Lac-Phe

Lactoylphenylalanine, or Lac-Phe, is an N-lactoyl-amino acid metabolite produced by mammals and microorganisms. In humans, levels are increased by intense exercise and in the inborn error of metabolism phenylketonuria. In mice, high levels of Lac-Phe in the blood cause a decrease of food intake and in humans, its production has been shown to correlate with adipose tissue loss during an endurance exercise intervention. In mammals it is created from (S)-lactate and L-phenylalanine by the cytosol nonspecific dipeptidase (CNDP2) protein. It is classified as N-acyl-alpha-amino acid and pseudodipeptide.

It has also been reported that as an additive, N-L-lactoyl phenylalanine improves the taste of food, conferring an umami flavor. It is found naturally in significant amounts in some traditional Chinese fermented foods such as preserved pickles and soy sauce, and in Parmigiano-Reggiano cheese. Oral intake of Lac-Phe does not have anti-obesity effects in mice, though intraperitoneal injection does reduce food intake and weight gain. Activity dependent cell labeling indicates Lac-Phe activated neural populations in the hypothalamus and brainstem.