Inositol, also part of the B vitamin complex, is closely associated with choline. Like choline, inositol (as phosphatidylinositol) is also found in lecithin, though in lesser amounts than choline, and acts as a lipotropic agent (milder than choline) in the body, helping to emulsify fats. The body can produce its own inositol from glucose, so it is not really essential. We have high stores of inositol; its concentration in the body is second highest of the B vitamins, surpassed only by niacin.
Sources: Inositol is present in both plants and animals. It is part of phospholipids in animals; in plants, it is contained in phytic acid, which can bind calcium and iron. It is not totally clear how inositol is produced by the body; it may be made by intestinal bacteria. It is stored in the body, but drinking lots of coffee can deplete these stores. Inositol is found in the whole, unprocessed grains, citrus fruits (except lemons), cantaloupe, brewer’s yeast, unrefined molasses, and liver. It is also available in wheat germ, lima beans, raisins, peanuts, cabbage, and some nuts. And, of course, lecithin is a good source.
Functions: Inositol, as phosphatidylinositol, has its primary function in cell membrane structure and integrity. Other functions of phosphatidylinositol are somewhat obscure. With choline, it may help in brain cell nutrition. Inositol is especially important for the cells of the bone marrow, eye tissue, and intestines. And it may also have something to do with hair growth.
Uses: Although inositol has been used to treat and prevent progression of athero-sclerosis throughout the body and to help reduce cholesterol, there is no good evidence from human studies that inositol lowers cholesterol and protects against cardiovascular disease. As a mild lipotropic agent, though, it is commonly used by overweight people to help with weight loss, and it may help in redistributing body fat. Exercise helps, too, of course.
Inositol helps promote healthy hair and skin. It has been used to treat eczema, and it may help the hair, especially if there is an inositol deficiency. For sleep, 500 mg. of inositol before bed has a mild antianxiety effect (placebo?) as well as possibly helping to utilize fat and cholesterol during sleep.
Inositol has also had some success therapeutically in improving the nerve function in diabetic patients with pain and numbness due to nerve degeneration. Generally, diabetic people should take extra inositol. People with multiple sclerosis may also receive some benefit with inositol supplementation, as there seems to be a higher percentage of inositol deficiency in nerve cell membranes in those patients.
Deficiency and toxicity: There is no known toxicity with inositol even in amounts of 50 grams, which are much higher than normal uses. Deficiencies are also uncommon, since inositol is so available in foods and the body also makes it. Caffeine, however, can produce an inositol deficiency. Some problems that have been associated with low levels of inositol in the body are eczema, constipation, eye problems, hair loss, and elevations of cholesterol. There may also be a greater propensity for fatty plaques to form in the heart and arteries and more likelihood for cardiovascular disease.
Requirements: There is no specific RDA for inositol, since it can be made in our bodies. We usually obtain it readily from food in an amount of about 1 gram daily. A therapeutic dosage is usually about 500 mg.; however, it should be taken with choline and other B vitamins and mainly as lecithin, which contains the natural balance of phospholipids. I do not recommend taking separate inositol capsules. Needs are increased with regular coffee consumption of more than two cups daily. Soy lecithin contains about 40 mg. of phosphatidylinositol per capsule.