The researchers at the Greater Los Angeles Veterans Affairs Medical Centre at the University of California discovered an ingredient called bisdemethoxycurcumin found in the spice boosts the brain's natural ability to mop up nerve-destroying protein plaques associated with the condition.
The researchers say their epidemiological studies suggest that the curry diet might explain why Alzheimer's disease is so rare in India.
For the study the researchers extracted immune cells from healthy people and from patients with Alzheimer's disease, and tested how well they absorbed and destroyed protein plaques.
Many experts believe the destruction of the protein plaques to be the primary cause of Alzheimer's.
The team led by Milan Fiala found that immune cells from Alzheimer's patients were worse at clearing up the plaques than cells taken from healthy people but when they added the turmeric the immune cells became more active.
Further testing revealed that the ingredient altered the expression of key genes in the immune cells, overcoming the damage that had originally weakened them.
At this stage precisely how the ingredient works in the body and whether a lifetime of eating curries has any preventative effect against Alzheimer's, is unclear but the team say studies are continuing to see whether a supplement is effective.
Dr. Fiala says the study could lead to drug which is able to counteract the damaging effects of Alzheimer's.
The study appears in Proceedings of the National Academy of Sciences.
The study also looked at whether regular exercise is related to risk of multiple myeloma. There was not a clear effect of exercise on risk, although the results among women suggested that those who exercise more might have a lower risk. "We cannot say with certainty that exercise reduces the risk of multiple myeloma, but there is ample evidence that regular exercise offers many other health benefits," Birmann said.
The study findings do show, however, that the effect of BMI on risk of multiple myeloma is separate from any possible effect of physical activity.
According to Birmann, previous research has identified possible biological links between obesity and multiple myeloma. For example, adipocytes, cells found in fat tissue, produce a cell signal, called interleukin-6 (IL-6), which promotes the immune system's inflammation response. In obese people, this can cause an overproduction of IL-6, which in turn creates a cellular environment that sustains multiple myeloma. "The IL-6 chemical pathway is one possible way obesity could influence the risk of developing diseases like cancer or cardiovascular disease, but the answer might also lie in other relationships between obesity and cancer," Birmann said.
Further research, she said, will uncover more about the relationships between obesity and cancers such as multiple myeloma. The researchers believe their findings may lead to examination in greater detail of the BMI/multiple myeloma link, including the role of IL-6 and other chemical signals, energy metabolism, and other risk factors such as weight change or weight cycling.
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