According to a new Stanford study published in the journal Nature Medicine, caffeine may help to counter the inflammatory process that occurs in some older people. The researchers have found a connection between advancing age, systemic inflammation, cardiovascular disease and coffee consumption by analyzing blood samples, survey data and medical and family histories obtained from more than 100 human participants in a multiyear study. Stanford Medical Center Report adds: The study implicates this inflammatory process as a driver of cardiovascular disease and increased rates of mortality overall. Metabolites, or breakdown products, of nucleic acids -- the molecules that serve as building blocks for our genes -- circulating in the blood can trigger this inflammatory process, the study found. The study also provides evidence that caffeine and its own metabolites may counter the action of these circulating nucleic-acid metabolites, possibly explaining why coffee drinkers tend to live longer than abstainers. Notably, this inflammatory mechanism was found to be activated only in some, but not all, of the older study participants. Those in whom it was relatively quiescent tended to drink more caffeinated beverages. Laboratory experiments revealed that the mechanism was directly countered by caffeine and associated compounds. For the new study, the researchers compared blood drawn from older versus younger study participants to see which genes tended to be more highly activated in older people. They zeroed in on two clusters of genes whose activity was associated with the production of a potent circulating inflammatory protein called IL-1-beta. The genes within each cluster appeared to work in coordination with one another. The researchers found that incubating a type of immune cell with two of those nucleic-acid metabolites boosted activity in one of the gene clusters, resulting in increased IL-1-beta production. When injected into mice, the substances triggered massive systemic inflammation, along with high blood pressure. In addition, immune cells infiltrated and clogged the animals' kidneys, increasing renal pressure substantially. Intrigued by the correlation between older participants' health, gene-cluster activation and self-reported rates of caffeine consumption, the researchers followed up and verified that blood from the group with low cluster activity was enriched for caffeine and a number of its metabolites, compared with blood from the group with high cluster activity. (Examples of these metabolites are theophylline, also found in tea, and theobromine, which abounds in chocolate.) Incubating immune cells with caffeine and its breakdown products along with the inflammation-triggering nucleic acid metabolites substantially prevented the latter from exerting their powerful inflammatory effect on the cells.
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