Table 2 Suitable excipients with some considerations for HFI patients

Ammonium sulfite caramel (E 150)

Brown colouring is a complex mixture of compounds obtained by heat treatment of carbohydrates (glucose, fructose, sucrose and/or invert sugar) with ammonia. The high-molecular-weight fraction can be composed of sugars, mainly pseudodisaccharides (anhydrous d-fructose dimers) and other monosaccharides depending on the origin source of carbohydrates (fructose, glucose or sucrose) [17, 18].

Arabic gum

Galactose polysaccharide is a mixture of polysaccharides and glycoproteins (galactans), composed of chains of D-galactose and D-glucuronic acid with terminal L-rhamnose and L-arabinose. It is a soluble fibre not digestible by intestinal enzymes or acidic environments [19].

Carrageenans

A mixture of copolymer esters of galactose and 3,6-anhydrogalactose with sulfates. Their absorption at the gastrointestinal level is minimal as it is not degraded by gastric pH or gut microbiota, although some absorption of the polysaccharide may take place and lower-molecular-weight fractions may be absorbed. They may include sugars for standardisation purposes [20].

Ethyl alcohol/ethanol

Alcohol should be used with caution due to possible liver damage and its potential endogenous fructose production [21].

Glucose, dextrose

High dose of glucose could be converted into fructose due to the polyol pathway [21].

Guar flour

A combination of galactose and mannose polysaccharide, it is a soluble fibre made up mainly of galactomannan, which consists of a linear chain of mannopyranose joined by glycosidic β linkage (1 ◊ 4) and branches of galactopyranose joined by α linkage (1 ◊ 6). It is not absorbed by the gastrointestinal tract [22].

Mannitol (E 421) (oral)

Fructose polyalcohol. Oral mannitol has an absorbance of 25–65%. In the liver, 7–10% of the absorbed mannitol can be transformed into fructose or oxidised to CO₂ by unknown pathways [5, 23, 24].

Polydextrose

Polymer of glucose with glycosidic β linkage (1 ◊ 6) and sorbitol end groups (10%). In the human gastrointestinal tract, these links are resistant to hydrolysis by digestive acid and enzymes. However, the percentage of links that rupture is unknown [25].

Sucrose (intravenous)

Fructose and glucose disaccharide. Approximately 70–90% of the intravenous infusion dose is eliminated unaltered in urine as disaccharide, but there is substantial interindividual variability [26].

Starch syrup, glucose syrup

A mixture of glucose derivatives obtained from starch hydrolysis (glucose, maltose and oligosaccharides). Sometimes, part of the syrup is treated enzymatically, transforming some glucose into fructose to achieve greater sweetness [5]. Also, high dose of glucose could be converted into fructose due to the polyol pathway [21].

Tragacanth gum

A mixture of polysaccharides, mainly basorine and tragacanthin (water-soluble fraction of L-arabinose, L-fucose, D-xylose, D-galactose and D-galacturonic acid). Its degree of hydrolysis is unknown, giving rise to short-chain fatty acids [27].

Xanthan gum, corn sugar gum (E 415)

A combination of galactose and mannose polysaccharide, it is obtained by fermentation of carbohydrates (glucose or sucrose). It is mainly a salt of a high-molecular-weight polysaccharide containing D-glucose, D-mannose, D-glucuronic acid and pyruvic acid. It is not digestible by digestive enzymes and acidic medium [28].

Vanillin, vanilla flavouring

A flavour that contains fructose in its composition.