EXERCISE YOUR MUSCLE MOLECULE
Super-brain Ross Harper writes about something to do with water-cleaning carbon nanotubes and Simon Makin covers a story about the weird things that happen when you exercise. It’s the news you almost certainly missed. Page 22 is where you want to be.
Was one of your New Year’s resolutions to get more exercise? How’s that “working out” for you? Would it help if you knew exactly how exercise has such long-lasting effects on good health? Well Guru is here to tell you that scientists have just made a big step forward in understanding exactly that. Think of it as a geeky pep talk… A landmark new study has found that exercise not only makes your heart and muscles stronger but may actually change the type of fat in your body. Researchers discovered that exercise triggers muscles to produce a small molecule that travels through the blood and into ‘white’ fat, changing it into calorie-burning ‘ brown’ fat. This transformation may be a ‘missing link’ between exercise and its wide-ranging benefits. There are two kinds of fat. Everybody knows about horrid white fat – the stuff that gives us adorable ‘love handles’ and ‘bingo wings’ – but its lesser known cousin, brown fat, is a very different beast. White fat cells are where our bodies store energy from the food we eat. Think of them as fuel stores; we need that reserve just in case we don’t eat enough to fuel our daily activities. But snaffle more calories than you use up each day and you’ll start to get bigger. Brown fat cells are more like fuel burners – they burn fat to generate heat. Scientists used to think brown fat was only found in new-born babies and disappeared by adulthood, but we now know that most adults still have some. Also – interestingly – it tends to be more plentiful in thin people.
So what does this have to do with exercise? Well, researchers from Bruce Spiegelman’s lab at Harvard Medical School in Boston, MA, found that when muscles are exercised they release a newly-discovered hormone called irisin – and irisin can make white fat behave more like brown fat. These experiments were done on mice, although lots of researchers are pretty confident that the same thing happens in human muscle It’s not yet clear whether irisin affects all humans in the same way though, as other researchers could only find effects in elderly people.
Fitness in a bottle
Irisin isn’t the whole picture however. In this latest study a team led by Robert Gerszten, in collaboration with Spiegelman’s group, found another substance called beta-aminoisobutyric acid (or BAIBA for short). BAIBA is much smaller than irisin (a single amino acid for the real geeks out there), but has been found to ‘brown’ the white fat cells by making their DNA behave more likea brown fat cell. BAIBA also encourages liver cells to break down fats – a sure sign of increased metabolism. Indeed, mice given water laced with BAIBA to drink had a higher metabolism, healthier blood sugar, and lost weight. To check whether these effects are likely to apply to humans, the scientists analysed samples from over 2000 patients (from the long-running Framingham Heart Study) and found that people with low levels of BAIBA in their blood had high cholesterol levels – putting them at a higher risk of heart disease – and more insulin resistance – putting them at risk of diabetes. But when people had taken part in a 20 week exercise programme, as part of another study, their BAIBA blood levels increased by 17%. The researchers now think that having more BAIBA protects you from conditions like diabetes and heart disease. It could therefore be used as the inspiration for new treatments – perhaps even in the development of drugs to fight obesity, or even just to help people lose weight. Maybe your doctor could even test your BAIBA levels and find out how much exercise you have really been doing! But we shouldn’t get too excited just yet: there’s still a lot of work to be done, such as finding out if BAIBA has any unforeseen side effects in animals, before they can even start down the road towards drug development. So don’t go turning in your gym shoes just yet – there’s still no substitute for a good old-fashioned work out.