Evidence: Very High Possible Benefits: Very High Safety: High
TABLE OF CONTENTS
What is inositol?
Inositol, also known as vitamin B8, is not a vitamin but a type of sugar that helps your body process insulin. Inositol is commonly used as a dietary supplement for its wide variety of benefits. It is most helpful for people with PCOS or those who experience anxiety and panic attacks. This article is about the main benefits of Inositol, its potential side effects, the best time to take it, and more.
Possible benefits
All of the potential benefits mentioned below are dose-dependent. As with most other supplements, there is a sweet-spot dose that allows you to get most of the benefits without causing meaningful side effects or tolerance buildup in the body. We will discuss the best dosing protocol later in this article.
Major benefits
Reduced symptoms of PCOS – Doses of 200-4000 mg/d can be very effective for improving fertility in women with polycystic ovary syndrome (PCOS). The higher end of this range (2-4 grams) can also improve testosterone, insulin, blood glucose, cholesterol, triglycerides, adiponectin, and blood pressure levels in these women. The supplement was also shown in one study to abolish acne in over 50% of women with PCOS within 3-6 months.
Reduced anxiety – Inositol can greatly reduce anxiety and panic attacks, especially at high doses (6+ grams). It can also help with depression but the impact of it on anxiety is more notable.
Minor benefits
Improved thyroid health – Inositol helps regulate thyroid-stimulating hormone (TSH) levels and supports healthy thyroid function.
Reduced symptoms of OCD – Inositol can mildly reduce some of the unpleasant symptoms of obsessive-compulsive disorder (OCD).
Reduced symptoms of PMS – Inositol can reduce dysphoric and depressive symptoms during PMS.
Reduced binge eating – Very high doses (18 grams daily) were able to reduce binge eating in women who tend to overeat in one study.
Antioxidant properties – The supplement has antioxidant properties and can reduce damage caused by free radicals and oxidative stress. This benefit is most notable in women with PCOS.
Reduced risk of lung cancer – One human study found a reduction in lung cancer risk in smokers taking 18 grams of inositol daily.
Possible side effects
The side effects below are dose-dependent. The risk for them increases (often linearly but sometimes exponentially) as you increase the dose. Some of the side effects only apply to very high doses.
Allergic reaction – An allergy to this supplement is rare but possible.
Nausea – This side effect is most common when people take the supplement on an empty stomach.
Diarrhea – You can usually prevent diarrhea or stomach discomfort by taking this supplement with a meal.
Toxicity – While acute toxicity is extremely rare, taking high amounts of this supplement could lead to chronic toxicity and cause health problems over time. Regularly taking high doses can also cause the body to develop a tolerance to the supplement. To prevent chronic toxicity or the buildup of tolerance, staying below 12 grams in a day is best unless you have a great reason to take more.
Contamination – Contaminated supplements are uncommon in the USA and other well-regulated countries. However, if you wish to buy products from China, India, or other countries without strict regulations, beware that the supplements may be contaminated. Either way, you need to choose the brand you order from wisely. Always read through some reviews for the specific product before you buy it. The FDA (Food and Drug Administration) has the power to regulate dietary supplements but can only do so after they have been on the market for a while. That’s because supplement companies are not obligated to announce to the FDA when releasing a new product. The FDA has to discover the product and test it for potential impurities, which can take a lot of time. During that time, the supplement can be sold on the market even if it’s impure. Also, supplement companies can change their manufacturers without announcing it to the FDA.
Who should not take inositol?
You should probably avoid taking inositol if you:
are allergic to this supplement
experience a severe adverse reaction after taking the supplement
are pregnant or breastfeeding (while it can be safe to take this supplement during pregnancy or breastfeeding, it can put some unnecessary risk to the child)
Who will benefit the most?
You should consider taking the supplement if you:
have polycystic ovary syndrome (PCOS)
experience reduce anxiety, depression, or panic attacks
have OCD (obsessive-compulsive disorder)
have a high budget for supplements and are willing to experiment with a variety of them (assuming you don’t fall into any of the categories that should avoid this supplement, inositol appears relatively safe and is unlikely to do more harm than good for most people)
How much inositol should you take?
The sweet spot dose typically ranges between 2000-6000 mg daily for most people. This amount should provide most of the benefits without meaningful side effects.
The higher end of this range usually provides slightly more benefits in the short term. If you plan to take this supplement for a longer time (multiple months or years), the lower end is probably a better way to go since it is safer, and you would develop tolerance faster if you were to take higher doses.
The upper safety limit for this supplement is not well-established. To stay on the safe side, don’t take more than the recommended dose unless you have a great reason to do so. Higher amounts may cause problems if you take the supplement for a prolonged period.
Like most other supplements, it is best to cycle inositol and take about two days off weekly to reset your tolerance. That will allow you to keep getting the benefits in the long term.
Best time to take inositol
Inositol is water-soluble, so you don’t have to take it with food to absorb it well.
Whether you take the supplement in the morning or the evening does not make much difference. Both options are fine so feel free to experiment.
Interactions
Lithium Lithium works by depleting inositol levels in the brain. Many of lithium’s side effects are related to inositol depletion. Low doses of inositol can help reduce some of these side effects by preventing the depletion of this compound in the rest of the body.
Melatonin This combination is either additive or synergistic for improving fertility in women, especially those with PCOS.
Selenium Combining these two compounds may support healthy thyroid function.
Phytic acid Phytic acid is an anti-nutrient found in nuts, seeds, grains, and legumes. While it is often seen as a negative, it can have benefits related to reducing the risk of many types of cancer and improving general health and well-being, especially when combined with inositol.
Where to buy inositol?
In most countries, Amazon is the best option for ordering inositol supplements. They offer some very affordable products backed by many positive reviews. Also, you can choose from a wide range of brands without having to search through other markets on the Internet.
Some brands display the dosage per serving instead of per pill or capsule. Therefore, you may accidentally buy something less potent than you intended. Do not fall for this marketing trick.
FAQ
Like most other supplements, it is best to cycle inositol and take a break from it for about two days per week to reset your tolerance back to baseline. That will keep your body sensitive to the supplement and allow you to keep getting the benefits in the long term.
All of these options are fine. The two most important things to consider are the price and dosing. Powders are almost always the cheapest form. However, you may need a highly accurate scale to dose them correctly (preferably 0.001g). You can get one for as little as $20 from Amazon. Dosing the powders also takes time which can add up over months or years. The disadvantage of capsules is that they are often made of bovine gelatine, which rarely comes from ethical sources.
Yes. Whether you take the supplement in the morning or the evening does not make much difference. Both options are fine so feel free to experiment.
This supplement should not become harmful once it exceeds the expiration date. However, it can lose potency over time. Keep this supplement in a cold, dark, and dry place so it remains as potent for many months or even years.
While acute toxicity is rare, taking very high amounts of this supplement could lead to various problems over time. High doses can also make you develop tolerance much faster than lower doses.
While you could safely take higher doses, there is usually no point in taking more than 10 grams daily. This amount should give you most of the benefits without meaningful side effects.
The half-life of inositol in the body is about 8 hours. Most of this compound gets metabolized within a day after you consume it. However, most of the effects of this supplement are cumulative, so they mainly happen in the long term rather than acutely. Therefore, the half-life of this supplement isn’t very relevant in practice.
In the long term, you must take the supplement for about 2-4 weeks to begin noticing most of the benefits.
Yes, inositol is vegan-friendly. If you buy the supplement in a capsulated form, beware that the capsules often contain animal-based gelatin. Instead, find a brand that puts its products into cellulose capsules.
No, it does not. The supplement should not interfere with fasting in any significant way. However, you still want to take the supplement with food as it will absorb better.
References
Most of the information in this guide is based on scientific research that can be found and verified in the PubMed medical library. We highly encourage you to use the library to verify anything you read in this article. We excluded from consideration studies that are either confounded or have a high conflict of interest.
