London: Calorie labelling is misleading, underestimating the energy content of processed foods and exaggerating that of raw ingredients, nutritionists have warned.
Failure to take account of modern science in assessing calories could lead to errors of up to 30 per cent in figures on labels and websites, the international group of nutritionists told the American Association for the Advancement of Science (AAAS) annual meeting in Boston on Monday.
Reform of the so-called Atwater system, the basis of estimating the energy content of foods since the early 20th century, was essential: “Given the rising prevalence of obesity and malnutrition worldwide, achieving great accuracy in food labelling has significant global health and economic consequences.”
“The public is given erroneous information about the energy value of many foods,” added Richard Wrangham of Harvard University, who organised the AAAS food symposium. “We believe it is time for a high-level panel to consider how best to improve the quality of information provided about the real energy value of foods.”
According to the researchers, the conventional system, formulated in about 1900 by US nutritionist Wilbur Atwater, fails in several important ways to reflect the real calorie content of food.
It does not take account of the work done by the gut in digesting less processed and particularly raw food, which takes energy and reduces the net calorie count of the meal. Another issue is “bioavailability”: the consumer extracts almost all the energy content of highly processed foods while some of the calories in less processed meals pass straight through the body.
“The number of calories made available to the body by food processing depends on the food and the method and degree of processing applied, but in some cases can exceed 50 per cent of the caloric value of the unprocessed item,” said Rachel Carmody, also of Harvard.
Some nutritionists believe calorie counting has assumed too much importance in modern obesity control.
“By focusing so much on calories we will not solve the problem,” said David Ludwig, an endocrinology professor at Boston Children’s Hospital. “It is the quality of calories that matters. A single-minded focus on calories would suggest that, say, an eight-ounce [225ml] serving of cola is better than a handful of nuts — when clearly it is not.”
However, Professor Ludwig agreed a more accurate way of assessing the real calorific impact of foods was needed.
“The composition of our diet can alter hormones and biological pathways in a very important ways,” he said. “Just by changing its composition, we may add or subtract several hundred calories a day — equivalent to an hour’s physical activity.”
Geoffrey Livesey, an independent nutritional consultant based in the UK, said labelling and advice must now be brought into line with the latest research: “The scientists are doing the work — now the regulatory authorities need to reflect it.”
The international body responsible is the Codex Alimentarius commission, established by United Nations Food and Agriculture Organisation and the World Health Organisation in 1963 to harmonise food standards, guidelines and codes of practice. Its policies are then implemented by national authorities.