Fancy that?

Seeing as they started 28 years ago we can hardly blame members of the Harvard School of Public Health for publishing the results of their labours in tracking 120,000 people, asking them every few years what they’ve eaten and seeing what happened to them (a ‘prospective’ study). About one in five of the subjects died while this was going on but the message to emerge was that eating red meat contributes to cardiovascular disease, cancer and diabetes. The diabetes is non-insulin-dependent diabetes mellitus (NIDDM) or adult-onset diabetes – about 90% of diabetes cases. The cancers weren’t specified, although the evidence for a dietary link is generally strongest for colon carcinoma. The risk is a little higher for processed red meat than unprocessed.

How much?

Massive, if you mean the amount of data they accumulated from such a huge sample size followed over many years. If you mean on a plate, their standard serving size was 85 grams (3 ounces) for unprocessed beef, pork or lamb) and 2 slices of bacon or a hot dog for processed red meat. One of those a day and your risk of dying from heart disease is increased by about 20 per cent and from cancer by about 10 per cent – and the risks are similar for men and women. Just to be clear, that is a daily consumption – and the authors very honestly acknowledge that ‘measurement errors inherent in dietary assessments were inevitable’. They also mentioned that one or two things other than steak can contribute to our demise.

Are we any wiser?

If you recall from Rasher Than I Thought? the risk of pancreatic cancer is increased by just under 20 per cent if you eat 50 grams of processed meat every day. This report suggests that a limit of 1.5 ounces (42 grams) a day of red meat (one large steak a week) could prevent around one in 10 early deaths. So does it tell us anything new? Not really. Was it worth doing? Yes, because it adds more solid data to that summarized in Are You Ready To Order?

And the message?

Unchanged. Do some exercise and eat a balanced diet – just in case you’ve forgotten, that means limit the amount of red meat (try fish, poultry, etc.), stick with the ‘good carbs’ (vegetables, fruits, whole grains, etc.), cut out the ‘bad’ (sugar – see Biting the Bitter Bullet), eat fishy fats not sat. fats and, to end on a technical note, don’t pig out.

 References

Pan A, Sun Q, Bernstein AM; et al. Red meat consumption and mortality: results from 2 prospective cohort studies [published online March 12, 2012]. Arch Intern Med. doi:10.1001/archinternmed.2011.2287.

Pan A, Sun Q, Bernstein AM; et al. Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. Am J Clin Nutr. 2011;94(4):1088-1096.

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Cooperative Cancer Groupies

Few words carry more impact than the gentle syllables of cancer. Transform it into any language, its effect is unchanged: cancer, cancro, Krebs, рак … Always that inner tightening as we prepare ourselves for something we’d prefer not to hear. And yet, and yet … like so much of life there is an obverse – more than one in fact. Down the years few things have revealed more of the greatness of the human spirit – the fortitude, resilience and compassion of which mankind is capable. And it’s also a wonderful thing because, whatever its downsides, without cancer we would know far less about the amazing flexibility and adaptability of nature. Endless beautiful examples have been teased from its mysteries by inquisitive, curious and sometimes plain lucky scientific detectives.

Of late a particularly fertile facet has been what one might call the supporting cast: not tumour cells themselves but families that have moved in next door. If the idea that both normal and abnormal may play a role seems a bit strange, recall that, as well as being wonderful, cancer’s also funny – peculiar, that is – in being generated within ourselves: something goes wrong with cells that are perfectly normal and the result is something unusual. A new growth. A neoplasm. And our body reacts as it almost always does when something odd happens: it sends reporters along to find out what’s happening and put a stop to it. These roving sleuths are cells of the immune system – collectively white cells.

As with almost any unusual event – a new kid in school, a spotted celeb, a traffic accident – a crowd has started to gather round. In the body it’s called inflammation and it’s the first sign that our immune response is being switched on. The cellular groupies that turn up at the earliest signs of a tumour are a motley lot: all the broadsheets and tabloids are there, so to speak. But they differ from human onlookers in that each has a job to do. The first response is that some of the groupies release chemical signals that can target tumour cells for destruction by other groupies. The tumour is seen as ‘foreign’, just like an infection, and the response is ‘get rid of it’. We have no idea how efficient this kind of tumour elimination is but we might guess it’s not bad as most cancers don’t appear until we’ve been around for over 60 years.

When a tumour does manage to grow to a detectable size, that protection has clearly been overcome. But astonishingly, when this happens it’s not merely that the anti-tumour armoury has failed. It’s worse than not having enough fire-power: it’s actually been subverted, perverted if you wish, ‘turned’ as John le Carré might say, so that the immune cells that set out as assassins have become genuine groupies. Now the chemical signals they throw onto the tumour stage support growth and protect the cancer cells from destruction. Normal cells, recruited to the scene of cellular abnormality, have become in effect part of the tumour, essential for its survival and continued growth.

A stunning example of the tumour cooperative happens in chronic lymphocytic leukaemia. The leukaemia cells are a typical tumour in that their metabolism is abnormal. One upshot of this is that they make a lot of very reactive things called free radicals that are toxic – that is, will kill the leukemia cells unless they can make a neutralizing chemical called A. But to make A they need a building block B. B needs a carrier to get across the outer membrane into cells and the leukemia cells don’t make that carrier. But one of the ‘groupies’ does: it takes up lots of B, turns it into C and then pumps that out so that the tumour cells are bathed in C – which they can take up. The leukemia cells convert C into B, then make A, which knocks out their free radicals – so they survive and the tumour grows. If you can describe a thriving tumour as wonderful, it’s jaw-droppingly clever. And it’s not all bad news because blocking the transfer of C offers a new drug target for treating the most common adult leukemia in the Western world.

Reference

Zhang, W. et al., (2012). Stromal control of cystine metabolism promotes cancer cell survival in chronic lymphocytic leukaemia. Nature Cell Biology 14, 276-286.

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.