The nutrient inositol plays various roles in the body. A variety of foods contain a precursor to this substance, and your body can typically get all it needs from your diet. Supplementing with inositol might offer benefits for a number of conditions ranging from polycystic ovary syndrome to depression. This supplement appears generally safe, and some conditions might require much more than you get from your diet to achieve a therapeutic effect. Inositol does not appear to have an upper dose limit that carries a risk of negative side effects if exceeded. This does not mean, however, that you should just take unlimited amounts. Ultimately, you should consult with a doctor well-versed in nutritional supplements for guidance on how much inositol you should take for your particular health concern.
Safety of Supplemental Inositol
The Beth Israel Deaconess Medical Center states you get about 1,000 mg of inositol in the diet daily. It reports that some studies have used up to 18 times this dose without any reports of significant adverse effects. This suggests that using up to 18 g daily -- which is considered high for this supplement -- appears safe. Whether or not taking more than this is safe or not has not been established nor has it been established that higher doses would offer any additional therapeutic benefits. More is not always better. Based on the fact that research has not tested the safety of inositol dosages beyond 18 g per day, it is prudent to avoid using more than that, unless your doctor advises you otherwise.
Doses Used for Specific Conditions
Studies examining the effects of inositol on various conditions have used a wide range of doses. The University of Michigan Health System reports the following doses were used in studies: anxiety: 4 to 6 g three times a day; depression: 12 g; bipolar disorder; 12 g; type 2 diabetes: 500 mg twice a day. The Beth Israel Deaconess Medical Center reports the following doses were used in studies: polycystic ovary syndrome: 100 mg twice a day; metabolic syndrome: 2 g twice a day.
Dosage Considerations for Particular Individuals
The University of Michigan Health System cautions you to consult with your doctor before using inositol if you have kidney disease as tests have shown people with renal disease tend to have elevated levels of this nutrient in their body. Whether or not that would pose any risk has not been established, but your body is particularly sensitive to what you put in when you have impaired kidney function. The same precaution goes if you have liver disease. If your doctor does approve the use of this supplement, she might suggest different doses than those normally used.
The Memorial Sloan Kettering Cancer Center reports inositol might increase the effectiveness of blood-thinning medications like warfarin. Do not combine these treatments without talking to your doctor first. It also notes evidence that suggests supplementing with inositol might lower levels of nutrients such as iron, calcium, zinc, copper and magnesium by binding with them in the stomach, but that not all data supports this contention.