Table 3.

Host factors influencing carotenoid release from food matrix and bioaccessibility

Phase of digestion	Factor	Study description	Carotenoids investigated	Possible role in bioavailability	Reference
Oral	Lingual lipase, other lipase	No data available	n/n	Low	n/n
	α‐amylase	No data available	n/n	Low	n/n
Gastric	Non‐dietary phospholipids/ mucin	No data available	n/n	Low compared to dietary phospholipids	n/n
	Gastric lipase (GL)	GL from fungi (Rhizopus oryzae), pH optimum 5–9, in‐vitro	β‐carotene	No effect of gastric lipase detected	64
	Pepsin	No effect in in vitro trials	Lutein, β‐carotene, lycopene	Presumable low effect in most carotenoid rich foods	57, 58
	Pepsin	Tomato puree in vitro	Lycopene	Enhancing effect on lycopene micellization	59
	pH	Digestion of spinach, in vitro	β‐carotene, lutein	Presumably negligibleb, though extreme pH may facilitate degradation	55, 292
Duodenum	Pancreatic lipase	Digestion of spinach, in vitro	β‐carotene, lutein, zeaxanthin	Low micellization (<5% original conc.) without pancreatina	57
		Digestion of carrots+spinach+ tomato, in vitro	Total carotenoids	Micellization drop to 50% without pancreatin	58
	Pancreatic amylase	Intake of amylase inhibitor ascarbose reduced vit. A levels in blood	Only vit. A	Low	293
	Pancreatic proteases, PLRP2	No data available	n/n	Low	n/n
	Pancreatic colipase	Tomato puree, in vitro digestion	Lycopene	Reduced intestinal recovery without colipase, no effect on micellization	59
	Carboxyl‐esterase	Digestion of wolfberry, pepper, squash in vitro	Zeaxanthin‐esters	Enhanced xanthophyll bioavailability	77
	Bile salts	Digestion of spinach, in vitro	β‐carotene, lutein, zeaxanthin	Micellization drop to 30% original conc. without bile salts	57
	Bile salts	Digestion of carrots+spinach+ tomato, in vitro	Total carotenoids	Low micellization (<2% original conc.) without bile extract	58
Colon	Microbiota	Lower circulating carotenoids in subjects with higher Collinsella and atherosclerosis	β‐carotene	Unclear	133
	Microbiota	Higher liver storage of α ‐and β‐carotene in germ‐free rats	α‐, β‐carotene	Prevention of breakdown products? Transit time? Bile‐salts?	45

n/n: no data available.

^athough containing also other enzymes, pancreatic lipase is presumably the enzyme most important for carotenoid digestion.

^bexcept for epoxy‐carotenoids (violaxanthin, neoxanthin).