A tale of chemistry, biochemistry, physics and astronomy – and shiny, silver balls

A new school term has started here, and for me this year that’s meant more chemistry experiments – hurrah!

Okay, actually round-bottomed flasks

The other day it was time for the famous Tollens’ reaction. For those that don’t know, this involves a mixture of silver nitrate, sodium hydroxide and ammonia (which has to be freshly made every time as it doesn’t keep). Combine this concoction with an aldehyde in a glass container and warm it up a bit and it forms a beautiful silver layer on the glass. Check out my lovely silver balls!

This reaction is handy for chemists because the silver mirror only appears with aldehydes and not with other, similar molecules (such as ketones). It works because aldehydes are readily oxidised or, looking at it the other way round, the silver ions (Ag+) are readily reduced by the aldehyde to form silver metal (Ag) – check out this Compound Interest graphic for a bit more detail.

But this is not just the story of an interesting little experiment for chemists. No, this is a story of chemistry, biochemistry, physics, astronomy, and artisan glass bauble producers. Ready? Let’s get started!

Bernhard Tollens (click for link to image source)

The reaction is named after Bernhard Tollens, a German chemist who was born in the mid-19th century. It’s one of those odd situations where everyone – well, everyone who’s studied A level Chemistry anyway – knows the name, but hardly anyone seems to have any idea who the person was.

Tollens went to school in Hamburg, Germany, and his science teacher was Karl Möbius. No, not the Möbius strip inventor (that was August Möbius): Karl Möbius was a zoologist and a pioneer in the field of ecology. He must have inspired the young Tollens to pursue a scientific career, because after he graduated Tollens first completed an apprenticeship at a pharmacy before going on to study chemistry at Friedrich Wöhler’s laboratory in Göttingen. If Wöhler’s name seems familiar it’s because he was the co-discoverer of  beryllium and silicon – without which the electronics I’m using to write this article probably wouldn’t exist.

After he obtained his PhD Tollens worked at a bronze factory, but it wasn’t long before he left to begin working with none other than Emil Erlenmeyer – yes, he of the Erlenmeyer flask, otherwise known as… the conical flask. (I’ve finally managed to get around to mentioning the piece of glassware from which this blog takes its name!)

It seems though that Tollens had itchy feet, as he didn’t stay with Erlenmeyer for long, either. He worked in Paris and Portugal before eventually returning to Göttingen in 1872 to work on carbohydrates, going on to discover the structures of several sugars.

Table sugar is sucrose, which doesn’t produce a silver mirror with Tollens’ reagent

As readers of this blog will know, the term “sugar” often gets horribly misused by, well, almost everyone. It’s a broad term which very generally refers to carbon-based molecules containing groups of O-H and C=O atoms. Most significant to this story are the sugars called monosaccharides and disaccharides. The two most famous monosaccharides are fructose, or “fruit sugar”, and glucose. On the other hand sucrose, or “table sugar”, is a disaccharide.

All of the monosaccharides will produce a positive result with Tollens’ reagent (even when their structures don’t appear to contain an aldehyde group – this gets a bit complicated but check out this link if you’re interested). However, sucrose does not. Which means that Tollens’ reagent is quick and easy test that can be used to distinguish between glucose and sucrose.

Laboratory Dewar flask with silver mirror surface

And it’s not just useful for identifying sugars. Tollens’ reagent, or a variant of it, can also be used to create a high-quality mirror surface. Until the 1900s, if you wanted to make a mirror you had to apply a thin foil of an alloy – called “tain” – to the back of a piece of glass. It’s difficult to get a really good finish with this method, especially if you’re trying to create a mirror on anything other than a perfectly flat surface. If you wanted a mirrored flask, say to reduce heat radiation, this was tricky. Plus it required quite a lot of silver, which was expensive and made the finished item quite heavy.

Which was why the German chemist Justus von Liebig (yep, the one behind the Liebig condenser) developed a process for depositing a thin layer of pure silver on glass in 1835. After some tweaking and refining this was perfected into a method which bears a lot of resemblance to the Tollens’ reaction: a diamminesilver(I) solution is mixed with glucose and sprayed onto the surface of the glass, where the silver ions are reduced to elemental silver. This process ticked a lot of boxes: not only did it produce a high-quality finish, but it also used such a tiny quantity of silver that it was really cheap.

And it turned out to be useful for more than just laboratory glassware. The German astronomer Carl August von Steinheil and French doctor Leon Foucault soon began to use it to make telescope mirrors: for the first time astronomers had cheap, lightweight mirrors that reflected far more light than their old mirrors had ever done.

People also noticed how pretty the effect was: German artisans began to make Christmas tree decorations by pouring silver nitrate into glass spheres, followed by ammonia and finally a glucose solution – producing beautiful silver baubles which were exported all over the world, including to Britain.

These days, silvering is done by vacuum deposition, which produces an even more perfect surface, but you just can’t beat the magic of watching the inside of a test tube or a flask turning into a beautiful, shiny mirror.

Speaking of which, according to @MaChemGuy on Twitter, this is the perfect, foolproof, silver mirror method:
° Place 5 cm³ 0.1 mol dm⁻³ AgNO₃(aq) in a test tube.
° Add concentrated NH₃ dropwise untill the precipitate dissolves. (About 3 drops.)
° Add a spatula of glucose and dissolve.
° Plunge test-tube into freshly boiled water.

Silver nitrate stains the skin – wear gloves!

One word of warning: be careful with the silver nitrate and wear gloves. Else, like me, you might end up with brown stains on your hands that are still there three days later…


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Spectacular Strawberry Science!

Garden strawberries

Yay! It’s June! Do you know what that means, Chronicle Flask readers? Football? What do you mean, football? Who cares about that? (I jest – check out this excellent post from Compound Interest).

No, I mean it’s strawberry season in the U.K.! That means there will be much strawberry eating, because the supermarkets are full of very reasonably-priced punnets. There will also be strawberry picking, as we tramp along rows selecting the very juiciest fruits (and eating… well, just a few – it’s part of the fun, right?).

Is there any nicer fruit than these little bundles of red deliciousness? Surely not. (Although I do also appreciate a ripe blackberry.)

And as if their lovely taste weren’t enough, there’s loads of brilliant strawberry science, too!

This is mainly (well, sort of, mostly, some of the time) a chemistry blog, but the botany and history aspects of strawberries are really interesting too. The woodland strawberry (Fragaria vesca) was the first to be cultivated in the early 17th century, although strawberries have of course been around a lot longer than that. The word strawberry is thought to come from ‘streabariye’ – a term used by the Benedictine monk Aelfric in CE 995.

Woodland strawberries

Woodland strawberries, though, are small and round: very different from the large, tapering, fruits we tend to see in shops today (their botanical name is Fragaria × ananassa – the ‘ananassa’ bit meaning pineapple, referring to their sweet scent and flavour.

The strawberries we’re most familiar with were actually bred from two other varieties. That means that modern strawberries are, technically, a genetically modified organism. But no need to worry: practically every plant we eat today is.

Of course, almost everyone’s heard that strawberries are not, strictly, a berry. It’s true; technically strawberries are what’s known as an “aggregate accessory” fruit, which means that they’re formed from the receptacle (the thick bit of the stem where flowers emerge) that holds the ovaries, rather than from the ovaries themselves. But it gets weirder. Those things on the outside that look like seeds? Not seeds. No, each one is actually an ovary, with a seed inside it. Basically strawberries are plant genitalia. There’s something to share with Grandma over a nice cup of tea and a scone.

Anyway, that’s enough botany. Bring on the chemistry! Let’s start with the bright red colour. As with most fruits, that colour comes from anthocyanins – water-soluble molecules which are odourless, moderately astringent, and brightly-coloured. They’re formed from the reaction of, similar-sounding, molecules called anthocyanidins with sugars. The main anthocyanin in strawberries is callistephin, otherwise known as pelargonidin-3-O-glucoside. It’s also found in the skin of certain grapes.

Anthocyanins are fun for chemists because they change colour with pH. It’s these molecules which are behind the famous red-cabbage indicator. Which means, yes, you can make strawberry indicator! I had a go myself, the results are below…

Strawberry juice acts as an indicator: pinky-purplish in an alkaline solution, bright orange in an acid.

As you can see, the strawberry juice is pinky-purplish in the alkaline solution (sodium hydrogen carbonate, aka baking soda, about pH 9), and bright orange in the acid (vinegar, aka acetic acid, about pH 3). Next time you find a couple of mushy strawberries that don’t look so tasty, don’t throw them away – try some kitchen chemistry instead!

Peonidin-3-O-glucoside is the anthocyanin which gives strawberries their red colour. This is the form found at acidic pHs

The reason we see this colour-changing behaviour is that the anthocyanin pigment gains an -OH group at alkaline pHs, and loses it at acidic pHs (as in the diagram here).

This small change is enough to alter the wavelengths of light absorbed by the compound, so we see different colours. The more green light that’s absorbed, the more pink/purple the solution appears. The more blue light that’s absorbed, the more orange/yellow we see.

Interestingly, anthocyanins behave slightly differently to most other pH indicators, which usually acquire a proton (H+) at low pH, and lose one at high pH.

Moving on from colour, what about the famous strawberry smell and flavour? That comes from furaneol, which is sometimes called strawberry furanone or, less romantically, DMHF. It’s the same compound which gives pineapples their scent (hence that whole Latin ananassa thing I mentioned earlier). The concentration of furaneol increases as the strawberry ripens, which is why they smell stronger.

Along with menthol and vanillin, furaneol is one of the most widely-used compounds in the flavour industry. Pure furaneol is added to strawberry-scented beauty products to give them their scent, but only in small amounts – at high concentrations it has a strong caramel-like odour which, I’m told, can actually smell quite unpleasant.

As strawberries ripen their sugar content increases, they get redder, and they produce more scent

As strawberries ripen their sugar content (a mixture of fructose, glucose and sucrose) also changes, increasing from about 5% to 9% by weight. This change is driven by auxin hormones such as indole-3-acetic acid. At the same time, acidity – largely from citric acid – decreases.

Those who’ve been paying attention might be putting a few things together at this point: as the strawberry ripens, it becomes less acidic, which helps to shift its colour from more green-yellow-orange towards those delicious-looking purpleish-reds. It’s also producing more furaneol, making it smell yummy, and its sugar content is increasing, making it lovely and sweet. Why is all this happening? Because the strawberry wants (as much as a plant can want) to be eaten, but only once it’s ripe – because that’s how its seeds get dispersed. Ripening is all about making the fruit more appealing – redder, sweeter, and nicer-smelling – to things that will eat it. Nature’s clever, eh?

There we have it: some spectacular strawberry science! As a final note, as soon as I started writing this I (naturally) found lots of other blogs about strawberries and summer berries in general. They’re all fascinating. If you want to read more, check out…


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Is acrylamide in your toast really going to give you cancer?

Acrylamide has been in the news today, and this might be the understatement of the year. Front page newspaper headlines have been yelling everything from “Brits officially warned off chips” to “Over-cooked potatoes and burnt toast could cause cancer” to the marginally more restrained “What is the real cancer risk from eating roast potatoes or toast?” All this has been accompanied by radio interviews with everyone from actual scientists to professional chefs to people keen to share their roast potato recipes. I expect there have been television interviews too – I haven’t had a chance to watch.

Hey, what could be more traditional, or more fun, than a food-health scare in January?

Acrylamide

Acrylamide

Never fear, the Chronicle Flask is here to sort out the science. Let’s get to the facts: what is acrylamide?

It’s actually a rather small molecule, and it falls into a group of substances which chemists call amides. Other well-known amides include paracetamol and penicillin, and nylon is a polyamide – that is, lots of amide molecules joined together. Amide linkages (the CO-NH bit) are a key feature of proteins, which means they appear in all kinds of naturally-occurring substances.

And this is where the food-acrylamide link comes in. Because acrylamide, or prop-2-enamide to give it its official name (the one only ever used by A-level chemistry students), forms when certain foods are cooked.

Acrylamide occurs naturally in fried, baked, and roasted starchy foods.

Acrylamide occurs naturally in fried, baked, and roasted starchy foods.

It begins with an amino acid called asparagine. If you’re wondering whether, with that name, it has anything to do with asparagus, you’d be on the right track. It was first isolated in the early 1800s from asparagus juice. It turns out to be very common: it’s found in dairy, meat, fish and shellfish, as well as potatoes, nuts, seeds and grains, amongst other things.

This is where the trouble begins. When asparagine is combined with sugars, particularly glucose, and heated, acrylamide is produced. The longer the food is heated for, the more acrylamide forms. This is a particular issue with anything wheat or potato-based thanks to the naturally-occurring sugars those foods also contain – hence all the histrionics over chips, roast potatoes and toast.

How dangerous is acrylamide? The International Agency for Research on Cancer have classified it as a Group 2A carcinogen, or a “probable” carcinogen. This means there’s “limited evidence” of carcinogenicity in humans, but “sufficient evidence” of carcinogenicity in experimental animals. In other words (usually) scientists know the thing in question causes cancer in rats – who’ve generally been fed huge amounts under strictly controlled conditions – but there isn’t any clear evidence that the same link exists in humans. It’s generally considered unethical to lock humans in cages and force feed them acrylamide by the kilo, so it’s tricky to prove.

screen-shot-2017-01-23-at-22-10-46At this point I will point out that alcoholic beverages are classified as Group 1 carcinogens, which means there is “sufficient evidence” of carcinogenicity in humans. Alcohol definitely causes cancer. If you’re genuinely concerned about your cancer risk, worry less about the roast potatoes in your Sunday roast and more about the glass of wine you’re drinking with them.

But back to acrylamide. In animals, it has been shown to cause tumours. It’s one of those substances which can be absorbed through the skin, and after exposure it spreads around the body, turning up in the blood, unexposed skin, the kidneys, the liver and so on. It’s also been shown to have neurotoxic effects in humans. BUT, the evidence that it causes cancer in humans under normal conditions isn’t conclusive. A meta-analysis published in 2014 concluded that “dietary acrylamide is not related to the risk of most common cancers. A modest association for kidney cancer, and for endometrial and ovarian cancers in never smokers only, cannot be excluded.” 

The dose makes the poison is an important principle in toxicology (image credit: Lindsay Labahn)

The dose makes the poison (image credit: Lindsay Labahn)

As I so often find myself saying in pieces like this: the dose makes the poison. The people who have suffered neurotoxic effects from acrylamide have been factory workers. In one case in the 1960s a patient was handling 10% solutions of the stuff, and “acknowledged that the acrylamide solution frequently had splashed on his unprotected hands, forearms and face.” The earliest symptom was contact dermatitis, followed by fatigue, weight loss and nerve damage.

Because of these very real risks, the Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health have set occupational exposure limits at 0.03 mg/m3 over an eight-hour workday, or 0.00003 g/m3.

Let’s contrast that to the amount of acrylamide found in cooked food. The reason all this fuss erupted today is that the Food Standards Agency (FSA) published some work which estimated the amounts of acrylamide people are likely to be exposed to in their everyday diet.

The highest concentrations of acrylamide were found in snacks (potato crisps etc), and they were 360 μg/kg, or 0.00036 g/kg or, since even the most ardent crisp addict doesn’t usually consume their favoured snacks by the kilo, 0.000036 g/100g. (Remember that those occupational limits are based on continuous exposure over an eight-hour period.)

In other words, the amounts in even the most acrylamide-y of foodstuffs are really quite tiny, and the evidence that acrylamide causes cancer in humans is very limited anyway. There is some evidence that acrylamide accumulates in the body, though, so consuming these sorts of foods day in and day out over a lifetime could be a concern. It might be wise to think twice about eating burnt toast every day for breakfast.

Oh yes, and there’s quite a lot of acrylamide in cigarette smoke. But somehow I doubt that if you’re a dedicated smoker this particular piece of information is going to make much difference.

As the FSA say at the end of their report:

Your toast almost certainly isn't going to kill you.

Your toast almost certainly isn’t going to kill you.

“The dietary acrylamide exposure levels for all age classes are of possible concern for an increased lifetime risk of cancer. The results of the survey do not increase concern with respect to acrylamide in the UK diet but do reinforce FSA advice to consumers and our efforts to support the food industry in reducing acrylamide levels.”

This is not, I would suggest, QUITE the same as “Crunchy toast could give you cancer, FSA warns” but, I suppose, “FSA says risk hasn’t really changed” wouldn’t sell as many newspapers.

One last thing, there’s acrylamide in coffee – it forms when the beans are roasted. There’s more in instant coffee and, perhaps counterintuitively, in lighter-roasted beans. No one seems to have mentioned that today, possibly because having your coffee taken away in January is just too terrifying a prospect to even contemplate. And also perhaps because coffee seems to be associated with more health benefits than negatives. Coffee drinkers are less likely to develop type 2 diabetes, Parkinson’s disease, dementia, suffer fewer cases of some cancers and fewer incidences of stroke. Whether the link is causal or not isn’t clear, but coffee drinking certainly doesn’t seem to be a particularly bad thing, which just goes to show that when it comes to diet, things are rarely clearcut.

Pass the crisps, someone.


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Is it possible to give up sugar completely?

It’s January, a month that’s traditionally marked by cold weather, large credit-card bills and, of course, an awful lot of highly questionable health stuff. Juicing, detox, supplements… it’s all good fun. Until someone gets hurt.

"Refined" sugar is almost entirely made up of a molecule called sucrose.

“Refined” sugar is almost entirely made up of a molecule called sucrose.

One substance that regularly gets a bashing is sugar, particularly so-called “refined” sugar. We’re told it’s toxic (it’s not), it’s more addictive than cocaine (it isn’t) and we should definitely all be trying to give it up.

Now, before I go any further with this, a word about healthy eating. I’m not a dietician. I don’t even claim to be a nutritionist (although I could, if I wanted). However, I think I’m on fairly safe ground if I say that we should all be striving for a healthy, balanced diet. That is, a diet containing a broad range of foods, plenty of fruits and vegetables, healthy amounts of protein and some good fats.

A lot of people have diets that fall short of this ideal. Cutting back on foods which contain a lot of added sugar (cakes, chocolate, fizzy drinks, etc) and eating more vegetables and fruits is a good, and sensible, course of action.

The problem is that bit of common-sense advice doesn’t sell books or make an interesting TV show. It’s all a bit boring and, worse, it’s freely available. Compelling entertainment needs to be more exciting, more dramatic, more… extreme.

Which brings us to ITV’s Sugar Free Farm.

Page 81 of the current issue of Radio Times tells us that the celebrities face a "completely sugar-free regime".

Page 81 of the current issue of Radio Times tells us that the celebrities face a “completely sugar-free regime”.

This is actually the second series of this show, which first aired last year. According to the 7-13th January 2017 issue of the Radio Times:

“Seven celebrities who admit to terrible diets succumb to a few weeks of hard farm labour and a completely sugar-free regime (so no white carbs or fruit, let alone chocolate).”

Hm. Now, I’ve written about sugar more than once before, but to save clicking back and forth, here’s another quick summary:

Sugar is not one thing. The chemistry of sugars is quite complicated, but a human being trying to understand the food they eat probably needs to be aware of three main types, namely: glucose, fructose and sucrose.

180px-Glucose_chain_structure

glucose

Glucose is the sugar that all your cells need. Not having enough glucose in your bloodstream is called hypoglycaemia, and the result is seizure, coma and ultimately death. This isn’t a risk for healthy people without pre-existing conditions (like diabetes, for example) because evolution has put some clever safety-nets in place. First, our bodies are extremely efficient at carrying out the necessary chemistry to turn the molecules we eat into the molecules we need. Should that fail, our bodies are very good at storing nutrients to use in times when our diet doesn’t supply them. If you don’t eat glucose, your body will break down other foods to produce it, then it’ll start on your glycogen stores, move on to fat stores, and eventually start breaking down protein (i.e. the stuff in your muscles). This means that unless you stop eating completely for a fairly long period of time, you’ll survive.

Still, I think it’s important to emphasise the point: glucose is essential for life. The suggestion that this substance is “toxic” and thus should be completely eliminated from our diets is really, when you think about it, a bit odd.

Sucrose ("refined sugar") is a unit of glucose joined to a unit of fructose

Sucrose (“refined sugar”) is a unit of glucose joined to a unit of fructose

Ah but, I hear some people saying, no one is saying that glucose is toxic! They’re talking about refined sugar!

Fine. So what’s “refined” sugar? In simple terms, it’s pure sucrose. And sucrose is just a molecule made from a unit of glucose stuck to a unit of fructose. As I said, our bodies are really good at breaking up the molecules we eat into the molecules we need: our cells can’t use sucrose for energy, so all that happens is that it more or less instantly gets broken up into glucose and fructose.

Refined sugar is, basically, half glucose and half fructose, and it’s no more dangerous or “toxic” than either of those substances. And while I’m here, “natural” sugar options are little different: honey, for example, contains similar ratios of fructose and glucose.

200px-Skeletal_Structure_of_D-Fructose

Fructose

Allrighty then, what’s fructose? Fructose is another simple sugar, and it’s the one that plants produce. For that reason it’s sometimes called “fruit sugar”.

Our cells can’t use fructose for energy, either. But, same thing again: if you eat it your body will still use it. In this case, your liver does the heavy lifting; changing fructose into glucose and other substances, some of which are fats. On the one hand, this is a slower process so you don’t get the blood sugar spike with fructose that you get with glucose. On the other, some of the fructose you eat inevitably ends up being converted into fat.

As I mentioned, fructose is the sugar in plants. It’s found in almost all plant-based foods. For example, the USDA food composition database tells us that 100 g of carrots contains about 0.6 g of fructose. Perhaps surprisingly, broccoli contains slightly more: about 0.7 g per 100 g. Iceberg lettuce contains even more, at 1 g per 100 g, whereas green peas contain a mere 0.4 g.

Even a really small glass of fruit juice contains about 150 g.

Even a small serving of fruit juice usually contains at least 150 g.

None of this comes close to fruit. Apples contain about 6 g of fructose per 100 g, grapes 4 g and bananas 5 g. Dried fruit, as you’d expect, has considerably higher amounts by weight – because the water’s gone. Juices have similar amounts of fructose per unit of weight but, of course, you tend to drink a lot more than 100 g of juice at a time.

Now we understand why “Sugar Free Farm” has banned fruit. But this is why I have a problem with the title: you CAN’T eat an entirely “sugar-free” diet, unless all you eat is meat, fish, eggs and dairy products like cream and butter (but not milk, which contains lots of another sugar: lactose). This would be a far from healthy diet, seriously lacking in fibre as well as a host of vitamins and minerals (even “phase 1” or the “induction” period of the controversial Atkins diet isn’t quite this extreme).

The show hasn’t aired yet, and I admit I didn’t watch it last year, so I don’t know if that’s what they’re doing. But I seriously doubt it – it would be unethical and irresponsible. Plus, the words “white carbs” in the listings blurb make me suspicious. Why specify “white”? Are whole grains included? And what about pulses? Whole grain foods might be relatively low in fructose and glucose before you put them in your mouth, but as soon as saliva hits them the starch they contain is broken down into…. glucose. By the time you swallow that chewed-up food, it contains sugar.

In summary, Sugar Free Farm is almost certainly not sugar free. What they appear to have set up is a place where sugars are restricted and foods with added sugar are banned, and then mixed that with lots of outdoor activities (the celebrities are also expected to work on the farm).

Most people would lose weight following such a regime, because it’s likely that calories in are going to be lower than calories out. It’s a simple calorie deficit.

give-up-sugarWhat bothers me is that the show might go on to conclude that we should all “give up” sugar to lose weight – and some people might misinterpret that and end up embarking on an unbalanced, unhealthy and ultimately unsustainable diet – when in fact the results are simply due to calorie deficit.

There’s no need to try to give up sugar. Cut down, yes, but you can eat some sweet foods and still manage a calorie deficit. In fact you probably should: fruit in particular has lots of nutrients, including fibre. Besides, such a diet will probably be a lot more sustainable in the long term.

Unfortunately, “Eat Fewer Calories And Do Some Exercise Farm” doesn’t have quite the same ring, does it?


EDIT, 11th Jan 2017

Well, the first episode aired last night. No, the diet is not “zero sugar”. It’s very low in sugar, yes, but there are sugars. They used milk (contains lactose), ate wholemeal bread, brown rice and oats (all of which are broken down into glucose) and ate a variety of vegetables which, as I mentioned above, all contain small amounts of sugar. In fact, on their very first morning they eat a strange granola mixture made with sweet potato. The USDA food database tells me that sweet potato contains about 0.4 g of fructose, 0.5 g of glucose, 3.3 g of maltose AND 1.4 g of sucrose per 100 g. Yep. Sucrose. The stuff in “refined” sugar.

There was much talk of “detox” and “detoxing” from sugar. Sigh. That’s not a thing. Most worryingly of all, poor Peter Davison (he was “my” Doctor, you know) was carted off in an ambulance on the second day, suffering with dizzy spells. Everyone immediately started talking about how dreadful it was that “sugar” had caused this. There was only one, in passing, comment shown suggesting that perhaps the 65-year-old might have something else wrong with him. In fact, it turned out that he had labyrinthitis, an inner-ear condition. It’s usually viral. It’s not caused by “sugar withdrawal”. I’m sure they’ll make that clear in the next episode, right?

Speaking of which, the celebrities are on Sugar Free Farm for 15 days. A safe rate of weight loss is generally considered to be 0.5-1 kg (or 1-2 lb) a week. So they should lose about 2 kg, or 4 lb, on the outside. A snippet was shown at the end of the program in which Alison Hammond said she was “pleased” she’d lost 8 lbs. Whether that was after two weeks or a shorter period of time wasn’t clear, but either way, it’s a lot. It suggests that her diet is/was too low in calories, particularly considering all the extra physical activity.  Perhaps some of her so-called “sugar withdrawal” symptoms were actually simply due to the fact that she wasn’t consuming enough to keep up with her energy needs?

That aside, the diet they followed did seem to be fairly balanced, with plenty of vegetables and adequate healthy fats and protein. They had all been eating huge quantities of sugary foods beforehand, and cutting down is no bad thing. I’m just skeptical about exactly how much of the bad, and indeed the good, can be pinned on sugar.

Still, it made good telly I suppose.


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The Chronicles of the Chronicle Flask: 2016

2016 is limping to its painful conclusion, still tossing out last-minute nasty surprises like upturned thumb tacks in the last few metres of a marathon. But the year hasn’t been ALL bad. Some fun, and certainly interesting, things happened too. No, really, they did, honestly.

So with that in mind, let’s have a look back at 2016 for the Chronicle Flask….

January kicked off with a particularly egregious news headline in a well-known broadsheet newspaper: Sugar found in ketchup and Coke linked to breast cancer. Turns out that the sugar in question was fructose. Yes, the sugar that’s in practically everything, and certainly everything that’s come from a plant. So why did the newspaper in question choose ketchup and Coke for their headline instead of, oh, say, fruit juice or honey? Surely not just in an effort to sell a few more newspapers after the overindulgent New Year celebrations. Surely.

octarineThere was something more lighthearted to follow when IUPAC  verified the discoveries of elements 113, 115, 117 and 118. This kicked off lots of speculation about the elements’ eventual names, and the Chronicle Flask suggested that one of them should be named Octarine in honour of the late Sir Terry Pratchett. Amazingly, this suggestion really caught everyone’s imagination. It was picked up in the national press, and the associated petition got over 51 thousand signatures!

In February I wrote a post about the science of statues, following the news that a statue to commemorate Sir Terry Pratchett and his work had been approved by Salisbury City Council. Did you know that there was science in statues? Well there is, lots. Fun fact: the God of metalworking was called Hephaestus, and the Greeks placed dwarf-like statues of him near their Hearths – could this be where the fantasy trope of dwarves as blacksmiths originates?

MCl and MI are common preservatives in cosmetic products

MCl and MI are common preservatives in cosmetic products

My skeptical side returned with a vengeance in March after I read some online reviews criticising a particular shampoo for containing a substance known as methylchloroisothiazolinone. So should you be scared of your shampoo? In short, no. Not unless you have a known allergy or particularly sensitive skin. Otherwise, feel free to the pick your shampoo based on the nicest bottle, the best smell, or the forlorn hope that it will actually thicken/straighten/brighten your hair as promised, even though they never, ever, ever do.

Nature Chemistry published Another Four Bricks in the Wall in April – a piece all about the potential names of new elements, partly written by yours truly. The month also brought a sinus infection. I made the most of this opportunity by writing about the cold cure that’s 5000 years old. See how I suffer for my lovely readers? You’re welcome.

In May I weighed in on all the nonsense out there about glyphosate (and, consequently, learned how to spell and pronounce glyphosate – turns out I’d been getting it wrong for ages). Is it dangerous? Nope, not really. The evidence suggests it’s pretty harmless and certainly a lot safer than most of its alternatives.

may-facebook-postSomething else happened in May: the Chronicle Flask’s Facebook page received this message in which one of my followers told me that my post on apricot kernels had deterred his mother from consuming them. This sort of thing makes it all worthwhile.

In June the names of the new elements were announced. Sadly, but not really very surprisingly, octarine was not among them. But element 118 was named oganesson and given the symbol Og. Now, officially, this was in recognition of the work of Professor Yuri Oganessian, but I for one couldn’t help but see a different reference. Mere coincidence? Surely not.

July brought another return to skepticism. This time, baby wipes, and in particular a brand that promise to be “chemical-free”. They’re not chemical-free. Nothing is chemical-free. This is a ridiculous label which shouldn’t be allowed (and yet, inexplicably, is still in use). It’s all made worse by the fact that Water Wipes contain a ‘natural preservative’ called grapefruit seed extract which, experiments have shown, only actually acts as a preservative when it’s contaminated with synthetic substances. Yep. Turns out some of Water Wipes claims are as stinky as the stuff they’re designed to clean up.

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

August brought the Olympics, and speculation was rife about what, exactly, was causing the swimming pools to turn such strange shades of green. Of course, the Chronicle Flask knew the correct solution…

August also saw MMS and CD reared their ugly heads on social media again. CD (chlorine dioxide) is, lest we forget, a type of bleach solution which certain individuals believe autistic children should be made to drink to ‘cure’ them. Worse, they believe such children should be forced to undergo daily enemas using CD solutions. I wrote a summary page on MMS (master mineral solution) and CD, as straight-up science companion to the commentary piece I wrote in 2015.

mugsSeptember took us back to pesticides, but this time with a more lighthearted feel. Did you know that 99.99% of all the pesticides you consume are naturally-occurring? Well, you do if you regularly read this blog. The Chronicle Flask, along with MugWow, also produced a lovely mug. It’s still for sale here, if you need a late Christmas present… (and if you use the code flask15 you’ll even get a discount!)

In October, fed up with endless arguments about the definition of the word ‘chemical’ I decided to settle the matter once and for all. Kind of. And following that theme I also wrote 8 Things Everyone Gets Wong About ‘Scary’ Chemicals for WhatCulture Science.

Just in case that wasn’t enough, I also wrote a chapter of a book on the missing science of superheroes in October. Hopefully we should see it in print in 2017.

Sparklers are most dangerous once they've gone out.

Sparklers are most dangerous once they’ve gone out.

I decided to mark Fireworks Night in November by writing about glow sticks and sparklers. Which is riskier? The question may not be as straightforward as you’d imagine. This was followed by another WhatCulture Science piece, featuring some genuinely frightening substances: 10 Chemicals You Really Should Be Scared Of.

And that brings us to December, and this little summary. I hope you’ve enjoyed the blog this year – do tell your friends about it! Remember to follow @ChronicleFlask on Twitter and like fb.com/chronicleflask on Facebook – both get updated more or less daily.

Here’s wishing all my lovely readers a very Happy New Year – enjoy a drop of bubbly ethanol solution and be careful with the Armstrong’s mixture…. 

See you on the other side!

new-year-1898553_960_720

No, ketchup does not cause cancer

ketchup and coke

Do these things really cause breast cancer? (Spoiler: no)

Less than two days into the new year, and I’d already found what might well be one of the silliest health headlines of the year. What is it I hear you ask? Well, it was in a national newspaper on New Years Day, and it was this:

Sugar found in ketchup and Coke linked to breast cancer

This, to borrow a favourite line from an online greetings card company, had me rolling my eyes so hard I could practically see my brain. Why? Because even without reading any further, I knew immediately that it was the equivalent of saying, “too much of thing found in most stuff might cause cancer!”

But let’s not be one of the 70% of users that only read the headline, let’s dig a little further. The newspaper article, which in fairness isn’t too bad – it’s just a bit of a silly headline, alludes to work carried out the University of Texas’ MD Anderson Cancer Centre. If you click on the link I’ve added back there, you’ll see that MD Anderson’s headline was:

“Sugar in Western diets increases risk for breast cancer tumors and metastasis”

Note, they just say ‘sugar’, not sugar in two apparently randomly-selected foodstuffs. The researchers divided mice into four groups, fed some a diet high in sucrose (more commonly called table sugar – in other words, the stuff in the sugar bowl) and compared them to others fed a low-sugar, ‘starch-controlled’ diet. They found that the high-sugar diet lead to increased tumour growth, particularly in mammary glands.

I’ve covered forms of sugar before but still, here’s a quick reminder before we go any further: this is a molecule of sucrose:

Saccharose2

Sucrose

Sucrose is made of two ‘bits’ joined together: one unit of fructose and one unit of glucose.

157px-Alpha-D-Glucopyranose

Glucose

These two molecules are what chemists call isomers. They contain the same number and type of atoms, just joined up differently. They’re both sugars in and of themselves. Glucose is used directly by cells in your body for energy. Fructose, on the other hand, is trickier. It has a lower glycemic index than glucose, in other words, it doesn’t raise your blood sugar as rapidly as glucose, but this doesn’t mean it’s healthier. It’s metabolised almost exclusively in the liver and, long story short, invariably ends up being converted into, and stored as, fat.

179px-Beta-D-Fructofuranose

Fructose

Fruit is high in fructose, and fructose tastes very sweet to us (sweeter than either glucose or sucrose). This is nature’s way of telling us, and other animals that might eat the fruit, that it’s high in nutrients. From the plant’s point of view, it’s an incentive to eat the fruit and, ahem, spread the seeds around.

Humans have, of course messed around with this perfectly sensible survival mechanism by stuffing all kinds of easily-available and not particularly nutrient-rich foods with fructose, and herein lies the problem. Co-author of the paper that started all this, Lorenzo Cohen, Ph.D., professor of Palliative, Rehabilitation, and Integrative Medicine, said “we determined that it was specifically fructose, in table sugar and high-fructose corn syrup […] which was responsible for facilitating lung metastasis and 12-HETE production in breast tumors.” Notice that he mentions fructose in table sugar; this is because, once you eat sucrose, it breaks down into units of glucose and fructose.

The article goes on to suggest that sugar-sweetened beverages are a significant problem, so was the newspaper wrong to pick on Coke? It’s a popular drink after all, and a standard can of Coca-Cola contains approximately 35 grams of sugar (which might come from either sucrose or high fructose corn syrup mainly depending on where you buy it). The guidance for adults is no more than 30 grams of sugar per day, so a single can of regular Coca-Cola would take you over that limit, and it’s very easy to drink two or even three cans without giving it a second thought.

sugar

Soft drinks and fruit juice both contain a lot of sugar

However, the same goes for pretty much any non-diet soft drink.  Pepsi, for example, has a similar amount. Lemonade can be even more sugary, with some drinks hitting 40 grams per 330 ml can. Ginger beer might well be the worst; there are 53 grams per 330 ml in Old Jamaica Ginger beer for example. Fruit juice is no better, with many juices containing 35 g of sugar per 330 ml, although at least fruit juice might contain some other nutrients such as vitamin C.

So really, I’d say it’s a bit unfair to single out Coke in a headline like this.

What about the ketchup (note they didn’t pick a specific brand here, just generic ‘ketchup’)?

Well, ketchup IS high in sugar. It contains about 24 grams of sugar per 100 grams. But hang on, 100 grams of ketchup is quite a lot. A more realistic serving size of a tablespoon is only about 15 grams, which works out at about 3.5 grams of sugar. Still quite a lot, but probably a drop in the ocean compared to all the sugar in cake, bread, drinks, fruit juice, breakfast cereals and the tubs of Roses and Quality Street you scoffed over Christmas. Unless you make a habit of drinking ketchup by the bottle (apparently some people do) this is frankly a ridiculous foodstuff to pick on.

I imagine that someone did a quick search for ‘foods that contain fructose’ and picked Coke because, well, everyone knows that Coke’s bad, right? So that sounds credible. And ketchup because we all sort of suspect it’s probably not that healthy, but it hasn’t been the subject of a health scare recently so that makes it stand out. Great clickbait, bad science.

mouse

Mice are not people

Plus, let’s be absolutely clear, the study was in mice. Mice are not people. While a study that shows an effect in mice is an interesting start, and may well be good reason to conduct more studies, quite possibly in humans, it’s not proof that this mechanism exists in humans. Humans have, after all, evolved to eat a very different diet to mice. There might well be a link, but this doesn’t prove it, and even if a link does exist we certainly can’t say anything about the significance or size of it from this research.

I’m not a dietician, but I’m going to go out on a (fairly sturdy) limb here and say that cutting back on sugar will not do you any harm and is likely to be a jolly good thing. Let’s also be clear that sugar in fruit juice, agave, honey etc is still sugar and is no healthier than table sugar. Eating too much of the sweet stuff is almost definitely bad for your waistline and, as we all learned as children, bad for your teeth too – something which is often overlooked but really shouldn’t be, poor dental health having been linked to other serious health problems including diabetes and heart disease.

ketchup on bread

Maybe cut back on the fried ketchup sandwiches

But, and here’s my big problem with the newspaper’s headline, none of this means that Coke and ketchup directly cause breast cancer which is how, I fear, some people will interpret it. Cut out sugary fizzy drinks by all means, and perhaps ditch the ketchup sandwiches (especially fried ones), but please don’t worry that the occasional dollop of red sauce is going to kill you. I’m pretty certain it won’t.

Follow The Chronicle Flask on Facebook for regular updates.

A small edit was made on 6th January to clarify that pure fructose isn’t used as an ingredient in Coke, but rather high fructose corn syrup.

 

 

Sugar that’s not sugar?

A couple of days ago I was catching up with last Sunday’s Dragon’s Den. For the non-Brits out there, this is a show in which entrepreneurs pitch business ideas to a panel of ‘dragons’ – i.e. successful business people – to get an investment of money and, perhaps more importantly, expertise and contacts. It’s a great show that’s been running for quite a few years now and has resulted in a number of products and brands becoming household names – in the UK anyway.

LinusGorpeDragonsDen

Linus Gorpe on BBC’s Dragon’s Den

The last entrepreneur to pitch in the show was the founder of the Raw Chocolate Company, an interesting character called Linus Gorpe (quote: “I love life. Life is the dance for me. I play a lot. I play in the woods. I eat a lot of healthy food. I love clean living. I love women, oh I love women.” Ahem).

He was promoting his ‘raw’ chocolate products. The Dragons asked what he meant by raw: he said something about heating up apples for two hours in an oven. I don’t think anyone was much the wiser. But I’m not going to pick holes in the ideas behind raw food diets (Science Based Medicine wrote a great article on that topic a little while back, I urge you to check it out).

No, I was more bothered by this little exchange:

Deborah Meaden: “So, the sugar content when comparing it to other chocolate. Same?”
Linus: “No. I use coconut palm sugar, which is um, not refined white sugar. It’s the sugar that’s been made from-”
DM (interrupting): “That’s interesting, so it’s unrefined?”
LG: “It’s unrefined. It’s boiled. So it doesn’t raise your blood sugar levels.”

Peter Jones chimed in at this point on something else entirely, leaving me shouting pointlessly at the telly. Not least because hadn’t he just said heating food was basically bad? And now he’s talking about boiling?!

Saccharose2

Sucrose

But that’s the least of my problems with this. Firstly, what is the difference between refined sugar and unrefined sugar? As the name suggests it’s really just a question of processing. Somehow the word ‘refined’ seems to have become irrevocably linked in people’s minds with ‘horribly unhealthy’ whereas ‘raw sugar’ somehow sounds much better. In reality, in the case of cane sugar (for the sake of comparing like with like), all the ‘refined’ bit means is that any non-sugar ingredients, which mainly provide flavour and colour, have been removed and the water has been rapidly evaporated from the sugar solution to produce fine, white crystals of pure sucrose.

Raw sugar, before the refining process, is still mostly sucrose. And truly raw sugar syrup, i.e. completely unprocessed, doesn’t often work very well as an ingredient. So when people talk about ‘unrefined’ sugar, what they usually mean is ‘a bit less refined’ sugar.

Ah, I hear you say, but he didn’t say cane sugar. He said coconut palm sugar. Yes, he did. So what’s that, then?

Coconut palm sugar, or just coconut sugar, is sugar produced from the sap of the cut flower buds of the coconut palm plant. It is usually less refined than cane sugar: essentially the syrup is harvested from the plant and then simply heated to remove the excess water. It’s a pretty simple process.

But does that make it any healthier? What does it actually contain?

179px-Beta-D-Fructofuranose

Fructose

157px-Alpha-D-Glucopyranose

Glucose

Well, coconut palm sugar is, guess what, about 80% sucrose. The remaining 20% is made up of a mixture of glucose and fructose. Both of which are also sugars. In fact, if you have a look at the images I’ve inserted here, they’re very similar molecules. Chemists describe them as isomers; they have the same number and types of atoms, just arranged slightly differently. If you’ve really been paying attention, you might notice that sucrose is, in fact, just a glucose molecule joined up with a fructose molecule.

When you eat sucrose, your body breaks it down into glucose and fructose. So practically, consuming any of these will have basically the same result, which is to raise your blood sugar. Pure glucose causes the biggest spike, because your body doesn’t have to do anything very much at all in the way of digestion, but just to make this absolutely clear: table sugar is not glucose. It is sucrose.

How much your blood sugar rises when you eat mostly depends on what else is in the food. A whole piece of fruit, for example, also contains a lot of fibre. That fibre slows down digestion, which means the sugar (there’s a lot of fructose in fruit) is absorbed more slowly than if you, say, swallowed a teaspoon of the same sugar on its own.

Coconut palm sugar

Coconut palm sugar

In short, refined sugar raises your blood sugar levels. But so does unrefined/raw/partially-refined/whatever-we’re-calling-it-today sugar. It was frankly flat-out incorrect of Linus to state that coconut palm sugar doesn’t raise blood sugar levels, because it does.

There is a bit of debate around how much it raises blood sugar levels. One oft-quoted study (consisting of a grand total of ten participants, and carried out by the Philippine Food and Nutrition Research Institute – incidentally the Philippines is one of the world’s largest producers of coconut palm sugar) quoted a glycemic index (GI) for coconut sugar of about 35, which would compare quite favourably with table sugar (about 58) and pure glucose (100, by definition).

On the other hand, hunt around a bit and another source pops up quoting a GI of 54 for coconut sugar. Which is… about the same as table sugar (and given the chemical make-up of coconut sugar, it’s hard to think of a good reason why they should be very different).

The truth is, there isn’t any such thing as ‘healthy’ sugar, certainly not in the way we talk about ‘healthy fats‘. If you’re going to eat products made with sugar, any sugar, you have to accept that while they may be jolly tasty (that ought to be a give-away, really) they’re treats, and should probably still be enjoyed only in moderation.

I’m sure that the Raw Chocolate Company’s products are delicious, and I’m not particularly anti-sugar. But let’s not be misleading. If someone genuinely cares, for whatever reason, about the sugar in their food, it’s important they get accurate information. Saying things like “it doesn’t raise your blood sugar” is, well, frankly a bit naughty.

The dragons know their stuff, and Deborah Meaden (who eventually invested) is a very smart lady. There’s no way she’ll allow any inaccurate, or even questionable, claims to persist in the long term, so I daresay this is the last time we’ll hear the blood sugar thing in relation to these products. But still, if he’d quoted dubious sales figures they’d have been all over it. Grrr.

About this time last year I wrote a post about a company claiming that their agave-sweetened products are ‘sugar-free’. They’re still out there. They still say their products are sugar-free (although they are making some that are sweetened with the sweetener xylitol now, which they’ve bizarrely chosen to label ‘no added sugar’). Their products still do, in fact, contain sugar. Sigh.