Edited by Kate Findley and proofread by Angela Shoemaker, The Great Courses Daily
You may know that lack of protein leads to weakness and fatigue, but did you know that it can also lead to fluid retention and adverse reactions to medications? Professor Anding explains some of the lesser-known functions of protein as well as the dangers of consuming too much protein.
Protein Function and Digestion
Protein has many beneficial functions besides building muscle, including post-surgery recovery, infant growth, and immune system support. An additional function of protein is in the synthesis of enzymes. These are compounds that accelerate chemical reactions, but they’re not broken down themselves.
For example, lactase is an enzyme that helps to digest milk sugar, which is lactose. Transaminase—”trans” means transfer, “amine” means amino acid, “ase” means enzyme—helps in the synthesis of non-essential amino acids. Hormones are types of protein, and they are chemical messengers that are produced in one part of the body but actually used in another.
The first protein sequence that scientists discovered was insulin. If somebody has type 1 diabetes, they have to inject insulin as opposed to taking it in pill form.
Why is that the case? Like any protein, insulin is going to be broken down in the small intestine and rendered ineffective.
If you see a commercial for an insulin-type substitute that you can take by mouth, you should question it because insulin is a protein and will be digested. Glucagon, its opposing hormone, is also a protein.
Protein and pH Balance
Proteins can be integral in the creation of what’s called an “acid-based balance.”
Most substances in our body are neither all acidic nor all basic. We’re designed to live down the middle of that pH road.
However, increased amounts of protein in the diet can actually yield excess hydrogen ion or excess acid. Most research suggests that an increased amount of protein creates an increased amount of hydrogen ion that needs to be urinated out.
Otherwise, this increased urinary acid load can increase the likelihood of developing some forms of kidney stones. Thus, protein is essential for many bodily functions, including building and repairing tissue, but you should not consume it in excess.
Also, what ends up happening in terms of protein function is that you have proteins transporting drugs, vitamins, and minerals throughout your body. Probably the most important of these is albumin.
Any time you’ve had blood work done, you’ll see albumin as one of the things that they measure. It’s central in terms of its transport function.
If your physician prescribed a drug, and your albumin is low, that drug doesn’t have a carrier protein anymore, so it’s floating around in your blood supply as a free drug. You can end up having an adverse reaction to a prescription medication if the protein in your blood is low. Transferrin is linked with iron transport, and retinol-binding protein will help to carry vitamin A.
Protein’s Role in Fluid Balance
Additionally, protein is important in the balance of fluid. Your blood has a significant amount of fluid in it.
Protein in your blood hangs onto that fluid and prevents it from leaking into the non-vascular space between cells. With inadequate amounts of protein—most notably albumen—that water can leak from your blood into your tissues.
This causes you to gain water weight. Critical illness is almost always present with fluid retention.
If you go into an ICU unit, you’ll see loved ones who look a little puffy and edematous. They’re retaining extra fluid.
Albumin drops as part of the stress response, and thus fluid leaks into that non-vascular space. That fluid is not available to urinate out.
Overall, then, protein is essential in helping your body to maintain proper fluid and pH balance. It also plays a crucial role in digestion.
This article was edited by Kate Findley, Writer for The Great Courses Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.
Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.