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Neem: nice, nasty or… not sure?

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A few days ago it was sunny and slightly breezy outside (yes, it’s August, but I live in the UK – this isn’t as common as you might imagine) and I thought, I should make the most of this and do something about my orchids.

Now, anyone that reads this blog regularly will know that my Dad is a horticulturist. I, however, am not. My fascination with bright colours, interesting smells and complicated naming conventions went down the chemistry route. But I am, oddly, quite good with Phalaenopsis, aka, moth orchids. I don’t really know why, or how, but I seem to have come to some sort of agreement with the ones that live on my kitchen windowsill. It goes along the lines of: I’ll water you once a week, and you make flowers a couple of times a year, and we’ll otherwise leave each other alone, okay?

Scale bugs secrete honeydew, which encourages the growth of sooty moulds

Well, this was fine for years, until we somehow acquired an infestation of scale bugs. These tiny but extremely annoying pests feed by sucking sap from leaves of plants, and they excrete a sticky substance called honeydew. Trust me, it’s not as nice as it sounds. Firstly, it really is sticky, and makes a horrible mess not just of the orchid leaves, but also the area around the plants.

Then it turns out that certain types of mould just love this stuff, so you end up with black spots on the leaves. And, not surprisingly, all this weakens the plant.

So, what’s the answer? Well, there are several. But the one I tend to default to is neem oil.

This stuff is a vegetable oil from the seeds of the Azadirachta indica, or neem, tree. It has a musty, nutty sort of smell, and is fairly easy to buy.

It’s indigenous to the Indian subcontinent and has been historically important in traditional medicine. In fact, The Sanskrit name of this evergreen tree is ‘Arishtha’, which means ‘reliever of sickness’.

So it’s a natural vegetable oil and people have been using it as a remedy for thousands of years – must be totally safe, right? Right?

Well… I’ve said it before, but some of the very best horribly toxic things are entirely natural, and neem is yet another example. Ingestion of significant quantities can cause metabolic acidosis (finally, something that really does have the potential to change blood pH! Er… but not… in a good way), kidney failure, seizures, and brain damage in children. Skin contact can cause contact dermatitis. It’s been shown to work as a contraceptive and, more problematically, it’s a known abortifacient (causes miscarriage).

Neem oil is easy to buy, but it needs to be handled with caution

All this said, as always, the dose make the poison.

One case study in the Journal of The Association of Physicians of India reported on a 36-year-old man who swallowed 30–50 ml (about three tablespoons) of neem oil, in the hope of treating the corns on his feet. As far as I can tell, it didn’t help his corns. It did cause vomiting, drowsiness, a dangerous drop in blood pH and seizures. There’s no specific antidote for neem poisoning, but the hospital managed his symptoms. Luckily, despite the hammering his kidneys undoubtedly took, he didn’t need dialysis, and was discharged from hospital after just over a week.

Now, okay, you’re unlikely to accidentally swallow three tablespoons of any oil, especially not neem which does have quite a strong, not entirely pleasant, smell and (reportedly – I haven’t tried for obvious reasons) a bitter taste. But nevertheless, it’s wise to be cautious, particularly around children who have a smaller body mass and therefore are much more likely to suffer serious effects – up to and including death. In one reported case, a mother gave a 3-month-old child a teaspoon of neem oil in the hope of curing his indigestion – fortunately he survived, but not without some seriously scary symptoms.

Nimbin, a chemical found in neem oil, is reported to have all sorts of beneficial effects [image source]

Okay, so those are the dangers. Let’s talk chemistry. The Pakistani organic chemist Salimuzzaman Siddiqui is thought to be the first scientist to formally investigate the various compounds in neem oil. In 1942 he extracted three compounds, and identified nimbidin as the main antibacterial substance in neem. He was awarded an OBE in 1946 for his discoveries.

I will confess, at this point, to running into a little bit of confusion with the nomenclature. Nimbidin is described, in some places at least, as a mixture of compounds (collectively, tetranortriterpenes) rather than a single molecule. But either way, it has been shown to have anti-inflammatory properties – at least in rats.

Another of the probably-mostly-good substances in neem is nimbin: a triterpenoid which is reported to have a whole range of positive properties, including acting as an anti-inflammatory, an antipyretic, a fungicide, an antiseptic and even as an antihistamine. Interestingly, I went looking for safety data on nimbin, and I couldn’t find much. That could mean it’s safe, or it could mean it just hasn’t been extensively tested.

Azadirachtin, another chemical found in neem, is a known pesticide [image source]

The substance that seems to do most of the pesticide heavy lifting is azadirachtin. This is a limonoid (compounds that are probably best known for their presence in citrus fruits). It’s what’s called an antifeedant – a substance produced by plants to deter predators from munching on them. Well, mostly. Humans have a strange habit of developing a taste for plants that produce such substances. Take, for example, odoriferous garlic, clears-out-your-sinuses horseradish, and of course the daddy of them all: nicotine.

Azadirachtin is known to affect lots of species of insects, both by acting as an antifeedant and as a growth disruptor. Handily, it’s also biodegradable – and breaks down in a few days when exposed to light and water.

That makes it appealing as a potential pesticide, and it’s also generally described as having low toxicity in mammals – its reported LD50 tends to fall into the grams per kilogram range, which makes it “moderately to slightly toxic“. Wikipedia quotes a value (without a source, as I write this) of >3,540 mg/kg in rats.

But… I did find another page quoting 13 mg/kg in mice. That’s quite dramatically different, and would make it extremely/highly toxic. Unfortunately I couldn’t get my hands on the original source, so I haven’t been able to verify it’s not a transposition error.

Let’s assume it isn’t. It would be odd to have such a big difference between mice and rats. Things that poison mice tend to poison rats, too. There might be some confusion over pure azadirachtin vs. “neem extract” – it could be the case that the mixture of chemicals working together in neem create some sort of synergistic (toxic) effect – greater than the sum of all the individual substances. It could be an experimental error, including a contaminated neem sample, or something to do with the way the animals were exposed to the extract.

Neem soap is widely available online, but that may not be a good thing…

It’s difficult to say. Well, it’s difficult for me to say, because I don’t have access to all the primary sources. (Any toxicologists out there, please do feel free to weigh into the comments section!) But either way, as I’ve already mentioned, several case studies have fingered azadirachtin as one of the substances likely to be causing the well-reported nasty side effects.

If you’re asking this chemist? I say be careful with the stuff. If you decide to use it on your plants, keep it out of reach of children, and wear some good-quality disposable gloves while you’re handling it (I put some on after I took that photo back there). If you’re pregnant, or trying to become pregnant, the safest option is to not use it at all.

Which brings me to neem soap.

Yup. It’s sold as a “natural” treatment for skin conditions like acne. I won’t link to a specific brand, but it’s easy to find multiple retailers with a simple Google search. I looked at one selling soap bars for £6.99 a pop, containing 10% (certified organic, because of course) neem oil. Did I mention back there that neem is known to cause contact dermatitis? I’m fairly sure I did. None of the products I saw had obvious safety warnings, and I certainly found nothing about safety (or otherwise) for pregnant women.

Plus – worryingly, not least because children are more likely to get things in their mouth – you can also buy kids and babies versions, again purporting to contain 10% neem oil.

I even found neem toothpaste. Which… given people often swallow toothpaste… yikes.

My moth orchids are looking much healthier now I’ve got rid of all the scale bugs!

Now again, and for the umpteenth time, the dose makes the poison. The case studies I’ve mentioned involved, at a minimum, swallowing a teaspoon of pure neem oil, and you’re not getting that sort of quantity from smears of toothpaste. But, at the same time, when it comes to pregnancy and babies, it’s generally sensible to apply a precautionary principle, especially for things like soap and toothpaste for which alternatives with well-established safety profiles exist.

Bottom line? Would I use these products? I would not.

But I do use neem to treat the scale bugs on my orchids, and they’re doing much better than they were. Fingers crossed for more flowers!

Do you want something non-sciency to distract you from, well, everything? Why not take a look at my fiction blog: the fiction phial? You can also find me doing various flavours of editor-type-stuff at the horror podcast, PseudoPod.org – so head over there, too!

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Is there NO way to stop COVID-19?

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UK trials have begun of a nasal spray that could prevent COVID-19 infections

A few weeks ago, it was announced that UK trials were beginning of a nasal spray proven to kill 99.9% of the coronavirus that causes COVID-19. The idea, broadly, is that you’d use the spray first thing in the morning, during the day after social interactions, and then again in the evening — and it would prevent the virus from taking hold and making you ill.

Awesome, right? Simple, cheap, portable. Sort of like cleaning your teeth regularly: prevention rather than cure. Combined with a vaccine, particularly for anyone at high risk such as those in healthcare settings, it could put a stop to the whole thing — and might also turn out to be effective on other, less deadly but still annoying, viruses.

But, I hear you ask, what is it? Because if I’m going to squirt something up my nose several times a day, I have questions…

Nitric oxide has the chemical formula NO

Fair enough. It’s actually, mostly, nitric oxide, which has the chemical formula NO.

Yes, there are plenty of wordplay options here. The researchers have already jammed the letters NO into their company name, and done the acronym thing, to get SaNOtize Nitric Oxide Nasal Spray (NONS). If the trials are successful, it’s probably only a matter of time before we get: “Say NO to coronavirus!” marketing. (Any ad agencies reading this, I’m claiming copyright.)

But that aside, unless you’re a chemist you might be thinking about some half-remembered chemical names and frowning at this point. Isn’t that… used in rocket fuel? Or… wait… isn’t that… the nasty smoggy stuff that causes lung problems?

Ah, well, there are several nitrogen oxides. Let me summarise:

Nitric oxides in the atmosphere cause photochemical smog.

There are other nitrogen oxides, not to mention ions — but let’s not spend all day on this. Nitrogen forms this confusing hodgepodge of oxides because it has five electrons in its outermost shell (it’s in group 15 of the periodic table) and because there’s not much difference in the electronegativities of oxygen and nitrogen. So essentially, it can share electrons with oxygen to form bonds in a number of different ways to obtain a stable, full outer shell.

For any students reading this, I’m sorry. You… pretty much just have to remember these. Yes, I know. That’s why experienced chemists so often use the shorthand NOx — we just can’t be bothered keeping all the names straight. (Okay, before someone shouts at me, actually NOx is handy because we’re often talking about more than one oxide at a time, and it allows us to easily express that.)

Back to NO. It’s a colourless gas, and it has an unpaired electron, which makes it a free radical. And… here we go again. Aren’t we supposed to eat lots of antioxidant-rich fruit and vegetables to mop up free radicals? They’re bad, aren’t they?

Viagra (Sildenafil) makes use of the nitric oxide pathway which causes blood vessels to dilate…

Yes and no. Free radicals are reactive species which damage cells and can cause illness and ageing. Too much exposure to free radicals causes something oxidative stress, which is definitely bad. But. It turns out that nitrogen oxide is an important signalling molecule, that is, a molecule which is the body uses to send chemical signals from one place to another. In particular, nitrogen oxide “tells” the smooth muscle around blood vessels to relax, causing those blood vessels to dilate, and increasing blood flow. Viagra (aka Sildenafil) uses the nitric oxide pathway, and I think we all know what that does, don’t we? Good.

Nitric oxide has also been shown to reduce blood pressure, which is generally considered a good thing — up to a point, obviously. This is why you can buy lots of so-called nitric oxide supplements, which, since nitrogen oxide is a gas at room temperature, don’t actually contain nitric oxide on its own. Rather, they’re a mixture of amino acids and other things that supposedly help the body to make NO. But it might be cheaper, and healthier, to eat plenty of beetroot or drink beetroot juice, since there’s evidence that does the same sort of thing.

As always, the dose makes the poison. Too much nitric oxide is definitely problematic, but administered in the right way and in appropriate doses, it’s extremely safe.

It’s suggested that the nitric oxide in the SaNOtize nasal spray destroys the virus and also helps to stop viral replication within cells. Plus, it blocks the receptors that the virus uses to enter cells in the first place. Essentially, it locks the doors and rains down fire on the potential intruders — nice work.

You only need to use the spray occasionally, because developing a COVID-19 infection isn’t instant. First the virus gets into your nose, then it attaches to cells, then it replicates, and then it sheds into your lungs. There are timescales involved here — so long as the spray is used every so often it should do the trick.

Another advantage is that this should, theoretically, work on other strains — where the current vaccines may not. So it could provide a very important stopgap when vaccination isn’t immediately available.

This is only in the early stages of clinical trials so, for now, wear your mask.

All sounds fabulous, doesn’t it? It might be, but, we’re in the early stages with this. Clinical trials have now started in the UK, are already in Phase II in Canada and have been approved to start in the USA. Researchers are hopeful, but we need to wait for the evidence.

So in the meantime, wear a mask, wash your hands, and take a vaccine if you’re offered one. Stay safe out there!

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Absurd alkaline ideas – history, horror and jail time

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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 http://www.bbc.co.uk/news/magazine-38650739

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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Words of woo: what does ‘alkalise’ mean?

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220px-Marketvegetables

‘alkaline’ diets usually revolve around eating lots of fruit and vegetables – no bad thing, but it won’t change your body’s pH

If you hang around in the unscientific chunks of the internet for any length of time, as I find myself doing from time to time, you start to come across certain words that get used over and over. They are usually words that sound very sciency, and they’re being used to make things sound legitimate when, if we’re honest, they’re really not.

One such word is ‘alkalise’ (or ‘alkalize’). I’ve met it often ever since I wrote my post ‘Amazing alkaline lemons?‘. So, what does this word mean?

Good question. Google it, and at least the first three pages of links are about diets and how to ‘alkalise your body’ featuring such pithy lines as:

“It’s not really a diet… it’s a way of eating” (is there a difference?)
“Alkalise or live a life of misery” (gosh)
“Alkalise or die” (blimey)
“Alkaline water” (apparently this is a thing)
“Why it’s important to alkalise your water” (using our overpriced products)

In fact, I had to click through several pages of Google links before I even got to something that was simply a definition. (I’m aware that Google personalises its search results, so if you try this yourself you might have a different experience.) Certainly, there are no legitimate chemistry, biochemistry – or anything else like that – articles in sight.

Hunt specifically for a definition and you get ‘turn basic and less acidic; “the solution alkalized”‘ (The Free Dictionary), ‘to make or become alkaline.‘ (Dictionary.com) and, simply, ‘to make alkaline’ (Collins).

Universal_indicator_paper

pH 7 is neutral, more than 7 is basic

The first of these is interesting, because it refers to ‘basic’. Now, as I’ve explained in another post, bases and alkalis are not quite the same thing. In chemistry a base is, in simple terms, anything that can neutralise an acid. Alkalis, on the other hand, are a small subset of this group of compounds: specifically the soluble, basic, ionic salts of alkali metals or alkaline earth metals.

Since there are only six alkali metals (only five that are stable) and only six alkaline earth metals (the last of which is radium – probably best you steer clear of radium compounds) there are a rather limited number of alkalis, namely: lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, caesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide and radium hydroxide. There you go. That’s it. That’s all of them. (Okay, yes, under the ‘soluble in water’ definition we could also include ammonium hydroxide, formed by dissolving the base, ammonia, in water – that opens up a few more.)

This, you see, is why real chemists tend not to use the term ‘alkalise’ very often. Because, unless the thing you’re starting with does actually form one of these hydroxides (there are some examples, mostly involving construction materials), it’s a little bit lead-into-gold-y, and chemists hate that. The whole not changing one element into another thing (barring nuclear reactions, obviously) is quite fundamental to chemistry. That’s why your chemistry teacher spent hours forcing you to balance equations at school.

No, the relevant chemistry word is ‘basify‘. This is such a little-known word that even my spell checker complains, but it’s just the opposite of the slightly better-known ‘acidify’ – in other words, basify means to raise the pH of something by adding something basic to it. Google ‘basify’ and you get a very different result to that from ‘alkalise’. The first several links are dictionary definitions and grammar references, and after that it quickly gets into proper chemistry (although I did spot one that said ‘how to basify your urine’ – sigh).

What does all this mean? Well, if you see someone using the word “alkalising” it should raise red flags. I’d suggest that unless they’re about to go on to discuss cement (calcium hydroxide is an important ingredient in construction materials) cocoa production or, possibly, certain paint pigments, then you can probably write off the next few things they say as total nonsense. If they’re not discussing one of the above topics, the chances are good that what they actually know about chemistry could safely fit on the back of a postage stamp, with space to spare, so nod, smile and make your escape.

For the record, you absolutely don’t need to alkalise your diet. Or your urine*. Really. You don’t.

And please don’t waste your money on alkaline water.

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Lemon

There’s no good evidence that drinking lemon juice has a significant impact on urine pH.

* In the event that you actually have problematically acidic urine, perhaps due to some medical condition, there are proven treatments that will neutralise it (i.e. take it to around pH 7, which is the pH urine ought to be, roughly). In particular, sodium citrate powder can be dissolved in water to form a drinkable solution. Of course, if this is due to an infection you should see a doctor: you might need antibiotics – urinary tract infections can turn nasty. Yes, I am aware that the salt of the (citric) acid in lemons is sodium citrate, however there is no good evidence that drinking lemon juice actually raises urine pH by a significant amount. And yes, I’m also aware that dietary intake of citrate is known to inhibit the formation of calcium oxalate and calcium phosphate kidney stones, but that’s a whole other thing. If you have kidney stones there are a number of dietary considerations to make, not least of which might be to cut down on your consumption of certain fruits and vegetables such as strawberries and spinach (and ironically, if you look at some of the – entirely unscientific – lists of acid-forming and alkali-forming foods these are almost always on the alkaline side).

Buffers for bluffers

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buffering

No, not that kind…

A little while ago now I wrote a post entitled Amazing Alkaline Lemons?. It’s been very popular, sort of. Well, it’s elicited an awful lot of comments anyway. Quite a few have mentioned buffers, which are jolly important things. They also seem to be somewhat misunderstood. So here we go, buffers 101:

Buffers regulate pH (remember that pH is the scale that measures how acidic, or basic, a solution is), and they’re essential in the body. Without them, your blood pH would fluctuate, and that that would be a very bad thing indeed. Outside a very narrow pH range (7.38 to 7.42, which is essentially neutral) proteins are denatured and enzymes stop working. In short, your body would quickly stop functioning in a really quite fatal way.

So what is a buffer? A buffer is actually a mixture, of a weak acid and its salt. Or, as chemists would say, its ‘conjugate base‘. (I’m deliberately avoiding the word ‘alkali’, because alkali has a specific meaning and it would be wrong to use it in this situation – I mention this because the word ‘alkalising’ has come up more than once).

The main buffer system in the blood is the bicarbonate buffering system. We need it because our blood has to transport carbon dioxide out of our bodies, and when carbon dioxide is dissolved in solution it forms an acid called carbonic acid. If this weren’t somehow controlled, our blood pH would quickly plummet and, as I’ve already mentioned, we’d die. This would obviously be something of an evolutionary dead-end.

Chemistry to the rescue! Carbonic acid (H2CO3) forms, but it also breaks apart again to form hydrogen ions (H+) and bicarbonate ions (HCO3–) producing something chemists call an equilibrium (symbolised by the funny two-way arrow you can see below).

H2CO3 ⇌ H+ + HCO3–

Equilibria have a way of balancing themselves out, and this is key to how buffers work. If you add some extra hydrogen ions to a buffer system the equilibrium shifts to absorb those hydrogen ions, keeping the pH constant. Likewise, if an alkali (or base) is added, it goes the other way and actually causes more hydrogen ions to be released. This is remarkably difficult to budge, unless you swamp it with a really strong acid (or base).

As a result, your blood pH stays perfectly balanced, and a good thing too. And all you need for it to work is to breathe. I recommend that if you want to stay healthy you don’t stop doing that.

There are other important buffer systems in the body. One that gets mentioned quite a lot is the phosphate buffer system. This plays a relatively minor role in controlling blood pH, but it is pretty important for your cells. This buffer is made up of dihydrogen phosphate ions and hydrogen phosphate ions. Phosphate plays an important role in bone health, not to mention your body’s ability to use energy effectively. Fortunately, unless you have some kind of fairly serious health problem your kidneys do a cracking job of controlling phosphate levels, so there’s no need to worry too much about it, beyond aiming, as we all should, for a generally healthy diet.

So there we are. Buffers are a mixture, they form naturally in the body, you don’t really need to do anything to help them along, and they quietly keep you alive. Pretty cool bit of everyday chemistry really.

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Amazing alkaline lemons?

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Tonight on How Not to Get Old (I really shouldn’t have been watching it) I heard the following gem:

Lemon

Can lemons neutralise acids? (Spoiler: no)

“Lemons neutralise acidity.”

In fact, not only did I hear it, it even flashed up on the screen in a helpful little box. The speaker was Elizabeth Peyton-Jones, who says on the Channel 4 website that she is a “herbalist, naturopath and food and health consultant” and that she has “run a highly successful alternative health clinic in Central London for over a decade.”

Hm.

256px-Zitronensäure_-_Citric_acid.svg

A molecule of citric acid. Definitely not an alkali.

Let’s start here: lemons are acidic. Why are they acidic? They contain citric acid, about 5% by weight. Citric acid has the chemical formula C6H8O7, and the catchy systematic name of 2-hydroxypropane-1,2,3-tricarboxylic acid. If you look at the molecule you can see why it’s an acid. See those OH’s that are sitting next to =O’s? Those are acid groups. There are three of them. This is most definitely an acid.

Why do they make it an acid? Or rather, what is an acid? Well there is a bit more to this than I’m about to explain (interested parties could read about Lewis acids) but essentially acids are substances that can release H+ ions (‘hydrogen ions’) when they’re dissolved in water. Those three acid groups in citric acid can, in theory, release three H+ ions per molecule. So you might expect that citric acid is a pretty strong acid.

In fact, it’s not.  It’s actually what chemists call a weak acid, because although it can release three hydrogen ions per molecule it doesn’t really want to that much. It’s a stingy old Scrooge and likes to keep hold of them. But that doesn’t make it somehow not an acid, it still is one. The pH of lemon juice is about 2.

Which brings me to pH. It’s possibly the most abused and misunderstood scale ever. (There are two wonderful blog posts on that very subject, written by Marc Leger, which you really should read, obviously after you’ve finished here.) I’ve even found a school text book, yes honestly a school text book, that said “no one really knows what pH stands for”. Er. What?

Chemists know what it stands for thank you very much (I suspect, or at least hope, that the author of that book was not a chemist). The H stands for, guess what? Yes, the amount of hydrogen ions. The p is a symbol chemists use as shorthand for ‘negative log10‘ (it’s p because it comes from the German word for potency or power, potenz, and this might be why some books claim that pH stands for ‘potential hydrogen’, which it doesn’t really).

Log refers to logarithms. I’m not going to explain those in depth here – if you want to know more, this page has a clear explanation – but you will have come across other log scales. Probably the best-known is the one used to describe earthquakes: the Richter scale. Basically when you go up by a factor of 1 on the scale, it’s actually a power of 10. A major would-seriously-damage-buildings earthquake that measures 7 on the Richter scale is 1000 times more powerful than a light crockery-rattling quake that only measures 4. The pH scale is like this: every point on the scale represents ten times more (or fewer, depending on which way you’re going) hydrogen ions.

Slightly counter-intuitively (but the maths works out, honest) a lower pH means more hydrogen ions. An acidic solution with a pH of 2 has 1000 times more free hydrogen ions than one with a pH of 5. The pH scale goes from 14 down to 0, and actually negative pH values are possible as well. Values above 7 are described as alkaline (or basic), 7 itself is neutral and those below 7 are acidic.

Saying that this or that acid has a pH of a specific number (like I sort of did back up there when talking about lemons, remember I started with lemons?) is a bit of a nonsense, although many authors do it. pH refers to the concentration of hydrogen ions. You could get some hydrochloric acid (the stuff in your stomach) and dilute it, and its pH would actually go up. Really. If you drop a bit of lemon juice in a big glass of water its pH would be closer to neutral (pH 7) than 2. If you think about it you know this: drink neat lemon juice and you’re puckering up your lips in a classic ‘sour’ face. Drink some water with a bit of lemon in and you barely notice it.

Phew. Ok. Back to the frankly silly statement that lemons neutralise acid. We’ve established that lemons contain citric acid, and although citric acid is a weak acid, it still is an acid. It produces hydrogen ions when you put it in water, and for that reason the pH of lemon juice – as it comes out of the lemon – is about 2.

If you want to neutralise an acid, you need an alkali (or, more generally, a base). Alkalis contain OH– ions (hydroxide ions) which can react with hydrogen ions and actually remove them from a solution, like this:

H+  +  OH–  –>  H2O

Look, that’s water on the right hand side of that slightly-wonky arrow. Pure water has a neutral pH of 7. If you add exactly enough hydroxide ions to join up with all the hydrogen ions, you get water (and a salt, because there will have been some other stuff in there as well).

Once you get this far, it becomes fairly obvious that adding more hydrogen ions to hydrogen ions isn’t going to neutralise anything. It’s like trying to turn your blue paint purple by adding more blue paint.

If anything, adding more acid will make your solution even more acidic (although with a weak acid it may not be quite that simple, is it ever?) Again, experience bears this out. Your stomach contains hydrochloric acid, along with some other stuff, and has a pH of between 1.5 and 3.5. Fortunately your stomach is lined with special cells that protect you from this powerful stuff. Acid indigestion, something many of us have experienced at one time or another, happens (usually) when that stomach acid gets where it shouldn’t be, i.e. into your esophagus, where it burns.

If you have indigestion, do you drink lemon juice? No you do not. Not unless you actively like pain, that is. No, you take an indigestion remedy. Guess what they’re made of? Yes, alkalis, or bases (and sometimes other clever ingredients as well). They really do neutralise the excess acid by way of the equation I wrote up there.

And unless you have indigestion, why would you want to ‘neutralise acidity’ anyway? Stomach acid evolved for a reason. It helps to break down your food, proteins in particular, and it also keeps you safe from lots of bacteria and other nasties which usually don’t like acidic conditions. Once your stomach has done its thing the partially-digested food passes into your small intestine where it gets squirted with bile, which actually does neutralise it so it can pass through your intestines without doing any damage.

Your body has this covered. There really is no need to mess with it, and in any case, you can’t really. At least, not beyond your stomach (and urine, possibly – see my comment at the end). Homeostasis insures that everything stays remarkably consistent, and good thing too. There are lots of chemical reactions going on in your body that keep you alive, whether you realise it or not. If you could actually mess with the pH of your blood (pH 7.35-7.45) you’d be in a whole heap of trouble.

So can lemons neutralise acid? No. Can what you eat ‘alkalize’ your blood? (It’s terrifying just how many websites there are about this.) No. Absolutely not. Under no circumstances. If you were to eat a lot of indigestion tablets they would neutralise the acid in your stomach, but that would have no effect on your blood. Literally no effect.

By all means eat a healthy diet. Fruit and vegetables are definitely good for you. Lemons contain vitamin C (yet another acid: ascorbic acid) which is a vital nutrient. Eating them will certainly do you no harm and might well do you some good. But don’t let anyone tell you they’re anything more than a healthy citrus fruit.

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Note: 
As you can see, this post has generated a lot of comments. Some more scientific than others.  In particular, a lot of them have focused on urine, and the effect lemon juice might or might not have on urine pH. My original post was not about urine, but clearly a lot of people are fascinated by the subject. Who knew?

So here’s a little extra on that topic to save me repeating myself in comments.

It’s well-known that chemical makeup of urine can be affected by what we eat. We’ve probably all experienced the odd effects of asparagus, or beetroot, or even sugar puffs, so the idea that certain dietary substances make their way into urine is nothing particularly new or surprising.

And following from this it IS possible to affect urine pH by eating or drinking certain substances. For example, if you’re a cystitis sufferer, you might have used a sodium citrate-containing product such as Cymalon. During a cystitis attack the urine becomes more acidic. These products work by creating a buffer effect in the bladder, which means they raise the pH slightly towards neutral and, crucially, stabilise it so that it doesn’t drop again (or, indeed, rise).

Lemons contain citric acid, the salt of which is citrate. So it’s possible eating a lot of lemons (or drinking a lot of lemon juice) could have a similar effect. I found a paper on this very topic. The researchers found that drinking lemon juice produced a small increase in urinary pH from about 6.7 to 6.9. So, ok, it went up a tiny bit (remember that pH 7 is neutral) but given that the error in their measurements was +/- 0.1, that’s virtually no change at all.

That said, the main focus of their interest was actually treatment of kidney stones, which are, in some cases, caused by a build-up of calcium oxalate which then forms crystals. The researchers found that the lemon juice helped the body to get rid of oxalate, and they’re not the only ones to draw this conclusion. Magnesium can also help prevent kidney stone formation (magnesium-rich foods include leafy greens, nuts and seeds, oily fish and whole grains – basically all that ‘healthy diet’ stuff, funnily enough).

So in summary (and I stress, I am not a medical doctor and you should take your GP’s advice over that of some blogger on the internet), if you suffer from kidney stones, lemon juice might be helpful. It certainly won’t do you any harm (well, except possibly to your tooth enamel). A generally healthy diet will also, not surprisingly, be beneficial. Lemon juice might have a very tiny effect on urine pH. However if it does, the result is only to raise the pH a tiny bit closer to pH 7 (i.e. neutral). It does not make your urine alkaline.

The topic of gout has also come up. Vitamin C is known to help with gout. Lemons contain a lot of vitamin C (ascorbic acid, not to be confused with citric acid). If you’re a gout sufferer, drinking lemon juice might help. Although taking a vitamin C supplement might be even better.

None of this in any way relates to the blood, or ‘the body’ in general. You cannot, absolutely cannot, affect your blood pH with your diet, and nor would you want to.

Oh, and buffers seem to come up a lot too. To save time I put all of that in a separate blog post: buffers for bluffers.

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Note: comments have been closed on th

is post because I found myself repeatedly refuting the same arguments over and over again. One in particular is the notion that lemon juice somehow becomes alkaline once in the body, and that this is why lemons are considered ‘alkaline’. Lemon juice will certainly be neutralised during the digestive process but there is no mechanism by which it could possibly “become alkaline”. Please don’t post comments on other pages in this site to get around the fact that comments have been closed.

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