myo-Inositol (free of phosphate) was once considered as a member of the vitamin B complex, however, because it is produced by the human body from glucose, it is not an essential nutrient. Some substances such as niacin can also be synthesized in the body, but are not made in amounts considered adequate for good health, and thus are still classified as essential nutrients. However, there is no convincing evidence that this is the case for myo-inositol.
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Phytic acid, which is inositol hexakisphosphate (IP6), also known as phytate when in salt form, is the principal storage form of phosphorus in many plant tissues, especially bran and seeds. Neither the inositol nor the phosphate in phytic acid in plants is available to humans, or to animals who are not ruminants, since it cannot be broken down, except by bacteria. Moreover, phytic acid also chelates important minerals such as calcium, magnesium, iron, and zinc, making them unabsorbable, and contributing to mineral deficiencies in people whose diets rely highly on bran and seeds for their mineral intake, such as occurs in developing countries.
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Inositol has been used as an adulterant (or cutting agent) in many illegal drugs, such as cocaine, methamphetamine, and sometimes heroin. It is presumed that this use is connected with one or more of the substance's properties of solubility, powdery texture, or reduced sweetness (50%) as compared with more common sugars.