The New York Times ( http://www.nytimes.com/2010/01/03/opinion/03kristof.html) has deemed folate as the world's healthiest food based on the profound impact it can have on forming embryos. It makes sense that if folate has this much power that it's benefits would also transend to adults. Scientists know that older people tend to be deficient in folate, which enables vitamins B6 and B12 to aid in hormone secretion, synthesize DNA, and manufacture the protective coating around the nerves. These three tasks are thought to be the major elements in our bodies' defenses against fatal age-related disorders such as Parkinson's or Alzheimer's. So, increase your folate and we can lower our odds of contracting one of these conditions.
The good news is that folate is found in numerous foods, including spinach, kale, brussel sprouts, asparagus, black beans and brocolli, but it is destroyed by heat, so these vegetables have to be eaten raw. You can also obtain your RDA for folate by eating a morning breakfast cereal (most fortified with 25-100% of your RDA @ 400 mcg, not the 800 mcg needed for over 50). Cereals with the highest levels of folic acid include Whole Grain Total, Cap'n'Crunch Peanut Butter, Cinnamon Life, Frosted Wheaties, Special K, and Raisin Bran.
The good news for any non-cereal eater (like me!) is that this is one case where the natural form of folic acid is not as easily absorbed by the body as the syntheic form. So, simply head to your closest Vitamin store and stock up for good health! I'm headed there now!