Serendipity: Breast really is best

EARLIER this year, researchers based at Lund University in Sweden made an extraordinary claim. Catharina Svanborg and her team announced that milk has the ability to kill cancerous cells, and, furthermore, they had identified the key ingredient that made it such a potent anti-cancer agent.

The story of Svanborg's discovery starts in 1993. Scientists have long been aware that breast-fed infants are much less likely to suffer from a whole series of illnesses. To find out why, Svanborg was conducting experiments in which she added nasty microbes to living cells, and then added milk to find out how this helped the cells to survive. The cells were cancer cells, because these are the cellular equivalent of lab mice, acting as a worldwide standard for experiments.

Instead of protecting the cancer cells against the microbes, though, the milk caused the cancer cells to self-destruct. The result was so astonishing that Svanborg did not publish it until she had successfully replicated the effect and found studies that supported her work. One crucial study showed that breast-fed babies were nine times less likely to suffer from childhood lymphoma. This was independent evidence that also implied that milk did indeed contain an anti-cancer agent.

The agent turned out to be a protein called alpha-lactalbumin, or alpha- lac for short. This was a surprise, because alpha-lac had been thoroughly studied in the past, and scientists had assumed that it merely helped to manufacture lactose, the sugar found in milk. However, the Swedes showed that when the protein finds itself in an acid environment, it changes shape and is able to attack cancer cells.

Each protein is a long chain of atoms, and its function is determined not only by the type of atoms in the chain, but also by the shape formed by the chain. In other words, intially the milk contains alpha-lac in its lactose-producing form, but once it reaches the acidic environment of the baby's gut, it changes into its anti-cancer form. The science magazine Discover described alpha-lac as a "microscopic version of a comic-book superhero, leading a quiet life by day, transforming itself into a swashbuckling crime-fighter by night."

The Lund researchers have tested alpha-lac on various cancer cells (lung, throat, kidney, colon, bladder, lymphoma and leukaemia) and it has proved effective in each case. Furthermore, Svanborg believes that alpha-lac will not harm healthy cells, because it is a naturally occurring substance. To prove her non-toxic hypothesis, she has already started to test alpha- lac on mice with tumours, and so far the results have been very encouraging. If the experiments continue to be successful, then she will proceed to human trials.

'The Code Book - the Science of Secrecy from Ancient Egypt to Quantum Cryptography' by Simon Singh is published by Fourth Estate, pounds 16.99

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