Importance of Functional Ingredients in Yak Milk-Derived Food on Health of Tibetan Nomads Living Under High-Altitude Stress: A Review

Abstract

Tibetan nomads have lived since ancient times in the unique and harsh environment of the Qinghai-Tibetan Plateau with average altitudes over 4000 m. These people have been able to live and multiply healthily over numerous generations under the extreme stress of high-altitude environment, including cold, hypoxia, and strong ultraviolet radiation, and with a simple diet devoid of vegetables and fruits for most of the year. Their survival depends heavily on yak milk, and its products comprise the main portion of their daily diet. In this review, yak milk and its derived products are examined in detail and compared with milk from other ruminant species. Yak milk products seem to be particularly rich in functional and bioactive components, which may play a role in maintaining the health status of Tibetan nomads. This includes particular profiles of amino acids and fatty acids, and high levels of antioxidant vitamins, specific enzymes, and bacteria with probiotic activity (yoghurt is the main food). Based on that, it is proposed that the Tibetan nomads have developed a nutritional mechanism adapted to cope with the specific challenges posed by the environment of the world's highest plateau. Systematic studies are required to demonstrate this in a more mechanistic way.

Keywords:

• Yak milk
• bioactive components
• high altitude
• oxidative stress
• nutritional adaption
• hypoxia

ACKNOWLEDGMENTS

This work was supported by grants from the National Natural Science Foundation of China (project number 31170378) and the Program for New Century Excellent Talents in University (program number NCET-11-0209). The authors would like to express their great appreciation to Mr Malcolm Gibb (formerly of the Institute of Grassland and Environment Research, Aberystwyth, United Kingdom) for revision of the manuscript.