Is sugar toxic? The bitter truth

A recent editorial of The Times repor­ted a WHO survey revealing 70 per cent of Maltese over 15 were overweight and that the Cook islanders, including children, were, inexplicably, even more overweight.

Having practised medicine in the South Pacific area, I am able to offer an explanation which, firstly, requires an understanding of the effects of dietary changes in the last few decades.

For many years, conventional wisdom from Ancel Keys, a physiologist, was that eating too much natural animal fat caused fat deposition, with an increased risk of cardiovascular disease. This “fat is evil” hypothesis accelerated a worldwide change to eating predominantly carbohydrate-based food. However, a recent survey of 350,000 subjects by Ronald Krauss found no relationship between saturated animal fat consumption and disease. So Prof. Keys chose the wrong fat. Synthetic trans-fat lard was the fat that caused obesity, with adverse cholesterol and triglycerides and arterial and other disease risks.

Knowing that the presence of insulin facilitated the entry of glucose into the cells of the body, John Yudkin proved that excessive dietary glucose caused excessive insulin release to reduce the raised blood glucose by converting it to fatty acids leading to fat deposition. Subsequently, the cells became resistant to insulin and, thus, devoid of glucose. The cells switched their functioning to fat sources, causing excessive rises of blood fatty acids, cholesterol and fat deposition, leading to high blood pressure, diabetes mellitus type 2 and arterial disease – collectively known as the metabolic syndrome.

A recent wave of obesity in children prompted research to see if glucose, sucrose and fructose, behaved similarly in the body. Table sugar, known as sucrose, is 50 per cent glucose and 50 per cent fructose. Robert Lustig discovered that fructose, being a different chemical to glucose, was metabolised by a different route via the cells of the liver alone. An excess did not stimulate insulin production but made all the cells of the body resistant to insulin and, thus, starved of glucose. The cells then switched to fats as an energy source, causing obesity and the same metabolic syndrome. In addition, the fructose had a toxic effect on the liver causing a fatty cirrhosis due to the accumulation of abnormal ketone breakdown products. Alcohol and trans-fats behaved similarly.

The price of table sugar rose steeply many years ago, so a cheaper alternative, high fructose corn syrup (HFCS), was developed by synthetically converting glucose to fructose. HFCS is now used extensively as a sweetener for soft drinks and bulk-manufactured, processed food items (many of which also contain trans-fat) such as cereals, cakes, biscuits, doughnuts, pasta, canned fruit in syrup, protein bars, “fat-free” items and “slimming” shakes. The HFCS fructose content being very high caused obesity and the same metabolic syndrome but at a younger age and with increased severity. The normal replacement of cells was often accelerated, provoking cancer.

Years ago, the traditional diet of the South Pacific islanders was a healthy mix of fish, root vegetables, coconuts and other fruits but, gradually, western-processed food with its deleterious HFCS and trans-fats, appeared, both causing a rapid rise in obesity and the metabolic syndrome. The children, particularly, started drinking large amounts of HFCS-sweetened beverages, leading to childhood obesity and metabolic syndrome. Many of these children at age 10 already showed arterial narrowing disease, risking death from complications at 30.

Malta is facing the same problem. The answer is to replace a diet of processed foods and HFCS-sweetened beverages with consumption of organic foods and fresh, unsweetened fruit juices. Although fresh fruit contains fructose, the amount of naturally occurring fructose is small, having no deleterious effect. In fact, fruit contains health-promoting vitamins and anti-oxidants. Eating items containing synthetic trans-fat lard or margarine should be avoided. Butter or cold-pressed vegetable oils are better choices. Replacing some of the carbohydrate (like pasta and pizza) main courses with protein, such as organic chicken, fish or free-range eggs, helps to reduce weight and bring about wellness.

The body is well-designed for protein but not for high amounts of sugar, carbohydrates, alcohol and trans-fat, all of which cause obesity and metabolic syndrome, risking ill-health and life-shortening conditions.

Dr Corney is a medical practitioner and researcher.