RE: Forget Rat Studies, Call NASA!!!

[Guest guest]

Seems to me that the fact that astronauts lose bone mass comes as no

surprise. Weight-bearing exercise is known to increase bone mass at

least in women, and is recommended for younger women to increase bone

density before they start losing it. While diet must certainly also

play a factor, the gravity factor I don't think can be ignored.

Since weight-bearing exercise is hard to come by in orbit, and what

they come up with as a substitute doesn't seem to be doing it, means

we evolved to live in gravity and our bodies decide that in

weightlessness all that rigid bone is not necessary. I also wonder

about the phosphorous level of the diet they consume while in space.

Might this and the acid/base issues that have been discussed also

have some relevance, although they might not be acceted by the

dietitians that design the crew diet?

Iris

--- In @y..., " Dean M. " <bordercollie@a...>

wrote:

> Hi everyone, (cross-posted w/crsociety)

>

> Let's see, one of NASA's biggest problems is keeping bone mass on

> astronauts.

>

[Guest guest]

NASA Speaks on Bone Loss

& Prevention:

Dean - (cross-posted w/crsociety)

Thanks for your note and interest in

NASA's Nutritional Biochemistry Laboratory.

Bone loss is obviously one of the

greatest challenges we face when considering extended-duration

spaceflight. NASA is currently

investigating many potential countermeasures to help reduce or eliminate this

bone loss, and also to assess implications for recovery of lost bone. The primary countermeasures being

studied at this point include resistive exercise, and bisphosphonates

(anti-resorptives).

I am sure you are aware that caloric

intake and body mass are two important factors in bone health. One of the confounding factors that we

have noted during space flight is that often crewmembers don't eat enough and

subsequently lose body mass. We

are collaborating on a study in Germany where they are assessing the impact of

hypocaloric diets (i.e., undernutrition) on bone loss during bed rest.

Postflight rehabilitation involves a

carefully monitored program of exercise rehabilitation, with recommendations

for adequate dietary intake. Unfortunately - the dietary recommendations are the

same as for Earth-based populations - adequate calories, protein, vitamins,

minerals, etc. Obviously key bone-related nutrients include calcium, vitamin D,

and others - however - the amounts recommended for typical healthy diets will

support the rehabilitation. The

bodies needs for extra calcium, for instance, are met through increasing the

efficiency of absorption, i.e., typically only 25-40% of dietary calcium is

absorbed, extra dietary calcium will not change

that.

Thanks again for your interest, I hope

this information is helpful.

, Ph.D.

Nutritionist, Manager for Nutritional

Biochemistry

Human Adaptation and Countermeasures

Office

Best, deVries

Mental Health = EPA + DHA + O6 calories @ 2-3% of Daily Caloric

Intake

( p.s. alternative " equations " are always welcomed

" : )

..