Tool User: Kendal Mint Cake

As he prepared for the 1953 Chomolungma (Everest) expedition, Dr. Griffith Pugh worried about a strange affliction that struck members of past attempts: once they climbed above a certain altitude, they began struggling to eat; and insufficient calories, combined with low oxygen and physical strain, rapidly diminished any chance of success. Studying the diets of previous teams, he noticed one possible solution: high in the Himalaya, even climbers who avoided sweets at sea level craved sugar. Thus, when he designed his “assault ration” of rolled oats, milk powder, sugar, jam, sweet biscuits, cheese, boiled sweets, salt, cocoa, tea, soup and lemonade powder, he added a little-known, glucose-laden substance called a “mint bar.”

Since the beginnings of alpinism, mountaineers have asked the question: What should a climber eat? In Mountain Craft (1920), Geoffrey Winthrop Young recommended packing “pleasant luxuries” that would “go down easily” on high peaks. Nineteenth-century alpinists brought brandy and sardines for ascents in the Alps. But in 1924, when Edward Norton became the first to climb above 28,000 feet on Chomolungma, he experienced not only a sense of extreme exhaustion, but also a severe loss of appetite. You could put plenty of appealing food in a pack, expedition organizers realized, but you couldn’t make a climber consume what they found there.

In his report on the 1933 British attempt of the same peak, Dr. Raymond Greene observed that men at Camp IV “dreamed, with childlike blissful smiles…of steak and onions,” even as they disposed of their “loathsome tinned-meat” rations in a crevasse. Consequently, Greene suggested, “The individual tastes of every member must be studied with the greatest of care and without any regard to economy.”

High-altitude mountaineers themselves tried to figure out ways to digest enough calories. Eric Shipton obtained the food logs of climbers who ventured between 18,000 and 21,200 feet on Chomolungma in 1935. According to his 1938 article in Chemistry and Industry, team members ate a mere 1,500 to 2,000 calories per day at those heights, not nearly enough to sustain the effort required to climb and haul for even a short stretch of time.

Using custom-built pressure chambers during World War II, mountaineer and physician Charles S. Houston conducted research on the effects of altitude. Known as Operation Everest I, the study concluded that, at extremely high elevations–especially when people aren’t using supplementary oxygen–more blood flows to the heart, brain and lungs, and less to other organs and muscles. With decreased oxygen, the digestive system has fewer resources, and the desire for food diminishes as a part of the body’s general stress response.

To understand how these changes affected expedition members, Dr. Griffith Pugh studied the 1952 attempt on Cho Oyu (8188m). Above 18,000 feet, climbers were able to consume around 3,000 calories a day. Pugh attributed the increase in caloric intake from the time of Shipton’s study to the larger availability of sugar. The carbon dioxide produced while digesting and oxidizing simple carbohydrates is much greater than what would be produced for a similar quantity of fat or protein. Dissolved in the bloodstream, the increased carbon dioxide helps to stimulate respiratory activity and aid in subsequent oxygenation.

English confectioner Joseph Wiper discovered the mint cake by chance in 1869 when he turned his back on a boiling vat of candy and ended up with a concoction of nearly pure glucose. The same company has been manufacturing this accidental creation, known today as Kendal Mint Cake, for more than one hundred years. When the 1953 expedition requested thirty-eight pounds of Mint Cake from the George Romney Company, the UK Ministry of Foods had to approve their purchase of so much sugar (World War II rationing was still active at the time).

In a 2004 article in Wilderness and Environmental Medicine, physiologist E. Wayne Askew cited modern studies that confirmed Pugh’s ideas on the benefits of simple carbohydrates for many climbers at altitude. Breakthroughs in nutrition research–as well as in equipment, training and acclimatization–have allowed today’s alpinists to push the boundaries of human endurance to levels that Pugh and early mountaineers could scarcely have imagined. It’s still possible, however, to get a taste of what those years were like, by throwing a Kendal Mint Cake in your pack, lacing up your studded leather boots and taking a wooden-handled alpenstock on your next adventure.

[This story originally appeared in Alpinist 68, which is now available on newsstands and in our online store. Only a small fraction of our many long-form stories from the print edition are ever uploaded to Alpinist.com. Be sure to pick up Alpinist 68 for all the goodness!–Ed.]