Awards Ceremony and Marloth Commemorative Lecture: 4 March 2015
Professor Timothy Noakes OMS, MBChB, MD, DSc, (he) PhD, FACSM, (hon)
Reversing the greatest blunder in the history of medicine. Can South African medical science (and activism) lead the way?
In 1977 for political and economic reasons, the United States Department of Agriculture (USDA) produced the Food Pyramid that promoted substitution of especially saturated fat in the diet with increased daily servings (6 to 11) of cereals and grains. It was argued that replacing fat in the diet with (less energy dense) carbohydrates would reduce calorie consumption, thereby preventing obesity. A diet lower in saturated fats would also lower blood cholesterol concentrations and according to the diet-heart hypothesis of American biochemist, Dr Ancel Keys, prevent the development of coronary atherosclerosis thereby preventing heart attack.
Unfortunately these guidelines were introduced even though there was no evidence from randomized controlled clinical trials that this radical change from what humans have eaten for more than 2 million years, would obviously produce these desirable outcomes.
Instead as so often happens when radical interventions are introduced without proper thought and in the absence of detailed scientific testing, there are likely to be unforeseen and unfortunate consequences.
The first unforeseen consequence was a global obesity epidemic that began after 1980, three years after the promulgation of the USDA Food Pyramid. This is associated with an increased consumption of both carbohydrates and calories as established from data on USA citizens. On simple biological principles this was entirely predictable, as carbohydrates do not satiate hunger; instead they drive appetite and the overconsumption of calories. Dietary fats especially and proteins satiate human hunger as they have for the greater than 2 million years of human adaptation to high-fat protein diets provided by our (only recently documented) success as hunters of the largest (and fattest) animals on the planet. That evidence is the ability of humans to exterminate all the largest mammals on each continent within a few centuries of our first arrival there.
Somewhat less foreseeable was the global diabetes epidemic that began 15 to 20 years after the 1977 guidelines were first promulgated. Whilst this epidemic is clearly associated with higher carbohydrate and sugar intakes, the exact biological mechanisms for causation have still to be established. (The initial defect in Type 2 Diabetes Mellitus (T2DM) is, as my colleague and former co-worker Professor Johan Koeslag from Stellenbosch University predicted in 2002, a failure of the normal intra-pancreatic inhibition of glucagon production by insulin. For without appropriate inhibition of glucagon secretion when carbohydrate is ingested, the metabolic state ofT2DM must develop leading ultimately to the metabolic syndrome and heart disease, and perhaps also cancer and dementia, although links to those latter conditions are, as yet, less clearly established. A Nobel Prize awaits the person who identifies the initiating mechanisms explaining this intra-pancreatic failure of insulin's action and who develops mechanisms to block the uncontrolled action of glucagon in T2DM).
However it is now clear that the key driver of the obesity-diabetes epidemic has been the development of the highly processed "industrial" diet that the 1977 USDA Food Pyramid help to establish. For when fat is removed from foods they lose their taste. And the processed food industry soon discovered to its unashamed delight, that replacing the fact with sugar and high fructose corns syrup produced highly appetising (non)foods that are also utterly addictive.
The reversal of the current obesity /diabetes epidemic will come, not from the government, but from the people who, when properly informed, will begin to demand healthy food choices. This means eating real foods, not highly processed industrial foods that are full of obesogenic and diabetogenic ingredients, but completely lacking in the nutrients we need to eat to be healthy. For a number of reasons the peoples of South Africa are closer than the citizens of any other country (of which I am aware) to be ready for that change. My wish is that South Africa will be the country that will lead the global Real Food Revolution that is already happening and which time will prove to be irreversible.
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