Protein toxicity is the effect of the buildup of protein metabolic waste compounds, like urea, uric acid, ammonia, and creatinine. Protein toxicity has many causes, including urea cycle disorders, genetic mutations, excessive protein intake, and insufficient kidney function, such as chronic kidney disease and acute kidney injury. Symptoms of protein toxicity include unexplained vomiting and loss of appetite. Untreated protein toxicity can lead to serious complications such as seizures, encephalopathy, further kidney damage, and even death. Definition Protein toxicity occurs when protein metabolic wastes build up in the body. During protein metabolism, nitrogenous wastes such as urea, uric acid, ammonia, and creatinine are produced. These compounds are not utilized by the human body and are usually excreted by the kidney. However, due to conditions such as renal insufficiency, the under-functioning kidney is unable to excrete these metabolic wastes, causing them to accumulate in the body and lead to toxicity. Although there are many causes of protein toxicity, this condition is most prevalent in people with chronic kidney disease who consumes a protein-rich diet, specifically, proteins from animal sources that are rapidly digested and metabolized, causing the release of a high concentration of protein metabolic wastes in the blood stream rapidly. Causes and pathophysiology Protein toxicity has a significant role in neurodegenerative diseases. Whether it is due to high protein intake, pathological disorders lead to the accumulation of protein waste products, the no efficient metabolism of the proteins, or oligomerization of the amino acids from proteolysis. The mechanism by which protein can lead to well known neurodegenerative diseases includes transcriptions dysfunction, propagation, pathological cytoplasmic inclusions, mitochondrial and stress granule dysfunction. Ammonia, one of the waste products of protein metabolism, is very harmful, especially to the brain, where it crosses the blood brain barrier leading to a whole range of neurological dysfunctions from cognitive impairment to death. The brain has a mechanism to counteract the presence of this waste metabolite. One of the mechanisms involved in the impairment of the brain is the compromise of astrocyte potassium buffering, where astrocytes play a key role. However, as more ammonia crosses, the system gets saturated, leading to astrocyte swelling and brain edema. Urea is another waste product that originates from protein metabolism in humans. However, urea is used by the body as a source of nitrogen essential for growth and life. The most relevant disorders on the urea cycle are genetic, leading to defective