Do antioxidants really keep you young?

As part of the Naked Scientists Mythconception series, I question my choice of new year resolution as I investigates the science behind the infamous ‘free-radicals’ and their sworn enemy, the all-conquering antioxidants…

Tom – We’re now well into the new year – how are those resolutions going? If, like me, you’ve decided to eat more healthily, maybe you’ve been stuffing yourself with antioxidants. They’re good for you… right? And they attack free radicals, those naughty things flying around in your body causing damage to your cells and making you age faster. At least that’s what we’re told by the so-called ‘health experts’. Let’s see what science has to say on the subject…

The story begins in 1945, when the wife of chemist Denham Harman suggested that he read an article in Ladies Home Journal entitled “Tomorrow you may be younger.” This sparked his interest in the process of aging and a few years later whilst working at the University of California, Berkeley, he proposed that ageing is caused by reactive molecules that build up in the body as by-products of your body’s natural processes and lead to cellular damage. These are what he called “free radicals.” Harman himself described his discovery as ‘a thought out of the blue.’

Scientists began to rally around the theory of free radical ageing and that antioxidants such as vitamin C and beta-carotene were able to neutralise them. The antioxidant boom occurred in the 1990’s with the word entering into the public domain and supplements being added to foods and taken as tablets. It wasn’t until the early 2000’s, however, that scientists began testing the theory and they encountered some interesting results. Two separate studies compared mice, which were genetically engineered to overproduce either free radicals or antioxidants, with normal mice and they saw no change in the life span in each case. Further studies in humans found antioxidant supplements negate the health promoting effects of exercise and may even lead to a higher chance of death.

The increase in life expectancy which is often attributed to antioxidants is, in fact, likely to be a by-product of a generally healthier lifestyle. People that take antioxidant supplements tend to be more health conscious in general and as a result, are likely to live longer.

The bottom line is that scientists are still unsure of the exact roles of free radicals and antioxidants in the body and more studies are required. Most researchers do agree, however, that free radicals cause cellular damage but this is not necessarily a bad thing. In many cases is seems to be a normal part of the body’s reaction to stress. We are certainly not being oxidised and therefore do not require antioxidants to save us from impending doom as the health experts would like us to believe.

Nonetheless, the global antioxidant market was worth 2.1 billion dollars in 2013 and is expected to continue to grow by a further billion by 2020. I’ll leave you with a quote from Professor David Gems from University College London, which sums it all up quite nicely – “It’s a massive racket. The reason the notion of oxidation and ageing hangs around is because it is perpetuated by people making money out of it.”

You can listen to the full interview with the Naked Scientists here.

The Naked Science of a DNA test

I had my genes sequenced by 23andMe in the name of science… and of course I had to ask about the ‘maths’ behind the results.

Nowadays, a lot of companies offer online ancestry tests, or tests to quantify your risk of inheriting some life-changing diseases. But how seriously should we take their results? Izzie Clarke and Tom Crawford spoke to Garrett Hellenthal from UCL and Julianna Cintron from 23andMe in order to find out…

Tom – Fill the tube with saliva to the black wavy line… shall we just crack on?

Izzie – Okay! You get the idea. But in order for companies to analyse our genetic information, all we have to do is spit into a test tube and send it off to the lab. Tom sent his to a company called 23&Me to find out about his health and physical traits, and I wanted to explore my family history. So, how does a bit of my saliva reveal so much about my ancestry?

Garrett Hellenthal from University College London’s Genetics Institute…

  • Saliva contains your genetic code in a series of cells which can be extracted and identified via a series of genetic markers that define your unique DNA sequence.
  • They look at about 500,000 different pieces of genetic code and compare them to the codes of people in the company database to determine who you share matching DNA patterns with.
  • Izzie found out that she is 30% Irish, 24% Western European, 15% Great Britain and 15% Scandinavian.

Izzie – But what about health and physical appearance? Let’s take a look at Tom’s results…

Tom – I think most of them are correct for me like I should likely have lighter eyes, and I have blue eyes. It says likely little upper back hair, and I can fortunately report I have minimal upper back hair. I was also pleased to see that I’m likely not to have a bald spot; I really hope that one’s true.

Izzie – In addition to appearance, Tom’s test was able to look at specific parts of his genetic code and explain the likelihood of there being a change called a ‘variant’, which could possibly lead to a life-changing illness.

Julianna – My name is Julianna Cintron and I’m a produce specialist on the customer care team at 23andMe.

  • There are some traits that are more influenced by genes than others, for example if you have two copies of the gene associated with having red hair then you are much more likely to have red hair.

Tom – Just with you mentioning there this idea of it’s to do with the confidence in something, or there’s a probability. We’re using phrases like more likely, it’s not sort of fixed. In my result I was told that I have a particular variant which leads me to be at a higher risk of Alzheimer’s disease and I was just wondering what exactly does this mean? Does this mean I will get Alzheimer’s; does this just mean I’m above average likely; how does this result actually relate to the risk factor?

  • The e4 variant is known to impact your risk of developing Alzheimer’s and having one copy of the variant puts you at a slightly increased risk of developing Alzheimer’s by a certain age. Having two copies increases the risk further.
  • Most of the genetic risks are actually relatively small, much less than say smoking or unhealthy lifestyles in general.
  • The most important thing is to use the results as ‘one piece of the puzzle’ and not as a diagnosis that you will or will not get a certain disease.

You can listen to the full interview with the Naked Scientists here.

How old is Homo naledi?

Back in September 2015, a new species of early human – Homo naledi – was announced to the world. The remains were found in the aptly named ‘Cradle of Humankind’ near Johannesburg, South Africa at the Rising Star cave system. Since their discovery they have changed the way that we think about human evolution. Now another chamber has been discovered containing yet more remains and analysis of the skeletons within has shed light on what Homo naledi looked like and where they fit into the timeline of evolution. I spoke to the lead researchers Lee Berger and John Hawks…

  • The new ‘Lesedi chamber’ is located 100 metres from the original and contains multiple partial skeletons which have been dated at 2 to 300,000 years old.
  • Homo naledi has human-like hands, wrists, feet, body size and teeth, but the rest of the body is primitive in nature, including the skull, trunk and the brain, which is about one third of the size of modern human brains.
  • It was originally thought that Homo naledi branched from human evolution around 2 million years ago, but the fact that the new skeletons seem to be much younger suggests that there was another lineage evolving in Africa at the same time as our Neanderthal ancestors.
  • The Rising Star cave system has up to 2 kilometres of passageways and the entrance to the Lesedi chamber was found branching off from the original Dinaledi chamber through a 25cm gap.
  • The Dinaledi chamber contains at least 15 individuals of all ages and the Lesedi chamber at least three individuals.
  • Homo naledi are believed to have been purposefully entering these caves up to 30 metres underground to ritually dispose of their dead.

You can listen to the full interview for the Naked Scientists here.

Naked mole rats could help stroke victims

Stroke occurs every 2 seconds worldwide and is the second largest cause of death. When a stroke happens, the most important tissues of our body, the brain and heart, are starved of oxygen causing cell damage. To improve therapies for stroke patients we need to understand how the human body copes without oxygen and one researcher at the University of Cambridge thinks he may have found the answer in the form of a small rodent called a naked mole rat. Dr Ewan St John Smith and his colleagues were able to identify a new mechanism used by the naked mole rats to maintain an energy supply to the cells in their body without using oxygen. He told me more about these fascinating creatures…

  • Naked mole rats are the same size as a mouse, are the only cold-blooded mammal that we are currently aware of and they live for over 30 years despite the maths suggesting they should only live between 3-5 years.
  • They live underground in large colonies of up to 300 and so have adapted to be able to function normally in a low-oxygen environment.
  • A low-level oxygen environment, such as that experienced by the brain when a human suffers a stroke, will kill a mouse, but the naked mole rats are able to survive for 20 minutes without experiencing any side effects.
  • The heart rate of the naked mole rats drops to around 20-25% of normal levels during the oxygen deprivation and the question faced by the researchers was where does the energy come from, as it can’t be via the usual method of aerobic respiration with glucose.
  • Their findings suggest that the brain and heart cells of the naked mole rats are able to undergo respiration using fructose in their blood, rather than glucose from their cells, and while this also has a limited supply, it does provide a back-up plan to survive the oxygen depletion.
  • With this new understanding of how nerve cells function, Ewan and his colleagues hope to be able to develop a similar response in human cells to act as a preventative strategy to stop brain damage during a stroke.

You can listen to the full interview with the Naked Scientists here.

Photo credit: Jedimentat44 on Flickr

 

Men and women may feel pain differently

It’s an age-old debate, who feels more pain, men or women? Scientists at McGill University have taken us one step closer to answering this question with a study using mice. Jeff Mogil and his team have discovered that the biological pathway that causes chronic pain is completely different in male and female mice. If the same is found to be true in humans it could lead to gender specific, or ‘his n’ hers’, painkillers in the not too distant future… You can listen to the full interview with the Naked Scientists here.

Jeff – We found that a major biological pathway involved in pain processing that’s been studied for the last 15 years or so by researchers around the world is actually only relevant and valid in male mice. And in fact it appears not to be used at all in female mice who instead appear to be using a completely different biological pathway.

Tom – What did you actually do in these experiments?

Jeff – Well we were studying a common and important symptom of chronic pain called mechanical allodynia. Mechanical allodynia is when a stimulus that should be perceived as touch is actually perceived as pain. 

Tom – Could you give an example of what that would be in a human?

Jeff – Everyone has had mechanical allodynia. If you’ve ever had sunburn – let’s say you’ve sunburnt your back and I came by and sort of gave you a playful slap on your back. Under normal circumstances that wouldn’t be painful, but if you had a sunburnt back you would go through the roof and that in fact is mechanical allodynia. Before injury mice will tolerate about a gram of force applied to their hind paw. After the injury, they will now withdraw form fibres that are 0.1 or maybe 0.2 grams of force. And then we looked at how we could block that mechanical allodynia, by blocking a cell in the spinal cord called microglia. In males what we would see is that the withdrawal thresholds would go right back up to 1 gram, whereas in females they would stay down at 0.1 grams. There has to be another system that is picking up the slack and performing the same function in female mice. In our study, we preliminarily identified another system involving T-cells, which are also immune cells, but a completely different type of immune cell than microglia.

Tom – And you think this potentially could translate to humans?

Jeff – I think our default assumption is always that the biology of pain in mice and humans is likely very similar until proven otherwise. Now of course there are always species differences, but in general biomedicine only works because these species differences are few and far between. 

Tom – So you’ve shown this in mice and this potentially could be the same in humans, but what does this actually mean?

Jeff – There’s a lot of drug development going on – there’s great need for new analgesics because the analgesics that we have available either don’t work very well or have really terrible side effects. So, there’s a huge need for new analgesics in the world, new painkilling drugs and there are lots of people trying to develop them. Many of the compounds that are under development are actually working on this biological circuit that we have now shown only applies to males. That of course is a problem because what that would predict is that the drugs that are going to be developed will work in men, it’s just that we have no reason to believe that they will work in women. The clinical trial is going to come along, which by law are half men and half women and what might happen is that if the drug works in the men but doesn’t work in the women, overall it’s going to look like the drug doesn’t work and that clinical trial is going to fail. The drug will never get on the market, it will never help the half of the population that it could’ve helped and hundreds of millions of dollars will have been wasted and no-one will really know why. The other thing is that while there’s a whole biological circuit that applies to females and not males, then eventually drugs might come out of that which work on women and not men. So, you can think of the idea of blue pills and pink pills for pain. I really believe that one of these years that’s actually going to be reality.

Part of the ‘Throwback Thursday’ series – you can find all of the highlighted interviews here.

Anglerfish

In the final Critter of the Week for Marine Month, I introduce the villainous Anglerfish with the help of SeaLife Europe’s Joe Lavery…

  • There are more than 200 species of anglerfish identified and they can range in size from a tiny thumbnail to a small dog.
  • The name Anglerfish comes from the ‘fishing rod’ on their head which is in fact a modified dorsal spine called an illicium that’s used for hunting.
  • They can go for days on end without eating but when the time does come they’re able to eat a fish which is twice their own size.
  • The deep-sea Anglerfish lives more than a mile underwater on the desolate ocean floor, meaning that when a male and female cross paths they don’t hang around.
  • The male angler bites into the female and fuses its mouth to her body, eventually becoming a part of her used only to fertilise her eggs.

You can listen to the full interview for the Naked Scientists here.

Turning useless Methane into useful Methanol

Methane is 20 times worse than C02 as a greenhouse gas, so when it’s created as a by-product at oil rigs it’s burned. This is better than releasing the methane into the atmosphere, but it’s not an ideal solution as it creates more C02. Jeroen Van Bokhoven and his team at ETH Zurich have found a new way to convert the methane into something cleaner, and a bit more useful…

Jeroen – We form it into methanol. Methanol itself is a resource for many chemicals, we can even convert this to fuels in the end. Methanol is a base chemical which has many different applications.

Tom – Is methane generally quite a reactive substance?

Jeroen – Methane is a rather unreactive substance. One of the difficulties to activate methane is the product that you make, the methanol, is more reactive than the methane itself. That’s why this reaction is so difficult to perform selectively, because the methanol will react further and then you will not end up with the useful product. That’s why this reaction is called the ‘dream reaction’ because it’s so difficult to perform and to achieve a high yield.

Tom – How do you do this? How do you convert methane into methanol?

Jeroen – Well we defined a stepwise process where we have a material which we activate and this activated material is then reacting with methane. Then we switch the conditions and then we have the activated methane reacting with water and this generates the methanol and at the same time it reactivates the material so it can react with another molecule of methane. The novelty is that we use the water and oxygen from the water molecule ends up in the methanol. The previous methods that have been used will always use an oxidant. The novelty here is that we use water, it simplifies the process very much.

Tom – Before your discovery, how do we currently convert methane into methanol?

Jeroen – Currently that is a very involved process. There are two largescale processes involved. One is the steam reforming of methane making ‘sin gas’ that is carbon monoxide and hydrogen. This is high temperature, high pressure process and then in the second step this mixture is reacted over a novel catalyst to methanol. This is only commercially viable if it’s done at largescale. And that’s why at smaller scales the methane is not viable to convert into methanol, so that’s why its burnt. Our process, we envision you can do it at much smaller scales and that it would be profitable to do it that way.

Tom – So is that the end goal here? To use your process at oil well sites where currently methane is just being burnt as flares and you’re saying no what we can do is, ideally, at these sits convert this to methanol and then do something useful with it?

Jeroen – Yes, that is correct. It’s to do something useful with what us now considered a waste product.

Tom – How far away are you from that? What would a setup to do your process look like at, for example, a well site?

Jeroen – At the moment, we are far from a commercial and an actual application. We have shown that the concept works on the very small scale and the next steps in the lab are to scale-up this process as well as to make sure that the rates of reactions – the speed that the reactions run – are sufficient for a largescale operation.

Tom – When you say, you’ve done this in the lab, how much of this methanol are you making? Is it really quite small amounts currently then?

Jeroen – At the moment it is really small amounts yes, but we also have not optimised this at all, so there are huge opportunities for optimisation. We have shown the proof of concept – that’s what the paper is about – and of course the next steps are to understand what the chemical mechanism is better than we do now, and as well as directly trying to scale this up. There are huge opportunities to do the scale up, but the research is not in the stage that we have looked at it. That is really the next thing to do.

Volcanoes may have ended the Roman Empire

Volcanic eruptions can be both beautiful and destructive at the same time, but researchers have found evidence they may have also been linked to plagues, and even the fall of the Roman Empire. When a volcano erupts, chemicals are released into the atmosphere in huge quantities, which reflect light away from the earth and therefore cause climate change, in the form of summer cooling. These chemicals are also locked away in the ice, providing a snapshot of the time of an eruption. Now scientists have dated the ice cores, and the records of summer cooling, from tree rings and have found they match perfectly. Gill Plunkett from Queen’s University Belfast was one member of that team…

Gill – Now that we have much better dating for these events in the ice cores we can correlate them with other sets of evidence for past climate change and look at the historical records as well. And we can see that there’s a very strong correlation between summer cooling and volcanic eruptions. So, for example, of the sixteen largest events that are recorded in the ice cores fifteen of them are associated with summer cooling.

Tom – Did you look at a specific period over the last 2500 years?

Gill – One of the periods we were interested in was a very large acid spike. Well a species of large acid spikes in and around the middle of the 6th century. So we could see a very large acid spike at 536 AD, the acid tells us that volcanic eruptions occurred but it doesn’t tell us what volcanoes were erupting. To do that we have to look at volcanic particles. So when we looked at the particles associated with 536 acid layer we found that there was evidence not of just one eruption, but at least 3 eruptions.

Tom – And where were these eruptions from?

Gill – In this case it looks as if we have potentially unnoticed, unrecorded eruptions happening. The sources seem to be California, British Columbia and Alaska. The chemistry most closely matches volcanic systems in these areas. The idea is perhaps that these were relatively small eruptions that haven’t been noticed on the ground, but yet their combined effects were enough to cause a large acid spike and potentially climatic change.

Tom – How did you know then that these eruptions occurred at this time?

Gill – We can date the ice very accurately because snow is accumulating all the time in the polar areas. So within the ice there are seasonal changes in the chemistry, and by analysing these changes you can actually pick out changes from year to year.

Tom – I’ve also heard of things such as tree rings being used as a record for climate?

Gill – Yes, tree rings are an extremely good way of looking at past climate change. First of all, the trees grow on an annual basis so most trees would put on one growth ring per year. So, we can date the tree rings precisely to the year and also the trees respond to the climate conditions that they’re growing under. If the climate is favourable for the trees, the trees are going to grow well and if the climate is not favourable for the trees you’ll get less growth.

Tom – And so you were using a combination of the tree rings and the ice cores and this is what allowed you to get such precise dating?

Gill – Before it was recognised that the trees had these periods of unusual growth downturns suggesting that there was a severe climate deterioration. But they couldn’t link them up to the ice core records, because the dating didn’t seem to be the same. Now with the improved methods of dating we were able to show that the extreme events in the trees corresponded with the volcanic events in the ice cores.

Tom – So going back to the eruption in 536 with these three different eruptions happening, what were the actual effects that this caused?

Gill – We can surmise that the summer cooling could have been detrimental for crops growing and certainly in the historic records we start to see that there are issues happening. We start to see food shortages, famines, and from the 540’s we get the outbreak and spread of the Justinian plague. We have a series of volcanic events happening in close succession and this is likely to have put strain on crops, harvests and crop failure would have weakened populations potentially. That could have made a population more vulnerable to the spread of disease.

You can listen to the full interview with the Naked Scientists here.

BBC Cambridgeshire Interview

Starting from my love of multiplication questions at primary school, I talk about my new role as a maths tutor at the University of Oxford, what a typical day looks like for the Naked Mathematician and give a sneak preview of my upcoming talk at New Scientist Live later this year… Live interview with BBC Radio Cambridgeshire.

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