Negative effects of divalent mineral cations on the bioaccessibility of carotenoids from plant food matrices and related physical properties of gastro-intestinal fluids

Abstract

Carotenoid intake and tissue levels have been frequently associated with reduced risk of chronic diseases. However, their bioavailability is low and influenced by many dietary related parameters. Divalent mineral cations have been suggested to interfere with carotenoid digestion and to hamper micellarization, a prerequisite for their uptake, via complexation of bile salts and precipitation of fatty acids. In the present investigation, we have evaluated the effects of increasing concentrations of magnesium (0-300 mg L), calcium (0-1500 mg L), zinc (0-200 mg L), and sodium (0-1500 mg L; control monovalent cation), on carotenoid bioaccessibility from frequently consumed food items rich in carotenoids (tomato juice, carrot juice, apricot nectar, spinach and field salad), following simulated gastro-intestinal digestion. In addition, physicochemical parameters of digesta (macroviscosity, surface tension), micelle size, and zeta-potential were evaluated. All divalent minerals (DM) reduced bioaccessibility of total carotenoids (P < 0.01), as well as of individual carotenoids. Calcium and magnesium led to reductions of up to 100% at the 2 highest concentrations. Curiously, sodium increased (P < 0.01) carotenoid bioaccessiblity of most investigated matrices. The absolute value of the zeta-potential decreased with increasing concentrations of DM, suggesting a decreased stability of the colloidal digesta dispersion. Viscosity decreased, except for apricot nectar samples, while surface tension increased with DM concentration (P < 0.05). Thus, at physiological ranges, calcium and magnesium could negatively impact carotenoid bioavailability, while for zinc, negative effects were only seen at supplemental concentrations. The potential negative effects of DM on carotenoid bioavailability should be further studied in vivo.

Magnesium affects spinach carotenoid bioaccessibility in vitro depending on intestinal bile and pancreatic enzyme concentrations

“…Similar as for earlier in vitro studies with calcium Corte-Real, Bertucci et al, 2017;Corte-Real et al, 2016), it was found that increasing the concentration of magnesium significantly decreased the bioaccessibility of all individual and total carotenoids, especially at the highest concentration of 400 mg/ L, chosen to reflect a supplement containing approximately the RDA (400 mg/d for adult men). The observed effects were in line with a decreased absolute zeta potential of the micellar fraction, suggestive of rather less stable particles.…”

“…Previously, we reported that varying concentrations of divalent minerals, including magnesium, can significantly affect the in vitro bioaccessibility of carotenoids, either of pure standards or from food sources Corte-Real, Bertucci et al, 2017;Corte-Real et al, 2016), with the limitation that static in vitro models were used, with only 1 fixed concentration for bile extract and pancreatin, and thus digestive enzymes. For this reason, we here Fig.…”

“…Carotenoid extraction procedures have been described previously (Corte-Real, Bertucci et al, 2017). In short, aliquots of 4 g of spinach were wetted with 5 mL of MeOH, and 1 mL of 30% aqueous KOH for saponification of chlorophylls, vortexed, sonicated, and incubated in the dark for 20 min.…”

“…Recently, it has been hypothesized ) that dietary divalent cations, such as calcium and magnesium could negatively affect carotenoid absorption, by preventing the formation of mixed-micelles as a result of fatty acid (Atteh & Leeson, 1985;Boyd, Crum, & Lyman, 1932) and bile salt precipitation (Gu, Hofmann, Ton-Nu, Schteingart, & Mysels, 1992;. This has been shown in vitro for a variety of divalent cations and trace elements, following simulated digestion experiments with isolated carotenoids (Corte-Real et al, 2016) and carotenoids released from regular food matrices, such as spinach or carrot juice (Corte-Real, Bertucci et al, 2017). The concentrations required to observe these negative effects were equivalent to approximately half the recommended dietary allowance (RDA) for calcium and magnesium.…”

“…type and source of lipids, and bile and pancreatic enzyme concentrations) would influence the effect of magnesium on the bioaccessibility of carotenoids, as determined by fractional carotenoid bioaccessibility, following in vitro gastro-intestinal digestion. Frozen spinach leaves were chosen as a model matrix due to their high carotenoid content (>5 mg/100 g), the presence of both xanthophylls (lutein, neoxanthin and violaxanthin) and carotenes (β-and α-carotene), and their previous use as a model vegetable Castenmiller, West, Linssen, van het Hof, & Voragen, 1999;Corte-Real, Bertucci et al, 2017;Rock et al, 1998). As the interactions are expected to affect the extent of lipolysis and the micelle size and stability of the colloidal system, these parameters were also assessed.…”