Powders are a convenient way to reach your recommended daily intake (RDA) of protein, but they also make it easier to overconsume this macronutrient, potentially causing problems with your liver and other parts of your body in the long term.
Overconsumption of supplements can have short-term impacts on liver enzymes, potentially affecting liver tests, although the research on these impacts is sparse. More studies focus on the risks of longer-term overconsumption of animal protein.
Understanding Liver Blood Tests
Your liver is the largest organ in your body and a crucial one. Apart from helping to digest food and make proteins, it also stores nutrients like sugar, vitamins, and minerals; produces bile to help digest fat and absorb the fat-soluble vitamins A, D, E, and K; produces blood-clotting substances; filters your blood; and gets rid of harmful bacteria and toxins to prevent infections.
Your liver carries out all these functions with the help of enzymes, which are compounds that speed up the chemical reactions in your body. There are several different types of enzymes, but the most common ones are aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), and gamma-glutamyl transpeptidase (GGT). When the liver is damaged or unable to function properly, these enzymes leak into the bloodstream. They can be detected by blood tests, which show elevated levels of liver enzymes.
Acute liver damage, for example, is marked by greatly increased levels of AST and ALT, with ALT levels generally higher than AST levels and normal or moderately increased ALT and GGT levels.
Well-Known Factors That Affect Liver Tests
Many factors aside from liver-related health issues can affect your liver blood tests. For example, AST is also found in your heart and skeletal muscles, so people with heart problems can have high levels of AST in the blood.
Over-the-counter pain medications like acetaminophen (found in Tylenol and other painkillers), certain prescription medications like statin drugs used to manage cholesterol, alcohol consumption, heart failure, hepatitis, and obesity are some of the other factors and health conditions that can cause abnormal enzyme levels in your liver blood tests.
Can Protein Supplements Affect Liver Blood Tests?
Aside from research on how overconsumption of protein is associated with longer-term health issues like nonalcoholic fatty liver disease, there is little research on the topic of supplements and liver blood tests.
A 2022 study in Knowledge – International Journal found that protein supplements may lead to higher ALT levels, as well as other liver enzymes, which could impact liver blood tests. But these levels returned to normal after a weeklong break from supplementation.
Can Protein Supplements Cause Liver Damage?
As long as you consume a healthy amount of protein, whether through food or supplements, it should not damage your liver. The recommended dietary allowance (RDA) for protein is 0.8 grams of protein per kilogram of body weight, or 0.36 grams per pound. That means a person who is 150 pounds, for example, should have at least 56 grams of protein a day.
Your liver plays an important part in digesting the amino acids that are the building blocks of proteins. The process of breaking down amino acids begins in the stomach and is completed in the liver. The amino acids in protein contain nitrogen, so breaking them down releases ammonia, which is a toxic compound made up of nitrogen and hydrogen. The liver converts the ammonia into urea, which is then excreted by the kidneys.
Excessive consumption of protein supplements like whey is linked to liver and kidney damage, but consuming the recommended dose of protein is unlikely to cause damage in the generally healthy population.
If you have a preexisting liver condition, you may be advised to consume less protein. That's because if your liver is badly damaged, it may not be able to process protein, causing a buildup of toxins in your system that can affect your brain.
The Takeaway
Protein supplements may cause a temporary rise in liver enzymes like ALT and AST, but this typically signals a higher metabolic workload, not permanent damage, in healthy individuals.
The primary danger lies in significantly overconsuming protein, which can strain the liver and may contribute to long-term issues like nonalcoholic fatty liver disease.
People with preexisting liver disease face a more serious risk, as their liver's inability to process excess protein can be impaired and cause further organ damage.
