Thanks! That's very helpful.
From that document:
European research has tended to use products concentrated to contain 90% phosphatidylcholine in lecithin, and the following dosages are based on that type of product. For psychological and neurological conditions, doses as high as 5 to 10 g taken three times daily have been used in studies. For liver disease, a typical dose is 350 to 500 mg taken three times daily; for high cholesterol, 500 to 900 mg taken three times daily has been tried.
So, it seems that even up to 30 g a day has been used in at least one study. Very cool!