Carbohydrates were put under the microscope in Sydney last week in a symposium organised by the International Life Sciences Institute (ILSI). The risks and benefits of carbohydrate intake were widely discussed. Here is a taste of what we heard, some observations and a few key references.
Recommended carbohydrate intakes
A couple of speakers discussed the recommended range for carbohydrate intakes, which is 45-65% of daily calories in both Australia and the United States. In the United States, the major factor that determined the upper boundary of intake was adverse effects of carbohydrate on levels of triglycerides and HDL-cholesterol in the blood. At the lower end of the scale it was argued that fibre requirements are unlikely to be met at intakes of carbohydrate below 45% of energy (in the low fibre US context). It’s interesting that dietary fibre is considered as a carbohydrate-amount issue in the United States. To my mind it is very much a carbohydrate quality issue.
Mean adult intake of carbohydrate in Australia is about 46% of daily calories, right at the lower end of recommended intake range. This was perceived as low by some speakers and a reason for focussing on glycaemic index as the preferred means of lowering the total glycaemic load of the Australian diet. Others saw the current intake as ‘moderate’, pointing out that the beneficial diets in the Diogenes study contained just 43% of calories from carbohydrate – below the lower boundary of recommended carbohydrate intake.
I introduced my talk by arguing that both the upper and lower boundaries of carbohydrate intake were too high. They were framed at a time when it was thought that a higher percentage of dietary energy from fat was detrimental to health. However, the preferred model for healthy eating is now one with more unsaturated fats and less of both saturated fat and carbohydrate – a Mediterranean-type diet.