Ingredient review —Inositol
What is it?
Description
Inositol is a constituent of phospholipids in cellular membranes, a precursor of secondary messengers in metabolic pathways, a component of reproductive fluids, and essential for tissue growth. (32)(39) Previously considered an essential B vitamin (vitamin B8), it is now known that the human body can synthesize four grams of inositol per day, whereas approximately one gram per day can be obtained from the diet. (14) For this reason, inositol is now mainly referred to as an essential pseudovitamin. (24)
Not be confused with: D-pinitol (structurally related)
Main uses
Endocrine disorders
Hormonal and reproductive disorders
Metabolic disorders
Neurological disorders
Formulations
Form
Comparison
Myo-inositol
Hormonal and reproductive:
↑ mature oocytes, embryo quality, & sex hormone-binding globulin (SHGB);
Hormonal and reproductive:
↓ LH/FSH ratio, total testosterone, HOMA index, and immature oocytes by MI compared with D-chiro-inositol supplements in polycystic ovarian syndrome patients (34)(40)
Endocrine:
More involved in regulating intestinal glucose absorption in rats (9)
More involved in glucose uptake from plasma via glucose receptor activation (16)
Dosing & administration
Female infertility under in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI)
General outcomes from A-level evidence
No data currently available.
Dosing & administration
2000 mg (MI) + 200 μg folic acid twice per day for 3 months in non-PCOS women undergoing IVF or ICSI
Outcomes
r-FSH to form mature follicles, number of retrieved oocytes, metaphase II eggs, inseminated eggs, 2PN oocytes & embryos
LH (29)
Class of evidence
b
Dosing & administration
4000 mg (MI) + 400 μg folic acid for 3 months in IVF poor-responders
Outcomes
r-FSH, low quality oocytes (M1, Germinal Vesicle, only zona and degenerated oocytes)
mature oocytes retrieved, ovarian sensitivity index. Trended towards increased fertilization, implantation, grade 1 embryo, & pregnancy rates (6)
Class of evidence
b
Gestational diabetes (GDB)
General outcomes from A-level evidence
No data currently available.
Dosing & administration
2000 mg (MI) twice per day
Outcomes
rate of GDB & preterm delivery (42)
Class of evidence
a
Dosing & administration
4000 mg (MI) + 400 μg folic acid per day for 8 weeks
Outcomes
fasting glucose & insulin, HOMA-IR
adiponectin (11)
Class of evidence
b
Dosing & administration
4000 mg (MI) + 400 μg folic acid per day over pregnancy duration
Outcomes
GDB incidence, insulin therapy requirements, baby size with decreased rate of neonatal hypoglycemia
gestational age of delivery (30)
Class of evidence
b
Dosing & administration
2000 mg (MI) + 200 μg folic acid per day from 1st trimester to delivery
Outcomes
rate of GDB, HOMA-IR (13)
Class of evidence
b
Male infertility
General outcomes from A-level evidence
No data currently available.
Dosing & administration
2000 mg (MI) + 200 μg folic acid twice per day for 3 months
Outcomes
serum inhibin B, acrosome-reacted spermatozoa, sperm concentration, total sperm count & motility
FSH & LH (5)
Class of evidence
b
Metabolic syndrome in post-menopausal women
General outcomes from A-level evidence
No data currently available.
Dosing & administration
2000 mg (MI) twice per day for 1 year
Outcomes
number of px with metabolic syndrome via ↓ serum glucose, insulin, TGs, total cholesterol, BP, HOMA-IR
HDL-C (35)
Class of evidence
b
Dosing & administration
2000 mg (MI) twice per day for 6 months
Outcomes
DBP (11%), TGs (20%), HOMA-IR (75%)
HDL-C (22%) (20)
Class of evidence
b
Panic disorder
General outcomes from A-level evidence
No data currently available.
Dosing & administration
1200 mg (inositol) per day for 1 month
Outcomes
panic attack frequency & agoraphobia severity (3)
Class of evidence
c
Polycystic ovarian syndrome
General outcomes from A-level evidence
No data currently available.
Dosing & administration
1.0-4.0 g (MI) + 400 μg folic acid for 12-24 weeks; divided doses, twice per day
Outcomes
fasting serum insulin, HOMA index, leptin, LH, prolactin, testosterone, androstenedione, LH/FSH, TGs, SBP, DBP, 1st ovulation time, immature oocytes, & associated erythrocyte oxidative stress
Class of evidence
a
Dosing & administration
100 mg (inositol) twice per day for 14 weeks
Outcomes
ovulation frequency (23%), estradiol, weight loss, HDL
1st ovulation time (23.6 days), ovulation failure frequency, leptin (18)
Class of evidence
b
Dosing & administration
1200 mg (DCI) daily for 6-8 weeks
Class of evidence
c
Dosing & administration
550 mg (MI) + 13.8 mg (DCI) twice per day for 6 months
Outcomes
LH, free testosterone, fasting insulin, HOMA index
17-beta-estradiol (2)
Class of evidence
c
Respiratory distress syndrome in preterm infants
General outcomes from A-level evidence
No data currently available.
Dosing & administration
120-160 mg/kg (MI, intravenously) for the first 10 days of life
Outcomes
ventilation support, deaths, bronchopulmonary dysplasia
ductus arteriosus closure (22)
Class of evidence
b
Dosing & administration
80 mg/kg (MI intravenously) for first 5 days of life
Outcomes
requirements for inspiratory O2 & airway pressure, bronchopulmonary dysplasia, premature retinopathy (21)
Class of evidence
b
Adverse effects
At doses greater than 12 g per day, gastrointestinal effects, such as nausea, flatulence, and diarrhea, may occur. However, the incidence of these events is considered mild and does not increase in severity as the dose increases. (8) Increasing doses (300 to 2400mg) of DCI has been shown to negatively impact oocyte quality in patients with PCOS. (25)
Pharmacokinetics
Absorption
Distribution
- SMIT1/SMIT2 and the H+ myo-inositol transporter are responsible for inositol uptake throughout the body and brain. (14)
- Myoinositol can pass the blood-brain barrier for distribution to the brain and cerebrospinal fluid in rats. (36)(37)
- Myoinositol is also distributed to seminal fluids, prostate, epididymis, and seminal vesicles, and is high in follicular fluid of healthy Px, but low in PCOS Px. (4)
- D-chiro-inositol is highly distributed to fat, muscle, and the liver, but is low in the brain and heart in humans. (31)
- D-chiro-inositol is high in follicular fluid of PCOS Px, but low in healthy Px. (4)
Metabolism
References
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