Is dodging Alzheimer's, cancer possible with diet?

What you eat can have long-term impact on health, from possibly reducing risk of cancer to heading off Alzheimer's, according to new studies.

Research published this week in Cancer Research, the journal of the American Association for Cancer Research, indicates that a low-carbohydrate, high-protein diet seems to reduce tumor growth rates and overall cancer risk. And it may also have a desireable anti-inflammatory effect, as well.

It's a study conducted in mice, but many of the scientists say "the strong biological findings are definitive enough that an effect in humans can be considered," according to a release from the American Association for Cancer Research.

Meanwhile, a study published in the Archives of Neurology this week found that a low-fat, low-glycemic diet may reduce the risk of developing Alzheimer's disease if it is adopted early in life. The study indicates it does not help stop brain deterioration once the disease is showing symptoms.

For the mice study, headed by Gerald Krystal of the British Columbia Cancer Research Centre, the scientists implanted human or mouse tumor cells in different strains of the mice and then made sure they were fed one of two different diets: a typical Western diet with 55 percent carbohydrates, 23 percent protein and 22 percent fat or something more like the South Beach diet, only with extra protein. That second diet had 15 percent carbohydrates, 58 percent protein and 26 percent fat. Tumor cells grew slower "consistently" on the higher-protein diet.

They further found that about half of mice that were genetically predisposed to breast cancer developed it within their first year on the Western diet (mice typically only live about two years), while none did on the low-carbohydrate, high-protein diet. The mice on the Western diet also died younger, overall.

The researchers speculated that tumor cells need more glucose than normal cells to thrive. Restricting carbohydrate intake reduces glucose and insulin, shown in many studies to promote tumor growth in mice and people.

They also believe the high-protein diet helps prevent obesity, which has been linked to chronic inflammation and cancer. And a recent study also linked obesity, particularly belly fat, to dementia.

For the Alzheimer's study, researchers at the Zucker Hillside Hospital and the Feinstein Institute for Medical Research at Manhasset, N.Y., build on evidence that midlife obesity increases the chance of late-life dementia. While such results are tantalizing, there exists no solid evidence that anything in particular will prevent Alzheimer's, researchers said.