Screens and eyes

For as long as we’ve had televisions they have been accused of damaging our eyes – but now, with screens everywhere, what’s the true picture?

When I was young, older people were always telling us not to sit too close to the TV or to spend too much time watching it. Yet back then, we only had a fraction of the screen time that most of us experience today. You may well spend all day at work looking at a computer screen, then come home to spend the evening in front of the TV. And what were you doing in between these times? Looking at your phone or tablet.

In 2014 there was a scare story that overusing smartphones may damage the eyes. The concern was that the light from LED screens contains more blue/violet light than the natural light that best suits our eyes, and the higher energy blue/violet light can overload the sensors on the retina, increasing the risk of macular degeneration, a common cause of blindness.

The story particularly highlighted the risks from smartphone use, where the screen is held considerably closer to the eyes than a computer or TV screen and is often used in lower lighting condi- tions, where the dilated irises of our eyes allow more light in.

We have to approach this story with a little caution. There is no study showing that exposure to screens, even smartphones, causes eye problems – this is extrapolating from laboratory-based evidence that light in this region can cause damage to the type of cells used in the retina. So at the very most, this is a precautionary warning as yet.

What is certainly true is that our eyes don’t respond well to being focused as closely as a smartphone requires (TVs are usually positioned at a better distance) for long periods of time, and this can cause eye strain. Taking a break from screens for at least five minutes in each hour, and a few longer breaks during the day is highly recommended. Furthermore, regular screen users – which is pretty well all of us – should have regular check-ups with an optician.

UPDATE: In December 2014 a different study showed that people who read backlit screens in before going to sleep produced less of the hormone melatonin. This can make it harder to get to sleep, and in the long term, sleep deficiency can produce significant health problems. As yet the evidence is relatively limited - this was a very small study with just six people on each kind of book. However if you do have trouble getting to sleep, and you read from a screen for your bedtime reading it is worth switching to a paper book (or an e-ink reader like a basic Kindle that doesn't have a backlight) to see if it helps make sleep more easy. Ideally avoid close backlit screens (including phones and computers as well as tablets and backlit e-readers) for a couple of hours before trying to sleep. TVs don't seem to be a problem as we don't sit anywhere near as close, so the blue backlight is a relatively small part of our incoming light - and the generally darker coloured picture of video is better than the stark white of a page to read. If you have to use a backlit e-reader, try turning down the brightness.

The numbers game

The media, politicians and interest groups love to throw numbers at us to support their cause - and they can be very useful - but we always ought to ask: 'Where did those numbers come from?' and 'What does that actually mean?'

Here's a good example. In 2015, a website attacked the UK Labour Party's policy on arts funding pointing out 'Just so you know, arts funding brings in £4 for every £1 spent.' It's quite likely this statistic will get a life of its own and be used many times in the future. But what does this actually mean, and where did the numbers come from?

As far as a source, the figure seems to be genuine. After following a chain of different people using it, it originated in a 2013 report by Arts Development UK. So I was, with a little work, able to check where it came from. Yet the chances are, when a figure like this is used, it will often not be possible to easily find out its exact source.

And what does it actually mean? I asked quite a few people who all, like me, assumed that the claim 'arts funding brings in £4 for every £1 spent' meant that if you fund the arts, for each £1 you spend, £4 will come in either directly (through entrance fees, brochures etc.) or indirectly (for instance by more tourists coming and spending money in your town or city). But look at that original report and you'll find something entirely different was intended.

The report says 'For every £1 spent by local authorities on arts service, leverage from grant aid and partnership working brings in £4.04 of additional funding.' So, when a local authority spends £1 it gets that additional money from grant aid and partnership - which is largely with other authorities and with bodies like Arts Council England. In other words, £1 of local government spend brings the local authority another £4 of public money. Excellent for the local authority, but hardly supporting the argument in which it was used. Whether intentional or (probably as here) accidental, this is a kind of deception.

We usually don't have the time to trace back a statistic to its source like this - but don't be taken in by numbers picked out of the air. Anyone who uses numbers like this should expect to have them challenged - and needs to be able to show exactly what they mean and where they come from.

Gluten

Gluten is a complex natural molecule that gives dough the stretchy, gooey texture that makes great bread. For most of us gluten is harmless, but a few are intolerant, and others believe a gluten-free diet would benefit us all. What’s the truth?

Between 1 and 2 per cent of the population is gluten or wheat intolerant. They get stomach pains, constipation and diarrhoea, most often because they have coeliac disease, a genetic disorder of the small intestine where the immune system gets it wrong and thinks that the gluten is attacking it, causing inflammation. Rather more people claim gluten intolerance than actually have it – for the rest it is a ‘nocebo’, the negative equivalent of a placebo effect, where believing something is bad for you causes pains with no physical cause.

There are simple tests that your GP can perform to check if you do have a genuine gluten intolerance. If this proves to be the case, then it’s a matter of ensuring that the diet is gluten-free, something that is increasingly easy with a wide range of gluten-free products available in the supermarket. In general, food should be fine as long as you avoid wheat, barley and rye. (Oats, while not a problem in themselves, are probably best avoided also as they are often contaminated with gluten from other grains.) Other cereals like maize and rice are fine.

There has been something of a fad diet of avoiding gluten – the kind of diet often endorsed by celebrities rather than experts – in those who don’t have a gluten intolerance, probably on the assumption that people must be intolerant because there is something toxic in the gluten and that avoiding gluten must be ‘good for digestive health’. In fact, it’s the reverse – people who are gluten intolerant have a mutation that makes them react badly to a harmless substance that is a normal part of our diet.

The general argument for a gluten-free diet if gluten doesn’t cause you problems is open to interpretation. Here’s nutritional therapist Deborah Thackery, quoted in the Morrison’s supermar- ket magazine:

Gluten doesn’t need to be in sausages or many other foods in which it is often present. There is growing evidence that gluten is difficult to digest and while we need protein, the right sort of fats and plenty of vitamins and minerals, we don’t need gluten. All of these nutrients can be found in other, non-gluten-containing foods.

This doesn’t make a lot of sense as dietary advice – after all, fibre is hard to digest, but it’s still good for you (see Fibre). All the evidence is that supermarkets are using ‘gluten-free’ rather as they do the ‘organic’ label: as a way to put a considerable mark-up on a product that doesn’t cost them much more to produce. Gluten-free products can be a rip-off. Trials have failed to demonstrate any health benefit to a gluten-free diet for those who aren’t intolerant, and it makes it significantly harder to get the fibre (and some vitamins) we all need. What’s more, many gluten-free products are higher in fat than their normal equivalents, as something has to be used as a substitute to give the textural contribution of gluten. So, a gluten-free diet is best avoided if you don’t have a medical reason to be on one.

A review published in November 2014 highlighted that those who aren't intolerant shouldn't avoid gluten, but should go for products made from whole grain cereals. The report concluded:

There is overwhelming evidence of clear health benefits of a whole grain based diets featuring store cupboard staples such as bread and cereal made from lightly processed wheat.  The benefits are increased where whole grains have undergone relatively little processing... the scientific evidence behind many of the most popular wheat and carbohydrate free diets turns out to be surprisingly thin and selectively used... Whole grain products are undoubtedly good for health and given their multiple beneficial aspects could easily be described as a super food. It might be possible to argue that they are superior to many other fruit and vegetable super foods since they have multiple modes of action and provide both short- and long-term health benefits.

The review was funded by the company that makes Weetabix, however it was undertaken by the University of Warwick, which points out that the 'company had no input into the conclusions of the research'. While clearly such research is beneficial to the manufacturer, there is no reason to suppose that the funding would bias the outcome.

Links:
• Fibre
• Placebo effect

Antibacterial handwash/ cleaners and cancer

A paper in late 2014 suggested a link between triclosan, the antibacterial agent in many hand washes, kitchen and bathroom cleaners, and liver cancer. This inevitably caused a fair amount of excitement in the press. But should we be abandoning these products immediately?

The trial involved mice being fed 3 grams of triclosan a day for six months. The mice suffered liver damage and as a result were more susceptible to cancer produced by other carcinogenic substances. What does this mean for us? It's almost impossible to say. To begin with, it is difficult to make a straight weight for weight comparison with animal trials. Dogs, for instance, are much more sensitive to the theobromine in chocolate than humans, weight for weight. But the best guesses we can make to see what the trial involved is that mice have a rough weight-for-weight comparison with us.

A mouse typically weighs about 20 grams, so they were receiving 3/20ths of their body weight in triclosan daily for six months. The average UK adult woman weighs about 70 kilograms, so the equivalent would be to consume 10.5 kilograms of triclosan a day for six months. A typical surface cleaner contains about 0.3 percent triclosan. So that would mean consuming the equivalent of the triclosan in 6,000 half litre bottles of cleaner every day.

This is not to say that it's a good thing to consume considerable quantities of triclosan - but this research provides no useful evidence on its lack of safety or on safe levels of use.

Let's look at the four main ways that we come across triclosan (and similar antibacterial agents).

• It is found in antibacterial handwash. There is no evidence this removes bacteria from the hands any better than washing with ordinary soap. This being the case, it is best not to use antibacterial handwash, both because of any risk from the substance and (more likely) in case of the risk of bacteria developing resistance mentioned below.
• It is found in antibacterial surface sprays. These do have some benefits in reducing bacterial contamination on surfaces and are probably still worth using.
• It is found in some toothpastes, where it is suggested (with very limited evidence) that it can help with gingivitis and plaque. Best avoided. This can be difficult, as the toothpaste itself doesn't have a contents list - but search for your toothpaste and 'contents' on the web to get the information. The best-known brand containing triclosan at the time of writing is Colgate Total - though bear in mind to get equivalent quantities to the mice you would have to swallow around 12,000 tubes of toothpaste a day.
• It is found in some cosmetics. There are no benefits other than as a preservative, but it is very difficult to discover which products contain it, and you are unlikely to consume much of your cosmetics, so this is unlikely to be a cause for concern.

Overall we ought to focus the use of antibacterial cleaners where they have the most benefit. There is limited evidence, though it hasn't been fully proven, that too high levels of antibacterial agents in the environment can trigger bacterial resistance to antibacterial agents or even antibiotics. While more evidence is required, it seems worth limiting use to surface cleaners.

You can see the original paper at the Proceedings of the National Academy of Sciences of the USA though you would need a subscription to read more than a summary. It is The commonly used antimicrobial additive triclosan is a liver tumor promoter. Mei-Fei Yueha, Koji Taniguchib, Shujuan Chena, Ronald M. Evansc, Bruce D. Hammockd,1, Michael Karinb, and Robert H. Tukeya, doi: 10.1073/pnas.1419119111

LINKS

• Chocolate
• Hand washing

Cocoa and the brain

There is a small possibility an extract of cocoa could help older people be better at certain memory tasks - but the trial done so far is not good enough to show this.

A paper published in October 2014 was reported in the media as showing that cocoa helped put off age-related memory decline. As is often the case, while the actual paper was interesting, and highlighted something worthy of further investigation, what it demonstrates is more complex than the simple headline suggests, and at this stage offers substantive proof of benefits.

In the trial, a group of healthy people aged between 50 and 69 were split into four groups. Two groups spent three months on a diet that was high in cocoa, two on a low cocoa diet. At least, that's how the paper describes it - in reality the 'high cocoa' group took a supplement of 99mg of cocoa flavanols. To get this much naturally you would have to eat 25 individual chocolate bars (not recommended!) - I don't know how much that is in cups of cocoa, but I suspect it's a lot. Each group was also divided into half that were sedentary and half that took regular exercise.

The scientists then looked at two things - how a particular part of the brain responded in an fMRI scanner, and how well the test subjects did at two memory tests. What they found was that those on a high cocoa diet did significantly better at one of the memory tests - the equivalent, it was claimed, of being almost 30 years younger.

This is interesting, but it isn't enough yet to suggest we should all get out and start consuming lots of cocoa flavanols. The test groups were small with only 8 to 11 people in each. This doesn't mean that the results are meaningless, but it does suggest further tests are required. It has also been pointed out that the claim that result is statistically significant is doubtful. The value isn't what most scientists would consider significant - the results could be obtained in error with about 50 per cent probability, which isn't good enough to be considered useful.

What was claimed to be observed is that the cocoa increased blood flow to the dentate gyrus region of the hippocampus in the brain, which is thought to have a role in memory handling. In the trial, the high cocoa group did better at a memory test where they had to remember whether a shape they were shown was one of 40 they had just seen in a sequence. But they didn't do any better in a test where they had to recall words from a list, 60 minutes after three attempts to learn it.

Another oddity of the trial is that no improvement was found in those who performed exercise, even though in a previous trial by the same experimenters had found a benefit. This doesn't rule out the findings, but does emphasise the need to repeat the trial, several times and with bigger groups. Oh, and the authors declared no personal interest, but it wasn't strongly flagged up that the study was funded by the Mars chocolate company.

There seems to be some evidence here that this cocoa-sourced substance might help with the short-term recognition of shapes, which is something we get worse at as we get older. This can't be a bad thing if true. But it isn't a miracle cure for the way that ageing effect our memories, and taken on its own, this trial is not enough even to be sure of that.

You can see the full paper at Nature Neuroscience, though you would need a subscription to read more than a summary. It is Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults - Adam M Brickman, Usman A Khan, Frank A Provenzano, Lok-Kin Yeung, Wendy Suzuki, Hagen Schroeter, Melanie Wall, Richard P Sloan & Scott A Small - Nature Neuroscience (2014) doi:10.1038/nn.3850

Could dinosaur DNA provide cures for human diseases?

Despite Jurassic Park, we can't use dinosaur DNA for anything, because we haven't got any, but we could learn something from the way dinosaurs survived injuries.

In July 2014, the Daily Mail carried a headline 'Could dinosaur DNA provide cures for serious human illness? Ancient fossils reveal evidence of powerful immune systems beating diseases such as cancer.' This seems very impressive - and there is an interesting health story here, but the headline is totally misleading.

Researchers examining a 72 million year old dinosaur skeleton had found evidence that it had survived serious injuries that a mammal would not be able to survive, and speculated that it might be that the animals had healing abilities that could be of benefit, if we could discover the mechanisms behind them. The only way this would be possible is if similar effects can be found in modern day relations of dinosaurs. The closest living relations are birds, but it has been suggested that a better model would be alligators and crocodiles, which are much more distantly related, but which do seem to resist infection despite living in bacteria-loaded environments.

However, the headline itself is pure science fiction. Despite the entertaining possibilities of Jurassic Park, dinosaur DNA simply doesn't exist any more. DNA deteriorates with time, and however it is preserved, it cannot last longer than around 6 to 7 million years. (The oldest sample found to date isn around half a million years old.) As the dinosaurs died out 65 million years ago, dinosaur DNA can't do anything for us at all.

Why food ingredients can have more than 100 percent

It's always a good idea to take a look at the ingredients lists on processed food, but it won't always make a lot of sense.

If you look at some food packaging, you will see that the manufacturers have something in common with the X-Factor. They believe that it's possible to give 110%.

There are two significant oddities in the ingredients list, for instance, of my cereal. One is the matter of nuts. Because it says that the product contains 10.5% nuts when in fact the true contents is only 0.3% - that's quite a big error. This is because neither peanuts nor coconut are actually nuts. But we'll let them off, because there is probably some sort of convention that allows them to come under this heading. (It can't just because they have 'nut' in their name, as 'Honey Nut Shredded Wheat', the cereal in question, has 'nut' in its name. So if that were the rule, the contents should read '100% nuts'.)

But the more interesting oddity is the maths. You might wonder what the problem is. With 84.1% wheat, 10.5% nuts and 2.8% honey, that still allows 2.6% for the other bits and pieces. But ingredients lists don't work like that. They have to be specified in order of weight - so there is more sugar than there is nuts, the list just doesn't mention how much sugar. With a minimum of 10.6% sugar, that makes a minimum contents of 108%.

We can get some idea of the quantity of sugar from the nutritional information. We are told that 100g of the product contains 15.9g of sugar - but we can't just take this number as the missing figure, as it will also include the sugar in the honey and molasses. So reasonably we can guess that the 'sugar' percentage is in the 10.6-12% range.

So what is going on? Thankfully, Nestlé has been helpful on the subject and told me this:

The basic maths does not add up and unfortunately this situation is replicated across many foods as they try to comply with QUID (Quantitative Ingredient Declaration) legislation. The complication comes from the requirement to list the amount of ingredients as they are added to the formula at each step. It is called the ‘mixing bowl’ rules.
In a simple process, this works well and the ingredients add up to 100%. In a process with many steps, and where moisture is lost in intermediate drying and toasting stages, the maths becomes more complex and illogical, and 100% is hard to achieve.   Each product must be viewed in isolation, and its manufacturing method affects the final result as well as the ingredients used.
We have to comply with 'The Food Labelling Regulations 1996' and its amendments.  There are two amendments which detail how we should declare the quantities of ingredients used, and the key requirement is in the second of these Amending Regulations, which states; 'Where the food has lost moisture as a result of treatment, the indication of quantity of the ingredient or category of ingredients used shall be expressed as a percentage which shall be determined by reference to the finished product”. 

 So there you have it. The percentages can't really be taken as sensible detailed information, just a broad brush guide. This doesn't of course, explain why peanuts and coconuts are nuts (no doubt another regulation), or why there is no percentage against sugar - but it does help us understand what is going on to allow Nestlé (and other food manufacturers) to give 110%.