151
9.2 Micronutrients: Health Benefits, Deficiencies and Risks
The human body needs micronutrients only in small quantities (in milligrams or
micrograms) although they are as important as the macronutrients (Welch and
Graham 2004). They are essential for the body’s healthy development. Some
vitamins for example work as cofactors or coenzymes in many metabolic processes. Trace elements like Zinc can help to improve immune function and minerals like Iron can prevent anemia among others (www.cdc.gov). As the body
cannot synthesize micronutrients, therefore, they need to be supplied in the diet
in adequate amounts. If their supply is not enough deficiency is possible and this
can results to a myriad of diseases. Vitamin A deficiency for example can lead
to blindness. A folic acid deficient pregnant woman can give birth to infants
with neural tube defects. Iodine deficiency can lead poor brain fetal development. Micronutrient deficiency can increase the risk of infections and can lead
to more micronutrient deficiencies (www.unicef.org). These are just the tip of
the iceberg. Micronutrient deficiency may lie hidden and usually, the signs and
symptoms develop late in the disease and are most often irreversible. The details
of the impact of these micronutrients on health and diseases are discussed in the
succeeding parts of the chapter.
9.3 Vitamins
Vitamins are essential substances for the normal functioning and development of
the body. There are two classes of vitamins namely: Fat-soluble and Water-soluble
vitamins (Table 9.1). The known vitamins include A, C, D, E, and K, and the B
vitamins: thiamin (B 1 ), riboflavin (B 2 ), niacin (B 3 ), pantothenic acid (B 5 ), pyridoxine (B 6 ), cyanocobalamin (B 12 ), biotin, and folate/folic acid.
9.3.1 Fat-Soluble Vitamins
As earlier mentioned, vitamins can be classified as either a water-soluble or fatsoluble vitamins. The fat-soluble vitamins are very vital for the smooth functioning
of the body. Their deficiencies have been implicated in several health disorders. The
recommended daily allowance (RDA) of the fat soluble vitamins A, D, E, and K is
8000–1000 μg/day, 8000–5000 μg/day, 8–10 μg/day, and 70–140 μg/day respectively (Kamangar and Emadi 2012). The RDA for water soluble vitamins including
thiamin, riboflavin, pyridoxine, niacin, biotin, ascorbic acid, and pantothenic acid
are 1 mg/day, 1.2 mg/day, 2–2.2 mg/day, 13 mili-equivalents, 100–200 μg/day,
60 μg/day, and 4–7 mg/day respectively (Kamangar and Emadi 2012).
9 Vitamins and Minerals: Types, Sources and their Functions
9.2 Micronutrients: Health Benefits, Deficiencies and Risks
The human body needs micronutrients only in small quantities (in milligrams or
micrograms) although they are as important as the macronutrients (Welch and
Graham 2004). They are essential for the body’s healthy development. Some
vitamins for example work as cofactors or coenzymes in many metabolic processes. Trace elements like Zinc can help to improve immune function and minerals like Iron can prevent anemia among others (www.cdc.gov). As the body
cannot synthesize micronutrients, therefore, they need to be supplied in the diet
in adequate amounts. If their supply is not enough deficiency is possible and this
can results to a myriad of diseases. Vitamin A deficiency for example can lead
to blindness. A folic acid deficient pregnant woman can give birth to infants
with neural tube defects. Iodine deficiency can lead poor brain fetal development. Micronutrient deficiency can increase the risk of infections and can lead
to more micronutrient deficiencies (www.unicef.org). These are just the tip of
the iceberg. Micronutrient deficiency may lie hidden and usually, the signs and
symptoms develop late in the disease and are most often irreversible. The details
of the impact of these micronutrients on health and diseases are discussed in the
succeeding parts of the chapter.
9.3 Vitamins
Vitamins are essential substances for the normal functioning and development of
the body. There are two classes of vitamins namely: Fat-soluble and Water-soluble
vitamins (Table 9.1). The known vitamins include A, C, D, E, and K, and the B
vitamins: thiamin (B 1 ), riboflavin (B 2 ), niacin (B 3 ), pantothenic acid (B 5 ), pyridoxine (B 6 ), cyanocobalamin (B 12 ), biotin, and folate/folic acid.
9.3.1 Fat-Soluble Vitamins
As earlier mentioned, vitamins can be classified as either a water-soluble or fatsoluble vitamins. The fat-soluble vitamins are very vital for the smooth functioning
of the body. Their deficiencies have been implicated in several health disorders. The
recommended daily allowance (RDA) of the fat soluble vitamins A, D, E, and K is
8000–1000 μg/day, 8000–5000 μg/day, 8–10 μg/day, and 70–140 μg/day respectively (Kamangar and Emadi 2012). The RDA for water soluble vitamins including
thiamin, riboflavin, pyridoxine, niacin, biotin, ascorbic acid, and pantothenic acid
are 1 mg/day, 1.2 mg/day, 2–2.2 mg/day, 13 mili-equivalents, 100–200 μg/day,
60 μg/day, and 4–7 mg/day respectively (Kamangar and Emadi 2012).
9 Vitamins and Minerals: Types, Sources and their Functions