Thomas B. Shea and his team at the University of Massachusetts — Lowell induced oxidative stress in mice by tweaking their diets — both normal mice and those lacking apolipoprotein E, a gene that helps protect the body from oxidative stress, were used in the study. Humans carrying a version of this apoliprotein E gene have been shown to be at greater risk for Alzheimer's disease.
[T]he study doesn't suggest that drinking lots of apple juice will stave off Alzheimer's disease. [I]t does underline the importance of eating (and drinking) a balanced, healthy diet...
The researchers gave half the mice in each group apple juice, which they had previously found to increase maze navigation as well as slow the deterioration in performance that is normally associated with age. In the mice that were not fed apple juice, beta-amyloid production just about doubled in the normal group, and also increased in the apolipoprotein E-deficient group. But in mice that were given apple juice, researchers did not see these increases beta-amyloid proteins in either group of mice.
What is it about apple juice that seems to have this effect? The researchers' previous work had also shown that apple juice inhibits a protein called presinilin 1, which, if over-expressed, can lead to greater apolipoprotein E production. The team suggests that this mechanism may be what's behind the current findings, too.
If you were just about to run out and buy a case of apple juice, that's probably not the best interpretation of the results of the study, the researchers say. While the study doesn't suggest that drinking lots of apple juice will stave off Alzheimer's disease in humans, it does underline the importance of eating (and drinking) a balanced, healthy diet that is rich in fruits and vegetables. Shea points out that while the natural aging process increases oxidative stress in the body, eating fruits and veggies works to reduce it.
Shea also notes that for those who aren't fans of apple juice, there are many other juices that may have similar effects: "It's what you stay with that's important."