No, ketchup does not cause cancer

ketchup and coke

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

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

Sugar found in ketchup and Coke linked to breast cancer

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

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

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

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

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

Saccharose2

Sucrose

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

157px-Alpha-D-Glucopyranose

Glucose

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

179px-Beta-D-Fructofuranose

Fructose

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

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

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

sugar

Soft drinks and fruit juice both contain a lot of sugar

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

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

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

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

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

mouse

Mice are not people

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

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

ketchup on bread

Maybe cut back on the fried ketchup sandwiches

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

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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.

 

 

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Sugar that’s not sugar?

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

LinusGorpeDragonsDen

Linus Gorpe on BBC’s Dragon’s Den

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

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

No, I was more bothered by this little exchange:

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

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

Saccharose2

Sucrose

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

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

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

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

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

179px-Beta-D-Fructofuranose

Fructose

157px-Alpha-D-Glucopyranose

Glucose

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

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

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

Coconut palm sugar

Coconut palm sugar

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

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

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

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

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

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

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