The Chronicles of the Chronicle Flask: 2018

As has become traditional, I’m finishing off this year with a round-up of 2018’s posts. It’s been a good year: a few health scares which turned out to be nothing much to worry about, one which turned out to be a genuine danger, a couple of cool experiments and some spectacular shiny balls. So without further ado, here we go…

Things were a bit hectic at the start of this year (fiction writing was happening) and as a result January was quiet on the blog. But not on the Facebook page, where I posted a couple of general reminders about the silliness of alkaline diets which absolutely exploded, achieving some 4,000 shares and a reach (so Facebook tells me anyway) of over half a million people. Wow. And then I posted a funny thing about laundry symbols which went almost as wild. It’s a strange world.

February featured BPA: an additive in many plastics.

In February I wrote a piece about BPA (Bisphenol A), which was the chemical scare of the day. There’s always one around January/February time. It’s our penance for daring to enjoy Christmas. Anyway, BPA is a chemical in many plastics, and of course plastic waste had become – and remains – a hot topic. BPA is also used in a number of other things, not least the heat sensitive paper used to produce some shopping receipts. It’s not a harmless substance by any means, but it won’t surprise anyone to learn that the risks had, as is usually the case, been massively overstated. In a report, the European Food Safety Authority said that the health concern for BPA is low at their estimated levels of exposure. In other words, unless you’re actually working with it – in which case you should have received safety training – there’s no need to be concerned.

In March I recorded an episode for the A Dash of Science podcast, and I went on to write a post about VARD, which stands for Verify, Author, Reasonableness and Date. It’s my quick and easy way of fact-checking online information – an increasingly important skill these days. Check out the post for more info.

April ended up being all about dairy and vitamin D.

April was all about dairy after a flare-up on Twitter on the topic, and went on to talk about vitamin D. The bottom line is that everyone in the UK should be taking a small vitamin D supplement between about October and March, because northern Europeans simply can’t make vitamin Din their skin during these months (well, unless they travel nearer to the equator), and it’s not a nutrient we can easily get from our food. Are you taking yours?

May featured fish tanks, following a widely reported story about a fish-owner who cleaned out his tank and managed to release a deadly toxin that poisoned his entire family. Whoops. It turns that this was, and is, a real risk – so if you keep fish and you’ve never heard of this before, do have a read!

In June I wrote about strawberries, and did a neat experiment to show that strawberries could be used to make pH indicator. Who knew? You do, now! Check it out if you’re looking for some chemistry to amuse yourself over the holidays (I mean, who isn’t?). Did you know you can make indicators from the leaves of Christmas poinsettia plants, too?

Slime turned up again in July. And December. And will probably keep on rearing its slimy head.

July brought a subject which has turned up again recently: slime. I wrote about slime in 2017, too. It’s the gift that keeps on giving. This time it flared up because the consumer magazine and organisation Which? kept promoting research that, they claimed, showed that slime toys contain dangerous levels of borax. It’s all rather questionable, since it’s not really clear which safety guidelines they’re applying and whether they’re appropriate for slime toys. Plus, the limits that I was able to find are migration limits. In other words, it’s not appropriate to measure the total borax content of the slime and declare it dangerous – they should be looking at the amount of borax which is absorbed during normal use. Unless your child is eating slime (don’t let them do that), they’re never going to absorb enough borax to do them any harm. In other words, it’s a storm in a slimepot.

August was all about carbon dioxide, after a heatwave spread across Europe and there was, bizarrely, a carbon dioxide shortage which had an impact on all sorts of things from fizzy drinks to online shopping deliveries. It ended up being a long-ish post which spanned everything from the formation of the Earth, the discovery of carbon dioxide, fertilisers and environmental concerns.

September featured shiny, silver balls.

In September I turned my attention to a chemical reaction which is still to this day used to coat the inside of glass decorations with a thin layer of reflective silver, and has connections with biochemistry, physics and astronomy. Check it out for some pretty pictures of silver balls, and my silver nitrate-stained fingers.

In October I was lucky enough to go on a ‘fungi forage’ and so, naturally, I ended up writing all about mushrooms. Did you know that a certain type of mushroom can be used to make writing ink? Or that some mushrooms change colour when they’re damaged? No? You should go back and read that post, then! (And going back to April for a moment, certain mushrooms are one of the few sources of vitamin D.)

Finally, November ended up being all about water, marking the 235th anniversary of the day that Antoine Lavoisier formally declared water to be a compound. It went into the history of water, how it was proven to have the formula H2O, and I even did an experiment to split water into hydrogen and oxygen in my kitchen – did you know that was possible? It is!

As December neared, the research for my water piece led me to suggest to Andy Brunning of Compound Interest that this year’s Chemistry Advent might feature scientists from the last 24 decades of chemistry, starting in the 1780s (with Lavoisier and Paulze) and moving forward to the current day. This turned out to be a fantastic project, featuring lots of familiar and not quite so-familiar scientists. Do have a look if you didn’t follow along during December.

And that’s it for this year. I hope it’s been a good one for all my readers, and I wish you peace and prosperity in 2019! Suggestions for the traditional January Health Scare, anyone? (Let’s hope it’s not slime again, I’m getting really tired of that one now…)


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Where did our love of dairy come from?

The popularity of the soya latte seems to be on the rise.

A little while ago botanist James Wong tweeted about the myriad types of plant ‘milk’ that are increasingly being offered in coffee shops, none of which are truly milk (in the biological sense).

This generated a huge response, probably rather larger than he was expecting from an off-hand tweet. Now, I’m not going to get into the ethics of milk production because it’s beyond the scope of this blog (and let’s keep it out of the comments? — kthxbye) but I do want to consider one fairly long thread of responses which ran the gamut from ‘humans are the only species to drink the milk of another animal’ (actually, no) to ‘there’s no benefit to dairy’ (bear with me) and ending with, in essence, ‘dairy is slowly killing us‘ (complicated, but essentially there’s very little evidence of any harm).

Humans have been consuming dairy products for thousands of years.

But wait. If dairy is so terrible for humans, and if there are no advantages to it, why do we consume it at all? Dairy is not a new thing. Humans have been consuming foods made from one type of animal milk or another for 10,000 years, give or take. That’s really quite a long time. More to the point (I don’t want to be accused of appealing to antiquity, after all), keeping animals and milking them is quite resource intensive. You have to feed them, look after them and ensure they don’t wander off or get eaten by predators, not to mention actually milk them on a daily basis. All that takes time, energy and probably currency of some sort. Why would anyone bother, if dairy were truly detrimental to our well-being?

In fact, some cultures don’t bother. The ability to digest lactose (the main sugar in milk) beyond infancy is quite low in some parts of the world, specifically Asia and most of Africa. In those areas dairy is, or at least has been historically, not a significant part of people’s diet.

But it is in European diets. Particularly northern European diets. Northern Europeans are, generally, extremely tolerant of lactose into adulthood and beyond.

Which is interesting because it suggests, if you weren’t suspicious already, that there IS some advantage to consuming dairy. The ability to digest lactose seems to be a genetic trait. And it seems it’s something to do, really quite specifically, with your geographic location.

Which brings us to vitamin D. This vitamin, which is more accurately described as a hormone, is a crucial nutrient for humans. It increases absorption of calcium, magnesium and phosphate, which are all necessary for healthy bones (not to mention lots of other processes in the body). It’s well-known that a lack of vitamin D leads to weakened bones, and specifically causes rickets in children. More recently we’ve come to understand that vitamin D also supports our immune system; deficiency has been meaningfully linked to increased risk of certain viral infections.

What’s the connection between vitamin D and geographic location? Well, humans can make vitamin D in their skin, but we need a bit of help. In particular, and this is where the chemistry comes in, we need ultraviolet light. Specifically, UVB – light with wavelengths between 280 nm to 315 nm. When our skin is exposed to UVB, a substance called 7-dehydrocholesterol (7-DHC to its friends) is converted into previtamin D3, which is then changed by our body heat to vitamin D3, or cholecalciferol – which is the really good stuff. (There’s another form, vitamin D2, but this is slightly less biologically active.) At this point the liver and kidneys take over and activate the chloecalciferol via the magic of enzymes.

We make vitamin D in our skin when we’re exposed to UVB light.

How much UVB you’re exposed to depends on where you live. If you live anywhere near the equator, no problem. You get UVB all year round. Possibly too much, in fact – it’s also linked with skin cancers. But if you live in northerly latitudes (or very southerly), you might have a problem. In the summer months, a few minutes in the sun without sunscreen (literally a few minutes, not hours!) will produce more than enough vitamin D. But people living in UK, for example, get no UVB exposure for 6 months of the year. Icelanders go without for 7, and inhabitants of Tromsø, in Norway, have to get by for a full 8 months. Since we can only store vitamin D in our bodies for something like 2-4 months (I’ve struggled to find a consistent number for this, but everyone seems to agree it’s in this ballpark), that potentially means several months with no vitamin D at all, which could lead to deficiency.

In the winter northern Europeans don’t receive enough UVB light from the sun to produce vitamin D in their skin.

In the winter, northern Europeans simply can’t make vitamin D3 in their skin (and for anyone thinking about sunbeds, that’s a bad idea for several reasons). In 2018, this is easily fixed – you just take a supplement. For example, Public Health England recommends that Brits take a daily dose of 10 mcg (400 IU) of vitamin D in autumn and winter, i.e. between about October and March. It’s worth pointing out at this point that a lot of supplements you can buy contain much more than this, and more isn’t necessarily better. Vitamin D is fat-soluble and so it will build up in the body, potentially reaching toxic levels if you really overdo things. Check your labels.

Oily fish is an excellent source of vitamin D.

But what about a few thousand years ago, before you just could pop to the supermarket and buy a bottle of small tablets? What did northern Europeans do then? The answer is simple: they had to get vitamin D from their food. Even if it’s not particularly well-absorbed, it’s better than nothing.

Of couse it helps if you have access to lots of foods which are sources of vitamin D. Which would be…  fatty fish (tuna, mackerel, salmon, etc) – suddenly that northern European love of herring makes so much more sense – red meat, certain types of liver, egg yolks and, yep, dairy products. Dairy products, in truth, contain relatively low levels of vitamin D (cheese and butter are better than plain milk), but every little helps. Plus, they’re also a good source of calcium, which works alongside vitamin D and is, of course, really important for good bone health.

A side note for vegans and vegetarians: most dietry sources of vitamin D come from animals. Certain mushrooms grown under UV can be a good source of vitamin D2, but unless you’re super-careful a plant-based diet won’t provide enough of this nutrient. So if you live in the north somewhere or you don’t, or can’t, expose your skin to the sun very often, you need a supplement (vegan supplements are available).

Fair skin likely emerged because it allows for better vitamin D production when UVB levels are lower.

One thing I haven’t mentioned of course is skin-colour. Northern Europeans are generally fair-skinned, and this is vitamin D-related, too. The paler your skin, the better UVB penetrates it. Fair-skinned people living in the north had an advantage over those with darker skin in the winter, spring and autumn months: they could produce more vitamin D. In fact, this was probably a significant factor in the evolution of fair skin (although, as Ed Yong explains in this excellent article, that’s complicated).

In summary, consuming dairy does have advantages, at least historically. There’s a good reason Europeans love their cheeses. But these days, if you want to eat a vegan or vegetarian diet for any reason (once again, let’s not get into those reasons in comments, kay?) you really should take a vitamin D supplement. In fact, Public Health England recommends that everyone in the UK take a vitamin D supplement in the autumn and winter, but only a small amount – check your dose.

By the way, if you spot any ‘diary’s let me know. I really had to battle to keep them from sneaking in…

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.

If you enjoy reading my blog, please consider buying me a coffee through Ko-fi using the button below. Black, though – I like dairy, just not in my coffee!

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