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Tumours with PI3K activation are resistant to dietary restriction. Nada Y. Kalaany & David M. Sabatini Nature. Published online 11 March 2009 doi:10.1038/nature07782

A signalling pathway that influences how sensitive cancer cells are to the beneficial effects of dietary restriction is described in this week's Nature. Dietary restriction - eating less calories while maintaining essential vitamins and minerals - can extend lifespan, and reduce cancer incidence and growth. But some types of cancer cell are more sensitive to the anti-growth effects of dietary restriction than others, Nada Kalaany and David Sabatini report. The effect hinges on the activity of the phosphatidylinositol-3-kinase (PI3K) pathway. If the pathway is active, dietary restriction has no effect on cancer cells. However, if the pathway is inactive, tumours are sensitive to dietary restriction.

ScienceDaily (May 26, 2009) - A protein that plays a key role in tumor formation, oxygen metabolism and inflammation is involved in a pathway that extends lifespan by dietary restriction. The finding, which appears in the May 22, 2009 edition of the online journal PLoS Genetics, provides a new understanding of how dietary restriction contributes to longevity and cancer prevention and gives scientists new targets for developing and testing drugs that could extend the healthy years of life.

Increased dietary protein consumed at breakfast leads to an initial and sustained feeling of fullness during energy restriction compared to other meal times. Heather J. Leidy, Mandi J. Bossingham, Richard D. Mattes and Wayne W. Campbell British Journal of Nutrition (2009), 101:798-803 Cambridge University Press doi:10.1017/S0007114508051532

Calorie-restricted diets are thought to protect against cancer and slow tumor growth, and a new study published in this week's Nature begins to tease out why the measure works for some tumors, and not for others. For almost a century, researchers have known that fasting helps animals live longer and avoid some cancers, "but which type of cancers would be amenable to this approach, from a therapeutic standpoint, is still an open question," said Pier Paolo Pandolfi, a cancer geneticist at Harvard Medical School and Beth Israel Deaconess Cancer Center in Boston, Mass., who was not involved in the study. The study is exciting because it is one of the first to start answering that question at the genetic level, he said.