What is inositol?
Inositol is a B-vitamin-like nutrient (sometimes – unofficially – referred as B8) found in whole grains, beans, nuts, and fruits. It is also made by the body and it’s available as a dietary supplement.
Even though there are 9 different types (isomers) of inositol, the two main forms used in supplements are myo-inositol and d-chiro-inositol. Inositol supplements have been successfully used for a variety of conditions, including PMDD, PCOS, type 2 diabetes, anxiety and depression.
Inositol benefits for PMDD
Intense cravings, mood swings, difficulty concentrating, tension, lethargy and irritability (among a few other unpleasantries) are a monthly reality for millions of women. Premenstrual Dysphoric Disorder (PMDD) can be described as PMS on steroids (no pun intended).
Though conventional treatment of PMDD usually involves the use of antidepressant/anti-anxiety meds such as fluoxentine (Prozac), setraline (Zoloft), and paroxetine (Paxil), inositol may offer the same benefits with no side-effects.
One study (1) followed 71 women supplementing with 3.6 g/day myo-inositol in soft gel capsule or 12 g/day myo-inositol in powder form throughout six menstrual cycles. Both forms of inositol were found to be effective in improving the symptoms of PMDD, particularly mood swings.
Inositol benefits for PCOS
Women with Polycystic Ovarian Syndrome (PCOS) tend to have high androgen levels (male hormones such as testosterone) as well as some level of insulin resistance. And though contradictory to the name, not all women with PCOS actually have ovarian cysts.
Symptoms of PCOS include irregular or absent menstrual periods, weight gain (though not always), excess facial hair, thinning of hair on the scalp, darkening of the skin in certain areas and infertility.
A review of several studies (2) concluded that myo-inositol improved PCOS symptoms. Particularly, it appears that myo-inositol has a regulatory effect on insulin and testosterone levels, restores regular menstruation and ovulation, and aids in weight loss. Even better, there we no reported side-effects.
Inositol benefits for type 2 diabetes
Given inositol’s role in insulin signaling, it’s no wonder it is also effective in preventing and improving type 2 diabetes. Both myo and d-chiro-inositol showed insulin mimetic effects in animal models of insulin resistance, meaning it was effective in lowering blood sugar levels (3, 4).
In a pilot study (5), 20 diabetic subjects received a combination of myoinositol (550 mg), d-chiro-inositol (13.8 mg), and folic acid (400 mcg) in addition to their usual diabetes treatment. It was found that supplementation for 3 months was effective in lowering both fasting blood sugar and HbA1c levels.
Inositol benefits for anxiety
Inositol is found in high concentrations in the brain where it enhances communication between brain cells. Neurotransmitters such as serotonin, dopamine, and GABA rely on inositol to transmit messages.
Given these neurotransmitters roles in mood, sleep, addictions, cravings, cognitive abilities, and productivity – among others – it’s no surprise inositol can have benefits when it comes to mood. It is hypothesized that inositol mediates serotonergic signaling within nerve cells to elicit an anxiolytic effect (6).
In a double-blind, crossover trial of inositol versus fluvoxamine (anti-anxiety drug), it was found that both groups had improvements in several anxiety scales, with inositol reducing the number of panic attack per week by 4 compared to 2.4 with fluvoxamine (7). In addition, there were no side-effects in the inositol group compared to nausea and tiredness in the fluvoxamine group.
Inositol benefits for depression
Inositol levels have been found to be lower than average on people with depression (8). Since it is a precursor for several neurotransmitters, serving as a secondary messenger for serotonin and dopamine, low levels of inositol may disrupt adequate neurotransmitter signaling, possibly contributing to a depressed mood.
One study showed that inositol led to major improvement in 9 out of 11 depressed patients resistant to previous treatment (10). Similarly, another study found overall improvement in scores on the Hamilton Depression Rating Scale significantly greater for inositol than for placebo at week 4 (11).
However, more research is needed in this area, since the evidence is not conclusive (12).
The majority of inositol supplements come in the form of myo-inositol, but you’ll also find combinations of myo and d-chiro-inositol, particularly for PCOS. Doses range from 1200 mg to 18 g per day, depending on the condition (13).
You can find inositol both in capsule and powder form, with some individuals preferring the latter given that it can be easily mixed with water and does not require swallowing several pills per day.
Inositol benefits: bottom line
Given the benefits and safety of inositol’s supplements, if you’re struggling with any of the above mentioned conditions it may be worth mentioning it to your healthcare provider to see how it can fit on your treatment plan.