No influence of supplemental dietary calcium intake on the bioavailability of spinach carotenoids in humans

Abstract

Dietary carotenoid intake, especially from fruits and vegetables, has been associated with a reduced incidence of several chronic diseases. However, its bioavailability can vary, depending on the food matrix and host factors. Recently, it has been suggested that divalent minerals negatively impinge on carotenoid bioavailability by reducing bile-salt and non-esterified fatty-acid levels in the gut, which normally aid in emulsifying carotenoids. The aim of the present study was to investigate whether supplemental Ca would negatively influence carotenoid absorption in humans. A total of twenty-five healthy, non-obese men (age: 20-46 years, BMI<30 kg/m2) were recruited for this postprandial, randomised, crossover, double-blinded trial. Following a randomised block design, each participant received (after 2-week washout periods), on three occasions separated by 1 week, 270 g of spinach-based meals (8·61 (sd 1·08) mg carotenoids/100 g fresh weight), supplemented with 0, 500 or 1000 mg of Ca (as calcium carbonate), with each participant acting as his or her own control. Blood samples were collected at regular postprandial intervals for up to 10 h following test meal intake, and standardised lunches were served. TAG-rich lipoprotein fractions were separated and carotenoid concentrations determined. AUC for meals without supplemented Ca were 22·72 (sem 2·78) nmol×h/l (lutein), 0·19 (sem 3·90) nmol×h/l (β-carotene) and 2·80 (sem 1·75) nmol×h/l (β-cryptoxanthin). No significant influence of supplementation with either 500 or 1000 mg of supplemental Ca was found. In conclusion, Ca - the most abundant divalent mineral in the diet - given at high but physiological concentrations, does not appear to have repercussions on the bioavailability of carotenoids from a spinach-based meal.

Opposite Effects of the Spinach Food Matrix on Lutein Bioaccessibility and Intestinal Uptake Lead to Unchanged Bioavailability Compared to Pure Lutein

“…Finally, a last factor that could interact with lutein transfer to mixed micelles may be presence of calcium (about 126 mg/100 g of canned spinach). However, consistently with our results, the negative effect of divalent cations seems to be nonsignificant at normal pancreatin and bile concentrations, and even at high doses, calcium appeared not to have any significant effect on spinach lutein absorption in humans …”

Bioaccessibility of carotenoids from plant and animal foods

“…191,192 Although the above mentioned conclusions on the effect of calcium had been obtained by in vitro digestion studies, human intervention studies have led to inconsistent results. Although a negative effect of added calcium has been observed with the supplementation of 2 g calcium by Chai et al,193 only insignificant effects were observed in a recent study conducted by Corte-Real et al 194 where a dose of 0.5 or 1 g was provided. Therefore, further in vivo studies are required to ultimately determine the effect of calcium on bioavailability of different carotenoids and food matrixes.…”

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

“…investigated whether altering the concentration of digestive enzymes and bile, with presumably crucial influence on carotenoid micelle formation (Bohn, 2012;Borel, 2003), would still yield similar negative influences of magnesium as a prominent dietary divalent mineral on carotenoid bioaccessibility, also in sight of recent contradictory results from human trials investigating the effect of calcium on carotenoid bioavailability (Borel et al, 2016;Corte-Real, Guignard et al, 2017). As less information was also available on magnesium compared to calcium regarding its interaction with bile salts and its role on lipid digestion, we focused on the second most abundant dietary cation.…”

“…However, recent human trials investigating the effect of calcium have found contradictory results. While in a study employing tomato paste, 500 mg of calcium decreased post-prandial plasma lycopene concentration (Borel et al, 2016), another trial employing spinach and calcium doses of 500 and 1000 mg did not find any significant changes in carotenoid concentrations in plasma triacylglycerol-rich lipoprotein (TRL) fractions (Corte-Real, Guignard et al, 2017).…”