Plant vs Animal Protein

This post was originally going to focus on the pros and cons of isolated protein sources: protein powders and processed forms of protein found in foods. However, I was unable to find significant studies that dealt with the bioavailability and biological usefulness of processed vs. proteins still found in a matrix of food (whole beans, meat….). Before discussing protein isolates and concentrates, it is important to understand that all whole foods have some amount of protein in them because cell walls, organelles, and cell membranes all have proteins. The main concern is getting proteins that the body can actually break down into amino acids efficiently and use. Since the protein in meat has a amino acid composition close to that of the human body people have looked to it and dairy products as ideal sources of “complete” protein. Recent studies (as mentioned in previous post) have discovered that as long as a variety of plant matter is consumed the amino acid composition will be sufficient to allow for proper protein synthesis in the body (growth and maintenance).

Aside from environmentally taxing production, dairy and meat products can also lead to low-level acidosis or diet induced acidosis. All foods are processed and broken down in the body into usable pieces (amino acids, sugars) and leave a basic or an acidic residue or end product. Foods such as legumes, fruits and vegetables for the most part produce an alkaline residue while meat, dairy, and eggs leave an acidic residue (Robey). Persistently high-protein diets can lead to low-level acidosis from an overload of acidic by-products. In this slightly acidic state the blood pH does not drop out of its tight biologically viable range, but does lower. This acidosis has been associated with a series of events that can lead to carcinogenesis (Robey). Another study showed that increases in dietary protein and decreases in vegetable/fruit consumption can lead to lower urine pH mirroring the body’s increased protein processing (Remer). The body needs to operate in a small window of pH that is slightly alkaline, so this production of excess acid can be considered a slight stress on the body’s well being and definitely something to think about when seeking optimal health and when recovering from sickness.

Sources:

Remer, Thomas, and Friedrich Manz. "Estimation of the renal net acid excretion by adults consuming diets containing variable amounts of protein." The American journal of clinical nutrition 59.6 (1994): 1356-1361.

Robey, Ian Forrest. "Examining the relationship between diet-induced acidosis and cancer." Nutr Metab 9 (2012): 72.