Choline is easily absorbed from the intestines and is one of the only vitamins that crosses the blood-brain barrier into the spinal fluid to be involved directly in brain chemical metabolism. Choline is referred to as the "memory" vitamin, as it is an important part of the neurotransmitter acetylcholine.

Sources: Choline is present in all living cells and is widely distributed in plants and animals. Humans can synthesize choline from the amino acid glycine. The highest amount of choline is present in lecithin, usually obtained from soybeans. Other good sources include egg yolk, brewer’s yeast, wheat germ, fish, peanuts, some leafy greens, and liver and other organ meats. Choline is probably also manufactured by intestinal bacteria.

Functions: Choline as phosphatidylcholine, is a basic component of soy lecithin and thereby helps in the emulsification of fats and cholesterol in the body, by helping form smaller fat globules in the blood and aiding the transport of fats through the smaller vasculature and in and out of the cells. Choline is combined with fatty acids glycerol and phosphate to make lecithin (see more on lecithin in Chapter 4, Lipids), an important part of cell membranes.

Choline is also an integral part of the neurotransmitter acetylcholine. Its availability preserves the integrity of the electrical transmission across the gaps between nerves, and this helps the flow of electrical energy within the nervous system. It is also important to the health of the myelin sheaths covering the nerve fibers. Choline helps the liver and gallbladder function and is vital to brain chemistry, as it seems to aid thinking capacity and memory.

Uses: There are a great many uses for this important B vitamin. Choline may be helpful in the treatment of nerve conduction problems, memory deficiencies, muscle twitching, heart palpitations, and Alzheimer’s disease, where it seems to help brain function and slow the progression of the disease. Evidence has been mixed, however, as to effectiveness of phosphatidylcholine/lecithin treatment for Alzheimer’s disease; it has certainly not been shown to be a great panacea.

Choline has also been used for many kinds of liver and kidney problems, especially hepatitis and cirrhosis, by improving fat emulsification, transport, and utilization. It may actually help with general body detoxification by "decongesting" the liver of excess fats. Choline has been helpful in reducing some side effects of the phenothiazine drugs, which may cause abnormal facial muscle twitching and spasms, a syndrome called "tardive dyskinesia." It probably works by increasing acetylcholine function, thus promoting the transmission functions at nerve synapses. Recently, purified egg lecithin, which contains choline, has been used in the treatment of AIDS.

Other possible uses for choline are for headaches, dizziness, insomnia, constipation, glaucoma and other eye problems, abnormal ear noises such as tinnitis (ringing), hypoglycemia, and alcohol problems. Choline may be helpful for fatigue, and athletes have benefited from choline supplementation. With high cholesterol and high blood pressure, two important factors in cardiovascular disease, phosphatidylcholine (lecithin) may be helpful in reducing the progression of atherosclerosis. It seems to be effective as a fat and cholesterol emulsifier, and supplementation has been shown to reduce some gallstones. Choline has also been used with some benefit in stroke patients.

Deficiency and toxicity:There are no known toxic effects from choline, though high doses could aggravate epileptic conditions because of its nerve stimulation potential. Neither is there a common deficiency problem, though the therapeutic amounts utilized are usually much higher than those acquired through food or made in the body. There are not any specific symptoms attributed to choline deficiency. When choline is depleted, fat metabolism and utilization may be decreased, conceivably leading to fat accumulations. However, the main concern could involve loss of cell membrane integrity and the effects on the myelin covering of the nerves.

Requirements: No specific minimums for dietary choline are listed. The average needs seem to be about 500 mg. per day, which is about the least amount consumed in an average diet. It is often supplemented at 500 mg. along with the same amount of inositol because both are necessary for membrane integrity. Soy lecithin is the most common source for choline supplementation. One capsule of lecithin contains about 40–50 mg. of choline, while a tablespoon (5 grams) of lecithin has about 500 mg. of choline.

Therapeutic amounts of choline are usually in the 500–1,000 mg. area. More than this may produce some side effects and is likely not needed, although some experiments have utilized higher amounts. It is best taken with other B vitamins. If large amounts of lecithin are taken, more calcium is usually needed to balance the phosphorus contained in the lecithin. Additional choline may be needed when higher amounts of niacin, such as 1–3 grams daily, are taken to lower cholesterol levels Recently, high-quality, concentrated phosphatidylcholine capsules have become available for specific use of this nutrient in place of the more variable lecithin.