What is going on with the 2016 census?

So if you’ve been an Australian on the internet in the past month, you will know there is a furore in process about changes to the way identifying information (names and birth dates) will be used and stored after the 2016 census.

This post is an attempt to explain what’s going on in laymen’s terms, based on my understanding as a researcher who uses this kind of linked data from the Australian federal government. This post reflects my understanding; as far I as I know it is free of errors, but please let me know if you believe I’m mistaken about any of the facts. It’s also not exhaustive; I’m focusing on the parts I feel strongly about as a public health researcher.

What the ABS appears to be proposing is that as part of completing the census this year is people will be expected to give their names, dates of birth, genders, and addresses. This data will be stored for up to four years, an increase on the previous time period, and will be used to create a linkage key to allow the ABS to do additional data analysis with other datasets (pdf link, see page 7 ).

What’s a linkage key?

A linkage key is an ID number that allows the linking together of multiple datasets, via identifying information. For example, one of the data sources that the ABS has mentioned is health data, i.e. the Medicare database. Medicare knows your name, your date of birth, and your current address. Once the ABS has this information on your census record, computer folk can use the identifying information to match the two records together.

This is done by assigning an ID number (the linkage key) in one dataset, and then matching the same number to the name, date of birth and address in the second dataset, in order to subsequently link the two datasets together. So Jennifer Smith, born 5th April 1979, living on Canterbury Rd in Malvern, gets ID number 300002 assigned to her in her Medicare record, and then this number gets matched to the census record with the same name, date of birth, and address. Then Jennifer’s name, date of birth and address can be deleted from both datasets, and the datasets can be linked together just using her ID number. This process is repeated for everybody. Eventually a researcher or a statistician ends up with a dataset containing everybody’s Medicare data, everybody’s Census data, and everybody’s ID numbers, but nobody’s name, address, or date of birth. The names, dates of birth, and addresses can then be discarded or destroyed. (This is what I assume the ABS is referring to when they say they will never share identified information about you – at the point it’s shared, your name has been removed from it).

Why do this kind of research?

There is a lot of information about people that is relevant to their health, but isn’t routinely recorded in their medical records. A key example in Australia is whether somebody identifies as Aboriginal and Torres Strait Islander, which is normally not recorded in their Medicare data, but is recorded in the census. Linking Medicare and census therefore allows detailed research into issues affecting the health of Aboriginal and Torres Strait Islander people, at the population level. This kind of research is immensely valuable, and whole-of-population linked datasets are the holy grail in terms of data sources. This is just one example; you can do data linkage research on anything if the information you need is contained in two or more separate databases; the ABS has also mentioned employment and unemployment as a topic of interest.

So what’s the problem?

The problem, at least for me as a researcher, is that people aren’t being given the option to withhold consent and opt out of this research. I don’t think people are morally obligated to allow their personal data be used to research if they don’t want it to be. I certainly don’t think they should be legally obligated to provide their names and dates of birth so that this kind of research can take place, if they would rather complete the census anonymously. The primary purpose of the census is to count and describe the Australian population, and names and dates of birth are not necessary for that; the data linkage research opportunity is a bonus, and I don’t believe it should be compulsory for people to participate in that.

Other people seem to object to the data being collected at all, regardless of what it’s used for later, and to my mind that’s potentially reasonable as well. But I’ll leave the debate about that for data security people, since it’s not really my area.

Don’t they already know all this stuff anyway?

My first reaction when I saw people starting to get upset about the census was, “Oh, wow, people have no idea how much of their personal data is already stored and can potentially be linked”. The government does indeed already have a great deal of data about us; they have our tax records, our Medicare and prescription medication data, our drivers licenses and traffic infraction histories, our criminal records, and on and on. But different government departments hold each of these data sets, and they’re not routinely allowed to link your data together without your consent.

Research involving data linkage has been going on in health for quite a long time, but unconsented linkage projects are very rare, and require a very compelling case for public benefit before they can proceed. Whether they should ever be approved at all is an important ethical question, and in my opinion, one which deserves a public debate. We’re starting to have that debate now. It is strange that the census is what prompted it, given that our Medicare or Centrelink data might be much more sensitive? Perhaps, but that doesn’t mean the debate isn’t worth having.

People are entitled to know how their data are collected, stored, and used. They’re entitled to have opinions about that, and to have strong feelings about which data they’re happy to share and what they prefer to withhold. If the research community want the public to support data linkage research, then we have to convince people that our work is sufficiently valuable that they should donate their data to assist us. I don’t think we’re entitled to people’s medical records and employment histories just because we want them; I think it should be up to individuals whether to participate in the kind of research we conduct. And if people don’t want to participate, I think they should be able to opt out.

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Thoughts on getting fitter / healthier / losing weight

I thought I would put all general advice on this in one place since it seems like something people are interested in sometimes. This is a hodgepodge of things I learned during my physiology degree, from watching other people lose weight and experiment with different types of exercise, having a bunch of gym friends who are also big exercise nerds, and from personal experience.

I think my previous post on healthy eating was too long, so this will be more dot points than endless exposition. There’s no justification for anything but I’m happy to provide my rationale if you’re interested in it.

General advice on exercise:

The best exercise regime is the one you’ll do. If you can’t fit more than once a week into your schedule, or you need to work up to doing more than that really slowly, don’t worry about it. Do what you can and see how you go. If you need to build it into every day or make it a habit or you’ll never do it at all, do that, even if it’s just walking to and from work.

Find the kind of exercise that you will do – everybody is different. Try a few different things and see what works for you. Exercise comes in a wide variety of forms – solo or with a friend or in a group; self directed (e.g. gym), vaguely structured (e.g. club / team sports), or highly structured (cross fit, aerobics); low (walking), medium (cycling), or high intensity (running); at home, in a gym, outside, or somewhere else.

I find personally that I am useless at exercising at home – I am full of good intentions but I just never do it. I need a specified time to go to another place and exercise, whether that’s to the gym, or to swing dancing, or by walking to and from work. But maybe you are good at self-motivating and home exercise will work for you! Try both and see which is easier.

I also find that running makes me feel like I am definitely going to die after less than two minutes, but that lifting weights is fun and that swing dancing are fun even though I also feel like I will die a little bit sometimes. Maybe you will be better at cardio than me! Most people are.

I fucking hate people telling me what to do and crossfit would make me stab someone, but I know heaps of people who need / love encouragement or instruction from other people. Try lifting weights on your own, try it at a club or with a personal trainer, and see if you like any of them. (Do get at least some instruction from someone knowledgable before lifting heavy weights, though, if you’ve never done it before, or your spine will explode and that will be really sad. I personally think Crossfit is a great way to get hurt unless you’re already very fit.)

If you are trying to lose weight from square one, walking a lot is a really good place to start. You don’t need to kill yourself with any crazy shit, just walking twenty minutes or half an hour once or twice a day will do wonders if you’re starting from zero. Otherwise cycling, swimming, dancing or other cardio – most weight lifting isn’t likely to help you lose weight, unless you are doing a *lot* of it, and this can be pretty tough on the body if you’re not used to it.

General thoughts on food:

Try eating healthier rather than simply eating less – I think that adding more healthy food to your diet is much easier than giving up everything you love forever (unless you are a hardcore all or nothing type person, in which case, do that!). I find it a lot easier to a mix of the somewhat healthy and somewhat unhealthy than to live exclusively on salads. Personally I exercise so that I can drink beer and eat snickers bars, so, y’know – I am not advocating asceticism here.

Having said that… More vegetables. More. More of them. Still more. Mooooooore.

Seriously though. There is no meal that is not made healthier by the addition of veggies – they add fibre, slow digestion, contain vitamins, and don’t contain (any meaningful amount of) fat or sugar. They tick all the boxes! Find whatever vegetables that aren’t potatoes that you can stand, and just go as crazy as you can go, at least one meal a day. I’ve found the one decent veggie stir fry within walking distance at work and because I am incredibly boring, I’ve been eating it for lunch basically every day for three years. You too could be like me! Live dangerously!

Cut down on alcohol, especially beer. Sorry. It’s not that different, nutritionally, to soft drink. (Cut down on that too.) Try to drink fewer days of the week and / or less when you do drink. Alternate alcoholic drinks with water or soda water when you’re out, and / or switch to a boring drink like vodka-soda instead of beer or things mixed with coke.

Cut down on obvious junk food (duh), and try not to fill up on empty carbs (rice / pasta / bread). Replace carbs with veggies for bulk wherever possible, since you’ll be hungry if you’re used to eating very carby meals. If you must have some kind of carby staple, barley is a good substitute for rice (and you cook it the same way).

Learn to read the bare basics of the nutritional information – read the per 100g column, and see how much sugar what you’re eating contains per 100g. If it contains more than 10g sugar per 100g, it’s junk food. If you’re trying to choose between products, choose the one with fewer calories / kilojoules per 100g.

Don’t worry about fat too much, provided you’re not living on ice cream or just eating cream with a spoon out of a jar in the fridge. (Don’t do that.)

Stop eating when you’re full and take the rest to go, or leave it – don’t clear your plate out of habit when you’re given a huge serve at a pub or whatever.

The food stuff requires organisation – if you’re used to eating out a lot, you need to either eat differently (Asian food is good for veggie heavy stuff, think stir fries etc), or cook at home more. Learn either a couple of healthy things that you can cook quickly (e.g. stir fries), or stuff you can cook once or twice a week and refrigerate / freeze (e.g. minestrone, curries / stews / pies with lots of vegetables, roast veggie salads). I’m terrible at doing enough shopping to cook every day, so I go the once a week route – but like with exercise, work out what you’re likely to actually do. Maybe walking to the store after work to buy vegetables to make a stir fry would be two birds with one stone for some people.

I find tracking what you eat, even just for a week, can be revealing. I had no idea how much beer I was drinking until I did that, and it was kinda horrifying. I’m glad I know now, though.

Finally, if you are trying to lose weight, don’t get disheartened and don’t have crazy expectations. Most people don’t lose more than a couple of kilos a month, and even though it’s possible to get hectic and lose weight faster than that, most people can’t sustain that or keep the weight off. Plus flying full tilt into crazy exercise from zero is a great way to injure yourself.

Obviously doing all this stuff at once would be major life upheaval for some people and it’s not mandatory. Any of it will make you healthier regardless of whether or not you’re trying to lose weight. Eat less unhealthy stuff, move your body more, that’s about all there is to it really.

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Lies, damned lies, and income distributions.

It’s been a while since I fired up the old blog machine, but this morning I came across an article so spectacularly misleading that I felt compelled.

The link showed up in my Facebook feed with the preview line “America’s poorest are about as rich as India’s richest”, which the author repeats again in the middle of the article.

The author is commenting on a feature of a graph contained in the article, which is that the top 5% of the Indian population clock in at the world’s 68th percentile for income (after adjustment for local purchasing power), as do the bottom 5% of Americans.

What isn’t stated explicitly is that those groups are composed of 50 million and 15 million people, respectively, and that the average income in each group (which is what the points in the graph are based on) is a basically meaningless number.

The first reason for this is that comparing income in purchasing power parity across very different economies doesn’t necessarily yield useful information, since it means very different things to be unable to afford different goods in different places. If you can’t afford a car in Kuala Lumpur, that doesn’t really matter, since you have a great public transport system available to get you to work – if you can’t afford a car in rural Queensland, you’re in deep shit.

The second reason, and the one that renders the leading line of the article so staggeringly wrong, is statistical. The statement that America’s poorest are as rich as India’s richest should be obviously wrong to anybody who knows anything at all about poverty in the U.S. or wealth in India. The richest people in India own companies, mansions, and BMWs, just like the richest people everywhere. The poorest people in America are either bankrupt or have debts greater than their assets (regardless of their income). And, as an aside, for this reason it doesn’t even make sense to equate “income” and “poverty”, really – one person might have a small income but own their own home, or while someone else might have both a high income and huge debts, and be living paycheque to paycheque. “Poverty” isn’t the same as “low income”.

But on top of that, even if it did make sense – because of the way income is distributed, the top and bottom 5% of the income distributions of any country contain huge, huge discrepancies in income within them. The Americans at the very bottom of the income scale aren’t just a little bit worse off than the people at the 4.5% mark – they are catastrophically worse off. Likewise, the top 0.5% of Indian society (about 6 million people) aren’t making a little bit more money than the people at the 95.5% mark – they are making orders of magnitude more.

Because India and the US have pretty high wealth inequality and very large populations, and because of this quirk of income distributions at the extremes, talking about the mean incomes of the top and bottom 5% of the population in each country is both economically and statistically meaningless.

 

The graphs above show the kind of shape that each end of the income distributions would have in each country (based on my knowledge of income distributions, not actual values – the values on the y axis don’t represent anything real). These two graphs have the same mean value – but it would be absolutely absurd to say the people on the far left of the US graph are as well off as the people on the far right of the Indian graph – you can see very clearly that that isn’t true. Means are only informative when they’re used to describe data that sit on a bell curve. I hope anybody reading this, even if they’re not into statistics, is able to see that those graphs are not bell curves. The average income of each group doesn’t tell you anything.

To give another example, it might be the case that the shortest quarter of men have the same mean height as the tallest quarter of women, but it would be absolutely ludicrous for me to use that fact as the basis for a statement that “the shortest men are as tall as the tallest women”. That’s obviously not true, because the mean height I’m using doesn’t actually give us any information about people at either extreme. That’s not what means do – they tell you about the middle of a bell curve, not its ends.

There are only two broader interpretations of the statement “America’s poorest are about as rich as India’s richest” that I can see – either India is a place of such misery that even it’s richest citizens live like the worst-off characters in The Wire, or the American poor are so fantastically well off that they live as well Bollywood’s biggest stars, and they ought to think themselves lucky. Both are simultaneously laughable and offensive, and I’m genuinely disappointed that this one got through to the keeper at a progressive news website.

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How I got out of iMessage purgatory (iOS 9.2.1 problem)

This isn’t normally a tech blog, and I’m not a tech person, but this seems to be an unsolvable problem for some folks, so here’s how I solved it.

The problem: Texts from iMessage disappear when texting some contacts. I recently bought an iPhone, and today I was texting a friend who also has an iPhone, but who had iMessage switched off. My texts looked like they were being delivered, and they were… to his iMac, in his house, but not to his phone in his pocket.

The problem seems to be that if someone uses iMessage to text someone who used to have iMessage but has it switched off on their phone (or has switched to Android), Apple wants to send the texts as iMessages, not as SMS’s. And off they go, sometimes to an iMessage account that is no longer active on any devices at all. If two people both have iMessage switched on, no problems – if they both have it switched off, also no problems. But one off, one on – texts get stuck in purgatory, with no error message alerting the sender that they’ve gotten lost.

I tried most of the fixes listed online, and eventually went for a complete nuke-it-from-orbit approach, which fixed it. This consisted of the following:

  1. Totally remove my Apple ID from iCloud and all associated apps on my laptop – not just log out / disable the account on Messages, this wasn’t enough. Remove. Obliterate. (Possibly overkill? Not sure.)

    Settings > iCloud > Sign Out > Delete From Mac (and yes to all “Delete X from Mac” queries.

  2. Also delete my Apple ID from Messages on my phone, and then turn iMessage off.

    Settings > Messages > Send and Receive > Apple ID > Sign Out

    back to Settings > Messages > then toggle iMessage off

  3. Deregister my Apple ID from iMessage at the following link, using the text message feature under “No longer have your phone” (not just turning iMessage and FaceTime off like it says at the top): https://selfsolve.apple.com/deregister-imessage

And lo, I can now both send and receive texts with other iPhone users, whether or not they have iMessage turned on or off. Magical!

This seems ridiculous, but it does seem to be the only way to ensure that you can both text other people *and receive texts*. Simply turning iMessage off worked fine for texting my friend, since then we both had it switched off and we were both trading SMS’s. But that put me in purgatory with him – when another friend with iMessage turned on tried to text *me* after I’d turned iMessage off on my phone and logged out on my laptop, his own texts went nowhere. So if you leave it on, you can’t talk to people who have it turned off; if you turn it off, people who have it turned on can’t talk to you. Nuke it from orbit seems the only way to ensure full functionality, as far as I can see. Seems mad, but there you go!

(Related: A different friend was having the same problem messaging me, in turned out, because of a similar problem with Signal – I was still registered on my old Android, and when I texted him, his replies were piling up in Signal on my old phone (no notifications), not coming to my iPhone. Simply deregistering from Signal in my Android phone fixed this immediately, though.)

 

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Antibiotic resistance 101

Discussing the recent coverage of increasing drug resistance among gonorrhoea infections made me realise that a lot of people don’t really understand how antibiotic resistance happens or spreads. This is an attempt at a 101-style explainer. I suspect most people already have 90% of the knowledge needed to make sense of this, they just haven’t put it all together yet. I’m going to start with an example from animals which I think will make intuitive sense to people, and then move onto the bugs.

Antibiotic resistance develops through a process of evolution, through natural selection. Most people are familiar with how natural selection works in animals. Our DNA is subject to a constant process of mutation, both during our lives and from one generation to the next. Some of these mutations are harmful, like the BRCA mutations that put women at high risk of breast cancer. Some are beneficial, like the development of the ability the digest lactose that arose in European populations after the domestication of cattle. And some are neutral, like the mutation for red hair, which looks nice but doesn’t really do much for you either way.

Mutations happen at random, but whether they are harmful or helpful determines how effectively they spread through populations. For example, acacia trees, which are common in parts of Africa where giraffes live, are covered in huge thorns, making them a very unattractive food source unless you happen to be a giraffe with a very tough mouth. This doesn’t really matter, provided there are other things to eat if you have a soft mouth. But say there is a terrible drought, and all the easier-to-eat plants die off – suddenly a giraffe with a tough mouth has a big advantage over other giraffes. It’s more likely to survive a drought and have children, and those children will probably also have tough mouths, enabling them to survive and reproduce during droughts in their own lifetimes.

Now, a giraffe with a tough mouth that breeds with a giraffe with a soft mouth may not pass on its tough-mouth gene to its offspring – its partner’s soft-mouth gene might override its tough-mouth gene. Because (most) animals reproduce sexually, which involves mixing the genes of two different animals together, some useful genes get lost between generations. This is not a problem for lifeforms like bacteria that produce asexually. Bacteria don’t need other bacteria to reproduce with – they just split themselves in half, cloning themselves. One bacteria splits in half to form two, they split in half to form four, they split in half to form eight, and so on – all clones of the original, except for any new mutations that occur along the way.

This has a big impact on the survival of useful mutations in bugs. Prior to the discovery of antibiotics in the mid 20th century, bacteria were just going about their business, infecting humans, and being transported from one place to another. My favourite bacteria, the tuberculosis (TB) bug, was being carried around and transmitted by people all over the world.

In the late 1940’s, doctors in the US realised that the antibiotic streptomycin killed TB bugs. Suddenly, being a bug that was immune to streptomycin was the equivalent of being a giraffe with a tough mouth – it meant particular bugs could survive circumstances that were a disaster for everybody else. By the time someone with TB gets to a doctor, their lungs are absolutely chock-full of bugs – millions upon millions of the little blighters. When they start taking streptomycin, all of those bugs get exposed to the antibiotic, and most of them die. But if a few bugs have a random mutation that makes them resistant, those bugs survive and continue multiplying while all the bugs around them die. Eventually, only resistant bugs remain in the person’s lungs, and the person may then cough those bugs onto someone else before the TB kills them.

In this way, antibiotic resistant bugs can spread from person to person, and in the modern age, from country to country. This is what we’re currently seeing with TB, gonorrhoea, and other bacterial diseases. Drugs that came into use provided a strong advantage for bugs that could resist them, and those bugs survived and spread around the world. As newer drugs get introduced in specific places, the bugs infecting the patients on those drugs become resistant to those as well. The streptomycin resistant TB bugs from the 1950s have continued circulating around the world, picking up resistance to more and more antibiotics, and some strains of TB are now resistant to basically all of the drugs we have.

Remember though that bacteria, like humans, are undergoing constant evolution. There are unimaginable squillions of individual TB bacteria around the world, and even though they are all clonal descendants of previous bugs, they are constantly evolving. This is what gives rise to different “strains” of various bacteria – like humans have a variety of lineages. We’re all the same species, but we have different characteristics. Most TB bugs are still vulnerable to all drugs, some are resistant to one or two, and some are resistant to many or all drugs.

When you read that “TB is becoming drug-resistant”, this doesn’t mean that all TB bugs in the world are acquiring resistance to the same drugs at the same time – this would be like if somehow, overnight, everybody in the world became a redhead. Drug resistance, like hair colour, is a characteristic that is mostly passed down from one generation to the next.

However, bacteria have an additional trick up their sleeves that animals like us do not – they can actually swap genetic material with one another within their own lifetimes. Human genes are all contained on chromosomes, and the 46 you’re born with are the ones you’re stuck with – you have 46 identical copies in every cell in your body. Bacteria, however, are a single cell – and they are capable of trading small individual chromosomes (called “plasmids”) with one another. What this means is that not only does one drug resistant bug divide to create two drug resistant clones of itself (who then divide to create four, and so on) – it can also simply give a copy of its drug resistance genes to a friend!

But to give something to a friend, you have to meet the friend in person – bacteria are yet to develop a postal system. Someone with TB will have millions of individual bacteria in their lungs, some clones of one another, some very different. Those bugs that get close enough to touch one another can swap copies of their plasmids, but a bug in my lungs can’t give a plasmid to a bug in yours, unless the bug itself gets transferred over.

So that’s the mechanics of drug resistance in bacteria. Individual bacteria develop a mutation that makes them resistant, and they can pass that mutated gene to their clonal children, and to friends in their immediate environment. But the gene still has to spread through the population basically the same way different characteristics do in humans – mutations for red hair have arisen several times in several different places, but not everybody in the world has red hair. Even if I could make other people into redheads by touching them, the way bacteria can swap genes between friends, I would still have to chase people around and lay hands on them.

Bugs that are resistant to common antibiotics have a big advantage, and we have to make sure we expose them to other drugs that will definitely kill them – for example by treating streptomycin resistant bugs with penicillin, and vice versa. This is difficult, but not impossible. Drug resistance is on the rise and is cause for concern, but bacteria are subject to most of the same genetic laws as the rest of life on earth, and the antibiotic era is not over just yet.

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Chicken little and child mortality

A couple of months ago I sat down in the bathroom at a comedy event and looked at a poster promoting the works of a large international charity. The poster was dominated by a photograph of a smiling child, but underneath were the words “In Kenya – where nearly two in every five kids won’t reach their 5th birthdays – clean water and toilets are life-savers”. I can’t claim an encyclopaedic knowledge of under five mortality rates in African nations, but that seemed really, really high. Kenya is actually quite a bit better off economically than a lot of countries in the region – it has less conflict, less poverty and better health services than many of its neighbours. So I did a quick google on my phone and came up with the UNICEF and World Bank figures, which are both freely available online.

According to the World Bank, which uses the same data as other UN Agencies, the estimated under 5 mortality rate in Kenya is 71 deaths per 1,000 live births, which works out to one in 14, a far cry from “nearly two in five”. Kenya is ranked 35th in the world, behind dozens of other African countries and countries that are heavily conflict affected like Afghanistan. Angola leads the world with 167 per 1,000 live births, equivalent to one in six, still far below the charity’s statistic. (For comparison, high income European countries have a rate around 2 per 1,000 or one in five hundred.)

Child mortality

That such a high profile charity made such an astonishingly inaccurate claim bothers me for a number of reasons. Firstly, how on earth did that make it onto a poster? Does the communications team at this charity have so little background in health and so little experience in African countries that nobody thought that sounded a little high? Secondly, what does a claim like this say about the role of data in charity? Does the average Australian who sees that poster believe that Kenya (of all places) is a place of such endless desperation that it seems credible that near enough to every third child born there dies before turning five? If not, are we so used to seeing figures like this thrown around that we don’t even stop to consider what they mean in practical terms? Either way, something is very wrong here, and not with Kenya.

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Aspartame and other boogeymen

There is a persistent and common belief that artificial sweeteners and other food additives are “bad for you”. This belief is sometimes very vague, but sometimes in connection with specific concerns such as cancer. Googling “aspartame” and “cancer” unsurprisingly turns up dozens of pseudoscientific, alarmist websites proclaiming its toxicity, and a much smaller number of websites such as those run by the National Cancer Society in the US and the UK’s National Health Service, trying to assure the public that it is safe.

The confusion about aspartame and other specific food additives speaks to a serious problem in both epidemiological research and in scientific journalism. Observational studies in nutrition suffer from a really serious signal-to-noise issue – separating out particular dietary causes of cancer or heart disease among the huge variation in people’s broader diets, exercise habits, family histories and general life conditions is extremely challenging.

The epidemiologists who do this type of research are often appropriately circumspect and carefully state the limitations of their conclusions, but this doesn’t make for exciting headlines. The media jump on particular studies – especially those that report that something may be dangerous – remove all the caveats, and report a completely sensationalised and de-contextualised version of the research findings. And six months later, when another study finds the opposite, the very same newspaper might run a story to the opposite effect. See the coverage of research into the health benefits of chocolate and red wine for an example.

screenshot-2015-05-05-15-09-57

This leaves the general public feeling like the scientific community is either constantly flip-flopping, since the media are perpetually reporting conflicting results about the same foods, or that we have decided something is definitely harmful because the only study that made the papers was the one reporting a link to cancer, while dozens of other studies showing no such association were ignored. In fact, the pace at which national dietary guidelines change is positively glacial, and most experts would be very guarded if you asked whether they thought this or that might be harmful, unless the evidence was absolutely overwhelming. (Most of us will unreservedly advise you not to drink lead paint, for example.)

Aspartame in particular is a frustrating example. Hysterical reporting on a couple of studies seems to have dominated the public perception of it, even though health authorities have been convinced by the weight of evidence that it’s safe for people without serious pre-existing kidney problems. Meanwhile, the additive that aspartame is supposed to replace – sugar – is the subject of far more damning evidence regarding its impact on obesity and type 2 diabetes.

In general, when you see newspaper articles about links between health and specific foods, you should assume they are overstating the case. Common sense – eat less junk food and more vegetables – doesn’t make for sexy headlines, even if that’s really what the public would benefit from hearing.

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