What it is

Pectins are gelling substances from plants, extracted mainly from citrus peel and apple pomace 1.

Pectin (E 440i) consists mainly of partial methyl esters of α-1,4-polygalacturonic acid; in amidated pectin (E 440ii), up to 25% of carboxyl groups are amides; both are INS 440 12. They gel, thicken and stabilise fermented milks, drinks and jams 13.

How often it is used

Pectins rank ninth among additives in French foods 4.

In 2019, 6,504 of 126,556 products listed them 4; 78.98% of 106,489 NutriNet-Santé adults consumed them, a mean 199.74 mg/day 5.

In the body

Pectins reach the large intestine mostly intact, where bacteria ferment nearly all of them 1.

In 7 men, 88.4% of 5 g reached the terminal ileum; faeces held 3.5–4.8% of intake 1. Cultured Bacteroides thetaiotaomicron degrades homogalacturonan to galacturonate, which Escherichia coli enzymes convert to pyruvate 67.

Bacterial degradation of pectin to pyruvateColonic lumen; periplasm and cytosol of pectin-fermenting bacteria
  1. Pectin (methyl-esterified homogalacturonan)
  2. Pectin methylesterase (EC 3.1.1.11)H2OHydrolyses galacturonate methyl esters, releasing methanol and H+
  3. Polygalacturonate
  4. several stepsEndo-lyases or endo-hydrolases; exo-α-galacturonidases release galacturonate
  5. D-Galacturonate
  6. Uronate isomerase (UxaC, EC 5.3.1.12)
  7. D-Tagaturonate
  8. Altronate oxidoreductase (UxaB, EC 1.1.1.58)NADH + H+ → NAD+
  9. D-Altronate
  10. Altronate dehydratase (UxaA, EC 4.2.1.7)Fe2+Releases H2O; product also named 2-keto-3-deoxygluconate (KDG)
  11. 2-Dehydro-3-deoxy-D-gluconate
  12. 2-Dehydro-3-deoxygluconokinase (KdgK, EC 2.7.1.45)ATP → ADP
  13. 2-Dehydro-3-deoxy-6-phospho-D-gluconate
  14. KDPG aldolase (Eda, EC 4.1.2.14)Also yields D-glyceraldehyde 3-phosphate
  15. Pyruvate

Fermentation yields short-chain fatty acids, including butyrate; pectins are dietary fibre 189.

Butyrate synthesis by colonic bacteria (acetyl-CoA pathway)Colonic lumen; cytosol of butyrate-producing bacteria
  1. Fermentable polysaccharides
  2. several stepsStarch, xylan and other polysaccharides that escape digestion; via pyruvate
  3. Acetyl-CoA
  4. Thiolase (Thl)Acetyl-CoACondenses two acetyl-CoA and releases CoA
  5. Acetoacetyl-CoA
  6. β-Hydroxybutyryl-CoA dehydrogenase (Hbd)
  7. 3-Hydroxybutyryl-CoA
  8. Crotonase (Cro)
  9. Crotonyl-CoA
  10. Butyryl-CoA dehydrogenase–electron-transferring flavoprotein complex (Bcd-Etfαβ)FerredoxinShared by all four butyrate pathways; postulated energy conservation
  11. Butyryl-CoA
  12. Butyryl-CoA:acetate CoA-transferase (But)Acetate → acetyl-CoAAlternative: phosphate butyryltransferase (Ptb) and butyrate kinase (Buk)
  13. Butyrate

What studies show

Pectin at 12 to 15 g/day lowered blood cholesterol 5 to 8%; at 36 g/day for 6 weeks, some of 5 men reported abdominal distension and flatus, judged not adverse 1.

A NutriNet-Santé additive mixture including pectin was associated with type 2 diabetes, hazard ratio 1.08 (95% CI 1.02 to 1.15) per standard deviation; over a mean 7.7 years, 465 of 36,214 (1.28%) in the top third and 260 of 36,215 (0.72%) in the bottom third developed it 10.

EFSA set no numerical acceptable daily intake; brand-loyal toddlers reached 442 mg/kg body weight/day at the 95th percentile 1. Infants under 16 weeks fed special medical formulae at the former 10,000 mg/kg limit would receive 2,000–2,600 mg/kg/day, above the piglet no-adverse-effect level of 1,069 mg/kg/day, and possibly harmful methanol 2.

Regulation

All four jurisdictions permit pectins 1631718.

JurisdictionRule
European UnionQuantum satis; 4,000 mg/kg in special medical foods for infants and young children from 18 August 2026 1619
United StatesGenerally recognised as safe, amidated pectins included 3
JapanExisting additive 17
ChinaAs production requires, except listed foods including infant formulae; juices up to 3.0 g/kg 18