not be one of them, because that's the route to helping you to lose weight and help your arthritis that way. 

Tegan Taylor: Kelly, thank you so much for writing in, and I hope your dad gets the relief that he needs, while also enjoying a nice big plate of Mediterranean vegetables, or American vegetables actually. And if you've got a question like Kelly, you can email us, we are thatrash@abc.net.au.

Norman Swan: And we asked you to send in your anti-aging tips, and you have.

Tegan Taylor: This has been so fun. I kind of wanted some really weird stuff, but of course the sorts of people who listen to What's That Rash? are sending in really sensible, lovely anti-aging tips. Megan says she's been lifting weights, and she's been going to bed as early as she wants to, she no longer judges herself for having an early bedtime. 

Norman Swan: Martin says it's all about working the body, resting when needed, and a good diet. He says he's hated Vegemite all his life, calls it (wait for it) the devil's faeces.  Of course I'd say that about Marmite, not Vegemite.

Tegan Taylor: So that's in reference to the fact that Vegemite is rich in B vitamins, and some people have tried to draw that bow between Vegemite and NAD+. Good on you, Martin. Linda says, number one, no car. Number two, stand up on the bus. She says it reduces osteoporosis because the jolts and jarring are a bit like NASA's body vibration training. Norman, is there anything to this? 

Norman Swan: Absolutely, you want to strengthen your bones, you want high impact exercise.

Tegan Taylor: Standing up on bus is high impact exercise?

Norman Swan: Particularly if you're going over bumpy territory in a council area where they haven't been maintaining the roads. Yep, standing on the bus. And, when you get out, walking. And these dance exercises where you're jumping around, what's it called, Zumba, and people have been told, oh, you've got to run on grass, you've got to be very careful about your joints, but you really want to get that impact going so that the bones are being strengthened. So, a good one, Linda. You probably want to do a bit more than stand on the bus though, but it's a beginning.

Tegan Taylor: Luke says it seems that there's a belief that the act of spending money on something is the key to longevity…

Norman Swan: Retail therapy, I'm into that.

Tegan Taylor: Then he says, 'We have powerful evidence that exercise is the most potent therapy and it's free.' Well, if exercise works for you, then that's fantastic. I think there's a lot of people who find they need that plus more, but absolutely, Luke, well done. 

Norman Swan: And as we record this we're coming into retail therapy big time as we approach Christmas. And Louise says, 'To slow aging I live in a town full of young people. It's a party town. This keeps my mind young, so I find I have a younger attitude to my body.'

Tegan Taylor: And the last piece of advice, and probably the most salient advice here, from Dina, who says, 'My best advice for fighting the effects of aging is to be very careful when selecting your parents.' 

Norman Swan: What great advice, I'll just go back and work that one out from scratch.

Tegan Taylor: Thank you everyone so much for sending in your anti-aging tips. If you have a favourite nightshade vegetable that you would like to sing the praises thereof, or a favourite poison that you like to use to knock off Roman emperors, do send them to us: thatrash@abc.net.au.

Norman Swan: And if you're still with us next week, we'll see you then.

Tegan Taylor: See you then.