Lactic acid is produced in varying amounts by most living tissues as a normal metabolic intermediate. The lactate turnover rate in man has been estimated to be of the order of 2g per kg per day.
An additional load of up to 1 mg per kg per day of lactic acid as the free acid or as calcium lactate contained in commercially prepared food commodities would not appreciably modify the normal metabolic processes. None of the limited toxicity data available raises any suspicion of adverse effects in adults at doses orders of magnitude above the estimated levels of human consumption. There is no indication that the per capita intake of lactate from processed foods will be substantially increased in the foreseeable future.
There is no evidence of potential toxicity of the L-isomer for individuals of any age. However, premature infants fed formulas acidified with DL-lactic acid (or, in one instance, D(-) lactic acid), have reported to develop metabolic acidosis and growth retardation. Results of studies of full-term infants are conflicting and difficult to interpret. Resolution of this conflict is needed even though, as far as the Select Committee is aware, lactic acid acidification of infant formulas is not currently being practiced in the United States except in products designed for special dietary or therapeutic purposes which are not being evaluated in this report.
In the light of these considerations, the Select Committee concludes that:
There is no evidence in the available information on L(+) calcium lactate that demonstrates or suggests reasonable ground to suspect a hazard to the public when they are used at levels that are now current or that might reasonably be expected in the future.
There is no evidence in the available information on either of the isomers of lactic acid, their calcium salts, and their racemates that demonstrates or suggests reasonable ground to suspect a hazard to individuals beyond infancy when they are used at levels that are now current or thar might reasonably be expected in the future.
There evidence on D(-)-lactic acid, DL-lactic acid and their calcium salts is insufficient to determine that the adverse effects reported would not be deleterious to infants should they be used in infant formulas. Lactic acid acidification of generally available infant formulas is not now being practiced in the United States.