Lamberts® Phenylalanine is the natural L-Phenylalanine and is presented in its free-form to help ensure optimal absorption. This product is made in the UK to pharmaceutical GMP standards. Please Note: People with a condition known as phenylketonuria (PKU), in which phenylalanine cannot be broken down, should not take phenylalanine supplements. Nor should phenylalanine supplements be taken in conjunction with prescription anti-depressants, particularly monoamine oxidase (MAO) inhibitors. Daily intake: 1 capsule