Factors affecting the fate of β-carotene in the human gastrointestinal tract: A narrative review

Abstract

Abstract. Carotenoids and their metabolites play crucial roles in human health such as in immunity, cell differentiation, embryonic development, maintenance of plasma membrane integrity, and gastrointestinal functions, in addition to counteracting night blindness and other eye-related diseases. However, carotenoid bioavailability is highly variable and often low. The bioavailability of β-carotene, among the most frequently consumed carotenoid from the diet, is determined by food matrix related factors such as carotenoid dose, its location in food the matrix, the physical state in food, the presence of other food compounds in the matrix such as dietary fiber, dietary lipids, other micronutrients present such as minerals, and food processing, influencing also the size of food particles, and the presence of absorption inhibitors (fat replacers and anti-obesity drugs) or enhancers (nano-/micro-formulations). However, also host-related factors such as physiochemical interactions by gastrointestinal secretions (enzyme and salts) and other host-related factors such as surgery, age, disease, obesity, and genetic variations have shown to play a role. This review contributes to the knowledge regarding factors affecting the bioavailability of β-carotene (food and host-relegated), as well as highlights in vitro models employed to evaluate β-carotene bioavailability aspects.

Fate of β-Carotene within Loaded Delivery Systems in Food: State of Knowledge

“…The release depends on the degree of structural disruption of the food matrix, which can be enhanced by subjecting various food processing techniques (mechanical and thermal) before ingestion. It is believed that mechanical processing (homogenization, cutting, crushing and pureeing) may significantly improve bioavailability as it reduces food particle size, hence offering a greater surface to volume ratio for digestive fluids and enzymes to act upon, resulting in a higher release of β-carotene [49]. An 18% higher bioavailability (in vitro) in homogenized carrot as compared to chopped raw carrot supports this assumption [55].…”

“…The fate of β-carotene in the human gastrointestinal tract (GIT) is determined by various factors, including the complexity of the ingested food matrix, its release from the food matrix, the transfer of the released molecule to the oil phase, its incorporation into mixed micelles, the entrance route into enterocytes and its incorporation into chylomicrons [49]. In the following, these processes are briefly explained.…”

“…Release of β-carotene from the food matrix is a multistage process, which begins by mastication in the mouth, followed by enzymatic and physiochemical process in the stomach and the small intestine [49]. The release of β-carotene begins with the physical disruption of ingested food particles in the buccal cavity of GIT to make β-carotene bioaccessible for absorption.…”

“…where, Br represents quantity of β-carotene released in GIT fluid in consequence to food matrix digestion, B t : total quantity of β-carotene existing in the food matrix, and B e : β-carotene secreted in the duodenal compartment along with bile salt. The complexity of the food matrix has a great impact on the bioaccessibility as well as bioavailability of β-carotene, as its release from food the matrix is the major limiting factor for its bioavailability [37,[49][50][51][52].…”

“…Hence, factors affecting mixed micelle formation can significantly impact the bioavailability of β-carotene. An array of factors affecting the formation of micelles has been reported, including the amount of lipids in the digesta [56,69,70], type of fatty acids [71], degree of unsaturation and length of fatty acid [71], presence/absence of dietary fibers [49], and the presence of high amounts of minerals [72,73].…”