Monday, February 01, 2010

After the war on salt, the battle against butter

Healthy-living killjoys now even want to ban the yellow creamy stuff that makes food so tasty and enjoyable. ‘By banning butter and replacing it with a healthy spread, the average daily sat-fat intake would be reduced by eight grams. This would save thousands of lives each year and help to protect them from cardiovascular disease - the UK’s biggest killer.’

So said London-based heart surgeon Shyam Kolvekar last week. He, along with many others, is offering us out-of-date advice that would rob us of one of life’s great pleasures.

The theory is that a diet high in saturated fats will lead to atherosclerosis - so-called ‘furry’ arteries. This narrowing and hardening of the arteries in turn is thought to make it more likely that we will suffer a clot in one of the blood vessels leading to the heart, causing a ‘heart attack’ as that vital organ is deprived of oxygen.

It’s the story we’ve been told for decades now. Rich, animal-derived foods like butter and other dairy products, eggs and meat are little more than a ‘heart attack on a plate’. Butter - with a saturated fat content of 50 per cent - is a prime target for health campaigners, and manufacturers of spreads with low levels of saturated fats make great play on how they are heart-healthy.

It certainly seems to be the case that eating more saturated fat increases the amount of cholesterol in your blood. It’s the cholesterol - or more particularly these days, the so-called bad cholesterol - which is deemed to cause those furry arteries. The trouble is that intervening in diet doesn’t seem to make a great deal of difference. In the early Eighties, a massive intervention trial called MRFIT reduced cholesterol and saturated fat intake for a large group of Americans. If the theory was right, the result should have been a sharp drop in heart attacks. The actual result? No change. The kind of dietary changes that people are constantly told to make had no effect on the risk of having a coronary. Incredibly, however, this negative result had no effect on the popularity of the diet-causes-heart-attacks thesis, either.

In 1998, the Danish doctor and cholesterol sceptic Uffe Ravnskov noted: ‘The crucial test is the controlled, randomised trial. Eight such trials using diet as the only treatment have been performed but neither the number of fatal or non-fatal heart attacks was reduced.’ Indeed, as Gary Taubes notes in his book The Diet Delusion, there was initially a lot of scepticism about the idea that cholesterol was a killer and it was only when the idea got the official stamp of approval from the US government in the 1960s that it became regarded as common sense; as Taubes shows, the epidemiological evidence for the theory was full of holes. (For a review of the book, see The Copernicus of the diet debate? by Rob Lyons.)

Kolvekar’s comments last week represent just the latest in a long line of attacks on the basic pleasures of food. If it’s not butter that’s going to kill us, apparently it will be salt or bacon or anything else that actually tastes of something. Time and again the evidence for these assertions turns out to be as feeble as the flavour of the salad we’re supposed to be munching instead. It’s all reminiscent of an old joke. A doctor advises his patient to stop smoking, drinking or eating rich foods. ‘Will this mean I’ll live longer?’, asks the patient. ‘No, but it’ll seem longer’, came the reply.

Even if there were some risk attached to eating butter, would we really want to do without it? In Kitchen Confidential, the American chef and writer Anthony Bourdain is forthright in his defence of butter: ‘I don’t care what they tell you they’re putting or not putting in your food at your favourite restaurant, chances are you’re eating a ton of butter. In a professional kitchen, it’s almost always the first and last thing in the pan… Margarine? That’s not food. I Can’t Believe it’s Not Butter? I can.’ Even the Italians, says Bourdain, famed for their olive-oil heavy diets, are in fact whacking loads of that yellowy, creamy nectar into the pasta, risotto and veal chop.

Celebrity chef Jamie Oliver, known as much for his health crusades as his cooking, knows which side his bread is buttered on. A spokesman told the Daily Mail: ‘He is completely against a ban on butter. He uses butter in his recipes, for example for roasting potatoes in his Christmas programme. He doesn’t like the whole kind of food police, we must ban everything, point of view.’ That last statement is a little hard to swallow, given some of the claims made in Oliver’s own TV shows, but he’s not so stupid that he thinks you can cook good food without butter.

It’s not even the case that butter is all that important as a source of fat in our diets. As Felicity Lawrence points out in the Guardian, ‘Butter and fat spreads between them make up just one-eighth of our total fat intake’, with meat, dairy products and even cereal products like bread and biscuits being more important. Unfortunately, Lawrence can’t help but see the whole affair as a scam on the part of food manufacturers who produce those ‘heart-healthy’ spreads, insinuating that the tentative links between the heart surgeon Kolvekar and food giant Unilever amount to a conflict of interest. But while manufacturers have undoubtedly pumped up advice in order to flog their products - and some cholesterol-lowering products come at a 300 per cent mark-up - the real source of confusion has been the willingness of some noisy doctors and health authorities to overstate the case against certain foods in order to influence how we live.

This has produced some notable ironies. For example, polyunsaturated fats have in the past proven difficult to use in certain situations like baking and high-temperature frying. The furore over saturated fats three decades ago led many manufacturers, particularly in the US, to replace products rich in saturated fat, like butter and lard, with partially-hydrogenated vegetable fats. In recent years, however, these new fats - which contain so-called ‘trans fats’ - have been claimed to be even worse than saturated fat for causing heart disease. It may well be that the case against trans fats is as ropey as the evidence linking butter with heart disease has proven to be. But whatever the truth is, a little more scepticism and careful evaluation of the evidence, rather than a hysterical leaping from one killer food to another, would make more sense.

Those who claim that our food is killing us are not averse to laying it on a bit thick when it comes to scare stories. But the only thing we should be laying on thick is that lovely, creamy butter.


Neuron breakthrough offers hope on Alzheimer’s and Parkinson’s

Neurons have been created directly from skin cells for the first time, in a remarkable study that suggests that our biological makeup is far more versatile than previously thought.

If confirmed, the discovery that one tissue type can be genetically reprogrammed to become another, could revolutionise treatments for conditions such as Parkinson’s disease and Alzheimer’s, opening up the possibility of turning a patient’s own skin cells into the neurons that they need.

The study by scientists from Stanford University, California, also suggests that skin cells could be reprogrammed to provide a limitless supply of blood or bone marrow for personalised transfusions.

Until now, the consensus was that only master cells from embryos, or adult cells that have been ‘rewound’ into an embryo-like state — a process that takes several weeks — have the ability to form all the different types of tissue in the body.

The latest study, carried out in mice, reveals that while cells choose and maintain their speciality during the earliest phase of development, they retain an underlying flexibility. Provided that the correct genes are turned on or off they could potentially be turned into any other variety of tissue in the body.

The work has been hailed as a huge conceptual leap forward in fundamental biology. “The possibility that cells could be directly reprogrammed is something that people had thought about, but to see it in black and white is still slightly shocking,” said Professor Jack Price, a neurobiologist at King’s College London. “This suggests that there are no great rules — you can reprogramme anything into anything else.”

The finding will address some of the ethical objections of groups who oppose embryonic stem-cell research, in which the embryo is destroyed. And the new process is much quicker than the alternative method, where adult cells are “rewound” to create versatile master cells, known as induced pluripotent stem (iPS) cells.

In the study, published in the journal Nature, skin cells were infected with a genetically modified virus that inserted genes into the cells’ DNA. The researchers began by introducing 19 genes that are known to be switched on when mice stem cells first differentiate into neurons during embryonic development.

Using a mix-and-match approach, the researchers found that of the 19 genes initially tested, only three were truly necessary to get the skin cells to develop into neurons. When these three genes were switched on, 20 per cent of the skin cells had turned into fully functioning neurons in less than a week. The neurons were able to make connections with and signal to other nerve cells — critical functions if the cells are eventually to be used as therapy for Parkinson’s disease or other disorders.

“We were very surprised by both the timing and the efficiency,” said Irving Weissman, a stem cell expert at Stanford University in California, who led the research. "This is much more straightforward than going through iPS cells, and it’s likely to be a very viable alternative.”

In terms of clinical applications, a further advantage of skipping out the intermediate iPS state is that it is known that iPS cells promote cancers. Many researchers believe it would be difficult to obtain a license for the use of cells that are grown from iPS cells.

“People have been saying that iPS cells could be used therapeutically in the near future, but frankly they’ve been lying,” said Professor Price. “These cells don’t go through a tumourigenic phase, which means it would be much easier to get a licence to use them.”

The Stanford group are now working to reproduce the finding using human cells, but say that there is no reason to expect it should not apply to most species.

A further question is why, if cells retain an underlying versatility, they don’t switch between cell types throughout our life. One possible explanation is that genes interact via “see-saw” mechanisms, whereby when one set of genes are switched on, they automatically keep other genes switched off unless an artificial intervention is made.


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