Iron is a critical micronutrient, and iron derived from heme contributes a large proportion of the total iron absorbed in a typical Western diet. Heme iron is absorbed by different mechanisms than non-heme iron, but d...Iron is a critical micronutrient, and iron derived from heme contributes a large proportion of the total iron absorbed in a typical Western diet. Heme iron is absorbed by different mechanisms than non-heme iron, but despite considerable study over many years these mechanisms remain poorly understood. This review provides an overview of the importance of heme iron in the diet and discusses the two prevailing hypotheses of heme absorption; namely receptor mediated endocytosis of heme, and direct transport into the intestinal enterocyte by recently discovered heme transporters. A specific emphasis is placed on the questions surrounding the site of heme catabolism and the identity of the enzyme that performs this task. Additionally, we present the hypothesis that a non-heme iron transport protein may be required for heme iron absorption and discuss the experiences of our laboratory in examining this hypothesis.展开更多
The human body requires about 1-2 mg of iron per day for its normal functioning, and dietary iron is the only source for this essential metal. Since humans do not possess a mechanism for the active excretion of iron, ...The human body requires about 1-2 mg of iron per day for its normal functioning, and dietary iron is the only source for this essential metal. Since humans do not possess a mechanism for the active excretion of iron, the amount of iron in the body is determined by the amount absorbed across the proximal small intestine and, consequently, intestinal iron absorption is a highly regulated process. In recent years, the liver has emerged as a central regulator of both iron absorption and iron release from other tissues. It achieves this by secreting a peptide hormone called hepcidin that acts on the small intestinal epithelium and other cells to limit iron delivery to the plasma. Hepcidin itself is regulated in response to various systemic stimuli including variations in body iron stores, the rate of erythropoiesis, inflammation and hypoxia, the same stimuli that have been known for many years to modulate iron absorption. This review will summarize recent findings on the role played by the liver and hepcidin in the regulation of body iron absorption.展开更多
Iron fortification can cause several biophysicochemical modifications. Those depend on many factors, such as iron fortificant and the food carrier. There were four groups of chips: 1) non-fortified wheat flour chips...Iron fortification can cause several biophysicochemical modifications. Those depend on many factors, such as iron fortificant and the food carrier. There were four groups of chips: 1) non-fortified wheat flour chips (K1); 2) non-fortified cassava flour chips (K2); 3) fortified cassava flour chips, each with ZnSO4 30 ppm and NaFe EDTA (K3) 30 ppm and 4) fortified cassava flour chips, each with ZnSO4 50 ppm and NaFe EDTA (K4) 50 ppm. The chips were evaluated for sensory characteristic (color, taste, flavor, and texture), organoleptic characteristics tested by preference test, as well as zinc and iron contents. Zinc and iron contents were analyzed by Atomic Absorption Spectophotometric method. The results showed that both fortificants did not affect the sensory characteristic of cassava flour chips. The preference test showed that color, taste, and flavor of Kl chips as a control, were mostly liked, but there was no significant difference preference of texture. Moreover, preference test using K2 as control showed that color of K3 was mostly liked, but there was no significant difference preference of taste, flavor and texture. Fortification can increase the contents of zinc and iron in cassava flour chips. The panelist can accept the fortified cassava chips as well as wheat flour chip, as a consequence, both can be a potential way to combat the iron deficiency anemia.展开更多
Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large- scale grids. Increasing the Na content in cathode materials is one of...Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large- scale grids. Increasing the Na content in cathode materials is one of the effective ways to achieve high energy density. Prussian blue and its analogues (PBAs) are promising Na-rich cathode materials since they can theoretically store two Na+ ions per formula unit. However, increasing the Na content in PBAs cathode materials remains a major challenge. Here we show that sodium iron hexacyanoferrate with high Na content can be obtained by simply controlling the reducing agent and reaction atmosphere during synthesis. The Na content can reach as high as 1.63 per formula, which is the highest value for sodium iron hexacyanoferrate. This Na-rich sodium iron hexacyanoferrate demonstrates a high specific capacity of 150 mAh·g^-1 and remarkable cycling performance with 90% capacity retention after 200 cycles. Furthermore, the Na intercalation/ de-intercalation mechanism has been systematically studied by in situ Raman spectroscopy, X-ray diffraction and X-ray absorption spectroscopy analysis for the first time. The Na-rich sodium iron hexacyanoferrate can function as a plenteous Na reservoir and has great potential as a cathode material for practical Na-ion batteries.展开更多
文摘Iron is a critical micronutrient, and iron derived from heme contributes a large proportion of the total iron absorbed in a typical Western diet. Heme iron is absorbed by different mechanisms than non-heme iron, but despite considerable study over many years these mechanisms remain poorly understood. This review provides an overview of the importance of heme iron in the diet and discusses the two prevailing hypotheses of heme absorption; namely receptor mediated endocytosis of heme, and direct transport into the intestinal enterocyte by recently discovered heme transporters. A specific emphasis is placed on the questions surrounding the site of heme catabolism and the identity of the enzyme that performs this task. Additionally, we present the hypothesis that a non-heme iron transport protein may be required for heme iron absorption and discuss the experiences of our laboratory in examining this hypothesis.
文摘The human body requires about 1-2 mg of iron per day for its normal functioning, and dietary iron is the only source for this essential metal. Since humans do not possess a mechanism for the active excretion of iron, the amount of iron in the body is determined by the amount absorbed across the proximal small intestine and, consequently, intestinal iron absorption is a highly regulated process. In recent years, the liver has emerged as a central regulator of both iron absorption and iron release from other tissues. It achieves this by secreting a peptide hormone called hepcidin that acts on the small intestinal epithelium and other cells to limit iron delivery to the plasma. Hepcidin itself is regulated in response to various systemic stimuli including variations in body iron stores, the rate of erythropoiesis, inflammation and hypoxia, the same stimuli that have been known for many years to modulate iron absorption. This review will summarize recent findings on the role played by the liver and hepcidin in the regulation of body iron absorption.
文摘Iron fortification can cause several biophysicochemical modifications. Those depend on many factors, such as iron fortificant and the food carrier. There were four groups of chips: 1) non-fortified wheat flour chips (K1); 2) non-fortified cassava flour chips (K2); 3) fortified cassava flour chips, each with ZnSO4 30 ppm and NaFe EDTA (K3) 30 ppm and 4) fortified cassava flour chips, each with ZnSO4 50 ppm and NaFe EDTA (K4) 50 ppm. The chips were evaluated for sensory characteristic (color, taste, flavor, and texture), organoleptic characteristics tested by preference test, as well as zinc and iron contents. Zinc and iron contents were analyzed by Atomic Absorption Spectophotometric method. The results showed that both fortificants did not affect the sensory characteristic of cassava flour chips. The preference test showed that color, taste, and flavor of Kl chips as a control, were mostly liked, but there was no significant difference preference of texture. Moreover, preference test using K2 as control showed that color of K3 was mostly liked, but there was no significant difference preference of taste, flavor and texture. Fortification can increase the contents of zinc and iron in cassava flour chips. The panelist can accept the fortified cassava chips as well as wheat flour chip, as a consequence, both can be a potential way to combat the iron deficiency anemia.
文摘Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large- scale grids. Increasing the Na content in cathode materials is one of the effective ways to achieve high energy density. Prussian blue and its analogues (PBAs) are promising Na-rich cathode materials since they can theoretically store two Na+ ions per formula unit. However, increasing the Na content in PBAs cathode materials remains a major challenge. Here we show that sodium iron hexacyanoferrate with high Na content can be obtained by simply controlling the reducing agent and reaction atmosphere during synthesis. The Na content can reach as high as 1.63 per formula, which is the highest value for sodium iron hexacyanoferrate. This Na-rich sodium iron hexacyanoferrate demonstrates a high specific capacity of 150 mAh·g^-1 and remarkable cycling performance with 90% capacity retention after 200 cycles. Furthermore, the Na intercalation/ de-intercalation mechanism has been systematically studied by in situ Raman spectroscopy, X-ray diffraction and X-ray absorption spectroscopy analysis for the first time. The Na-rich sodium iron hexacyanoferrate can function as a plenteous Na reservoir and has great potential as a cathode material for practical Na-ion batteries.