The special section on ageing research in this week's issue comes at a particularly exciting time for the field. Ageing may be inexorable — a steady accumulation of cellular damage that cannot be stopped — but it is increasingly seen as a process that can, at least in part, be regulated (see page 504).

Unfortunately, legitimate research advances in the field can sometimes give an unwanted boost to the charlatans pitching anti-ageing elixirs (see page 491).

Anything researchers say in the media must strike a careful balance between science, hope and hype.

A case in point is resveratrol, a compound found in grape skins and red wine. About a decade ago, researchers found that this compound seemed both to extend lifespan in some animals and to have health benefits in mice. The news media immediately leapt on the story — as did the pharmaceutical industry: Sirtris, a firm in Cambridge, Massachusetts, that was founded to develop resveratrol-like compounds in 2004, was sold in 2008 to London-based pharmaceutical company GlaxoSmithKline for $720 million.

Since then, resveratrol's possible role in ageing has turned out to be more complex than it first seemed (see pages 480 and 513), and there is still much to be learned about how, and whether, the compound affects ageing in humans. These subtleties are all but impossible to fit into a television sound bite — a fact that allows the snake-oil salesmen to gain the upper hand.

David Sinclair, a molecular biologist at Harvard Medical School in Boston, Massachusetts, found that out the hard way. As a co-founder of Sirtris, Sinclair has had his work touted in magazines and newspapers, and has appeared on US national television sipping red wine and discussing resveratrol's effects. But he now finds that quotes and images from his many media appearances are being taken out of context and used to pitch commercial resveratrol supplements of dubious value. Sinclair has had to pay lawyers tens of thousands of dollars to send letters demanding that his name be stripped from such advertisements.

Adding to the problem is the poor regulation of the thousands of varieties of dietary supplements for sale in the United States. Going in the opposite direction from Europe, where supplements must be shown to be safe in both quantity and quality, Congress in 1994 passed the Dietary Supplement Health and Education Act, a bill that limited the ability of the Food and Drug Administration (FDA) to rein in the burgeoning industry. Safety and the accuracy of advertising claims were left to be policed largely by the manufacturers themselves.

In the absence of adequate regulation, false claims by supplement makers abound. At best, these claims can cheat consumers of their money. At worst, as in the case of ephedra, widely touted for weight-loss, they could cost users their lives.

Since 1994, US lawmakers have repeatedly tried, and failed, to improve oversight of the dietary-supplements industry. The latest attempt will make its way through Congress this year in the shape of the Dietary Supplement Safety Act of 2010, a set of amendments to the FDA's legislative charter put forward in February by Senators John McCain (Republican, Arizona) and Byron Dorgan (Democrat, North Dakota). The provisions would require dietary-supplement manufacturers to register with the Health and Human Services secretary, and would give the FDA authority to immediately recall supplements that are misbranded or that pose a health threat. Although these provisions would not stop the sale of supplements that are a waste of money — a category that seems to include most or all of the anti-ageing elixirs — they are an important step forward, and Congress should approve them without delay.

Meanwhile, researchers should remain keenly aware of their responsibilities, especially in a field as fraught with anxiety and apprehension as ageing. Just as with stem cells or any other field with great medical promise but no clear timescale for delivery, anything they say in the media must strike a careful balance between science, hope and hype. Researchers must be honest with the public, and themselves, about what the science really is — what it can and cannot say, what it is and isn't likely to achieve (for example, allowing people to live forever) and what is still unknown. 'Let the buyer beware' may be a commercial maxim, but science can certainly reduce the risks.