Inositol is recognized as part of the vitamin B complex and is closely associated with choline and biotin. Like choline, inositol is found in high concentrations in lecithin. Animal studies have shown that the vita¬mins B6, folic acid, pantothenic acid, and PABA also have a close working association with inositol.
Both animal and plant tissues contain inositol. In animal tissues it occurs as a component of phospho-lipids, substances containing phosphorus, fatty acids, and nitrogenous bases. In plant cells it is found as phytic acid, an organic acid that binds calcium and iron in an insoluble complex and interferes with their absorption. Inositol is found in unprocessed whole grains, citrus fruits, brewer's yeast, crude unrefined molasses, and liver.
Inositol is effective in promoting the body's produc¬tion of lecithin. Fats are moved from the liver to the cells with the aid of lecithin; therefore inositol aids in the metabolism of fats and helps reduce blood chor lesterol. In combination with choline, it prevents the fatty hardening of arteries and protects the liver, kid¬neys, and heart.
Inositol is also found to be helpful in brain cell nutrition. Large quantities of inositol are found in the spinal cord nerves and in the brain and cerebral spinal fluid. It is needed for the growth and survival of cells in bone marrow, eye membranes, and the intestines. It is vital for hair growth and can prevent thin¬ning hair and baldness.
About 7 percent of ingested inositol is converted to glucose; inositol is only one-third as effective as glucose in alleviating ketosis, the incomplete metabolism of fatty acids.
There is some disagreement as to whether inositol is synthesized by the intestinal flora. One reliable source indicates it is,28 while another claims that synthesis occurs within the individual cell rather than by intes¬tinal organisms. The amount the body excretes daily in the urine is small, averaging 37 milligrams. The diabetic excretes more inositol than does the nondi-abetic. Large amounts of coffee may deplete the body's storage of inositol.
The Recommended Dietary Allowance has not yet been established, but most authorities recommend con¬suming the same amount of inositol as choline. The daily consumption of inositol in food is about 1 gram. The human body contains more inositol than any other vitamin except niacin. One tablespoon of yeast provides approximately 40 milligrams each of choline and inositol. Therapeutic doses range from 500 to 1000 milligrams daily. Fifty grams have been given by mouth and 1 gram intravenously with no side effects. There is no known toxicity of inositol.
Deficiency Effects and Symptoms
Tests on yeast cells have shown that when they are deprived of inositol, metabolic processes are prevented from functioning and consequently most of the cells die. In other studies, inositol deficiency in yeast cells led to abnormal cell walls and an inability of daughter cells to separate from the parent cells. Also found was the inhibition of fermentation and oxidation ac¬tions as well as a lower level of nucleotide coenzymes. Caffeine may create an inositol shortage in the body.