How many teaspoons of sugar in digestive biscuits?

Digestive biscuits are a semi-sweet British biscuit made with coarse wholemeal wheat flour, sugar, vegetable oil and raising agents. The name dates from the nineteenth century, when the bicarbonate of soda in the recipe was thought to help digestion. In the United States the nearest equivalent is the graham cracker, though the recipes differ.

Table 1 of the 2016 paper by Unwin, Haslam and Livesey lists plain digestive biscuits at 25g, a little under two biscuits. It gives a glycaemic index of 39, 16g of available carbohydrate and a glycaemic load of 6. Worked through without rounding, 16g at GI 39 is a load of 6.24.

A GI of 39 is in the low band. GI describes how quickly carbohydrate raises blood glucose rather than how much carbohydrate there is, and biscuits contain fat, which slows the emptying of the stomach. Part of their sugar is sucrose, half of which is fructose.

The sugar burden chart also includes digestive biscuits, in its column of foods with added sugars, at 8.8 teaspoons per 100g. For 25g that would be 2.2, a tenth below the Table 1 figure and consistent with it after rounding.

The row describes plain digestives. Chocolate digestives add a layer of milk or dark chocolate and are a different food, as are the reduced-fat and oat versions sold by several brands.

Biscuit weights vary by brand, so the number of biscuits in 25g does too.