Inositol is a supplement closely related to the B vitamin group. The structure of the compound is closely related to glucose. It is not considered an essential nutrient because it is produced within the body in adequate amounts.
Inositol falls into a group of supplements that are important for health in the body but not considered a vitamin or mineral. Other supplements in this group include: creatine, coenzyme 10, choline, L-carnitine and SAM-e. Inositol is comprised of 9 stereoisomers. The stereoisomer myo-inositol is 90% prevalent and shows the most benefit as a supplement. For this reason, the term myo-inositol and inositol are usually interchangeable. The majority of supplements are created solely from myo-inositol.
The safety of inositol has been evaluated in high dosages. It is a natural molecule with little toxicity. Lower dosages can have positive benefits on insulin sensitivity and fertility where much higher dosages have shown positive effects on neurological function. Inositol has a low permeability for the blood brain barrier which may explain why large dosages may be required to see benefits.
How Inositol Works In the Brain
Inositol’s primary neurological function is to produce the structural basis for secondary messengers within the brain. A secondary messenger works to transmit and amplify the signals of certain hormones and neurotransmitters. One common example of a secondary messenger system is the cAMP system. Inositol’s secondary messenger system is known as the phosphoinositol (PI) system.
The phosphoinositol (PI) system helps to act as signal transductor for a number of hormones. The two secondary massagers in this system are inositol trisphosphate (IP3) and diacylglycerol (DAG). These secondary messengers help to influence a number of hormones via their pathways. IP3 may control insulin homeostatsis via activation of M3 acetylcholine receptor pathway. This is likely the method to explain Inositol’s positive benefit on insulin sensitivity.
The PI system has an interaction with the a1 adrenergic receptors. Antagonists of the a1 receptors are common targets for anti-panic/anxiety and vasodilation drugs. The a1 receptors influence vasoconstriction, sweating and a number of other physiological symptoms in the body relating to panic. The PI system secondary messenger, DAG interacts with the calcium content and channels relating to the a1 receptors. This could explain the inhibitory effects of inositol on panic and anxiety.
The PI system also has effects on acetylcholine receptors. It seems to only influence M1 and M3 muscarinic receptors exclusively. The secondary messenger in the PI system, IP3 works as a signaling pathway for the M1 and M3 receptors. The M1 receptors help to control and regulate a number of functions in the body and may influence areas of cognitive functioning. M3 receptors influence insulin and smooth muscle tone.
Inositol Treatment for OCD, Panic & Anxiety
One study showed high dosages of inositol were as effective as an SSRI medication for treating panic disorders, OCD as well as general anxiety. This well published study claimed that higher dosages of Inositol in the 18 gram range showed the most positive results. The reason this high dosage is needed is because inositol is not efficient at crossing the blood brain barrier and these high dosages are needed for these results.
The effects on Inositol and panic/anxiety treatment are likely due to the manipulation of the a1 receptor. Many a1 blockers may help to treat bi-polar depression and related panic effects. This method of action is likely to explain positive effects of inositol on OCD, depression and anxiety/panic
Inositol Side Effects
The well published study relating to high dosage inositol treatment for OCD and panic showed little side effects. While typically, inositol has much less side effects than SSRI medication, it may produce some negative side effects in high dosages.
The cholinergic effects of high dosage inositol may produce negative side effects such as excessive salivation and sweating. This is due to the specific acetylcholine receptors inositol modulates. Other side effects such as gastrointestinal side effects are very common along with irritability. Inositol may be as effective as SSRI’s however these high dosages are likely to produce very subtle to mild side effects in these dosage ranges.