It is possible they do this by reducing inflammation which has been linked to cancerous tissue changes.

BBC: Aspirin

Vitamin D also appears to play a role in healthy immune function and reducing inflammation, a risk factor for numerous diseases including cancer, heart disease and diabetes.

CNN: How much vitamin D should someone over 55 take?

In a bewildering result, an experimental drug aimed at reducing inflammation in the arteries failed in a big clinical trial but prevented heart attacks, strokes and deaths, according to a press release from the drug's maker.

FORBES: Strange Days For AtheroGenics

The DeCode (nasdaq: DCGN - news - people ) results and other recent studies suggest that an old class of asthma drugs called leukotriene blockers might prevent heart attacks by reducing inflammation of the arteries.

FORBES: Magazine Article