Bioavailability of Iron From Spinach Using an in Vitro/Human Caco-2 Cell Bioassay Model

Abstract

Spinach (Spinacia oleracea) cv Whitney was tested for iron bioavailabilty using an in vitro human intestinal cell culture ferritin bioassay technique previously developed. Spinach was cultured in a growth chamber for 33 days, harvested, and freeze-dried. Total iron in the samples was an average of 71 µg/g dry weight. Spinach was digested in vitro (pepsin and 0.1 M HCl followed by pancreatin and 0.1 M NaHCO 3 ) with and without the addition of supplemental ascorbic acid. Caco-2 cell cultures were used to determine iron bioavailability from the spinach mixtures. Production of the iron-binding protein ferritin in the Caco-2 cells showed the supplemental ascorbic acid doubled bioavailability of iron from spinach. The data show fresh spinach is a poor source of iron, and emphasize the importance of evaluation of whole meals rather than single food items. The data support the usefulness of the in vitro/Caco-2 cell ferritin bioassay model for prescreening of space flight diets for bioavailable iron. tent of the food, the health and iron status of the individual, the chemical form of the iron, the presence of iron absorption enhancers or inhibitors in the meal, and the individual's genetic predisposition (11). Thus, total iron content measurements of a food do not indicate actual iron bioavailability or iron absorption. Heme-bound iron, as found in meats and fish, is more readily absorbed (more bioavailable) than nonheme iron. The predominant form of iron in vegetables is nonheme iron. Absorption of nonheme iron is enhanced by the presence of ascorbic acid (vitamin C)

Enhancement in growth rate and productivity of spinach grown in hydroponics with iron oxide nanoparticles

“…Naturally, spinach is considered as a reserve of iron. 43 The Fe content in the dried mass of spinach (control) is about 0.306 ppm and it is increasing with respect to dose dependent manner in the spinach treated with Fe 2 O 3 nanoparticles. However, there is no signicant change in the Fe content was observed in the case of iron salt treated spinach (about 0.317 ppm) compared to that of control.…”

“…This suggested the presence of iron mineral in the control plants which is due to the natural bioavailability of iron in spinach plants. 43 The hysteresis analysis of spinach plants 44 Further, assessment of cytotoxicity of these leave extracts will provide useful information on the effect of these spinach for applications in medical sectors. This study substantiates the linear increase saturation magnetization in spinach plants treated with different concentration of Fe 2 O 3 suggesting the iron content up taken by spinach plant might be of different size, or composition which needed to be studied in detail in the near future.…”

A Food-Derived Dietary Supplement Containing a Low Dose of Iron Improved Markers of Iron Status Among Nonanemic Iron-Deficient Women

“…While less is currently known about the impact of beetroot and vitamin B 12 on iron absorption, our findings suggest that they might merit future study as adjuvant ingredients in iron supplements. However, the addition of novel dietary ingredients to iron formulas must be selected and studied carefully, as some dietary polyphenols have been shown to decrease iron absorption (46,47). …”

Iron Absorption: Factors, Limitations, and Improvement Methods

“…The iron content of foods does not indicate its bioavailability because iron absorption depends on some factors, mainly the form of iron. Because plants mainly contain nonheme iron, even if its iron content is high, absorption of iron is low due to plant-based molecule–iron interactions . Red meat is the most significant source of iron since it is rich in heme iron, which is highly bioavailable. , Since 30–70% of the iron in meat is in the form of heme, the iron requirement for humans is mainly met by red meat in developed countries.…”