No, ketchup does not cause cancer

ketchup and coke

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

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

Sugar found in ketchup and Coke linked to breast cancer

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

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

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

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

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



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



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



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

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

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


Soft drinks and fruit juice both contain a lot of sugar

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

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

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

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

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


Mice are not people

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

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

ketchup on bread

Maybe cut back on the fried ketchup sandwiches

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

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




Words of woo: what does ‘alkalise’ mean?


‘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. ( and, simply, ‘to make alkaline’ (Collins).


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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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).

Does drinking alcohol actually cause dehydration?


Today I came across this article: Drinking water doesn’t prevent a hangover, study says, which includes the memorable line: “[the] study concluded, the only way to prevent a hangover is to drink less alcohol.”

Now, at first sight, you might think that surely this simply another piece of work from the University of the Bleedin’ Obvious.

But hang on. Alcohol does dehydrate you, doesn’t it? Everyone knows that! After all, don’t you wee more when you go drinking, and wake up all sweaty and with a dry mouth after a ‘heavy night’? Surely this is all evidence of fluid loss? Am I really about to suggest we should consign ‘alcohol causes dehydration” to the collection of alcohol-based myths such as mixing drinks gives you a worse hangover (only if you drink more as a result), a night cap will help you sleep (only temporarily, overall it tends to disrupt sleep), drinking beer will cause a ‘beer belly’ (too much of any type of drink can cause weight gain), and so on?



There are many alcohols; ethanol is the one we drink.

Firstly, what is alcohol or, more specifically (the word ‘alcohol’ actually refers to a group of compounds), ethanol? It’s a simple molecule, containing only two carbon atoms, an oxygen and some hydrogen atoms. It’s produced, as we all learned at school (or possibly when attempting home-brewing), by yeast during the process of fermentation. Feed this clever little single-celled organism some sugar and voilà, it produces ethanol (C2H5OH) and carbon dioxide via a remarkably simple equation:

C6H12O6 –> 2C2H5OH + 2CO2


Marula fruit naturally ferments.

Humans learned this trick a long time ago and have been brewing for literally thousands of years. In fact it doesn’t even require human intervention – marlula fruit is particularly famous for becoming naturally alcoholic (although stories of monkeys and elephants using it to get drunk might be somewhat exaggerated).

We like drinking because, of course, of what it does to us. In medical terms, it’s a central nervous system depressant with significant psychoactive effects (sounds fun, eh?) In English, it reduces anxiety, making drinkers feel relaxed and happy. This accompanies a decrease in motor skills of course, which is why drinking and driving is illegal virtually everywhere (although exact definitions of what this means do vary).

But while alcohol is all natural, it’s not what you’d consider healthy. Every now and then someone drags out some data that suggests that low to moderate alcohol intake is good for you, but this sadly appears to be more wishful thinking than good science. In terms of disease, alcohol consumption has been linked with stroke, high blood pressure, several liver diseases, pancreatitis, a weakened immune system and a handful of cancers including mouth, throat, liver and breast cancers.

In fact, alcohol has been categorised by the International Agency for Research on Cancer as a group 1 carcinogen, which puts it in the company of such other delights as asbestos, radium isotopes, ultraviolet radiation, diesel exhaust and tobacco.


Give up alcohol before you worry about your latte ingredients.

Of course, the dose makes the poison. Lots of people enjoy low to moderate alcohol consumption quite safely. Still, I have to admit to being amused by health nuts that insist on a diet consisting of little more than raw vegetables, make a fuss about so-called GMOs, campaign for additives (none of which are anywhere close to being group 1 carcinogens) to be removed from food, and then post pictures of themselves drinking wine. You really want to improve your health? Never mind caramel colour IV in your latte, give up the booze.

So, alcohol isn’t a health food, or indeed drink. But to get back to the original question, does it cause dehydration? Well, it would appear that while it does do a lot of bad stuff health-wise, that’s not one of the bad things it does. In a study, men drank six pints of beer and were then subjected to a number of tests. As the subsequent PubMed article states: “All subjects had a slight hangover, but none was fluid depleted”.

Screen Shot 2015-08-29 at 18.22.08

Twin doctors Chris and Xand van Tulleken in a recent BBC documentary.

In a recent BBC Horizon documentary, twin doctors Chris and Xand van Tulleken collected all their urine during a night in which Xand drank 21 units of alcohol in one sitting (while his brother only had one drink), and next morning demonstrated that the volumes were the same. In other words, the excessive alcohol consumption had not, as is widely believed, had a significant diuretic effect.

Admittedly, this was only two people, and the PubMed study only involved six participants – small sample size is often an issue with such work. The Dutch study I mentioned at the start was much larger, which is one reason it’s useful. In that study, drinking water appeared to make little difference to the severity of the hangover experienced. The only thing that really mattered was, not surprisingly, how much alcohol had been consumed.

In fact it’s not well-understood what does cause hangovers. It would appear it’s linked to an immune system response. In very simple terms, getting blind drunk is a little like self-imposed flu. Drinking plenty of fluids won’t do you any harm, but it’s not actually a solution. Of course, there’s no virus involved here to keep the immune system on the warpath, so for most healthy people the best, and probably only, hangover cure is time.

So in summary, yes, we probably can chuck “alcohol causes dehydration” in with all the other alcohol myths floating around out there, but that’s not an excuse to have a pint after your workout.

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