**6.10 Skeletal system**

Most changes occur in the skeletal system. Osteoporosis can be a major obstacle to the actions and activities of astronauts, especially in long-term missions and/or traveling to other planets [52].

Skeletal changes in spaceflights seem to be the most important alterations because they may limit or even stop a space program [53]. Rate of monthly 1–2% bone loss has been postulated during spaceflights [52] and 0.5–1.5% by some other investigators [54]. It could be up to 15%. Returning to normal values after landing

on the Earth is much slower, maybe only 6% annually [55]. Vico et al. did not observe recovery at skeletal sites the year after return from ISS in 2017 [56]. In 2010, Dana et al. stated prolonged consequences of bone loss even after 2.5 years following a stay on ISS [57].

It has been shown that bones of the lower extremities become more osteoporotic in comparison to other parts of the body. Skull bones are less affected, and even some report increased density of the skull. Then we may assume the most critical factor of osteoporosis to be unloading [16].

Several articles have shown the skeletal system and its physiology alterations due to spaceflight [54, 56–60]. LeBlanc et al. reported a 5% decrease of bone mineral density was observed in 92% of 60 American and Russian astronauts during long-term flights lasting 4–6.5 months [61]. The review by LeBlanc et al. showed that weight-bearing bones had more bone mineral loss [62]. The results of Skylab were repeated in the Soyuz and Mir missions [9]. 1,25-Vitamin D and its precursor reduced significantly in the Mir 18 mission [9]. Lang et al. claimed their data shows that full recovery of bone density was not complete even after 1 year [59]. Experiments conducted in the Mir station demonstrated 13% of osteoporosis in the pelvis which had the most significant range of bone loss in comparison with other parts of the skeleton [37].

### **7. Vitamin D**

In missions and space travels, the health of the astronauts and, consequently, its maintenance are essential, and it would be vital in some cases and situations. Proper nutrition will positively affect human health; vitamins such as vitamin D have important roles too.

Leach and Rambaut's research on Skylab 4, published in 1977, showed that the amount of vitamin D was lower in astronauts, even with supplementation of 500 units per day. Their mission was 84 days long, but such results were not observed for previous Skylab's short-term missions (28 and 59 days) [63].

The studies on astronauts of the Mir space station showed that the amount of vitamin D had dropped. The reasons were considered as the following [52]:


In 2001, Smith and colleagues conducted a study on nutrition status assessment in 2 isolated environments (2 missions 60 and 91 days long, 4 participants, on the Earth) and a 4-month residence of two astronauts at the Mir station. They found that the amount of vitamin D was 32–36% of the average value [64].

Smith et al. published the results of nutritional status of 11 astronauts with longterm missions on ISS (128–195 days, 2000–2004). The program contained 10 μg/d of supplementary vitamin D; 10 micrograms of cholecalciferol was in each supplement. A significant decrease (25%) was observed on 25-hydroxycholecalciferol after the mission, and bone markers showed increased resorption [63].

The report indicates weekly consumption of 5.7 ± 4.0 supplementary vitamin D per (and mean of 3.5 ± 2.9 supplementary multivitamins) [63]. It does not seem to be a sufficient amount of vitamin D for compensation.

Following the launch of the ISS, the order for supplementing vitamin D was issued to astronauts. Meanwhile, the twenty-first century had come. In the first

**73**

*Vitamin D in Space*

*DOI: http://dx.doi.org/10.5772/intechopen.82314*

800 units for astronauts on ISS [65].

available (as the source of vitamins).

**7.1 Vitamin D and the positive point**

changes (particularly in bone) [21].

**7.3 Vitamin D story continued**

thickness was also higher [21].

tific references [67].

**7.2 Vitamin D and the negative point**

decade of this century, vitamin D was considered by anyone, and a wave of research and reports began. Everywhere we heard and read about this vitamin, from newspapers, magazines, radios, and TVs. The Internet was also overwhelming. Are considerable number of articles and papers, and surprising notes showing that vitamin D is of tremendous importance and everything from cancer and a variety of serious diseases and dangers to a variety of even chronic infections such as tuberculosis would be impacted. The results of the mentioned wave were expanded from the Earth to the sky and space. Fortunately, this was a positive aspect of the case, so the daily dosage of vitamin D increased from 400 to

The research published by Smith et al. in 2012 was based on 13 astronauts (9 males and 4 females, between 2006 and 2009, length of mission as a long one between 4 and 6 months). It was the first study of this type that showed the mineral density of bones, and risk of osteoporosis would be reduced in long-term space mission by severe exercise and adequate feeding (good energy, plus 800 units of vitamin D per day, which was twice the amount of vitamin D prescribed in previous missions). Of course, the results were achieved by bone remodeling [66] more than by bone resorption reduction. Blood and urine specimens were prepared before, during, and after space travel, but densitometry was performed before and after the trip. Their findings can help ensure that vitamin D is sufficient to live in an environment that does not have any exposure to ultraviolet radiation and with limited food

Vitamin D is easy to use and available. Its cost is not so much, and it may be prescribed as an efficient strategy in hindrance and/or prevention of space-induced

An important subject that should be considered is vitamin D does not have an

In another research, our team measured the bone mineral density of 14 rats' femur and demonstrated morphologic changes for the contralateral femur after supplemental calcium/vitamin D. The bone mineral density and bone mineral content had a significant increase in the experiment group. The outer cortical bone

Astronauts should be healthy and able to maintain their health in order to be capable of performing their tasks as the best as possible. It should be implemented during and even after space travel (either landing on Mars or returning to the Earth). In this case, nutrition is of particular importance for the body as a whole and cellular processes. The food is packaged and ready for astronauts, which should be of good quality and, at the same time, meet the requirements of scien-

Cooper et al. published their research results on astronauts' food quality assessment in 2017 [67]. They examined 24 micronutrients including vitamin D in 109 food packages for 3 years and determined the amount of vitamin D at the beginning of the study, 1 and 3 years later. It turned out that vitamin D is not even adequate at

infinite capacity for preventing osteoporosis (cellular process) [22].

#### *Vitamin D in Space DOI: http://dx.doi.org/10.5772/intechopen.82314*

*Fads and Facts about Vitamin D*

ing a stay on ISS [57].

parts of the skeleton [37].

**7. Vitamin D**

important roles too.

• Consumption of low vitamin

• Lack of exposure to ultraviolet radiation

factor of osteoporosis to be unloading [16].

on the Earth is much slower, maybe only 6% annually [55]. Vico et al. did not observe recovery at skeletal sites the year after return from ISS in 2017 [56]. In 2010, Dana et al. stated prolonged consequences of bone loss even after 2.5 years follow-

It has been shown that bones of the lower extremities become more osteoporotic in comparison to other parts of the body. Skull bones are less affected, and even some report increased density of the skull. Then we may assume the most critical

Several articles have shown the skeletal system and its physiology alterations due to spaceflight [54, 56–60]. LeBlanc et al. reported a 5% decrease of bone mineral density was observed in 92% of 60 American and Russian astronauts during long-term flights lasting 4–6.5 months [61]. The review by LeBlanc et al. showed that weight-bearing bones had more bone mineral loss [62]. The results of Skylab were repeated in the Soyuz and Mir missions [9]. 1,25-Vitamin D and its precursor reduced significantly in the Mir 18 mission [9]. Lang et al. claimed their data shows that full recovery of bone density was not complete even after 1 year [59]. Experiments conducted in the Mir station demonstrated 13% of osteoporosis in the pelvis which had the most significant range of bone loss in comparison with other

In missions and space travels, the health of the astronauts and, consequently, its maintenance are essential, and it would be vital in some cases and situations. Proper nutrition will positively affect human health; vitamins such as vitamin D have

Leach and Rambaut's research on Skylab 4, published in 1977, showed that the amount of vitamin D was lower in astronauts, even with supplementation of 500 units per day. Their mission was 84 days long, but such results were not observed for previous Skylab's short-term missions (28 and 59 days) [63].

The studies on astronauts of the Mir space station showed that the amount of

In 2001, Smith and colleagues conducted a study on nutrition status assessment in 2 isolated environments (2 missions 60 and 91 days long, 4 participants, on the Earth) and a 4-month residence of two astronauts at the Mir station. They found

Smith et al. published the results of nutritional status of 11 astronauts with longterm missions on ISS (128–195 days, 2000–2004). The program contained 10 μg/d of supplementary vitamin D; 10 micrograms of cholecalciferol was in each supplement. A significant decrease (25%) was observed on 25-hydroxycholecalciferol

The report indicates weekly consumption of 5.7 ± 4.0 supplementary vitamin D per (and mean of 3.5 ± 2.9 supplementary multivitamins) [63]. It does not seem to

Following the launch of the ISS, the order for supplementing vitamin D was issued to astronauts. Meanwhile, the twenty-first century had come. In the first

vitamin D had dropped. The reasons were considered as the following [52]:

that the amount of vitamin D was 32–36% of the average value [64].

after the mission, and bone markers showed increased resorption [63].

be a sufficient amount of vitamin D for compensation.

**72**

decade of this century, vitamin D was considered by anyone, and a wave of research and reports began. Everywhere we heard and read about this vitamin, from newspapers, magazines, radios, and TVs. The Internet was also overwhelming. Are considerable number of articles and papers, and surprising notes showing that vitamin D is of tremendous importance and everything from cancer and a variety of serious diseases and dangers to a variety of even chronic infections such as tuberculosis would be impacted. The results of the mentioned wave were expanded from the Earth to the sky and space. Fortunately, this was a positive aspect of the case, so the daily dosage of vitamin D increased from 400 to 800 units for astronauts on ISS [65].

The research published by Smith et al. in 2012 was based on 13 astronauts (9 males and 4 females, between 2006 and 2009, length of mission as a long one between 4 and 6 months). It was the first study of this type that showed the mineral density of bones, and risk of osteoporosis would be reduced in long-term space mission by severe exercise and adequate feeding (good energy, plus 800 units of vitamin D per day, which was twice the amount of vitamin D prescribed in previous missions). Of course, the results were achieved by bone remodeling [66] more than by bone resorption reduction. Blood and urine specimens were prepared before, during, and after space travel, but densitometry was performed before and after the trip. Their findings can help ensure that vitamin D is sufficient to live in an environment that does not have any exposure to ultraviolet radiation and with limited food available (as the source of vitamins).
