Vegetarian low protein diet could be key to long life

This article reports that a diet low in the amino acid menthionine is hypothesized to be the key to longevity in humans, rather than calorie restriction.

  …in a series of new experiments on fruit flies, scientists
  discovered that simply varying the mix of amino acids in
  the diet affected lifespan.

  *Further study revealed that one particular amino acid,
  methionine, made all the difference.*

  Although flies and people are very different, the
  researchers believe the effects are likely to be conserved 
  throughout a wide range of different species including 
  humans…

  "If it turns it has the same effect on humans, then the 
  message is avoid high levels of methionine."
 

  High levels of methionine can be found in sesame seeds,
  Brazil nuts, fish, meats and some other plant seeds. Most
  fruits and vegetables contain very little of it. Most 
  legumes are also low in methionine.

So the instant article would make it appear that at least some scientists think they are closer to showing a similar mechanism at work in humans.

From 2005, "Aging Cell" journal:

http://www.ncbi.nlm.nih.gov/pubmed/15924568

Methionine-deficient diet extends mouse lifespan, slows immune and lens aging, alters glucose, T4, IGF-I and insulin levels, and increases hepatocyte MIF levels and stress resistance.