Health Benefits and Common Uses of Inositol

What is Inositol

Inositol is a type of sugar alcohol. Its chemical structure is similar to glucose. Inositol tastes about half as sweet as sugar table – sucrose.

Typically, when you come across the word inositol, this refers to its most common form, called myo-inositol. Myo-inositol can be found in many food sources, such as oranges, rice bran, and cantaloupes. Even so, some people have problems with its metabolism or they have a health condition that requires very high intake of inositol, so they need to supplement their diet with inositol supplements.

In the past, inositol was considered a vitamin from the vitamin B group and was called vitamin B8. Nowadays, we know that most people can synthesize it from glucose. That is why inositol lost its vitamin status and is no longer considered an essential nutrient that we must get from food. It is now referred to as a vitamin-like substance or pseudo-vitamin.

History of Inositol

Inositol was first discovered in 1850 by German physician named Johannes Joseph Scherer. Because he extracted it from muscle tissue, the substance was initially called “muscle sugar”. It was later named inositol after the Greek word ‘inos’ meaning muscle.

Inositol is also known as: Myo-Inositol, D-chiro-inositol, Inositol Monophosphate, 1,2,3,4,5,6-Cyclohexanehexol, cis-1,2,3,5-trans-4,6-Cyclohexanehexol, 1,2,5/3,4,6-inositol, (1S)-inositol, (1S)-1,2,4/3,5,6-inositol

Different Types of Inositol

There are 9 different types of inositol. Most prevalent type is called myo-inositol. This is also the type of inositol that is typically sold in the form of inositol supplements.

Myo-inositol

Myo-inositol is found in abundance in nature in both animal as well as plant sources. Myo-inositol that is packaged into nutritional supplemenst is usually gained from rice bran, which is a rich and affordable source of natural inositol.

Myo-inositol has many different actions in human body. One of inositol’s most important action is its involvement in insulin signalling. Inositol has been shown to increase insulin sensitivity and regulate glucose uptake. That is why it helps in conditions such as diabetes (including gestational diabetes), diabetic neuropathy, and PCOS.

D-chiro-inositol

Another important type of inositol is D-chiro inositol; most commonly called DCI. Only small amounts of DCI can be found in food sources; these are mostly buckwheat (a fruit seed substituted for grains) and fig leaf gourd (type of squash).  

Most people don’t get enough DCI from food sources. Luckily, our bodies are able to produce it from myo-inositol with the help of the enzyme epimerase.

Similar to myo-inositol, DCI also plays an important role in insulin action. DCI deficiency is also thought to play a role in the development of PCOS, so it is often used as a supplement for treating the symptoms of PCOS (usually, taken alongside myo-inositol).

Scyllo-inositol

Otherwise known as scyllitol, this type of inositol can be found in coconut palms. Recently, scyllo-inositol has been extensively studied due to its proposed benefits for cognitive health.

Several studies have examined the effects of scyllo-inositol supplementation on progression of Alzheimer’s disease. Preliminary animal and in vitro (test tube) studies have showed promising results for the use of scyllo-inositol in Alzheimer’s patients. It has been shown that scyllo-inositol reduces the formation of amyloid beta plaques in mice brain, prevents neuritic dystrophy (degeneration of brain cells) and improves cognition.

However, clinical trial of 250 mg of scyllo-inositol in patients with mild to moderate Alzheimer’s disease failed to show an improvement in symptoms. Since this trial involved only 84 patients, the sample size was too small to draw any definite conclusions. More studies are needed to assess the benefit of scyllo-inositol for people with Alzheimer’s disease. (1), (2), (3), (4).

Muco-inositol

Muco-inositol is another type of inositol. After muco-inositol reaches the brain, it is attached to our sensory neurons of taste (brain cells involved in processing taste signals).  Through this mechanism, muco-inositol affects the way we perceive taste.

Other Types

Other, less common, types of inositol include  Neo-inositol, L-chiro-inositol, Allo-inositol, Epi-inositol and Cis-inositol.         

How does Inositol Work and What Does it do in the Body

Inositol Balances Neurotransmitters in the Brain and Helps with Several Mental Conditions

Inositol and its metabolites play an important part in the normal functioning of our brain. They do that by facilitating the action of neurotransmitters (neurotransmitters are chemicals that enable the transmission of signals from one brain cell to another).

Inositol also specifically raises the level of one neurotransmitter, called serotonin. This neurotransmitter affects our mood, sleep patterns and our sense of general wellbeing.

Through its action on neurotransmitters, inositol has been shown to help with depression (specifically in those people that respond well to SSRI medications), lower anxiety, improve the symptoms of obsessive compulsive disorder, help with insomnia, and decrease the number of panic attacks.

Inositol Increases Insulin Sensitivity and Assists in Blood Sugar Regulation

Whenever there is too much sugar in our blood, pancreas secretes insulin, which facilitates the uptake of glucose from the blood into fat and muscle tissues. There are several ways through which insulin release is regulated. Inositol is involved in one of these so-called insulin signaling pathway. It helps to increase insulin sensitivity and contributes to the regulation of blood sugar levels.

Inositol has been found helpful in diabetes and other conditions related to insulin resistance (such as PCOS, metabolic syndrome, etc). Inositol has also been shown to reduce the risk of gestational diabetes and improve the fasting glucose and insulin levels in women who have already developed gestational diabetes (5), (6).

Improves ‘Bad’ Cholesterol Levels in People With Metabolic Syndrome

We used to believe that obesity directly causes high levels of cholesterol. Newer studies (7), (8) have shown, though, that insulin resistance is a major factor that affects cholesterol metabolism.  As a result, people with insulin resistance and type 2 diabetes typically also have unhealthy levels of cholesterol in their blood. 

Inositol is well known for its ability to increase insulin sensitivity. Through this action, it also helps to regulate cholesterol metabolism. It has been shown (9) that inositol decreases the level of small dense LDL cholesterol in people with metabolic syndrome (high levels of this type of cholesterol increase the risk of cardiovascular conditions that may lead to heart attack and stroke).

Inositol Helps With Excessive body Hair in Women Caused by Hormonal Imbalance

Often hirsutism (excessive body hair) in women is related to high levels of circulating androgens (male sex hormone such as testosterone). Inositol (especially d-chiro inositol brings down the levels of androgens in women suffering from hormonal imbalance and thus help reduce excessive body hair (10).

Common Medical Uses of Inositol

Polycystic Ovary Syndrome (PCOS)

One of the conditions that respond really well to inositol supplementation is PCOS. This condition affects large percentage of women and may cause many symptoms, such as problems with ovulation and difficulty getting pregnant, weight gain, acne, and excessive body hair.

It is though that insulin resistance leads to all other imbalances associated with PCOS. Medications that improve insulin sensitivity (such as Metformin) are the first line of treatment for PCOS. Similarly to Metformin, inositol also improves insulin sensitivity and thus addresses the root cause of PCOS. The body is then able to metabolize glucose better, which triggers other positive changes in patients with PCOS. These changes include improved blood lipids level (increase in good-HDL cholesterol and decrease in bad-LDL cholesterol), more regular menstruation cycles, higher pregnancy rates, and a decrease in hormonally caused excessive body hair and acne.

Diabetes and Related Health Complications

Inositol has been shown to help people with type 2 diabetes better control their blood sugar levels. Three months of supplementation (14) with both myo and d-chiro inositol resulted in lowered fasting blood glucose and HbA1c levels (form of hemoglobin bound to glucose that reflects how well diabetes is controlled).

Inositol also helps to prevent and alleviate the symptoms of conditions that are associated to diabetes, such as diabetic neuropathy, erectile dysfunction, and diabetic skin ulcers (15), (16), (17).

Depression

Inositol has a long history of use in depressed patients. It has been shown that people with depression and bipolar disorder tend to have lower levels of inositol in their brain (18).

Several independent studies confirmed that inositol supplementation improves the symptoms and quality of life in both depression and bipolar depression (19), (20).

Anxiety and Panic Disorders

Inositol also possesses sedative effects, so it is successfully used for relieving anxiety and decreasing the number and severity of panic attacks. One study (21) showed that inositol decreased the number of panic attacks more than an established drug fluvoxamine.

Obsessive-Compulsive Disorder (OCD)

OCD patients suffer from unwanted and repetitive thoughts and feelings that force them to do do certain behavior.  This disorder is marked by low levels of neurotransmitter serotonin in the brain.

Inositol influences different brain chemicals and raises levels of serotonin. That is why it brings relief to people suffering from OCD (22).

Acute Respiratory Distress Syndrome (ARDS)

Acute Respiratory Distress Syndrome (ARDS) is caused by widespread inflammation of the lungs. It often happens in critically ill patients and prematurely born infants. Study, examining Inositol supplementation in preterm infacts with ARDS (23), showed that inositol significantly reduced the risk of severe outcomes, such as brain bleeding (intraventricular hemorrhage) and death.

Food Sources of Inositol

Myo-inositol is found in abundance in many food sources. Highest concentration of inositol can be found in different fruits, such as orange, cantaloupe, grapefruit, lime, dried prunes, mango and kiwi. Grains and beans also contain large amounts of inositol, although it comes in the form of phytate. This form is less bioavailable, which means that our bodies are less able to utilize it.   

Meat, eggs and milk products contain smaller, almost insignificant amounts of inositol. 

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