Chemical du jour: how bad is BPA, really?

BPA is an additive in many plastics

When I was writing my summary of 2017 I said that there would, very probably, be some sort of food health scare at the start of 2018. It’s the natural order of things: first we eat and drink the calorie requirement of a small blue whale over Christmas and New Year, and then, lo, we must be made to suffer the guilt in January. By Easter, of course, it’s all forgotten and we can cheerfully stuff ourselves with chocolate eggs.

Last year it was crispy potatoes, and the year before that it was something ridiculous about sugar in ketchup causing cancer (it’s the same sugar that’s in everything, why ketchup? Why?). This year, though, it seems that the nasty chemical of the day is not something that’s in our food so much as around it.

Because this year the villain of the piece appears to be BPA, otherwise known as Bisphenol A or, to give it its IUPAC name, 4,4′-(propane-2,2-diyl)diphenol.

BPA is an additive in plastics. At the end of last year an excellent documentary aired on the BBC called Blue Planet II, all about our planet’s oceans. It featured amazing, jaw-dropping footage of wildlife. It also featured some extremely shocking images of plastic waste, and the harm it causes.

Plastic waste is a serious problem

Plastic waste, particularly plastic waste which is improperly disposed of and consequently ends up in the wrong place, is indisputably something that needs to be addressed. But this highlighting of the plastic waste problem had an unintended consequence: where was the story going to go? Everyone is writing about how plastic is bad, went (I imagine) editorial meetings in offices around the country – find me a story showing that plastic is even WORSE than we thought!

Really, it was inevitable that a ‘not only is plastic bad for the environment, but it’s bad for you, too!’ theme was going to emerge. It started, sort of, with a headline in The Sun newspaper: “Shopping receipts could ‘increase your cancer risk’ – as 93% contain dangerous chemicals also linked to infertility. Shopping receipts are, of course, not made of plastic – but the article’s sub-heading stated that “BPA is used to make plastics”, so the implication was clear enough.

Then the rather confusing: “Plastic chemical linked to male infertility in majority of teenagers, study suggests” appeared in The Telegraph (more on this in a bit), and the whole thing exploded. Search for BPA in Google News now and there is everything from “5 Ways to Reduce Your Exposure to Toxic BPA” to “gender-bending chemicals found in plastic and linked to breast and prostate cancer are found in 86% of teenagers”.

Yikes. It’s all quite scary. It’s true that right now you can’t really avoid plastic. Look around you and it’s likely that you’ll immediately see lots of plastic objects, and that’s before you even try to consider all the everyday things which have plastic coatings that aren’t immediately obvious. If you have young children, you’re probably drowning in plastic toys, cups, plates and bottles. We’re pretty much touching plastic continually throughout our day. How concerned should we be?

As the Hitchiker’s Guide to the Galaxy says, Don’t Panic. Plastic (like planet Earth in the Guide) can probably be summed up as mostly harmless, at least from a BPA point of view if not an environmental one.

BPA is a rather pleasingly symmetrical molecule with two phenol groups. (A big model of this would make a wonderfully ironic pair of sunglasses, wouldn’t it?) It was first synthesized by the Russian chemist Alexander Dianin in the late 19th century. It’s made by reacting acetone – which is where the “A” in the name comes from – with two phenol molecules. It’s actually a very simple reaction, although the product does need to be carefully purified, since large amounts of phenol are used to ensure a good yield.

It’s been used commercially since the fifties, and millions of tonnes of BPA are now produced worldwide each year. BPA is used to make plastics which are clear and tough – two characteristics which are often valued, especially for things like waterproof coatings, bottles and food containers.

The concern is that BPA is an endocrine disruptor, meaning that it interferes with hormone systems. In particular, it’s a known xenoestrogen, in other words it mimics the female hormone estrogen. Animal studies have suggested possible links to certain cancers, infertility, neurological problems and other diseases. A lot of the work is fairly small-scale and, as I’ve mentioned, focused on animal studies (rather than looking directly at effects in humans). Where humans have been studied it’s usually been populations that are exposed to especially high BPA levels (epoxy resin painters, for example). Still, it builds up into quite a damning picture.

BPA has been banned from baby bottles in many countries, including the USA and Europe

Of course, we don’t normally eat plastic, but BPA can leach from the plastic into the food or drink that’s in the plastic, and much more so if the plastic is heated. Because of these concerns, BPA has been banned from baby bottles (which tend to be heated, both for sterilisation and to warm the milk) in several countries, including the whole of Europe, for some years now. “BPA free” labels are a fairly common sight on baby products these days. BPA might also get onto our skin from, for example, those thermal paper receipts The Sun article mentioned, and then into our mouths when we eat. Our bodies break down and excrete the chemical fairly quickly, in as little as 6 hours, but because it’s so common in our environment most of us are continually meeting new sources of it.

How much are we getting, though? This is a critical question, because as I’m forever saying, the dose makes the poison. Arsenic is a deadly poison at high levels, but most of us – were we to undergo some sort of very sensitive test – would probably find we have traces of it in our systems, because it’s a naturally-occuring mineral. It’s nothing to worry about, unless for some reason the levels become too high.

When it comes to BPA, different countries have different guidelines. The European Food Safety Authority recommended in January 2015 that the TDI (tolerable daily intake) should be reduced from 50 to 4 µg/kg body weight/day (there are plans for a new assessment in 2018, so it might change again). For a 75 kg adult, that translates to about 0.0003 g per day. A USA Federal Drug and Administration document from 2014 suggests a NOAEL (no-observed-adverse-effect-level) of 5 mg/kg bw/day, which translates to 0.375 g per day for the same 75 kg adult. NOAEL values are usually much higher than TDIs, so these two figures aren’t as incompatible as they might appear. Tolerable daily intake values tend to have a lot of additional “just in case” tossed into them – being rather more guidance than science.

The European Food Standards Authority published a detailed review of the evidence in 2015 (click for a summary)

So, how much BPA are we exposed to? I’m going to stick to Europe, because that’s where I’m based (for now…), and trying to look at all the different countries is horribly complicated. Besides, EFSA produced a really helpful executive summary of their findings in 2015, which makes it much easier to find the pertinent information.

The key points are these: most of our exposure comes from food. Infants, children and adolescents have the highest dietary exposures to BPA, probably because they eat and drink more per kilogram of body weight. The estimated average was 0.375 µg/kg bw per day.  For adult women the estimated average was 0.132 µg/kg bw per day, and for men it was 0.126 µg/kg bw per day.

When it came to thermal paper and other non-dietary exposure (mostly from dust, toys and cosmetics), the numbers were smaller, but the panel admitted there was a fair bit of uncertainty here. The total exposure from all sources was somewhere in the region of 1 µg/kg bw per day for all the age groups, with adolescents and young children edging more toward values of 1.5 µg/kg bw per day (this will be important in a minute).

Note that all of these numbers are significantly less than the, conservative, tolerable daily intake value of 4 µg/kg bw per day recommended by EFSA.

Here’s the important bit: the panel concluded that there is “no health concern for BPA at the estimated levels of exposure” as far as diet goes. They also said that this applied “to prenatally exposed children” (in other words, one less thing for pregnant women to worry about).

When it came to total exposure, i.e. diet and exposure from other sources such as thermal paper they concluded that “the health concern for BPA is low at the estimated levels of exposure”.

The factsheet that was published alongside the full document summarises the results as follows: “BPA poses no health risk to consumers because current exposure to the chemical is too low to cause harm.”

Like I said: Don’t Panic.

What about those frankly quite terrifying headlines? Well, firstly The Sun article was based on some work conducted on a grand total of 208 receipts collected in Southeast Michigan in the USA from only 39 unique business locations. That’s a pretty small sample and not, I’d suggest, perhaps terribly relevant to the readership of a British newspaper. Worse, the actual levels of BPA weren’t measured in the large majority of samples – they only tested to see if it was there, not how much was there. There was nothing conclusive at all to suggest that the levels in the receipts might be enough to “increase your cancer risk”. All in all, it was pretty meaningless. We already knew there was BPA in thermal receipt paper – no one was hiding that information (it’s literally in the second paragraph of the Wikipedia page on BPA).

The Telegraph article, and the many others it appeared to spawn, also weren’t based on especially rigorous work and, worse, totally misrepresented the findings in any case. Firstly, let’s consider that headline: “Plastic chemical linked to male infertility in majority of teenagers, study suggests”. What does that mean? Are they suggesting that teenagers are displaying infertility? No, of course not. They didn’t want to put “BPA” in the headline because that, apparently, would be too confusing for their readers. So instead they’ve replaced “BPA” with “plastic chemical linked to male infertility”, which is so much more straightforward, isn’t it?

And they don’t mean it’s linked to infertility in the majority of teenagers, they mean it’s linked to infertility and it’s in the majority of teenager’s bodies. I do appreciate that journalists rarely write headlines – this isn’t a criticism of the poor writer who turned in perfectly good copy – but that is confusing and misleading headline-writing of the highest order. Ugh.

Plus, as I commented back there, that wasn’t even the conclusion of the study, which was actually an experiment carried out by students under the supervision of a local university. The key finding was not that, horror, teenagers have BPA in their bodies. The researchers assumed that almost all of the teenagers would have BPA in their bodies – as the EFSA report showed, most people do. No, the conclusion was actually that the teenagers – 94 of them – had been unable to significantly reduce their levels of BPA by changing their diet and lifestyle. Although the paper admits the conditions weren’t well-controlled. Basically, they asked a group of 17-19 year-olds to avoid plastic, and worked on the basis that their account of doing so was accurate.

And how much did the teenagers have in their samples? The average was 1.22 ng/ml, in urine samples (ng = nanogram). Now, even if we assume that these levels apply to all human tissue (which they almost certainly don’t) and that therefore the students had roughly 1.22 ng per gram of body weight, that only translates to, very approximately, 1.22 micrograms (µg) per kilogram of body weight.

Wait a second… what did EFSA say again…. ah yes, they estimated total exposures of 1.449 µg/kg bw per day for adolescents.

Sooooo basically a very similar value, then? And the EFSA, after looking at multiple studies in painstaking detail, concluded that “BPA poses no health risk to consumers”.

Is this grounds for multiple hysterical, fear-mongering headlines? I really don’t think it is.

It is interesting that the teenagers were unable to reduce their BPA levels. Because it’s broken down and excreted quite quickly by the body, you might expect that reducing exposure would have a bigger effect – but really all we can say here is that this needs to be repeated with far more tightly-controlled conditions. Who knows what the students did, and didn’t, actually handle and eat. Perhaps their school environment contains high levels of BPA in dust for some reason (new buildings or equipment, maybe?), and so it was virtually impossible to avoid. Who knows.

In summary, despite the scary headlines there really is no need to worry too much about BPA from plastics or receipts. It may be worth avoiding heating plastic, since we know that increases the amound of BPA that makes its way into food – although it’s important to stress that there’s no evidence that microwaving plastic containers causes levels to be above safe limits. Still, if you wanted to be cautious you could choose to put food into a ceramic or glass bowl, covered with a plate rather than clingfilm. It’ll save you money on your clingfilm bills anyway, and it means less plastic waste, which is no bad thing.

Roll on Easter…

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The Chronicles of the Chronicle Flask: 2017

We’ve made it! Not only to 2018 (which was starting to look doubtful earlier in the year), but also to the Chronicle Flask’s 100th post. Which doesn’t seem that many, really, but since posts on here frequently run to 1500 words, that adds up to a rather more impressive-sounding 150,000 words or so. I mean, that’s like… half a Brandon Sanderson novel. Oh.

Anyway, it’s time for a yearly round-up. Here goes!

Last January I began with a post about acrylamide. We’d all been enjoying lots of lovely crispy food over Christmas; it was time to tell us about the terrible dangers of such reckless indulgence. The newspapers were covered with pictures of delicious-looking chips, toast and roast potatoes alongside scary headlines such as:  “Crunchy toast could give you cancer, FSA warns”. The truth was not quite so dramatic. Acrylamide does form when foods are cooked to crispiness, and it is potentially harmful, but the quantities which form in food are tiny, and very unlikely to cause you any serious harm unless you literally live on nothing but burnt toast. The FSA (Food Standards Agency) hadn’t significantly revised their guidelines, it turned out, but were in fact only suggesting that the food industry should be mindful of acrylamide levels in food and seek to reduce them as much as possible. That wouldn’t have made for quite such a good “your food is going to killllll you!” story though, I suppose.

In February the spikey topic of vaccination came up. Again. Vaccines are awesome. They protect us from deadly diseases. No, I don’t want to hear any nonsense about “Big Pharma“, and I definitely don’t want to hear how “natural immunity” is better. It’s not. At best, it might provide a similar level of protection (but not in every case), but it comes with having to suffer through a horrible, dangerous disease, whereas vaccination doesn’t. It ought to be a no-brainer. Just vaccinate your kids. And yourself.

It was Red Nose Day in the UK in March, which brought some chemistry jokes. Turns out all the best ones aren’t gone, after all. Did you hear about the PhD student who accidentally cooled herself to absolute zero? She’s 0K now.

April brought a post which ought to have been an April Fool’s joke, but wasn’t. Sceptics often point out that homeopathy is just sugar and water, but the trouble is, sometimes, it’s not. There’s virtually no regulation of homeopathy. As far as I’ve been able to establish, no one tests homeopathic products; no one checks the dilutions. Since a lot of the starting materials are dangerously toxic substances such as arsenic, belladona, lead and hemlock, this ought to worry people more than it does. There has been more than one accidental poisoning (perhaps most shockingly, one involving baby teething products). It really is time this stuff was banned, maybe 2018 will be the year.

In May I turned to something which was to become a bit of a theme for 2017: alkaline water. It’s not so much that it doesn’t do anything (although it really doesn’t), more the fact that someone is charging a premium for a product which you could literally make yourself for pennies. It’s only a matter of dissolving a pinch of baking soda (sodium bicarbonate) in some water.

June brought a selection of periodic tables because, well, why not? This is a chemistry blog, after all! And now we’ve finally filled up period seven they do have a rather elegant completness. 2019, by the way, has just been announced as the International Year of the Periodic Table of Chemical Elements, to coincide with IUPAC’s 100th anniversary and the 150th anniversary of Mendeelev’s discovery of periodicity (his presentation, The Dependence Between the Properties of of the Atomic Weights of the Elements, was made on 6th March 1869). Looks like 2019 will be an exciting year for chemists!

In July it was back to the nonsense of alkaline diets again, when Robert O. Young was finally sentenced to 3 years, 8 months in custody for conning vulnerable cancer patients into giving him large sums of money for ineffective and dangerous treatments. Good. Moving on.

August brought me back to a post that I’d actually started earlier in the year when I went to a March for Science event in April. It was all about slime, and August seemed like a good time to finally finish it, with the school holidays in full swing – what could be more fun on a rainy day at home than making slime? Slime was a bit of a 2017 craze, and there have been a few stories featuring children with severely irritated skin. But is this likely to be caused by borax? Not really. Turns out it’s actually very safe. Laundry detergents in general, not so much. In short, if you want to make slime the traditional way with PVA glue and borax, fill your boots. (Not really – your parents will be uninpressed.)

In September it was back to quackery: black salve. A nasty, corrosive concoction which is sold as a cancer cure. It won’t cure your cancer. It will burn a nasty great big hole in your skin. Do not mess with this stuff.

October carried on in a similar vein, literally. This time with a piece about naturopaths recommending hydrogen peroxide IVs as a treatment for lots of things, not least – you guessed it – cancer. Yes, hydrogen peroxide. The stuff you used to bleach hair. Intraveneously. Argh.

The puking pumpkin!

The end of the month featured a far better use for hydrogen peroxide, that of the puking pumpkin. Definitely one to roll out if, for any reason, you ever find yourself having to demonstrate catalysis.

November brought us, somewhat unseasonally, to tomatoes. Where is the best place to store them? Fridge or windowsill? Turns out the answer involves more chemistry than you might have imagined.

And then, finally, December. Looking for a last-minute Christmas gift? Why not buy a case of blk water? I mean, other than it’s an exorbitantly priced bottle of mysterious black stuff which doesn’t do any of the things it claims to do, and might actually get its colour from coal deposits, that is.

And that, dear friends and followers, is it for 2017! Happy New Year! Remember to be sceptical when the inevitable “deadly food” story appears in a few weeks….

Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. All content is © Kat Day 2018. You may share or link to anything here, but you must reference this site if you do.

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Just what is blk water, and should you drink it?

Christmas is almost here! Are you ready yet? Are you fed up with people asking if you’re ready yet? Have you worked out what to buy for Great-uncle Nigel, who says he neither needs nor wants anything? Always a tricky scenario, that. Consumables are often a safe fallback position. They don’t clutter up the house, and who doesn’t enjoy a nice box of luxury biscuits, or chocolates, or a bottle of champagne, or spirts, or a case of blk water.

Wait, what?

Yes, this mysterious product turned up in my feed a few weeks ago. It’s water (well, so they say), but it’s black. Actually black. Not just black because the bottle’s black, black because the liquid inside it is… black.

It’s black water.

A bit like… cola. Only blacker, and not fizzy, or sweet, or with any discernable flavour other than water.

It raises many questions, doesn’t it? Let’s start with why. Obviously it’s a great marketing gimmick. It definitely looks different. It also comes with a number of interesting claims. The suppliers claim it contains “no nasties” and “only 2 ingredients”, namely spring water and “Fulvic Minerals” (sic). (Hang on, I hear you say, if it’s minerals, plural, surely that’s already more than two ingredients? Oh, but that’s only the start. Stay with me.)

It claims to “balance pH levels” and help “to regulate our highly acidic diets”. Yes, well, I think I’ve covered that before. Absolutely nothing you drink, or eat, does anything to the pH in any part of your body except, possibly, your urine – where you might see a small difference under some circumstances (but even if you do it doesn’t tell you anything significant about the impact of your diet on your long-term health). And bear in mind that a few minutes after you drink any kind of alkaline water it mixes with stomach acid which has a pH of around 2. Honestly, none of that alkaline “goodness” makes it past your pyloric sphincter.

Finally, blk water apparently “replenishes electrolytes”. Hm. Electrolytes are important in the body. They’re ionic species, which means they can conduct electricity. Your muscles and neurons rely on electrical activity, so they are quite important. Like, life or death important. But because of that our bodies are quite good at regulating them, most of the time. If you run marathons in deserts, or get struck down with a nasty case of food poisoning, or have some kind of serious health condition (you’d know about it) you might need to think about electrolytes, but otherwise most of us get what we need from the food and drink we consume normally every day.

Besides which, didn’t they say “only 2 ingredients”? The most common electrolytes in the body are sodium, potassium, magnesium, chloride, hydrogen phosphate and hydrogen carbonate. Most spring waters do contain some, if not all, of these, in greater or smaller amounts, but it’s not going to be enough to effectively “replenish” any of them. If, say, you are running marathons in the desert, the advice is actually to keep a careful eye on your water intake because drinking too much water can dangerously lower your sodium levels. Yes, there are sports drinks that are specifically designed to help with this, but they taste of salt and sugar and/or flavourings which have been added in a desperate attempt to cover up the salty taste. This is apparently not the case with blk water which, to repeat myself, contains “only 2 ingredients”.

And, according to the blk website the drink contains “0 mg of sodium per 500ml” so… yeah.

Speaking of ingredients, what about those so-called fulvic minerals? Maybe they’re the source of those all-important electrolytes (but not sodium)? And maybe they’re magically tasteless, too?

And perhaps, like other magical objects and substances, they don’t actually exist – as geologist @geolizzy told me on Twitter when I asked.

It’s not looking good for blk water (£47.99 for a case of 24 bottles) at this point. But hang on. Perhaps when they said fulvic minerals, what they meant was fulvic acid – which is a thing, or possibly several things – in a the presence of oh, say, some bicarbonate (*cough* 2 ingredients *cough*).

That could push the pH up to the stated 8-9, and didn’t we learn in school that:
acid + alkali –> salt + water
and maybe, if we’re being generous, we could call the salts of fulvic acids minerals? It’s a bit shaky but… all right.

So what are fulvic acids?

That’s an interesting question. I had never heard of fulvic acids. They do, as it turns out, have a Wikipedia page (Wikipedia is usually very reliable for chemical information, since no one has yet been very interested in spoofing chemical pages to claim things like hydrochloric acid is extracted from the urine of pregnant unicorns) but the information wasn’t particularly enlightening. The page did inform me that fulvic acids are “components of the humus” (in soil) and are  “similar to humic acids, with differences being the carbon and oxygen contents, acidity, degree of polymerization, molecular weight, and color.” The Twitter hive-mind, as you can see, was sending me down the same path…

A typical example of a humic acid.

Next stop, humic acids. Now we’re getting somewhere. These are big molecules with several functional groups. The chemists out there will observe that, yes, they contain several carboxylic acid groups (the COOH / HOOC ones you can see in the example) so, yes, it makes sense they’d behave as acids.

“No nasties”, blk said. “Pure” they said. When you hear those sorts of things, do you imagine something like this is in your drink? Especially one that, let’s be clear, is a component of soil?

Oh, hang on, I should’ve checked the “blk explained” page on the blk water website. There’s a heading which actually says “what are Fulvic Minerals”, let’s see now…

“Fulvic minerals are plant matter derived from millions of years ago that have combined with fulvic acid forming rare fulvic mineral deposits. They deliver some of the most powerful electrolytes in the world.”

“Fulvic minerals contain 77 other trace minerals, most of which have an influence on the healthiness of our body. They are very high in alkaline and when sourced from the ground contain a pH of 9.”

I don’t know about you, but I’m not totally convinced. I mean, as @geolizzy says in her tweet here (excuse the minor typo, she means humic, not humid),  it sounds a bit like… water contaminated with hydrocarbon deposits?


And, by the way, the phrase “very high in alkaline” is utterly meaningless. Substances are alkaline, or they contain substances which are alkaline. “Alkaline” is not a thing in itself. This is like saying my tea is high in hot when sourced from the teapot.

There’s one more thing to add. So far this might sound a bit weird but… probably safe, right? What could be more wholesome than a bit of soil? Didn’t your granny tell you to eat a pinch of soil to boost your immune system, or something? At worst it’s harmless, right?

Tap water is chlorine-treated to keep it free of nasty bacteria.

Maybe. But then again… water is often treated with chlorine compounds to keep it bacteria-free. Now, blk water is supposedly spring water, which isn’t usually treated. But hypothetically, let’s consider what happens when humic acids, or fulvic acids, or whatever we’re calling them, come into contact with chlorine-treated water.

Oh dear. It seems that dihaloacetonitriles are formed. (See also this paper.) This is a group of substances (possibly the best known one is dichloroacetonitrile) which are variously toxic and mutagenic. Let’s hope that spring water is totally unchlorinated, 100% “we really got it from out of a rock” spring water, then.

To sum up: it is black, and that’s kind of weird and a fun talking point – although if you like the idea of a black drink you can always drink cola. It doesn’t balance your pH levels – nothing does. I don’t believe it replenishes electrolyte levels either – how can it when it doesn’t contain sodium? – and I’m dubious about the “2 ingredients” claim (could you tell?). And the oh-so-healthy-sounding fulvic minerals are most likely due to contamination from coal deposits.

All in all, whilst it might not be quite such a conversation piece, I think it would be better to get Great-uncle Nigel a nice box of chocolates this year.

Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. All content is © Kat Day 2017. You may share or link to anything here, but you must reference this site if you do.

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In the fridge or on the windowsill: where’s the best place to keep tomatoes?

Fresh fruit and vegetables are great, but where’s the best place to store them?

I’ve mentioned before that my Dad is a professional plant-wrangler (if you’ve never read the electric daisies post, do go and have a look – it’s a little-read favourite) and he often brings me home-grown fruit and vegetables.

What follows is an inevitable disagreement about storage, specifically, my habit of putting everything in the fridge.

In my defence, modern houses rarely have pantries (boo) and we don’t even have a garage. We do have a shed, but it’s at the bottom of our poorly-lit, somewhat muddy garden. Do I want to traipse out there on a cold, dark, autumn evening? No, I do not. So the fabled “cool, dark place” is a bit of problem. My fridge is cool and dark, I have argued, but here’s the thing – turns out, it’s too cool. And quite probably too dark.

This I have learned from the botanist James Wong (@botanygeek on Twitter), whose talk I attended on Monday this week at the Mathematical Institute in Oxford. James, it turns out, had a rather similar argument with his Mum, particularly regarding tomatoes.

We should’ve listened to out parents, because they were right. A lot of fruit and vegetables really are better stored outside of the fridge, and for tomatoes in particular “better” actually means “more nutritious”.

Lycopene is a very long molecule with lots of double C=C bonds.

Tomatoes, James explained, contain a lot of a chemical called lycopene. It’s a carotene pigment, and it’s what gives tomatoes their red colour.

Lycopene has lots of double bonds between its carbon atoms which form something chemists call a conjugated system. This has some rather cool properties, one of which is an ability to absorb certain wavelengths of light. Lycopene is especially good at absorbing blue and green wavelengths, leaving our eyes to detect the red light that’s left.

Lycopene absorbs blue and green light, which is why tomatoes appear red.

Tomatoes and lycopene also seem to have a lot of health benefits. There’s some evidence that lycopene might reduce the risk of prostate and other cancers. It also appears to reduce the risk of stroke, and eating tomato concentrate might even help to protect your skin from sun damage (don’t get any ideas, you still need sunblock). Admittedly the evidence is currently a bit shaky – it’s a case of “more research is needed” – but even if it turns out to that the causative relationship isn’t terribly strong, tomatoes are still a really good source of fibre and vitamins A, C and E. Plus, you know, they taste yummy!

But back to the fridge. Surely they will keep longer in the fridge, and the low temperatures will help to preserve the nutrients? Isn’t that how it works?

Well, no. As James explained, once tomatoes are severed from the plant they have exactly one purpose: to get eaten. The reason, from the plant’s point of view, is that the critter which eats them will hopefully wander off and – ahem – eliminate the tomato seeds at a later time, somewhere away from the parent plant. This spreads the seeds far and wide, allowing little baby tomato plants to grow in a nice, open space with lots of water and sun.

For this reason once the tomato fruit falls, or is cut, from the tomato plant it doesn’t just sit there doing nothing. No, it carries on producing lycopene. Or rather, it does if the temperature is above about 10 oC. Below that temperature (as in a fridge), everything more or less stops. But, leave a tomato at room temperature and lycopene levels increase significantly. Plus, the tomato pumps out extra volatile compounds – both as an insect repellant and to attract animals which might usefully eat it – which means… yes: room temperature tomatoes really do smell better. As if that weren’t enough, chilling tomatoes can damage cell membranes, which can actually cause them to spoil more quickly.

In summary, not only will tomatoes last longer out of the fridge, they will actually contain more healthy lycopene!

Anecdotally, once I got over my scepticism and actually started leaving my tomatoes on my windowsill (after years of refrigeration) I discovered that it’s true. My windowsill tomatoes really do seem to last longer than they used to in the fridge, and they almost never go mouldy. Of course, it’s possible that I might not be comparing like for like (who knows what variety of tomato I bought last year compared to this week), but I urge you to try it for yourself.

James mentioned lots of other interesting bits and pieces in his talk. Did you know that sun-dried shiitake mushrooms are much higher in vitamin D? Or that you can double the amount of flavonoid you absorb from your blueberries by cooking them? (Take that, raw food people!) Storing apples on your windowsill is likely to increase the amount of healthy polyphenols in their skin, red peppers are better for you than green ones, adding mustard to cooked broccoli makes it more nutritious, and it would be much better if we bought our butternut squash in the autumn and saved it for Christmas – it becomes sweeter and more flavoursome over time.

In short, fascinating. Who wants to listen to some “clean eater” making it up as they go along when you can listen to a fully-qualified botanist who really knows what he’s talking about? Do check out the book, How to Eat Better, by James Wong – it’s packed full of brilliant tidbits like this and has loads of recipes.

And yes, Dad: you were right.

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Absurd alkaline ideas – history, horror and jail time

I’ve written about the absurdity of alkaline diets before, and found myself embroiled in more than one argument about the idea.

To sum up quickly, it’s the notion that our bodies are somehow “acidic”, and if only we could make them “alkaline” all our health problems – cancer included – would disappear. The way you make your body “alkaline” is, mainly, by eating lots of vegetables and some fruits (particularly citrus fruits – yes, I know, I know).

The eating fruit and vegetables bit aside (they’re good for you, you should eat them), it’s all patent nonsense. Our bodies aren’t acidic – well, other than where they’re supposed to be acidic (like our stomachs) – and absolutely nothing we eat or drink can have any sort of effect on blood pH, which is kept firmly between 7.35-7.45 by (mainly) our lungs and kidneys. And if your kidneys or lungs are failing, you need something a little stronger in terms of medical intervention than a slice of lemon.

But who first came up with this crazy idea?

Claude Bernard carried out experiments on rabbits.

Actually, we can probably blame a nineteenth century French biologist and physiologist, Claude Bernard, for kicking the whole thing off, when he noticed that if he changed the diet of rabbits from largely plant-based to largely animal-based (i.e. from herbivorous to carnivorous) their urine became more acidic.

This observation, followed by a lot of speculation by nutritionists and some really quite impressively dodgy leaps of reasoning (by others, I should stress – not Bernard himself), has lead us to where we are now: umpty-million websites and books telling anyone who will listen that humans need to cut out all animal products to avoid becoming “acidic” and thus ill.

Bernard’s rabbits were, it seems, quite hungry when he got them – quite possibly they hadn’t been fed – and he immediately gave them boiled beef and nothing else. Meat contains the amino acids cysteine and methionine, both of which can produce acid when they’re metabolised (something Bernard didn’t know at the time). The rabbits excreted this in their urine, which probably explains why it became acidic.

Now, many of you will have noticed several problems here. Firstly, rabbits are herbivores by nature (they do not usually eat meat in the wild). Humans aren’t herbivores. Humans are omnivores, and we have quite different digestive processes as a result. It’s not reasonable to extrapolate from rabbits to humans when it comes to diet. Plus, even the most ardent meat-lover probably doesn’t only eat boiled beef – at the very least people usually squeeze in a battered onion ring or a bit of coleslaw along the way. Most critically of all, urine pH has no direct relationship with blood pH. It tells us nothing about the pH of “the body” (whatever we understand that to mean).

The notion that a plant-based diet is somehow “alkaline” should really have stayed in the 19th century where it belonged, and at the very least not limped its way out of the twentieth. Unfortunately, somewhere in the early 2000s, a man called Robert O Young got hold of the idea and ran with it.

Young’s books – which are still available for sale at the time of writing – describe him as “PhD”, even though he has no accredited qualification.

Boy, did he run with it. In 2002 he published a book called The pH Miracle, followed by The pH Miracle for Diabetes (2004), The pH Miracle for Weight Loss (2005) and The pH Miracle Revised (2010).

All of these books describe him either as “Dr Robert O Young” or refer to him as “PhD”. But he has neither a medical qualification nor a PhD, other than one he bought from a diploma mill – a business that offers degrees for money.

The books all talk about “an alkaline environment” and state that so-called acidic foods and drinks (coffee, tea, dried fruit, anything made with yeast, meat and dairy, amongst other foodstuffs) should be avoided if not entirely eliminated.

Anyone paying attention will quickly note that an “alkaline” diet is basically a very restrictive vegan diet. Most carbohydrate-based foods are restricted, and lots of fruits and nuts fall into the “moderately” and “mildly” acidic categories. Whilst a vegan diet can be extremely healthy, vegans do need to be careful that they get the nutrients they need. Restricting nuts, pulses, rice and grains as well as removing meat and dairy could, potentially, lead to nutritional deficiencies.

Young also believes in something called pleomorphism, which is a whole other level of bonkers. Essentially, he thinks that viruses and bacteria aren’t the cause of illnesses – rather, the things we think are viruses and bacteria are actually our own cells which have changed in response to our “acidic environments”. In Young’s mind, we are making ourselves sick – there is one illness (acidosis) and one cure (his alkaline diet).

It’s bad enough that he’s asserting such tosh and being taken seriously by quite a lot of people. It’s even worse that he has been treating patients at his ranch in California, claiming that he could “cure” them of anything and everything, including cancer.

One of his treatments involved intravenous injections of solutions of sodium hydrogen carbonate, otherwise known as sodium bicarbonate or baking soda. This common cookery ingredient does produce an alkaline solution (about pH 8.5) when dissolved in water, but remember when I said blood pH was hard to shift?

Screenshot from a BBC article, see

Well, it is, and for good reason. If blood pH moves above the range of 7.35-7.45 it causes a condition called alkalosis. This can result in low blood potassium which in turn leads to muscle weakness, pain, and muscle cramps and spasms. It can also cause low blood calcium, which can ultimately result in a type of seizure. Putting an alkaline solution directly into somone’s blood is genuinely dangerous.

And this is before we even start to consider the fact that someone who was not a medical professional was recommending, and even administering, intravenous drips. Which, by the way, he was reportedly charging his patients $550 a pop to receive.

Young came to the attention of the authorities several times, but always managed to wriggle out of trouble. That is, until 2014, when he was arrested and charged with practising medicine without a license and fraud. In February last year, he was found guilty, but a hung jury caused complications when they voted 11-1 to convict on the two medical charges, but deadlocked 8-4 on fraud charges.

Finally, at the end of June 2017, he was sentenced. He was given three years, eight months in custody, but due to the time he’s already spent in custody and under house arrest, he’s likely to actually serve five months in jail.

He admitted that he illegally treated patients at his luxury Valley Center ranch without any medical or scientific training. Perhaps best of all, he was also made to publicly declare that he is not microbiologist, hematologist, medical doctor or trained scientist, and that he has no post-highschool educational degrees from any accredited school.

Prosecuting Deputy District Attorney Gina Darvas called Young the “Wizard of pHraud”, which is rather apt. Perhaps the titles on his books could be edited to read “Robert O Young, pHraud”?

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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?



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.



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.



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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