Tag Archives: babies

Phenylalanine amino acid: Importance of PKU Screening in Newborn Babies

In the United States a heel stick test (using a needle prick on the baby’s heel for a small blood sample) is done at the ripe old age of 3 days old to test for Phenylketonuria (PKU) and other disorders. PKU is a metabolic disorder that shows up when the gene is inherited from both parents of the newborn, which is an enzyme deficiency that is needed for proper metabolism of the amino acid phenylalanine.

People with PKU must avoid foods that contain phenylalanine altogether from birth, however, in order to survive since side effects can include pigmentation loss in the skin/eyes/hair, a “mousy” odor, muscles pains and aches, seizures, and mental retardation.

Newborn screening and phenylalanine-restricted diets for PKU patients

Phenylalanine is an essential amino acid that is in foods, including proteins like meats, dairy products, beans, eggs, tofu, nuts, and many others, including aspartame (the sugar substitute in diet soda). An “essential” amino acid means that the body cannot produce this amino acid on its own so it must be gotten from food. Aminos phenylalanine and tyrosine are both associated with PKU and are tested for in all newborn babies at clinics and hospitals.

According to the American Academy of Family Physicians, it is Dr. Richard Koch from the University of Southern California School of Medicine in Los Angeles, California, who promotes that repeat testing should occur in any child that tests positive for PKU. The amino acid phenylalanine in foods should be avoided and a special diet should begin from birth so as to prevent mental retardation.

Koch says, “Occasionally, cases of PKU are missed by newborn screening. Thus, a repeat PKU test should be performed in an infant who exhibits slow development.”

Phenlyketonuria (PKU) is a recessive defect in the enzyme phenylalanine hydroxylase

Koch discusses the enzyme deficiency: “Phenylketonuria (PKU) is caused by an autosomal recessive defect in the enzyme phenylalanine hydroxylase, which is required for converting phenylalanine to tyrosine. (Five percent of natural protein is composed of phenylalanine.)”

PKU is caused by a mutation that is located on chromosome 12, although the specific type of mutation may vary, which results in severity that is variable among those with the PKU disorder. Phenylalanine containing foods should be avoided in all of these cases. Of course, normal people who do not have PKU need phenylalanine and should have a diet consisting of enough proteins to provide this essential amino acid.




Amino Acids: Taurine Essential For Brain Development

An interesting study of human brain cells highlights the crucial role the amino acid taurine has on the development of our brains. This amino acid is vital for optimal development of newborn and infant brains.

Taurine is an important inhibitory neurotransmitter. It’s essential for our cardiovascular function, and the development and function of our central nervous system. Every human needs taurine, adults and babies. Adults metabolize taurine from cysteine, using vitamin B6. High levels of B6 are found in shellfish, such as oysters and clams. It’s also present in meat and fish proteins.

Newborns get their taurine from breast milk, and taurine has been added to many infant formulas.

The role of taurine for optimal brain development has been studied in animal trials. Taurine increases the proliferation of neural stem cells in embryonic and adult rodent brains. But what about humans?

Researchers Hernández-Benítez R, Vangipuram SD, et al, from the Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico, developed a study of taurine’s effect on cell numbers in human neural precursor cells, which are stem cells.

Neural precursor cells can become neurons (nerve cells), and can also become the two other main cell types in the nervous system. They can also be cultured in the laboratory, so have great potential for a variety of transplant treatments.

Effect of Taurine on human brain development

The researchers in this human cell study used neural precursor cells from three fetal brains (14-15 weeks of gestation). The cells were cultured, and then tested with taurine. After four days of culture, taurine induced an impressive increase of neural precursor cells: an increase of up to 188%. Taurine also dramatically increased the percentage of neurons formed: up to 480% in the best case.

These results show the positive effect taurine has on the formation and development of the brain.