Although recommended for a wide variety of conditions, very few of these applications have withstood rigorous scientific trials of their efficacy. Some evidence exists, however, suggesting that lecithin may help reduce low-density lipoprotein forms of cholesterol when taken alongside niacin or nicotinic acid. Lecithin may also help with some neurological conditions, treating the symptoms of tardive dyskinesia, potentially reducing the severity of manic episodes in bipolar patients, and slowing the progression of age-related cognitive decline and some forms of Alzheimer's disease. There is little concern of a lecithin overdose as the compound is found in a wide variety of foods, is a popular emulsifying food additive, and is classed by the United States Food and Drug Administration as a substance that is Generally Recognized as Safe. Lecithin dose recommendations vary widely among medical practitioners, with adjustments made according to the age, condition, general health and response of the patient.
Some of the best results of the therapeutic use of lecithin have been in the treatment of tardive dyskinesia. Double-blind, placebo-controlled studies of patients with tardive dyskinesia have found that patients receiving a 25 g to 50 g daily lecithin dose showed statistically significant improvement even in periods as short as seven days. Side effects were not found in these populations, and the effects were still present when the patients continued to be given the medications responsible for their condition.
Similarly positive results have been found in the treatment of manic episodes of bipolar patients. While more research needs to be performed as of 2011, preliminary results from a study using just 5 g of lecithin per day showed significant improvement in bipolar patients. Alterations to patients' lecithin dose and dosage timetable may improve the results in future studies.
The results of the use of a 100 g daily lecithin dose in the treatment of Alzheimer's have been equivocal. While in almost all studies performed as of 2011 the number of patients experiencing an improvement in their condition has not been statistically significant, nearly all of the studies found that a small subgroup of those studied responded well to the supplement. It is possible that research into the sub-types of Alzheimer's disease will provide a better understanding of which patients are most likely to benefit from the use of lecithin. Due to the excellent safety profile and low cost of the supplement, it is reasonable to recommend that patients be evaluated with a high lecithin dose regimen for possible benefit.
Similarly, a small number of studies in which patients were receiving treatment with nicotinic acid or niacin to treat hypercholesterolemia indicated that patients receiving lecithin improved their blood lipid profile. Several other studies where patients were receiving other medication have not replicated these findings. While the findings are ambiguous at best, the known capacity of high doses of niacinamide to deplete serum lecithin seems to suggest that patients using niacin may benefit from supplementation.
The lecithin dosages from these studies may not accurately represent those needed to replicate their effects using commercial lecithin products, though. Although within the scientific community the compound lecithin is understood to be solely phosphatidylcholine, due to the conventions of nutritional supplement manufacturers, supplements sold as lecithin may contain as little as 30% phosphatidylcholine. Instead, these supplements may contain a number of similar compounds with vastly different levels of potency or pharmacological activities. As a result of this unregulated variation from product to product, it may be necessary to give preference to the guidelines of the manufacturer over other recommendations.