Intuitively, it seems likely to me that his death is related to one or more of his self-experiments with supplements. This is based on the observation that it's pretty unusual for 60 year old men to collapse and die, particularly if they have no serious self-reported health problems. Calculating an actual probability seems like it would be pretty hard.

Edit: I suppose there is also an outside chance that this is a hoax. Has the death been reported in any newspapers?