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Tuesday, July 22, 2014

Super-foods, super-diets and pseudo science

From time to time, certain  “super-foods” and “super-diets” emerge to dominate the menus of fashionable restaurants and chique delicatessens. The most recent super-food has been quinoa (pronounced KEEN-wah). Apparently, it will treat hypertension, diabetes is a natural appetite suppressor and is anti ageing[1]. In fact, the UN Food and Agricultural Organization deemed 2013 to be “The Year of Quinoa”[2]. The Director General of FAO stated that “…quinoa can play an important role in eradicating hunger, malnutrition and poverty”. The facts are however somewhat at variance with this view of quinoa as a super-food. Firstly, it is stated that its protein quality is unique in the plant world in that it is complete in all the 8 essential amino acids. This leaves the non-expert think that some plant foods therefore lack one or more essential amino acids. Not so. All plant proteins contain all amino acids but they vary in the relative amount of each. To rank the quality of a protein, its “protein digestibility corrected amino acid” (PDCAA) score is calculated. Three proteins gain a perfect score of 1.0: two of animal source, egg and whey protein and one of plant origin, soy protein. According to an entry in Wikipedia (most Internet listings for quinoa are from advocacy groups), quinoa, along with amaranth, buckwheat, hempseed, and spirulina fall below 1.0 but they are still called complete proteins because they contain sufficient of all the nine essential amino acids to meet the dietary needs of man[3]. So, quinoa is hardly unique despite its hype. If we turn to protein levels, we find that the following are the levels of protein in average servings of some plant food: amaranth, 3.8; rice, 4.0; beans, 15.0; lentils, 18.0 and soybeans 29.0[4]. Again, this hardly qualifies quinoa as a super-food. Quinoa is putatively “packed” with dietary fibre. An average serving of quinoa has the same amount of fibre as amaranth (5g) which does not compare well with other plant foods: lentils with 16g per serving and both beans and soybeans with 30g. Quinoa is also a truly marvelous source of antioxidants but most of these are simply natural bioactives and not nutrients and there is no serious data linking such plant bioactives to the incidence of chronic disease or risk factors for chronic disease. The hype on quinoa has caught the interest of researchers. Thus in the 20 year period from 1991 to 2011, PubMed lists 20 studies published on quinoa. In the last 2.5 years, a further 20 were added to the literature. According to the Wall Street Journal, there was a 9-fold increase in quinoa imports to the US between 2000 and 2007 and the price per pound almost doubled. This is all good news for the Andean farmers who grow it but not for the Andean people who rely on this crop as a staple food. Quinoa is more likely to grace the shelves of niche food stores in Manhattan to feed the worried well than it is to feed the billion people who go to bed hungry every night.
Besides super-foods we have super-diets and to illustrate the nonsense of super-diets, I will draw heavily on the writings of Harvey Levenstein in his book: “Fear of Food[5]” and specifically the chapter on “Natural Foods in Shangri-La”.
Sir Robert McCarrison (1878-1960), a medical doctor with the British Army in India, toured a remote valley at the foot of the Himalayas, now in Kashmir, Pakistan, which was the home of the Hunza people, the Hunzakut. He attributed their longevity and their physical and sexual fitness to their diet of unprocessed natural foods of milk, eggs, grain, fruit and vegetables. In the late 1940’s a former employee of the US Inland Revenue Service, wrote a book on the Hunzakut, never having visited the region. His book began to attract some attention and by 1957, the New York Times chief foreign correspondent visited the Hunza valley and confirmed that indeed the inhabitants lived to a very old age on a diet of dried apricots and powdered milk. Films were made featuring the Hunzakut and more books were written on their great health, physique, longevity and sexual prowess which persisted well into their 90s. In 1959, President Eisenhower’s cardiologist had an air-force doctor fly to the Hunza valley to check out there cardiac function and sure enough, a perfect bill of health came back. He added: “ A man in really good shape can eat up to 3,000 apricots in one sitting”! If it takes say 20 seconds to eat an apricot, then an apricot feast would last over 16 hours!!! The Hunza fever in the US reached the dizzy heights of an editorial in the Journal of the American Medical Association[6]. Then in 1956, a US geologist set up a small clinic in the Hunza Valley and was instantly inundated with cases of malaria, dysentery, parasitic infestations and symptoms of vitamin deficiency. He noted that in Spring, the entire valley ran out of food and starved until the barley harvest arrived. The Mir who ruled the valley, owned 25% of the land and of course was well fed as were his lackeys. He did visit the clinic to be treated for dyspepsia, requiring an ant-acid for relief. Subsequent visits by British, Japanese and French physicians confirmed widespread deficiency diseases such as goiter, a deficiency of iodine. Malnutrition was found to be rampant. Hunzamania is still rampant. You can buy on Amazon “Crystal Energy Hunza Water” and if you buy 2 you get 1 free[7]. How much? US $99.99!!

The fashion for super-foods and super-diets isn’t new and we will see quinoa slip in favour of the next fad. Its mainly pseudo-science.

[5] Fear of Food is published by Chicago University Press (2012)
[6] JAMA (1961) February25th. “Longevity in Hunza land”

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