A 91-day subchronic toxicity study was conducted in male and female Sprague-Dawley rats following FDA Redbook protocols.  Rats were assigned to HMBFA treatments at either 0, 0.8, 1.6, or 4% of the diet by weight. The no-observed-adverse-event-level (NOAEL) was determined to be 4% of the diet, which corresponds to an intake of 2.48 and 2.83 g/kg BW d-1 in the males and females, respectively.  (Like an average human consuming about 25 g per day.)