551
fragments called peptides combine to make one larger functional protein. The
hemoglobin is an example of a protein that has quaternary structure. It is composed
of four peptides that bond together to form a functional oxygen carrier. A protein’s
structure also influences its nutritional quality. Large fibrous protein structures are
more difficult to digest than smaller proteins and some, such as keratin, are indigestible. Some fibrous proteins cannot be completely digested as all the amino acids are
not absorbed and available for the body to utilize, thereby decreasing their nutritional value (Mahan and Raymond 2016; Titchenal et al. 2018; Ribarova 2018;
Gibney et al. 2009; Lewis and Bayley 1995).
25.2.2 Micronutrients
Micronutrients are required by the human body in micro quantities and are considered essential for carrying out various functions. Sixteen minerals (Macro: Na, Cl,
K, Ca, P, Mg, S; Trace: Fe, Zn, I, Se, Cu, Mn, F, Cr, Mo) and thirteen vitamins (A,
B 1 , B 2 , B 3 , B 5, B 6 , B 7 , B 9 , B 12 , C, D, E, and K are the most significant essential micronutrients. Unlike macronutrients (carbohydrates, lipids, and proteins), micronutrients are not the sources of energy, but they assist in the process as cofactors and
components of enzymes (i.e., coenzymes). Adequate intake of these micronutrients
especially is necessary for healthy immune system and its normal functioning
(Gibney et al. 2009; Campbell 2017).
25.2.2.1 Minerals
Mineral micronutrients are needed for regular metabolism and must be supplied
with diet. While some minerals like calcium, phosphorus, magnesium and sodium
are needed in considerable quantities, the others like copper, zinc, selenium, fluorine and chromium are needed in lesser quantities. Summary of different types,
sources, and other valuable information of minerals is provided in Table 25.2.
Calcium Calcium is the most plentiful mineral in the body. About 99% of total
calcium is located in the human skeleton while the remaining 1% is divided between
teeth and soft tissues. Some amount is present in blood and other fluids in the human
body. It plays a significant role in balancing body fluid, blood clotting, blood pressure regulation, enzyme activation, muscle contraction and nerve transmission
(Marcus 2013; Gibney et al. 2009). It also helps in development and maintenance of
bone and prevention of osteoporosis (WHO/FAO 2004a, b; Marcus 2013), reduces
the absorption of dietary fat thereby lowering serum total cholesterol and low–density lipoprotein cholesterol concentrations (Vaskonen 2003). Calcium ion also plays
a vital role in neuromuscular function, many enzyme–mediated processes, as well as
providing rigidity to the skeleton by virtue of its phosphate salts (FAO/WHO 1998).
25 Bioavailability of Nutrients and Safety Measurements
fragments called peptides combine to make one larger functional protein. The
hemoglobin is an example of a protein that has quaternary structure. It is composed
of four peptides that bond together to form a functional oxygen carrier. A protein’s
structure also influences its nutritional quality. Large fibrous protein structures are
more difficult to digest than smaller proteins and some, such as keratin, are indigestible. Some fibrous proteins cannot be completely digested as all the amino acids are
not absorbed and available for the body to utilize, thereby decreasing their nutritional value (Mahan and Raymond 2016; Titchenal et al. 2018; Ribarova 2018;
Gibney et al. 2009; Lewis and Bayley 1995).
25.2.2 Micronutrients
Micronutrients are required by the human body in micro quantities and are considered essential for carrying out various functions. Sixteen minerals (Macro: Na, Cl,
K, Ca, P, Mg, S; Trace: Fe, Zn, I, Se, Cu, Mn, F, Cr, Mo) and thirteen vitamins (A,
B 1 , B 2 , B 3 , B 5, B 6 , B 7 , B 9 , B 12 , C, D, E, and K are the most significant essential micronutrients. Unlike macronutrients (carbohydrates, lipids, and proteins), micronutrients are not the sources of energy, but they assist in the process as cofactors and
components of enzymes (i.e., coenzymes). Adequate intake of these micronutrients
especially is necessary for healthy immune system and its normal functioning
(Gibney et al. 2009; Campbell 2017).
25.2.2.1 Minerals
Mineral micronutrients are needed for regular metabolism and must be supplied
with diet. While some minerals like calcium, phosphorus, magnesium and sodium
are needed in considerable quantities, the others like copper, zinc, selenium, fluorine and chromium are needed in lesser quantities. Summary of different types,
sources, and other valuable information of minerals is provided in Table 25.2.
Calcium Calcium is the most plentiful mineral in the body. About 99% of total
calcium is located in the human skeleton while the remaining 1% is divided between
teeth and soft tissues. Some amount is present in blood and other fluids in the human
body. It plays a significant role in balancing body fluid, blood clotting, blood pressure regulation, enzyme activation, muscle contraction and nerve transmission
(Marcus 2013; Gibney et al. 2009). It also helps in development and maintenance of
bone and prevention of osteoporosis (WHO/FAO 2004a, b; Marcus 2013), reduces
the absorption of dietary fat thereby lowering serum total cholesterol and low–density lipoprotein cholesterol concentrations (Vaskonen 2003). Calcium ion also plays
a vital role in neuromuscular function, many enzyme–mediated processes, as well as
providing rigidity to the skeleton by virtue of its phosphate salts (FAO/WHO 1998).
25 Bioavailability of Nutrients and Safety Measurements