Fibre

35 fibre products - psyllium, inulin, oat and mixed-fibre blends, in powders, sachets, capsules and gummies. Brands include Optibac, Bio&Me, Fibre Up, Greens Organic, Ortis and Doves Farm.

Fibre has real approved claims

Unusually for this part of the shop, several are authorised. Oat and barley beta-glucans contribute to the maintenance of normal blood cholesterol levels, at 3g a day. Wheat bran fibre contributes to an acceleration of intestinal transit and to an increase in faecal bulk. Rye fibre contributes to normal bowel function. These apply at specific daily intakes stated in the claims, so check the serving size against them.

Soluble, insoluble and prebiotic

Soluble fibre - psyllium, oat beta-glucan, inulin - forms a gel in water. Insoluble fibre, such as wheat bran, largely passes through intact and adds bulk. Prebiotic fibres such as inulin and FOS act as a food source for gut bacteria. Most whole foods contain a mixture, and most supplements here concentrate one type.

Start low and drink water

The commonest mistake is going straight to a full dose. Fibre supplements can cause bloating and wind if introduced abruptly, so build up over a week or two. Take them with plenty of water - psyllium in particular absorbs a great deal of it, and should never be taken dry.

Food first

UK adults are advised to aim for 30g of fibre a day and most of us manage around 20g. A supplement closes a gap; it does not replace beans, oats, wholegrains, fruit and vegetables, which bring a good deal else with them.

Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle.