Nature is usually pretty spectacular about providing us with remedies for common problems, if we’re looking closely enough. This is definitely true for inositol.
Never heard of it? You’re not alone. Although it’s a somewhat common supplement, it gets nowhere near the attention of some others on the market, as I think it deserves. You’re going to want to hear about this one, particularly if you’re a woman who has ever experienced infertility.
So, what is inositol, how might it benefit your health and what’s the best way to get more of it?
What Is Inositol?
Inositol is a chemical compound with nine stereoisomers, which is just a scientific way of saying that it exists in nature in nine almost identical forms. It’s technically a rearranged form (“isomer”) of glucose, which means it is a natural sugar. (1) This simple carbohydrate (most accurately defined as a sugar alcohol) is quickly broken down to be used as an energy source in the body.
Although it isn’t considered a “true” vitamin, inositol and adenosine monophosphate (AMP) are sometimes referred to collectively as “vitamin B8,” although most references to vitamin B8 are talking directly about inositol.
Inositol is used in the body a few different ways. For one, it’s essential in the process of building cell membranes. It’s also a “secondary messenger” in your central nervous system, which is one reason it’s known to increase the impact of neurotransmitters in your brain and, maybe, why it causes some mood-boosting effects in certain people. In addition, two forms of it together (myo-inositol and D-chiro-inositol, in a 40:1 ratio) increase insulin sensitivity. (3)
This molecule has some pretty powerful health benefits that I’ll get into in just a moment. Researchers typically use the various forms in powdered extract (supplement) form, but there are many foods that are rich in it.
Inositol is sometimes found in energy drinks, too, but the extremely small amounts in which it occurs are much too small to provide any real help, in my opinion. Plus, energy drinks are typically laden with ridiculous amounts of sugar and other unpleasant chemicals, so it’s best to stick to getting it in whole foods or supplement form.
8 Inositol Benefits
1. Effectively Treats PCOS and Improves Fertility
The most well-known and thoroughly researched benefit of inositol is its ability to treat polycystic ovarian syndrome (PCOS). PCOS is a very common syndrome that may affect up to 21 percent of women in a given population. Some reports find that as many as 72 percent of women who have PCOS have experienced some form of infertility versus about 16 percent of women without PCOS. (4)
For diagnosis, the three main features of PCOS are hyperandrogenism, oligomenorrhea and polycystic ovaries. Hyperandrogenism is an excess of male hormones, which commonly causes a combination of acne, skin issues, scalp hair loss, increased body or facial hair (known as hirsutism) and an elevated sex drive. When your doctor mentions “oligomenorrhea,” he or she is simply referring to a condition of infrequent periods. Finally, a woman with polycystic ovaries has at least one ovary with 12 or more cysts.
PCOS is also closely associated with metabolic syndrome — about twice as many of the PCOS population have metabolic syndrome than the general population (about half of women with PCOS are clinically obese). Women with PCOS are at a four times greater risk of developing Type 2 diabetes, and somewhat higher risks of non-alcoholic fatty liver disease, sleep apnea, dyslipidemia (high levels of cholesterol and/or high triglycerides), heart disease and mood disorders. (5)
There have been at least 14 high-quality human trials testing the benefits of inositol for PCOS. A 2016 review of 12 of these randomized, controlled trials found that this supplement “is capable of restoring spontaneous ovulation and improving fertility in women with PCOS,” both when using myo-inositol on its own (the most common method) or in combination with D-chiro-inositol.
Study authors pointed out that no relevant side effects occurred, even when the two forms were combined. It was also noted that ratios of 40:1 of myo-inositol to D-chiro-inositol helped to relieve “metabolic aberrations of PCOS,” which typically include issues with blood pressure, triglycerides and cholesterol, as well as restoring ovulation. (6)
On its own, D-chiro-inositol increases insulin activity in polycystic ovarian syndrome patients, which also may be one way this compound improves ovulation. This form is also associated with decreases in cholesterol, triglycerides and blood pressure and may be the form of this supplement most capable of reducing hyperandrogenism. (7, 8)
Typically, the dosage of myo-inositol for PCOS ranges from 1,500 milligrams per day to 4,000 milligrams per day. Some evidence suggests that the larger dose is more effective. (9) If taking alongside D-chiro-inositol, most studies suggest a 40:1 ratio, meaning 100 milligrams per day of D-chiro-inositol to 4,000 milligrams of myo-inositol.
2. May Combat Mental Illness
Because of its interaction with the central nervous system and neurotransmitter pathways, inositol has demonstrated possible effectiveness against certain types of mental illness. Since the true effect of most medications prescribed for mental illness is only about 10 percent–20 percent (and they come with a ton of undesirable side effects), natural alternatives to psychiatric drugs are an important part of future research in the mental health field.
It has been found to be effective in small human trials for:
- Depression (10, 11, 12)
- Panic disorder (13, 14)
- Obsessive-compulsive disorder (OCD) (11)
- Premenstrual dysphoric disorder (PMDD) (15)
- Anxiety (16)
When treating patients with depression symptoms, researchers found in one study that 6,000 milligrams per day “led to major improvement” in over 90 percent of participants. (10) In a follow-up to that first trial, scientists reported that subjects treated with inositol had an improvement in depression scores about three times more than those on placebo (11.8 points versus four). An “official improvement” is considered a decrease in 15 points, which was achieved by twice as many patients on the supplement than those on placebo. (12)
During this follow-up trial, patients with manic depression (also known as bipolar disorder) treated with it had no manic episodes, which was significant, although larger-scale trials have confirmed that it seems to have little significant effect on manic depression symptoms.
Another depression trial stated that the improvements for patients on inositol was similar to those on fluvoxamine and fluoxetine (two popular SSRIs for depression). (11)
For panic disorder, inositol outperformed fluvoxamine (also commonly prescribed for this condition) in one study by almost double in reducing the number of panic attacks per week — without side effects. (13)
Results are somewhat mixed in regards to depression and obsessive-compulsive disorder treated by inositol — both have been seen to have no statistically significant effects in some analyses, while others have the opposite result. (17, 18)
While it may not be useful for reducing symptoms of manic depression (bipolar disorder), for patients taking lithium, inositol may help reduce psoriasis symptoms, a common side effect of that medication. However, it does not affect psoriasis caused by factors other than lithium use. (19)
3. May Be Beneficial in Cancer Treatment
Certain forms have been researched for their connection with cancer treatment and relief. While there is still not research to suggest that it is definitely an effective natural cancer treatment, it’s possible that some inositol-containing foods may help fight cancer — or, at least, help patients during treatment.
Combining myo-inositol and another version, IP6 (also known as inositol hexaphosphate, phytic acid or phytate), may have anticancer effects and potentially improve the cancer-killing action of chemotherapy, according to a 2003 pilot study published in The Journal of Nutrition. The authors state:
IP6 plus inositol enhances the anticancer effect of conventional chemotherapy, controls cancer metastases, and improves the quality of life, as shown in a pilot clinical trial. The data strongly argue for the use of IP6 plus inositol in our strategies for cancer prevention and treatment.
They also point out the need for “phase I and phase II clinical trials in humans,” which have not be completed as of this writing. (20)
Another review, published in 2009, agrees that, “There is clearly enough evidence to justify the initiation of full-scale clinical trials in humans.” (21)
Regarding specific types of cancer, myo-inositol (at large doses like 18 grams per day) may protect against smoking-induced lung cancer. (22) In rats, IP6 suppresses colon cancer, even when cancer was induced a full five months before the treatment ever began. (23, 24)
The inositol and inositol-signaling systems in the body seem to play a large part in many types of cancer progression in both animal and human models. While only one of these (colon cancer) has been specifically proven to be slowed, stopped or reversed with supplementation, the function of it within the body is closely intertwined with the development of breast, colon and prostate cancer. (25, 26, 27)
One point to note here, though, is that phytic acid (IP6) is considered an antinutrient when consumed regularly, as it interferes with nutrient absorption.
What’s an antinutrient? A nutrient causes growth and life, but antinutrients cause death. In regards to cancer, it’s possible phytic acid/IP6 along with myo-inositol (which is a sugar alcohol) may function in a more symbiotic way like chemotherapy does with glucose. Some scientists have suggested that manipulating glucose intake and even delivering it alongside chemotherapy may help to target the “antinutrient” chemicals of chemotherapy because of the way cancer feeds on sugar. (28) This doesn’t mean you should eat loads of foods containing phytic acid if you have cancer, though. Nutrient absorption is very important for your body to fight any disease; IP6 administration in cancer should only occur under the supervision of a doctor.
The good news is that high-inositol foods are often known to be cancer-fighting foods for other reasons. However, take caution in eating foods high in phytic acid (like beans and sprouts) and soak them to decrease the phytic acid content before you eat them to avoid digestive issues.
4. Could Improve Insulin Sensitivity in Diabetes
Inositol definitely seems to decrease insulin resistance in PCOS patients, but does it do the same thing for diabetics?
When describing the relationship between insulin resistance and inositol, writers at a popular supplement information website explain: (29)
In pretty much all instances where insulin resistance is present, there is an increased urinary excretion of inositol metabolites… Due to this information, it is thought that persons who are insulin resistant are in a state of relative inositol deficiency due to an increased excretion rate.
Limited clinical studies have been done to see how inositol could reverse diabetes. However, in rats, Rhesus monkeys and humans, there is preliminary evidence that D-chiro-inositol supplementation may help restore insulin sensitivity in diabetes. (31, 32)
5. May Reduce Chances of Gestational Diabetes
While there isn’t definitive evidence yet about inositol and Type 2 diabetes, clinical reviews have found that: (33)
On the basis of current evidence, myo-inositol supplementation reduces the development of gestational diabetes mellitus (GDM), although this conclusion requires further evaluation in large-scale, multicenter, blinded randomized controlled trials.
6. Combats Metabolic Syndrome
For certain women (even those who do not have PCOS), it seems possible that myo-inositol could be beneficial in treating metabolic syndrome. In particular, postmenopausal women who have or are at risk for this condition may greatly profit from supplementing with it, according to a 2011 study involving 80 women. (34) However, it is not clear whether or not it may help you lose weight, although it does positively affect many factors related to obesity and weight.
7. Possible Therapy in Eating Disorders
Although research is currently limited, a pilot study in 2001 found positive results when supplementing with inositol in subjects suffering from bulimia nervosa, a common eating disorder, and binge eating. At a very large dose (18 grams per day), it outperformed the placebo, improving scores on all three basic eating disorder rating scales. The study authors suggested this result may have occurred because of its mood-altering effect, as these conditions have a lot in common as far as emotional symptoms are concerned. (35)
8. Improves Symptoms of Respiratory Distress Syndrome in Infants
Premature babies are often born with a condition known as neonatal respiratory distress syndrome (RDS). Infants with this condition have underdeveloped lungs and struggle to breathe. There are a few known causes, but it’s most common in babies born before the 37–39 week window and is also more of a risk when mothers are diabetic; delivery is via Cesarean section or induced labor; the child has siblings who were born with RDS; there is blood flow restriction to the baby during delivery; the mother has multiples in pregnancy (twins, etc.) or the labor and delivery occur very rapidly. (36)
In a trial comparing 221 infants, those given inositol at a dosage of 80 milligrams per kilogram of weight each day needed less external oxygen and airway pressure than those on placebo. The survival rate of those taking it was 71 percent versus 55 percent on placebo.
The conclusion? Administering inositol to premature babies with RDS can help to increase survival rates and reduce the development of both bronchopulmonary dysplasia (a chronic lung condition that sometimes occurs as a result of RDS) and another common disorder, retinopathy of prematurity (ROP), which can lead to blindness in some cases. (37)
It’s important to note that this study referred specifically to inositol given intravenously by a physician, not in food or supplement form.
9. Possibly Lowers Some PMS Symptoms
Over six menstrual cycles, a dose of 12 grams of inositol powder or 3.6 grams of topically applied gel helped patients in one study to reduce the dysphoria and depression associated with PMS. (38) As this is reflected in the meta-analysis confirming that it seems to be effective in reducing depressive symptoms of PMDD (a severe form of PMS), these results suggest that it may be a good option for those with consistent emotional complications of PMS. (15)
However, inositol is not known to reduce other PMS symptoms like cramps or digestive trouble.
History & Interesting Facts
Inositol in the human body was discovered more than 150 years ago. The first isomer (rearranged chemical structure) of it, myo-inositol, was isolated in 1850, and fully “purified” in 1887.
In the 1940s, a researcher by the name of Posternak determined the nine distinct isomers of it, which also includes D-chiro-inositol, the other commonly used form. Posternak was also the first to discover that phytic acid was a derivative of inositol (one of 63 total variations between all nine isomers). (39, 29)
Interestingly, inositol extracted from phytic acid in corn has been used as part of making rocket fuels and modern explosives. Technically, inositol itself isn’t used as explosive fuel, but inositol nitrate (a version of phytic acid) can gelatinize nitrocellulose, a part of these explosives. (40, 41)
Foods that Contain Inositol
Depending on the type of inositol you want to consume, there are several foods to consider. Myo-inositol is found most abundantly in fresh fruits and veggies, but frozen/canned varieties have lost at least some inositol content.
These foods to consider include: (42)
- Beans (preferably sprouted)
- Whole grains (preferably sprouted)
- Oats and bran
- Bell peppers
- Other green leafy vegetables (kale, spinach, etc.)
- Citrus fruits like lime and lemon
- Bananas and other potassium-rich foods
- Grass-fed beef and other organic meats
- Organic eggs
- Coconut products like coconut oil, coconut sugar and coconut aminos (a coconut-based replacement for soy sauce)
Keep in mind that animal products (meat and eggs) containing inositol should be consumed in organic varieties whenever possible, because the pesticides these animals eat and antibiotics or other drugs they may be given can do more harm than good.
How to Take Inositol Supplements
Inositol supplements are widely available in two forms: powder and capsules. Capsules are more useful for smaller doses, such as those to treat PCOS. Powders tend to be easier when you need a very large dose.
The amount to use greatly depends on what you’re trying to accomplish. The studies examining the effect of it on PCOS use doses between 200-4,000 milligrams per day before breakfast. The 4,000 milligram-per-day dose seems to be most effective, especially when taken with D-chiro-inositol in the 40:1 ratio (with a 4,000 milligram dose of myo-inositol, 100 grams per day of D-chiro-inositol would be suggested). Some sources also believe taking these with folate and chromium may increase their effectiveness, although this has not been scientifically proven.
However, for psychiatric treatments, as much as 12–18 grams each day are suggested and seem to be most effective. At this dosage, more side effects may occur (although these are pretty mild). (29)
Possible Side Effects/Caution
According to available research, inositol is a fairly safe supplement, particularly in smaller doses used for PCOS and insulin sensitivity. Typically, side effects are associated with only very large doses and include mild gastrointestinal distress, nausea, tiredness, headache and dizziness. (43, 29)
No evidence exists about the safety of taking it during pregnancy and breastfeeding, so use caution and consult with your health care provider if you are pregnant or nursing.
If you are on a Specific Carbohydrate Diet, it is recommended to avoid all sugar alcohols, including inositol. (2)
As with any new supplement regimen, it’s wise to first discuss any desired changes with your doctor before starting a supplement, especially if you are on prescription medications. There is a chance inositol may increase the effects of insulin-lowering medications, like metformin, or drugs used for depression, which is why your doctor should always be aware of co-occurring medications and supplements.
Inositol Key Points
The eight main inositol benefits are:
- Effectively treats PCOS and improves fertility
- May combat mental illness
- May be beneficial in cancer treatment
- Could improve insulin sensitivity in diabetes
- May reduce chances of gestational diabetes
- Combats metabolic syndrome
- Possible therapy in eating disorders
- Improves symptoms of respiratory distress syndrome in infants
- Possibly lowers some PMS symptoms
You can also take it in supplement form. Doses up to 4,000 milligrams per day of myo-inositol (plus 100 grams per day of D-chiro-inositol) are recommended for PCOS/fertility treatment, while very large amounts up to 18 grams are used in studies of the supplement for mental illness.
The side effects are typically minimal and usually associated with very large doses, like those for psychiatric issues.