Feng, Xiaodong_ Xie, Hong-Guang - Applying pharmacogenomics in therapeutics-CRC Press (2016)

Pharmacogenomics and Alternative Medicine
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rs6139591 C/C. Women with rs1776964 T/T genotype absorbed more vitamin C
from food compared with carriers of the rs1776964 C/C genotype, with an odds
ratio of 3.45. The results have shown that the SVCT2 genetic polymorphisms are
associated with ACS in females. Supplementing vitamin C may be an effective way
of preventing the disease. 8,9
Vitamin D
Vitamin D is a lipid-soluble vitamin, belonging to a steroid family. Among all
the required vitamins in humans, vitamin D is very special. It is a hormone precursor
and the human body can synthesize vitamin D 3 under sunny conditions.
7-Dehydrocholesterol is converted to vitamin D 3 after exposure to ultraviolet light.
Animal skin cells contain 7-dehydrocholesterol. So exposure to sunlight is an easy
way to get vitamin D 3 synthesized. However, the activity of vitamin D 3 is not high.
Vitamin D 3 must be converted to calcitriol (1,25-dihydroxy cholecalciferol) in the
liver and kidney. Calcitriol is the most active form, which can regulate the absorption
and metabolism of calcium in the small intestine, kidney, and bone.
Dysfunction of vitamin D–related endocrine systems can cause thyroid autoimmune
disease. Notably, 1,25(OH) 2 vitamin D 3 reduces HLAII molecule expression
through immunomodulation in thyroid cells, and it also inhibits lymphocyte proliferation
and inflammatory cytokine secretion. Therefore, in autoimmune thyroid disease
cases, plasma 1,25(OH) 2 vitamin D 3 decreases significantly. Vitamin D–binding
protein (DBP), the main transporter of 1,25(OH) 2 vitamin D 3 system, mediates endocytosis
of 1,25(OH) 2 vitamin D 3 . The genetic polymorphism of DBP microsatellite
sequences can significantly affect the function of vitamin D through regulating the
affinity between DBP and 1,25(OH) 2 vitamin D 3 . Michael et al. have found that a
genetic polymorphism in intron 8 of DBP gene, variable tandem repeats (TAAA)n,
is significantly associated with Graves disease. In DBP knockout mice, vitamin D
metabolism was significantly affected. 10
DBP plays an important role in in vivo transport and metabolism of vitamin D
(in particular 1,25(OH) 2 vitamin D 3 ). In healthy male subjects and male patients with
osteoporosis-related vertebral fractures (n = 170), DBP (TAAA)n-Alu*10 and *11
alleles had a protective effect on osteoporosis (OR = 0.39, p < 0.0005; OR = 0.09,
p < 0.007). In other words, when people carry 19–20 repeats (genotypes 9/10, 9/11,
and 10/10), the concentrations of circulating DBP and free vitamin D are high,
suggesting a higher bone density and a lower risk of osteoporosis. 11
Vitamin E
Vitamin E, also known as tocopherol, is an important antioxidant in the human
body. The main features of vitamin E include preventing polyunsaturated fatty acids
and phospholipids from being oxidized, thus maintaining cell membrane integrity.
Vitamin E also protects vitamin A from oxidative damage and strengthens the function
of vitamin A. Vitamin E reduces blood lipid peroxide, prevents excessive platelet
aggregation, increases erythrocyte membrane stability, promotes the synthesis of
red blood cells, and maintains cellular respiration.