547
three major biological functions in the body. They act as energy storehouses, serve
as major structural components of cell membranes, and exercise a key role in cell
signaling. In addition, they protect organs in fat–storing tissues, provide insulation
to aid in temperature regulation, as well as manage other functions in the body
(Mahan and Raymond 2016; Titchenal et al. 2018). There are three main types of
lipids: glycerides, phospholipids, and sterols. Glycerides are fatty acid esters of
glycerols. These are water insoluble and make up more than 95% of lipids in the
diet and are commonly found in vegetable oil, butter, whole milk, cheese, cream
cheese, and some meats. Phospholipids are water–soluble and make up about 2% of
the dietary lipids. They are found both in plants and animals and are crucial for
building the protective barrier around cell and organelle membranes. Sterols, the
least common type of lipid, regulate biological processes and sustain the domain
structure of cell membranes where they are considered as membrane reinforcers.
Some important animal and plant sterols include cholesterol, ergosterol, stigmasterol and sitosterol (Gibney et al. 2009; Mahan and Raymond 2016; Titchenal
et al. 2018).
Fatty Acids Fatty acid is a carboxylic acid with a long aliphatic chain that is either
saturated or unsaturated at room temperature. Fatty acids differ from one another in
carbon chain length and degree of saturation. The naturally occurring fatty acids
have an unbranched chain of an even number (from 4 to 28) of carbon atoms. They
usually have a cis configuration whereas trans ones are synthetic in origin. Vegetable
oils are converted into semisolid fats by hydrogenation of the double bonds to overcome rancidity and to increase their shelf life (Mahan and Raymond 2016; Titchenal
et al. 2018).
Fatty acids are required for the proper and normal function of all the body systems including circulatory, respiratory, nervous, integumentary, and immune system. The body is capable of synthesizing most of the fatty acids which are referred
to as nonessential fatty acids. Fatty acids that are not synthesized by the body, and
their requirement is fulfilled from diet are termed as essential fatty acids which play
an important role in the life and death of cardiac cells, immune system function, and
blood pressure regulation. Essential fatty acids also referred to as omega (ω) fatty
acids are characterized as ω–3 and ω–6, ω–7, and ω–9 where 3, 6, 7, and 9 refers to
the position of the first carbon–carbon double bond and the ω refers to the methyl
end of the chain. ω–3 and ω–6 fatty acids are precursors to eicosanoid hormones
which control other hormones to impart important body functions like the central
nervous system and immune system. Eicosanoids derived from ω–6 fatty acids are
known to increase blood pressure, immune response, and inflammation while those
derived from ω–3 fatty acids are responsible for healthy heart. Docosahexaenoic
acid (DHA), a ω–3 essential fatty acid plays an important role in synaptic transmission in the brain during fetal development (Gibney et al. 2009).
25 Bioavailability of Nutrients and Safety Measurements
three major biological functions in the body. They act as energy storehouses, serve
as major structural components of cell membranes, and exercise a key role in cell
signaling. In addition, they protect organs in fat–storing tissues, provide insulation
to aid in temperature regulation, as well as manage other functions in the body
(Mahan and Raymond 2016; Titchenal et al. 2018). There are three main types of
lipids: glycerides, phospholipids, and sterols. Glycerides are fatty acid esters of
glycerols. These are water insoluble and make up more than 95% of lipids in the
diet and are commonly found in vegetable oil, butter, whole milk, cheese, cream
cheese, and some meats. Phospholipids are water–soluble and make up about 2% of
the dietary lipids. They are found both in plants and animals and are crucial for
building the protective barrier around cell and organelle membranes. Sterols, the
least common type of lipid, regulate biological processes and sustain the domain
structure of cell membranes where they are considered as membrane reinforcers.
Some important animal and plant sterols include cholesterol, ergosterol, stigmasterol and sitosterol (Gibney et al. 2009; Mahan and Raymond 2016; Titchenal
et al. 2018).
Fatty Acids Fatty acid is a carboxylic acid with a long aliphatic chain that is either
saturated or unsaturated at room temperature. Fatty acids differ from one another in
carbon chain length and degree of saturation. The naturally occurring fatty acids
have an unbranched chain of an even number (from 4 to 28) of carbon atoms. They
usually have a cis configuration whereas trans ones are synthetic in origin. Vegetable
oils are converted into semisolid fats by hydrogenation of the double bonds to overcome rancidity and to increase their shelf life (Mahan and Raymond 2016; Titchenal
et al. 2018).
Fatty acids are required for the proper and normal function of all the body systems including circulatory, respiratory, nervous, integumentary, and immune system. The body is capable of synthesizing most of the fatty acids which are referred
to as nonessential fatty acids. Fatty acids that are not synthesized by the body, and
their requirement is fulfilled from diet are termed as essential fatty acids which play
an important role in the life and death of cardiac cells, immune system function, and
blood pressure regulation. Essential fatty acids also referred to as omega (ω) fatty
acids are characterized as ω–3 and ω–6, ω–7, and ω–9 where 3, 6, 7, and 9 refers to
the position of the first carbon–carbon double bond and the ω refers to the methyl
end of the chain. ω–3 and ω–6 fatty acids are precursors to eicosanoid hormones
which control other hormones to impart important body functions like the central
nervous system and immune system. Eicosanoids derived from ω–6 fatty acids are
known to increase blood pressure, immune response, and inflammation while those
derived from ω–3 fatty acids are responsible for healthy heart. Docosahexaenoic
acid (DHA), a ω–3 essential fatty acid plays an important role in synaptic transmission in the brain during fetal development (Gibney et al. 2009).
25 Bioavailability of Nutrients and Safety Measurements