We are all becoming more aware of the role our diet plays in our health and disease resistance. And of course, if anything goes wrong and we get sick we can always visit our doctor. Unfortunately, life will not be as simple for the first interplanetary space travellers. When the nearest hospital is 5-6 months away, it is important that astronauts stay as healthy as possible. Eating a good diet during long space voyages may be one way to do just that.
We have only limited experience related to space travel - with the majority of voyages "relatively close" to earth. However, in spite of this, several observations on the health and metabolism of the returning astronauts point to areas where diet will become important in long duration flights.
It is now well established that during missions lasting longer than one week, changes in bone calcium metabolism becomes a serious problem. While in zero gravity, for unknown reasons, calcium loss from bone becomes accelerated. This has very serious implications when long term voyages are being planned and can present a major threat to the health and well being of space travellers when they return to earth. It has also been noted that constipation sometimes affects space travellers, perhaps in part because of interference with normal peristalsis (contraction of the intestinal wall that directs food down the digestive tract) combined with an inadequate intake of liquid in the climate controlled space ships and, of course, the stress of space travel. Alterations in the diets of space travellers may be one way to overcome these two problems.
Diet may also help protect astronauts from a third phenomenon they experience in space. Beyond the protective layer of the earth's atmosphere, space ships and those inside are exposed to very high levels of ionized particles. Such particles are capable of damaging the DNA that is in our cells, which could lead to cell death or, in other cases, to the promotion of cancers. The longer the voyage, the more exposure and the greater the damage. At the present time, there are few options available that can protect space travellers from these damaging rays.
The reasons for the bone calcium loss is not known, therefore, at this time, the most prudent option is to consume foods that are high in very digestible calcium. Foods that are high in fat that could bind the calcium and make it unavailable for digestion should be avoided. In addition, it has been found that prolonged exercise during the space voyage helps cut down on bone calcium loss. Foods that are high in fibre, together with large quantities of liquid, may ease constipation problems. Constipation along with other gastrointestinal problems may not rank high in some people's health concerns, but they can affect performance and, if left too long, can lead to more serious problems. Many foods could be added to the diet that are high in antioxidants which would protect against tissue damage from ionized particles. It may be possible to increase the cellular concentration of a variety of antioxidants that can help reduce the damage of ionization.
As long as space travellers can take food from earth with them, it may be possible to design diets that are capable of reducing these problems and other problems. However, as voyages become longer and longer, and the crews become more dependent on food that they will grow and process during their flight, this becomes more of a problem. It is already apparent that as the diet of astronauts becomes more vegetarian, plant sources rich in calcium and high in antioxidants with a high energy content will be most desirable.
Osteoporosis, constipation and cancer are three major problems in our population here on earth. Any progress that can be made in overcoming these problems that occur during space travel will also benefit those who live on earth.