Monthly Archives: September 2010

Gastroneuromythbusting

Ok after all the serious discussion and meta-analysis and breaking out the graphs of the last post, it’s time for some fun! (Warning: my definition of fun almost guaranteed not to match your definition of fun.) Time for some mythbusting tangentially related to food and braaaaaaains!

Myth: Sugar makes you hyperactive (especially if you’re a kid).

Perhaps my favourite medical myth ever! It’s more like a pandemic than a myth, because it is just everywhere. So let me say it clearly: sugar does not cause hyperactivity. No ifs or buts. It doesn’t. End of story. Twelve well-conducted trials have found no relationship between sugar and hyperactivity. It doesn’t depend on the amount of sugar. It doesn’t depend on whether the kid has ADHD. It doesn’t matter if the sugar is processed and refined or natural. It doesn’t matter if it’s sweets or chocolate or fruit. There is no link.

“But but but,” you say, clearly ignoring my stipulation of no buts. “But my kid goes crazy after having something sugary. Every time! It’s a clear-cut case of cause-and-effect!” Ahh, my anecdote-spewing friend. You must remember the sheer power of the brain to see the things it wants to see or expects to see.

Scientists conducted a particularly cute little study to look at this. Parents and their kids participated in this one. In one condition, kids were given a placebo pill with no active ingredient and their parents were told this. In another condition, kids were given a pill containing a big dose of sugar and their parents were told this. Each kid would then have a bit of a play and his or her parent was asked to rate their kid’s behaviour. Parents whose child had received the big dose of sugar reported that their child was off the walls with hyperactivity, definitely more energetic than usual, more frenetic, way more active, more crazy. Too bad that in a charming little twist of the kind we have come to expect of psychology experiments like this, all the children had been given placebo. The only thing that varied was whether parents thought their kid had had sugar or not.

And before you say “Oh no, that doesn’t apply to me! My kid really does go hyper on sugar!”, please just stop and don’t say it. Because it does apply to you. Unless you’ve conducted your own strictly controlled trial where your kid was randomly given either a pill full of sugar or an inactive placebo on multiple occasions (in a way that hid the identity of the pill from the kid as well) and a panel of independent raters who had no knowledge of whether your kid had had sugar or placebo evaluated the kid’s behaviour and when the codes were broken, your kid consistently scored higher for hyperactivity symptoms in the sugar condition to a statistically significant extent. Did you do that? Huh? Huh? No, I didn’t think so.

I rest my case.

(But if you did do all that, well done you on your double-blind randomised placebo-controlled study and your weird kid.)

References
Vreeman, R.C. & Carroll, A.E. (2008) Festive medical myths. British Medical Journal, 337:a2760. (Seriously, I love this paper. Read the whole thing here.)
Hoover, D.W. & Milich, R. (1994). Effects of sugar ingestion expectancies on mother-child interactions. Journal of Abnormal Child Psychology, 22(4), 501-515.

Recipe for chocolate chai madeleines (which contain 3/4 of a cup of sugar) after the cut.

KNOW YOUR CHOCOLATE

(Epic post ahoy!)

Hello, come in, come in, please, come in and make yourself comfortable. How are you? Good? Good. Are those new mittens? They’re lovely. Can I offer you a drink, maybe a Pimms No. 1 with over-sized cucumber garnish? No? Would you like a delicious biscuit? Ok, here’s a delicious biscuit.

Now that you’re comfortable and have a delicious biscuit…

… we need to talk.

Please assume the brace position, as this is heavy news.

Chocolate is probably not that good for you. The antioxidants and all that good-for-you-heart stuff, well… it’s not all it’s made out to be.

There’s been a gargantuan 18-wheeler truckload of stuff in the media about how eating chocolate is good for you. Why is it good for you? It’s got antioxidants! Antioxidants that, well, they stop your body from ageing… and stuff. They stop your cells from getting attacked by, um… nasty things! They prevent cardiovascular problems. Chocolate is full of antioxidants so chocolate prevents cardiovascular problems! Right? Right?

Well, maybe, maybe not. I’m sorry, but it’s just not black and white like that. (It so rarely is with science. Sigh.) There is plenty of research being conducted into the cardiovascular-protective properties of chocolate consumption, and it’s been going on for a fair few years now. Unfortunately, the evidence is not conclusive, and we’re starting to realise that the research that’s gone on so far isn’t anywhere near detailed enough to tell us about whether we should eat chocolate for its cardio-protective qualities, and if so, how much.

It’s true that a fair few studies have found results like “consumption of dark chocolate is correlated with a reduction in blood pressure”. But! (There’s always a but in science, damn it.) When you look at the studies overall, there are a lot of problems.

The number of people in a lot of the studies is quite small, so that increases the chances that we might be seeing false positives in the results, i.e. we think we see a relationship between chocolate consumption and cardiovascular health but actually there isn’t one. The results we have so far just don’t allow us to reliably conclude that chocolate consumption definitely does (or does not) improve cardiovascular health in any specific way.

Some of the studies are conducted over a pretty short time period. These are acute intervention studies that only look at the effects of dark chocolate consumption over a few days (and for those few days, maybe people in the study are paying better attention to their health and stress levels purely by virtue of being in a study that draws attention to those aspects of their lives). These short studies don’t tell us much about the long-term effects of chocolate consumption on either cardiovascular health or other important aspects of health. Need more info.

The amounts of chocolate that should be consumed to achieve any reported improvement in blood pressure or whatever are all over the place. Some studies say you need to eat 2 squares a day to improve blood pressure, but don’t have more than 2 because that doesn’t improve blood pressure. Some studies say you need to eat a few squares daily, whereas others say you only need 10 square per month. It’s a big confusing mess, really. In fact, we’re not even sure if there are enough antioxidants in chocolate to have any impact on overall antioxidant levels in the body — studies that show antioxidants improve cell health in cell cultures in a dish in a lab have used antioxidant concentrations many many times greater than what could be achieved in the human body by eating chocolate. Basically your stomach would be exploding in chocolate pyrotechnics if you ate enough chocolate to get the same concentrations as the cells in the lab were being dosed with. I’d prefer not to explode, quite frankly.

And something that’s emerging as a major flaw in this research is that we don’t know the exact levels of antioxidants in different chocolates. We know dark chocolate is probably highest in antioxidants, but there’s a huge range of variation in the amounts depending not just on percentage cacao, but also how the cacao was treated and processed and where it originally came from. For example, some processing methods can radically reduce the key antioxidant compounds such as catechin and epicatechin. So essentially, when a study is done to see whether chocolate consumption results in improved health measures, we don’t actually know what sort of dose of antioxidants these people in the study are getting!

The upshot of this is that we can’t possibly recommend a particular amount of chocolate to consume in order to get health benefits — we don’t know what amount of antioxidants is in any given chocolate, and we don’t know what the ideal dose of antioxidants is anyway.

Alright, so antioxidants play an undeniably important role in the health of the human body. But here’s the thing: just because something is necessary for health, doesn’t mean that big amounts of it are good for you, and that even bigger amount are better. In fact, it’s usually quite the opposite.

If there’s one thing you learn this year about science and health, make it this: a lot of things are on what’s called an inverted-U curve. It’s not a linear trend of more = better. It’s more like not enough is bad, enough is good, too much is bad again. However, we have to do an enormous amount of research to establish what “enough” actually is. At the moment, we’re trying to work out what “enough” is for antioxidants, but it’s safe to assume that too much is probably a bad thing.

In fact, an enormous review was done of the antioxidant research. Bjelakovic and colleagues did a systematic review and meta-analysis of studies that looked at what happened when people were given antioxidants supplements. This means that they looked at a whole heap of studies, kicked out the ones that weren’t rigorous enough, then tried to figure out the bigger picture that the well-conducted, rigorous studies were painting. They looked at 68 of these good-quality studies, which altogether tested the effects of antioxidant supplementation (in the form of beta carotene, vitamin A, vitamin C, vitamin E or selenium) in 232,606 people. With that many people, surely you’ve got the ability to detect even tiny little relationships between the antioxidant supplementation and health outcomes.

And the results of this enormously powerful meta-analysis? Some antioxidant supplementation might cause bad health outcomes, whereas others still have an unclear effect. Still! After all those studies and all those people! There was no clear benefit to taking extra antioxidants. This could be because: (a) there’s no relationship between extra antioxidants and the health variables being measured, (b) the relationship is so small and subtle it’s difficult to detect or (c) the effects are dependent on other variables that we aren’t taking account. My money’s on (c).

So it’s kind of scary when you think about how frequently the media and various companies (with a financial interest in getting us to buy their products) tell us we should be indiscriminately cramming antioxidants every which-way into our bodies. (Goji berries! You need goji berries! Or was it acai berries that were the latest superfood du jour? Oh god just get some pomegranate before it’s too late! Don’t you want to live forever?) It’s entirely unsurprising that most of us have absorbed the inaccurate message that antioxidants are always good for us and we need as big a dose as we can get.

But even though we don’t know what the right amount of antioxidants is for optimal health benefits (yet), and even though we don’t know what precise levels of antioxidants are in various products, and even though we’re surrounded by products with labels zealously screaming “FULL OF ANTIOXIDANTS!”, and even though we don’t know if we’re getting too little or too much, don’t despair! What should you do? It’s old and tired and not that interesting, but it’s the truth: eat a balanced diet and eat things in moderation. If you do that (along with some exercise) you’ve got a very good chance of getting pretty much everything you need to achieve very good health. If you’re eating tomatoes and carrots and that sort of thing and maybe a bit of dark chocolate here and there, you’re probably getting the antioxidants you need. Don’t fret!

So maybe, eventually, research will be able to pin-point exactly what daily dose of antioxidants we should aim to get, and whether we can eat chocolate to get some of that dose. Until then, don’t use “it’s good for me!” as an excuse to eat chocolate. If you’re leading a generally healthy lifestyle, you can eat it chocolate just because you enjoy it — you don’t need much more justification than that, right?

Thank you for your time. And now: a recipe.

Recipe for not-actually-superfood cookie sandwiches under the cut.

Your imagination vs chocolate cravings

So, perhaps you’re craving chocolate (perhaps even those innocent little rose petal truffles in the photo). It’s just a fact of life for a lot of people, but sometimes, occasionally, maybe it’s just not convenient. Maybe you’re scuba diving or fighting a tiger or climbing a tower taller than the Empire State Building on your way to work. Or maybe you went to the cupboard to get some chocolate because you were longing, nay, aching for it, but it turns out you forgot you ate it all and a big vortex of horror and despair opens up in your heart. Luckily, using your imagination to conjure up vivid images and smells unrelated to chocolate will decrease that craving1.

Chocolate-loving participants in this study were asked to abstain from eating chocolate and were then asked to imagine themselves eating their favourite chocolate (oh the cruelty that exists in psychology experiments). This induced chocolate cravings, unsurprisingly, which participants rated on a scale of 0 to 100 (0 being no urge/desire to eat and 100 being extremely strong urge/desire to eat).

Each participant then performed a mental imagery task, in one of three modalities: visual, auditory or olfactory. So they had to vividly imagine sights, sounds or smells, as prompted by written instructions (e.g. “imagine the appearance of a rainbow”, “imagine the sound of a door squeaking”, “imagine the smell of pencil shavings”). They did this for 18 different instructions in their given sensory modality. They then rated how strong their craving for chocolate was, again from 0 to 100.

Turns out that there’s a pretty big decrease in average craving ratings in the group of people that imagined sights (ratings dropped from about 60/100 to 33/100) and the group that imagined smells (a drop from about 59/100 to 38/100), but not much of a decrease in the group that imagined sounds (a drop from about 54/100 to 45/100). Inquiring minds want to know why!

The suggested reason for the craving decrease is that your brain only has so much memory it can dedicate to things that are currently going on, so if your brain is currently thinking about how much you want to eat chocolate but you then force it to actively and vividly imagine something else, this part of your memory (known as working memory) runs out of resources and the craving gets shuffled aside and relegated to the background. Sights and smells are pretty important parts of the chocolate-eating experience whereas sound generally isn’t, potentially explaining why the craving reduction wasn’t seen after participant imagined sounds. Put that in your pipe and smoke it, inconvenient cravings!

And this doesn’t just work for chocolate cravings, of course. The chocolate craving experiment was the second experiment in the study; the first experiment looked at the imagination task’s ability to decrease food cravings for whatever your favourite food or meal might be, since it also worked for people who might have been craving Atlantic salmon, bacon and eggs or roast lamb.

Other studies by the same research group have found a few more interesting little relationships between food craving and working memory. For example, habitual chocolate cravers perform more poorly on working memory tasks (such as working out short little mathematical equations in their heads) because they allocate too much working memory capacity to their craving when they’ve been deprived of chocolate2, while chocolate cravers can reduce their cravings even just by passively watching a flickering pattern designed to tax the visual aspect of working memory3.

So if you’re craving chocolate (or some other food) and unfortunate circumstances have conspired to deny you that which you so desperately want, use your imagination to fill that working memory up and squeeze the cravings into the shadows. It might work, even if just in the very short term, and maybe, just maybe… you’ll be able to cope until you can get to the shop. Hang in there.

(Recipe for rose petal truffles after the cut. I made these for Dr Tash PhD because she brought me back so many nice chocolate things from her U.S. jaunt.)

Taste in the face

There’s no art
to find the mind’s construction in the face.

Macbeth, Act 1 Scene 4

I might be going out on a limb when I suggest that Shakespeare probably wasn’t a neuroscientist. I’m sure I can find some Shakespeare conspiracy theorists to tell me how wrong I am and that Christopher Marlowe was also a talented geneticist in between writing Shakespeare’s work, but for that line in Macbeth to suggest that our faces do not betray our thoughts and feelings and intentions indicates clearly that Shakespeare had a very poor understanding of modern social neuroscience research between the 1970s and 2010. How embarrassing for him.

These are “Old Fashioned” snickerdoodles, based on the sweet and bitter taste combination of the Old Fashioned cocktail. (This recipe is from the book The Boozy Baker, which Dan bestowed upon me after returning from a social cognition workshop via NYC and San Francisco — thanks, Dan!) One interesting bit of research looking and both sweet and bitter tastes found some very intriguing results about how our faces react to those tastes, and also how changing our emotional state changes our ability to perceive tastes. Who would have thought — eating is tied in with feelings! (Hi to all the other emotional eaters out there. Let’s have a piece of cake to celebrate how interesting neuroscience research is!)

In a study by Greimel et al., researchers video-recorded people’s facial expressions as they were drinking either a sweet chocolate drink, a bitter quinine drink, or a bitter-sweet carbonated drink. (The chocolate drink was Müllermilch Schoko and the carbonated drink was Schweppes Bitter Lemon, if you’re planning on replicating this experiment in the comfort of your own home or laboratory.) The researchers later watched these videos and scored a range of particular facial movements (brow lower, lip press, upper lip raise, etc.) to see what people did with their faces when they tasted a bitter or sweet taste.

In a not highly surprising result, sweet and bitter tastes elicited different facial expressions. Bitter tastes warranted brow lowering and lip raising just prior to swallowing, then brow lowering and mouth opening after swallowing, and on the odd occasion, a smile, presumably by the people cynically amused by their unfortunate situation of having to drink something gross like quinine. Sweet tastes reliably resulted in lip sucking before swallowing, lip wiping after swallowing, and of course, smiling (including the Duchenne smile, which is when you smile with your eyes as well as your mouth — yes, it has a name!).

So the specifics are interesting but overall, none of this is all that surprising — we all make the faces too and we’ve all seen other people make the faces. But the other thing the researchers did was that after people had tasted all the different drinks, they were shown one of two movie clips. One group was shown a clip that was intended to make them feel happy, whereas the other group was shown a clip that was intended to make them feel sad. Then — they tasted the different drinks again.

And what did this show? It showed that changing someone’s emotional state makes them perceive tastes differently. More specifically, people who had watched the happy clip then found the sweet chocolate drink even sweeter and more pleasant. People who had watched the sad clip then found the sweet chocolate drink less sweet and less pleasant. How nice this chocolate drink tasted was dependent on whether the person was a bit happier or a bit sadder.

This was not the case, however, for the bitter-tasting drink. Watching the happy movie clip or the sad movie clip didn’t change people’s ratings of how bitter or unpleasant the drink was. A potential explanation of this is that sugary sweetness plays with the neural wiring of our emotions a bit more because the brain wants to reward us for seeking out energy-rich sugar by giving us a pleasant, hedonic experience after we eat something sweet. Bitterness, on the other hand, doesn’t really need that kind of emotional involvement. It might play a role in telling us what foods to avoid, since bitterness can be associated with toxins in the things that our ancestors might have been jamming in their mouths to see if they were any good for eating — but if something is bad for us, and it tastes bitter when we eat it, and then we get physically sick from it, that association between the bitter taste and physical sickness is an association that doesn’t need more subtle emotional prompting from the brain to make us realise to not eat the bitter berries next time or we’ll end up with our stomach contents on our feet. Bitterness also doesn’t reliably tell us much about nutritional value of food. So if we want to learn to avoid something that could potentially kill us, probably better to not just have our brains’ perception of that bad taste be susceptible to our emotional state (and probably better to have a more emphatic response to bad food, rather than our brains just making us a feel a little bit sad after eating something potentially deadly).

So the next time you’re on a hedonic quest for enjoyment through the wonders of cake, chocolate, ice-cream, whatever, pre-emptively enhance your experience by watching something heart-warming or hilarious. If you wish to adhere to the rigours of scientific research, you can even use the exact movie clip used in the experiment in elicit the happy state. It’s this one.

References
Greimel et al. (2006). Facial and affective reactions to tastes and their modulation by sadness and joy. Physiology & Behavior, 89, 261-269.

Recipe for “Old Fashioned” snickerdoodles under the cut.

Sweet, sweet sugar: delicious pain-killer

Brace your teeth (figuratively, not orthodontically), for these are white chocolate mud cupcakes with honey-roasted soybeans, cocoa nibs, toffee mascarpone icing and crystallised violets.

Their technical name is Jess’s Hannah-Inspired Cupcakes of Amazing Wonderment Forever, as I made them as an adaptation of the customised chocolate bar dear Hannah of wayfaringchocolate.com wrote about here. “The sheer fantasticality of such an orchestra of flavours must surely be pursued and captured in cake format,” I thought to myself while stroking my imaginary goatee. So I sent out my ant army to collect sugar for me grain by grain, I milked some bees, and I laboured with many sugars over many hours to bring you these diabolically sugary little cakes.

And why not? I mean, other than the tooth decay?

Especially since sugar (sucrose, more specifically) is a genuine pain-killer. It acts as an analgesic and it has medical applications for pain management. Sweetness can numb the pain, so it seems.

It seems that sugar’s pain-killing effect results from the actual taste perception of sweetness. The pain reduction only occurs when a person consumes the sugar orally. If the sugar is administered directly into the stomach via a tube — no effect on pain1. So if actually tasting the sugar on your tongue is an essential part of its effect on pain, what does that tell us? We don’t know for sure yet, but at the moment it seems likely that the pleasant sensation of tasting something sweet releases opioids in the brain2, which is the usual way by which your brain decreases your perception of pain after taking a pain-killer. It’s as simple as tasting something that your brain is usually hard-wired to find pretty nice.

You can demonstrate this in the lab by getting people to submerge their arm in unpleasantly cold water for as long as they can — they can tolerate the painful coldness around 50% longer when they have sucrose dissolved in water in their mouth than when they just have plain water in their mouth (so around 75 seconds instead of around 50)3. Nifty! That’s all well and good, but that doesn’t tell us much about what sugar can do for people who don’t have the option of going “ok, yeah, that’s enough now” and walking away from the pain.

Well, sugar has been used for a long time to manage pain in infants. You don’t want to be giving infants and their young little nervous systems hard-hitting pain-killers and their associated side-effects if you can avoid it, and it turns out that giving them some sucrose dissolved in water does help decrease pain after things like minor invasive procedures4, 5. However, sugar’s pain-killing effects in adults are more modest6, possibly due to infants and children having a comparatively stronger liking for sugar (so their brains would get more of an opioid kick out of tasting something sweet), so dosing up on sugar is not of tremendous use for management of severe pain in adults.

So don’t you go and use this as an excuse to inhale a whole sugar-dusted sugar-cake studded with sugar lumps to ease the pain the next time you walk forcefully into the corner of a table. Unless you really, really want to. There are cons to accompany to pros of sugar consumption, so… everything in moderation! (Except high-fructose corn syrup — avoid that like the plague.)

Recipe for Jess’s Hannah-Inspired Cupcakes of Amazing Wonderment Forever, A.K.A. white chocolate mud cupcakes with toffee icing, after the cut.