The answer to … everything is …

42, as all fans of Douglas Adams and The Hitchhiker’s Guide to the Galaxy will instantly tell you. In the years before he produced his best-seller, a chance contact with Footlights had drawn me into spending many merry evenings with Douglas in The Baron of Beef public house, more or less opposite St John’s College, where he was studying – sporadically, he would doubtless have said – English.

Had a piece of work that’s just come out in The British Medical Journal been published 40-odd years earlier I suspect I would have mentioned it at one of those gatherings – early on before rational thought took alcohol-fuelled flight. It’s interesting because it says we can put off dying from the things that kill most of us (heart failure and cancer) by what Jason Gill, Carlos Celis-Morales and their pals in the University of Glasgow call ‘active commuting’. By that they mean cycling to work is good. Physical inactivity (e.g., spending happy evenings in the pub) is bad.

Had I mentioned it, rather than coming up with an entirely whimsical response to the “ultimate question of life”, Douglas would have spotted that the key to hanging on to life is “on your bike”. Just think: if Jason & Chums had got a move on, history would have been changed. Pondering all their evidence over several pints of The Baron’s best, it’s hard to imagine Douglas coming up with any title other than The Biker’s Guide to the Galaxy.

But hang on: isn’t this just another pretty useless survey?

Maybe – but for several reasons it’s hard to write it off.

First, there have been quite a few studies over the years showing that cycling is good for you.

Second, this is one was huge – so more likely to be meaningful. Using the UK Biobank data it looked for links between death and the way in which more than a quarter of a million people got to work.

Third, and the thing that really caught my eye: the key finding stuck out like the proverbial sore thumb. Usually in surveys of things that might affect our health any trends are difficult to spot: eating X makes you live 10% longer or be 5% less likely to get Y … bla, bla, bla. But here you didn’t need to peer: cycling (a ‘long distance’) to work makes you 40% less likely to die – from anything!

Below is just one bit of their data: I’ve re-drawn it with the cycling result in red but it hardly needs that to highlight the difference between it, walking (blues) and the ‘non-actives’ (green: car or public transport). It’s true, a bit of biking can help (orange: mixed mode cycling) but the really clear benefit comes from cycling (lots) – though they don’t actually say how many miles per day counts as ‘long-distance cycling.’ Modes of transport and distances were self-reported and the latter just divided into ‘long’ and ‘short’.

How you get to work impacts your life expectancy. The figure shows the risk of death from all causes as hazard ratios (ratio of the hazard rates of death): the reference (hazard ratio 1) is travel by car or public transport (green). (From Celis-Morales, C. et al., 2017).

So what of heart failure and cancer?

Perhaps not surprisingly then, commuting by cycling was also associated with a markedly lower risk both of getting heart disease or cancer and of dying therefrom. To give one specific figure: cycling to work lowers the chance of developing cancer by 45%.

It can’t be the lycra

These are horrible studies to undertake, partly because they rely on human beings telling the truth but also because of what are called ‘confounding factors.’ For example, if someone plays a lot of sport and eats sensibly, you might guess they’d be relatively healthy, regardless of how they get to work. Conversely for smoking. However, Celis-Morales & Co did their best to allow for such things and therefore to come up with results that mean something.

But, if you take their findings at face value there remains a key question that the authors do not mention: what is it about biking that’s such a life-saver (assuming you don’t get knocked-off and squashed)? It’s a real puzzle because walking is generally held to be very good for you whilst cycling is the most energy-efficient means of transport devised by man. Both activities use nearly all of your muscles, albeit that biking really works out your glutes and quadriceps, but because bikes are so efficient you use less energy.

Counting the calories

You can do the sums – i.e. work out how many calories used walking, running or cycling on Wolfram Alfra. It’s just confirmed that my daily bike commute does indeed use about half the number of calories required for the same walk.

If you take your commute as training you would suppose that expending more energy (i.e. walking rather than biking) would strengthen your heart and cardiovascular system – and indeed this study shows commuters who did more than 6 miles a week at ‘typical walking pace of three miles an hour’ slightly lowered their risk of cardiovascular disease. But cycling was far more beneficial.

As to cancer, beyond the simplistic notion that fitness = strengthening your immune system and hence capacity resist abnormal cell growth, it’s hard to see a mechanism for biking being so much better than anything else.

So, never mind the science …

Away with Ford Prefect and latter-day variants, automotive  or otherwise! On your bike!! And if you can do it with a friend on a tandem, so much the better!!! Though if you’re going to do it à deux, it might be worth recalling that the Jatravartids had the wisdom to invent the aerosol deodorant before the wheel.

Reference

Celis-Morales, C. et al. (2017). Association between active commuting and incident cardiovascular disease, cancer, and mortality: prospective cohort study. British Medical Journal 357 doi: https://doi.org/10.1136/bmj.j1456

Biting the bitter bullet

The other day we took a short trip around obesity (Obesity and Cancer) in the course of which we noted that the former is a bad thing. So, you might say, they make a good pair – indeed they quite often come hand-in-hand, as obesity significantly increases the risk of quite a lot of cancers as well as other unpleasant conditions. The nasty effects include heart diseases and diabetes, a collection of problems often referred to as metabolic syndrome.

Fed up?

Obesity is usually caused by eating too much of the wrong stuff whilst parked on your rear end. True enough, but folk sometimes get a bit cheesed off by repeatedly being told to do something about it. As it happens, turning to Cheddar, if you can face the stuff, may actually help weight loss as cheese is high in protein and fills you up. And you might just go for that escape route when you’ve been leaned on by a recent article that, in effect, calls for draconian measures to limit the amount of sugar we eat. To be slightly more precise, the target is the USA because, as is well known, Americans lead the world in pretty well everything, including bad eating habits. The scientific dynamite propelling the charge is that sugar consumption worldwide has gone up three-fold in the last 50 years. The average American now eats over 600 grams of the stuff every day, a feat that leaves the rest of the world scarcely within range of a podium spot. It may seem a bit odd to be left trailing at anything by the most obese nation in the world (let’s leave Nauru –pop. 9265 – and a few other South Sea islands out of it)  but the link here is, of course, that sugar is a great source of calories and that the more calories you shovel down – in whatever form – the bigger you tend to become. But don’t get too cheeky about Yankee obesity as us Brits aren’t in great shape either.

Condensed facts

Very roughly an ‘average’ person needs about 2,100 calories a day. 600 grams of sugar would give between one third and one quarter of that total requirement. For an historical perspective that’s about 14 times as much sugar as the denizens of Great Britain were allowed during the second world war under rationing – a period when our diet is generally considered to have made us healthier than we’ve ever been. So you could say an element of control has been lost.

Calorific confusion

The ‘2,100 calories’ above are ‘food calories’, the unit sometimes used in nutritional contexts. It’s 1000 times bigger than ‘scientific’ calories, or gram calories (cal). Scientifically therefore, we mean 2,100 kilocalories (kcal). Which is why your fruit juice carton may tell you one glass contains 50 kcal. And, just to stop you asking, 1 calorie is the heat (energy) you need to raise the temperature of 1 gram of water from 14.5oC to 15.5oC.

An all-round view of the problem

Sugar consumption has ski-rocketed, eating too much of it unbalances your diet and bad eating habits can cause obesity and metabolic syndrome. But these things aren’t black and white: 20% of obese people have normal metabolism and a normal lifespan whilst 40% of those of normal weight will get metabolic syndrome diseases. So, whilst obesity indicates metabolic abnormality, it is not per se the cause.

The underlying science remains a matter of debate – a story well summarized by Gary Taubes. What is not in question is that we eat more sugar than we need and the real crunch is that sugar is like tobacco and alcohol – no, it doesn’t make you smelly or do Sinatra impressions – but it is addictive. It actually manipulates your pathetic brain cells so you keep asking for more.

On your Marx

So we’re seduced into eating more and more of something that can help us get fat and ill. What’s to be done? Lenin, who was fond of asking this question, would have dealt with it in a trice by limiting sugar supplies to one tenth of the dietary minimum and seeing who survived. Ah! The good old days. But the authors of the recent article had to come up with a pc 21st century equivalent. Of course! Taxation. And they’ve a point – you can tell people that smoking will give them lung cancer til you’re blue in the face but the only thing that stops them committing suicide is jacking the price up. Don’t ask me. Something to do with human nature. So it sounds like a good idea – but to have an effect on sugar you’d need a huge increase across a vast range of foods – fruit juice, ‘sports’ drinks, chocolates, sweets, cakes – forget it.

Do I have a solution? Of course! Bring back rationing. For all foods. Set at the UK second world war levels. Now we’d think about what we eat – carbohydrate, protein and fat – reverse obesity trends, solve world food problem, slash health service costs, cut queues at supermarkets (so they’d be normarkets). And we’d be rid of most of those damned cheffy t.v. programmes. Vote for me!!

Reference

Lustig, R.H., Schmidt, L.A. and Brindis, C.D. (2012). The toxic truth about sugar. Nature 482, 27-29.

Gary Taubes (2011). Is Sugar Toxic? The New York Times.