High Altitude Diet: Diet to Counter Changes brought by Acclimitization
Foods to Counter Changes in Human Body due to Acclimatization
The decreased amount of oxygen in the air at altitudes above 2000 meters causes many short-term and long-term physiologic changes in the human body for acclimatization.
The short-term changes include the body increasing the respiratory rate and speeding up the heart rate to offset the lower partial pressure of oxygen, causing a change in the body’s acid-base balance. Such a change mostly affects athletes, mountain climbers, and people leading an extreme vigorous lifestyle.
The long-term changes in the human body that occurs due to extended stay at high altitudes include the following:
- Decrease in heart rate. This makes stimulating foods such as celery and fish best suited for a high altitude diet, and diary products and soy food that induces calming or low heart rates unsuited for regular consumption at high altitudes.
- Increased production of red blood cells and chemical changes within red blood cells, making them more efficient in providing oxygen to the tissues. This requires incorporation of iron rich foods such as red meat to boost hemoglobin in the body.
- Excretion of base through kidneys to restore acid-base balance, causing less tolerance for lactic acid. Foods rich in lactic acids such as cheese, soy, meat products, and pickled vegetables thus remain unsuited in a high altitude diet
- Increase production of mitochondria and oxidative enzymes
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Foods to Balance High Metabolism
The best high altitude diet is a carbohydrate heavy one, for carbohydrates require less oxygen for metabolism compared to fats and proteins. Experts recommend increasing the quantum of carbohydrates to as much as 70 percent of the total energy intake at altitudes above 5000 meters. Complex carbohydrates obtained from starchy and sweet foods provide ongoing fuel needed to replenish glycogen stores
An exclusively carbohydrates diet, however, does not meet the body’s overall nutritional needs.
The basal metabolic rate (BMR), or the amount of energy used to maintain the body’s essential functions, increases significantly during the first few days at high altitude. Extended stay at high altitudes cause the BMR to return close to normal levels, but remains higher when compared to the normal metabolism at lower altitudes.
The increased metabolism owing to increase of BMR leads to depletion of energy levels and weight loss. A high altitude diet, besides being rich in carbohydrates, also needs to be high in calories and fat to counter the increased burning of energy and thereby prevent weight loss. Research at the University of California suggests a high fat diet at high altitude does not have the same harmful effects as it does on ground level, thanks to the increased metabolism at high altitudes. A very high fat diet, with fat in excess of 30 percent of the total energy, however, remains harmful due to the increased requirement of oxygen for processing.
Typical mountaineers’ classics such as candy bars and cheese actually contribute to chronic muscular fatigue; however, they are ineffetive foods to balance high metabolism, for they are very high-fat snacks without adequate carbohydrates.
On the next page, we’ll look at more high altitude diet issues such as the diet to retain muscle mass, how to cope with loss of appetite and the need for plenty of fluids at high altitudes.
Foods to Retain Muscle Mass
Shrinking muscles is one of the long-term impacts of high altitudes on the human body. Studies show that mountain climbers who spend more than two months above 5500 meters lose five percent of their thigh muscle. The low oxygen at higher altitude depresses the rate of muscle protein production and increases the rate of protein breakdown.
Ways to retain muscle mass at high altitudes entails changing the diet patterns as follows:
- consumption of more proteins to slow down the deterioration of lean muscle mass
- consumption of supplements of branched chain amino acids such as leucine, isoleucine, and valine
- increased Vitamin E intake from sources such as vegetable oils, nuts, and seeds. A combination of Vitamin E and blood thinning drugs could, however, cause excessive bleeding.
- avoiding consumption of the much required protein and fat at night. The decreased respiratory rate during sleep and increased requirement for oxygen to metabolize fats and proteins accelerates depletion of energy from muscles
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Fluid Requirements at High Altitudes
The dry air resulting from low humidity at high altitude causes sweat to evaporate from skin rapidly. This combined with increased energy expenditure due to low levels of oxygen in circulatory system places a person at high risk of dehydration and altitude sickness. People at high altitudes, therefore, need to drink plenty of fluids, especially water. The minimum recommended fluid intake is three to four liters a day.
Diuretics such as alcohol and caffeine that encourages loss of fluids remain best avoided at high altitudes.
How to Cope with Loss of Appetite at High Altitudes
A high altitude diet to counter the effects of high metabolism, retain muscle mass, and prevent dehydration would be of no avail if the person living at high altitudes does not consume any food in the first place.
The failure to acclimatize to higher altitudes owing to hypoxia, or the body cells remaining deprived of oxygen, causes mountain sickness that induces loss of appetite, nausea, and vomiting. A move to higher altitudes usually results in reduction of food intake from 10 to 50 percent.
The following dietary strategies ensure that decreased food intake owing to hypoxia does not lead to harmful effects to the human body:
- making the high altitude diet dense in key nutrients such as carbohydrates and iron that increase oxygen absorption
- elimination of excess salt in foods that impair oxygen levels in the body
- eating smaller meals at frequent intervals
- a concerted, conscious effort of dietary management and forced eating
The role of diet in acclimatization and the prevention of high-altitude illnesses is, however, not conclusive.
This article does not constitute medical advise. Please read this disclaimer regarding the information in this article.
- Rice University. High Altitude and Athletic Training
- Pidcock, Janet. High-altitude Eating
- Science Daily. High-Altitude Metabolism Lets Mice Stay Slim and Healthy on a High-Fat Diet