Mineral and Vitamin Requirements of Long Flights

This brief review does not permit an extensive evaluation of such stresses as radiation,
reduced atmospheres, zero or reduced gravity, wearing of pressure suits, possible effects
of extremes in environmental temperature, and atmospheric toxicants. Neither has much
attention been given to such psychological stresses as isolation, monotony, loneliness, frustration, and speed-time or day-night sensations. These areas will require much attention
and definitive answers are in most instances lacking. What has been emphasized is that
present methodology for evaluating nutrient requirements of individuals under normal
day-to-day stresses on Earth imply that there is considerable variation among individuals.
This would suggest strongly that in the selection of astronauts considerable attention
should be directed toward establishing physiological behavior of individuals under controlled nutrient intake conditions. This might at least assure that individuals with
unusually high requirements for individual nutrients could be eliminated for consideration
for extended explorations into outer space. Since it is already known that adaptive
phenomena exert an effect, the suggested physiological studies should extend over a sufficient period to allow for evaluation of individual adaptability to specific stresses.

Even considering the relative importance of minerals and vitamins, with minor exceptions, possibly thiamine, several months to several years are required to deplete mineral
and vitamin stores in healthy adults placed on deficient diets. In meeting requirements
for extended space flights, first consideration should be given to the allowances for salt
since both excessive and deficient intakes have marked influences on maintenance of water
balance. The total requirement for other minerals and vitamins can be furnished, as
they are now known, without unduly adding weight to the total nourishment needs of
man. Their total weight would at most represent only a few percent of the total weight
of food and water. Brief note is taken of the special needs for considering ration or
nutrient stability under conditions of prolonged storage under flight conditions.