Dietary Intake Modifications to Protect Against Changes in Bone Metabolism

Bone loss is not only a well-documented effect of spaceflight on astronauts, but also a
condition that affects millions of men and women on Earth each year. Many countermeasures to
bone loss have been proposed, and many have been evaluated to some degree. To date, those
showing potential have focused on either exercise or pharmacological interventions, but none
have targeted dietary intake alone as a factor to predict or minimize bone loss during
spaceflight. The investigators proposed to document how the ratio of acid precursors to base
precursors in the diet is related to directional changes in markers of bone resorption and
formation during flight and recovery from flight. There is a high likelihood for success in
predicting the extent of bone loss from dietary intake patterns of astronauts during
spaceflight, given that this concept is strongly anchored in data obtained from ground-based
experiments in our laboratory and others. The notion of manipulating diet to minimize bone
loss could also have significant social and economic impacts for NASA and for the general
public - especially given the increasing trends for diets that are high in animal protein
and low in fruits and vegetables. The results of the proposed experiments will lead to
development of a dietary countermeasure for bone loss consisting of a balanced diet with no
associated risks for side effects that might be present with pharmaceuticals or supplements,
no requirement for payload mass, and no additional crew time necessary during flight.