Metabolic aspects of acute altitude exposure (4,300 meters) in adequately nourished humans

Consolazio, C. Frank; Johnson, Herman L.; Krzywicki, Harry J.; Daws, Ted A.

doi:10.1093/ajcn/25.1.23

Cited by 39 publications

(21 citation statements)

References 12 publications

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“…Exposure to altitude causes hypohydration, caused by increased diuresis and decreased water intake. Negative nitrogen balance have been reported at high altitude but this report is not reliable as the calorie intake was less 34 . To achieve a positive nitrogen balance the minimum intake of protein should be 0.96 g/kg for exercising men but there is increased excretion of protein and nitrogen at high altitude hypoxia 35 .…”

Section: Nutrition At High Altitudecontrasting

confidence: 56%

Nutritional requirement at high-altitude with special emphasises to behaviour of gastro-intestinal tract and hormonal changes

Naveen

Anusha

2017

Def. Life. Sc. Jl.

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8. The traditional classification of hypoxia has only two subgroups based on empirical observations i.e., chronic and acute hypoxia (Fig. 3). Acute hypoxia response occurs within minutes of exposure to a hypoxic environment i.e., symptoms occur in first few hours-days. Some of the symptoms are hyperventilation, insomnia, fatigue, dizziness and gastrointestinal disturbances. In chronic hypoxia, the term 'chronic' is used to indicate the time interval which ranges over weeks and months. However long term adaptation to hypoxia has been studied in human populations in Himalayas, Ethiopian and Andes over generation 9 . According to Best and Taylor 10 hypoxia is classified into four main type's i.e., Hypoxic hypoxia, anemic hypoxia, stagnant hypoxia and histotoxic hypoxia as shown in Fig. 4. Nutritional Requirement at High-altitude with Special Emphasis to ABSTRACTWhen people are exposed to the extreme environmental conditions, such as high altitude where there is decrease in temperature and partial pressure of oxygen induces fatigue, insomnia, loss of appetite and increased cardiac output. Hence there is need to improve the appetite through the diet and digestion clout of the individual. In the present review paper the efficiency of digestion is compromised at high altitude is discussed. Also about, Hypoxia, resulting by decreased partial pressure of oxygen can be classified into acute hypoxia and chronic hypoxia based on the exposure time. There is increased formation of reactive oxygen species due to less oxygen available in the air at high altitude which leads to oxidative stress. Lipid peroxidation caused by oxidative stress. Hypoxia is mediated through hypoxia inducible factors which maintain oxygen haemostasis in the body. At high altitude diet rich in carbohydrates have been found to be beneficial as it increases glucose metabolism. Requirement of nutrients such as vitamin A, vitamin E and vitamin C as well as micronutrients such as zinc, iron, selenium, copper and manganese will be required at high altitude. Hypoxia effect on the intestine leads to malabsorption and the lipid storage is stimulated and lipid catabolism is inhibited through β-oxidation. Defence Life Science Journal, Vol. 2, No. 2, April 2017, pp. 120-127, DOI : 10. Hypoxic hypoxia is caused when there is low oxygen tension in the inhaled air as a result of which the haemoglobin present in the erythrocyte cannot saturate the fully saturate with oxygen leading to lack of oxygen in arterial blood. This is one of the most serious forms of hypoxia. Anemic hypoxia is a less serious condition than hypoxic hypoxia and it may be caused by an insufficient transport function of the haemoglobin. Stagnant/ Circulatory hypoxia arises when the amount of oxygen reaching the tissue is inadequate. This turn leads to reduced rate of blood circulation thereby allowing accumulation of carbon dioxide in the tissue. Histotoxic hypoxia is a condition where there is normal amount of oxygen in the blood and under normal tension but the cells are unable to accept oxygen...

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Section: Nutrition At High Altitudecontrasting

confidence: 56%

Nutritional requirement at high-altitude with special emphasises to behaviour of gastro-intestinal tract and hormonal changes

Naveen

Anusha

2017

Def. Life. Sc. Jl.

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“…Some authors have claimed that body mass loss, such as reported above, can be prevented by simple dietary intervention (40)(41)(42)(43), but whether this claim is justified is debatable. First, studies that have successfully matched energy intake to energy expenditure have used enforced feeding (42) or used experimental conditions not applicable to field environments with "a large choice of palatable food in comfortable conditions" (41).…”

Section: Discussionmentioning

confidence: 99%

Body composition at high altitude: a randomized placebo-controlled trial of dietary carbohydrate supplementation

Macdonald¹,

Oliver²,

Hillyer³

et al. 2009

The American Journal of Clinical Nutrition

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“…Whether the degree of hypoxia or physical work is responsible for these differences remains unclear. On ascent to high altitude, fasting blood glucose is reported either to remain unchanged, including normal glucose tolerance curves (Consolazio et al 1972), or to increase on ascent (Sawhney et al 1991). Elevated blood glucose in sojourners to 3,500 m was paralleled by high insulin concentrations until day 7 at altitude, and subsequently returned to baseline values (Sawhney et al 1991).…”

Section: Altitude Exposure and Metabolismmentioning

confidence: 99%

Austrian Moderate Altitude Study 2000 (AMAS 2000). The effects of moderate altitude (1,700 m) on cardiovascular and metabolic variables in patients with metabolic syndrome

Schobersberger¹,

Schmid²,

Lechleitner

et al. 2003

Eur J Appl Physiol

105

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We investigated the changes in the cardiovascular system [resting blood pressure (BP) and heart rate (HR), measured by means of a 24-h ambulatory BP and a holter-electrocardiogram (ECG)], glycemic parameters, and lipid metabolism of subjects suffering from metabolic syndrome during a 3-week sojourn at 1,700 m in the Austrian Alps. A total of 22 male subjects with metabolic syndrome were selected. Baseline investigations were performed at Innsbruck (500 m above sea level). During the 3-week altitude stay the participants simulated a holiday with moderate sports activities. Examinations were performed on days 1, 4, 9, and 19. After returning to Innsbruck, post-altitude examinations were conducted after 7-10 days and 6-7 weeks, respectively. The 24-h ambulatory BP and holter ECG revealed a decrease in average HR, BP, and rate pressure product (RPP: systolic blood pressure x HR) after 3 weeks of altitude exposure. In some patients, an increase in premature ventricular beats was observed at the end compared to the beginning of the exposure to moderate altitude. The ECG revealed no ischemic ST-segment changes. Maximal physical capacity as measured by symptom-limited maximal cycle ergometry tests remained unchanged during the study. Six weeks after the altitude exposure the blood pressure increased again and returned to pretest levels. The Homeostasis Model Assessment index, which is a measure of insulin resistance, decreased significantly and glucose concentrations obtained after an oral glucose tolerance test were significantly lower after the stay at altitude compared to the basal values. We conclude that after a 3-week exposure to moderate altitude, patients with metabolic syndrome (1) tolerated their sojourn without any physical problems, (2) exhibited short-term favorable effects on the cardiovascular system, and (3) had significant improvements in glycemic parameters that were paralleled by a significant increase in high-density-lipoprotein-cholesterol.

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Metabolic aspects of acute altitude exposure (4,300 meters) in adequately nourished humans

Cited by 39 publications

References 12 publications

Nutritional requirement at high-altitude with special emphasises to behaviour of gastro-intestinal tract and hormonal changes

Nutritional requirement at high-altitude with special emphasises to behaviour of gastro-intestinal tract and hormonal changes

Body composition at high altitude: a randomized placebo-controlled trial of dietary carbohydrate supplementation

Austrian Moderate Altitude Study 2000 (AMAS 2000). The effects of moderate altitude (1,700 m) on cardiovascular and metabolic variables in patients with metabolic syndrome

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