Raccogliamo materiale a proposito? Potremmo col tempo giungere ad una prima bozza di proposta da pubblicizzare presso le associazioni mediche vegetariane del mondo per rivedere le raccomandazioni ufficiali. Intanto iniziamo, man mano che ci capita sotto mano uno studio, a segnarlo qui.
Io per ora segnalo questo articolo sul calcio della Harvard Medical School. Non è male, anche se non menziona il ruolo delle proteine animali nella perdita di calcio dalle ossa. In particolare cito:
http://www.hsph.harvard.edu/nutritionso ... index.html
At this time, however, the optimal intake of calcium is not clear, nor is the optimal source or sources of calcium. As noted earlier, the National Academy of Sciences currently recommends that people ages 19 to 50 consume 1,000 milligrams of calcium per day, and that those age 50 or over get 1,200 milligrams per day. Reaching 1,200 milligrams per day would usually require drinking two to three glasses of milk per day—or taking calcium supplements—over and above an overall healthy diet.
However, these recommendations are based on very short-term studies, and are likely to be higher than what people really need. Currently, there's no good evidence that consuming more than one serving of milk per day in addition to a reasonable diet (which typically provides about 300 milligrams of calcium per day from nondairy sources) will reduce fracture risk. Because of unresolved concerns about the risk of ovarian and prostate cancer, it may be prudent to avoid higher intakes of dairy products.
At moderate levels, though, consumption of calcium and dairy products has benefits beyond bone health, including possibly lowering the risk of high blood pressure and colon cancer. (20–25) While the blood pressure benefits appear fairly small, the protection against colon cancer seems somewhat larger, and most of the latter benefit comes from having just one or maybe two glasses of milk per day in addition to what we get from other foods in our diet. Getting more than this doesn't seem to lower risk further.
For individuals who are unable to digest—or who dislike—dairy products and for those who simply prefer not to consume large amounts of such foods, other options are available. Calcium can also be found in dark green, leafy vegetables, such as kale and collard greens, as well as in dried beans and legumes.