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Status and Intake

There are no known data on either changes in dietary intake or changes in status of this vitamin as a result of exposure to cold or high altitudes.

Author's Recommendation

A long period of time is required to produce deficiency in vitamin K. In addition, the vitamin is synthesized intestinally. Hence, it is suggested that the micronutrient intake goal for vitamin K be set at the RDA level of 70 to 80 µg, which is commensurate with what is found normally in foods.

WATER-SOLUBLE VITAMINS

All of the water-soluble vitamins, with the exception of folic acid and vitamin C, are intimately involved in the oxidation and conversion of food to energy at multiple steps leading up to and in the functioning of the Krebs cycle (see Hunt and Groff, 1990). Thus, an adequate nutritional status with respect to the water-soluble vitamins is essential for the production of sufficient energy for thermogenesis and for physical exertion while in the cold and at high altitudes.

Thiamin
Functions

Thiamin is essential for energy metabolism; it serves as a cofactor in the oxidative decarboxylation of pyruvate to acetylcoenzyme A (acetyl-CoA) immediately prior to its entrance into the Krebs cycle, in the conversion of α-ketoglutarate to succinylcoezyme A (succinyl-CoA) in the Krebs cycle with subsequent oxidation to adenosine triphosphate (ATP), and in the hexose monophosphate shunt. If the thiamin supply is insufficient, the increased demand for acetyl-CoA during physical activity or for thermogenesis may not be met. As a result, more pyruvate will be converted to lactate with subsequent early onset of fatigue (Williams, 1989).

Intake and Status

Draper (1976) reported that inadequate intake of thiamin was one of the primary dietary deficiencies among Norwegian Lapps. Hasunen and Pekkarinen



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