578
disorders (Gibney et al. 2009; Ravisankar et al. 2015; Schönfeldt et al. 2016). Vitamin
D helps absorb calcium from the small intestine into the bloodstream and helps to
maintain normal blood calcium, which is essential to cardiac function. Calcium
absorption in individuals is dependent on vitamin D status, and on the presence of
binding substances like uronic acid, phytate and oxalate in the food (Khokhar et al.
2012; Allen 1982). Vitamin B 6 can be less available than other food/food products
which is found in heat–processed milk products (e.g. pyridoxine β–D–glucoside) is
also reported (Gregory 1997). In plants, especially mature grains, vitamin B 3 can be
bound to sugar molecules which can significantly decrease its bioavailability (Gibney
et al. 2009; Mahan and Raymond 2016; Titchenal et al. 2018).
Minerals Minerals are not efficiently absorbed and so their bioavailability can be
very low. Plant based foods mostly contain factors, like oxalate and phytate,
that bind to minerals and inhibit their absorption. Some minerals influence the absorption of others. For example, excess zinc in the diet, affects absorption of iron and
copper. Conversely, certain vitamins enhance mineral absorption, like vitamin C
boosts iron absorption, and vitamin D boosts calcium and magnesium absorption.
Consumption of a high fiber diet interferes with mineral and nutrient bioavailability.
Iron is available in the heme or non–heme form. Although, 90% of the dietary
iron is consumed in the non–heme form, but due to its low bioavailability, only
about half of the iron is absorbed by the body. While absorption of heme iron is
dependent on the iron status of the individual, absorption of non–heme iron depends
not only on the individual’s iron status, but also on the absorption modifiers consumed during the same meal. In general, higher the non–heme iron content of the
diet, lower is the absorption efficiency (Yip and Dallman 2001; Gibney et al. 2009).
Absorption is highest for water soluble iron compounds (e.g., ferrous sulfate, ferrous fumurate, ferric saccharate). The presence of soluble enhancers, such as ascorbic acid, and inhibitors, such as phytates, polyphenols, and calcium, consumed in
the same meal showed a notable effect on the amount of non–heme iron absorbed.
Heme iron is much less affected by the dietary factors and contributes more significantly to absorbable iron (Schönfeldt et al. 2016).
A number of dietary factors influence zinc uptake. Ligands, such as phytate,
form insoluble complexes with zinc and prevent its absorption. Calcium increases
binding of zinc by phytate (Flynn et al. 2009), and thus decreases zinc bioavailability and absorption (Spencer et al. 1984; Wood and Zheng 1995; Flynn et al. 2009).
But high–fiber foods may also interfere with calcium absorption (Marcus 2013), the
organic form of zinc (e.g. in oysters) is less affected by absorption modifiers than
the inorganic forms (Solomons et al. 1979). High iron content in the diet also
decreases zinc absorption. Earlier reports indicated that folic acid can also inhibit
zinc retention and metabolism (Milne et al. 1984, 1990; Milne 1989; Flynn et al.
2009). Amino acids like histidine, methionine and cysteine facilitates zinc absorption (by removing zinc from the zinc–calcium–phytate complexes) (Mills 1985;
Flynn et al. 2009).
Potassium present in intracellular fluid plays a key role in maintaining sodium–
potassium balance for sustaining cell function. The small intestine is the primary
K. Sharma et al.
disorders (Gibney et al. 2009; Ravisankar et al. 2015; Schönfeldt et al. 2016). Vitamin
D helps absorb calcium from the small intestine into the bloodstream and helps to
maintain normal blood calcium, which is essential to cardiac function. Calcium
absorption in individuals is dependent on vitamin D status, and on the presence of
binding substances like uronic acid, phytate and oxalate in the food (Khokhar et al.
2012; Allen 1982). Vitamin B 6 can be less available than other food/food products
which is found in heat–processed milk products (e.g. pyridoxine β–D–glucoside) is
also reported (Gregory 1997). In plants, especially mature grains, vitamin B 3 can be
bound to sugar molecules which can significantly decrease its bioavailability (Gibney
et al. 2009; Mahan and Raymond 2016; Titchenal et al. 2018).
Minerals Minerals are not efficiently absorbed and so their bioavailability can be
very low. Plant based foods mostly contain factors, like oxalate and phytate,
that bind to minerals and inhibit their absorption. Some minerals influence the absorption of others. For example, excess zinc in the diet, affects absorption of iron and
copper. Conversely, certain vitamins enhance mineral absorption, like vitamin C
boosts iron absorption, and vitamin D boosts calcium and magnesium absorption.
Consumption of a high fiber diet interferes with mineral and nutrient bioavailability.
Iron is available in the heme or non–heme form. Although, 90% of the dietary
iron is consumed in the non–heme form, but due to its low bioavailability, only
about half of the iron is absorbed by the body. While absorption of heme iron is
dependent on the iron status of the individual, absorption of non–heme iron depends
not only on the individual’s iron status, but also on the absorption modifiers consumed during the same meal. In general, higher the non–heme iron content of the
diet, lower is the absorption efficiency (Yip and Dallman 2001; Gibney et al. 2009).
Absorption is highest for water soluble iron compounds (e.g., ferrous sulfate, ferrous fumurate, ferric saccharate). The presence of soluble enhancers, such as ascorbic acid, and inhibitors, such as phytates, polyphenols, and calcium, consumed in
the same meal showed a notable effect on the amount of non–heme iron absorbed.
Heme iron is much less affected by the dietary factors and contributes more significantly to absorbable iron (Schönfeldt et al. 2016).
A number of dietary factors influence zinc uptake. Ligands, such as phytate,
form insoluble complexes with zinc and prevent its absorption. Calcium increases
binding of zinc by phytate (Flynn et al. 2009), and thus decreases zinc bioavailability and absorption (Spencer et al. 1984; Wood and Zheng 1995; Flynn et al. 2009).
But high–fiber foods may also interfere with calcium absorption (Marcus 2013), the
organic form of zinc (e.g. in oysters) is less affected by absorption modifiers than
the inorganic forms (Solomons et al. 1979). High iron content in the diet also
decreases zinc absorption. Earlier reports indicated that folic acid can also inhibit
zinc retention and metabolism (Milne et al. 1984, 1990; Milne 1989; Flynn et al.
2009). Amino acids like histidine, methionine and cysteine facilitates zinc absorption (by removing zinc from the zinc–calcium–phytate complexes) (Mills 1985;
Flynn et al. 2009).
Potassium present in intracellular fluid plays a key role in maintaining sodium–
potassium balance for sustaining cell function. The small intestine is the primary
K. Sharma et al.