The question of how much protein is actually usable by the body, and when it crosses the line into excess, is one of the major topics of discussion in contemporary nutrition. Despite its crucial role in tissue regeneration, muscle building, and immune health, the increasing popularity of high-protein diets has led people to consume protein beyond necessary amounts. Establishing the limit up to which protein intake is helpful to the body involves consideration of the metabolic rate, physical activity, and possible physiological effects. This threshold will be better explained by examining the body’s physiology and how excess consumption affects it.
Protein Intake Upper Threshold
There is no specific value for the upper protein threshold or toxicity limit. Any amounts above 2.2 grams per kilogram of body weight can be regarded as excessive and unnecessary for most people.
Renal Function and Protein Intake
Intake of protein puts a strain on the kidneys since there is high nitrogenous waste production. Even though the kidney can adapt to changes in protein intake, it may be overworked when the intake is too much.
Dehydration Acceleration
Owing to the need for extra water for diluting and removing the excess urea produced by breaking down excess protein, dehydration may occur. Those who take excess protein will lose more water; hence, they will need more water to stay hydrated.
Digestive Issues and Constipation
If there is excess protein in the diet, then there is not enough carbohydrate in the diet, particularly dietary fiber. The lack of dietary fiber and the digestion of dense animal protein will make the process of digestion difficult, leading to digestive issues and constipation.
Hypercalciuria and Bone Mineral Density
An extremely high intake of proteins, specifically animal proteins, leads to a high acidic load in the body. Calcium is used by the body to neutralize the acid, which is then excreted through hypercalciuria. Whereby, in case the extremely high intake of proteins persists, there might be a negative effect on bone mineral density.
Increased Chance of Kidney Stone Formation
High intake of animal proteins leads to high excretion of uric acid and calcium, while at the same time, low excretion of citrate. Citrate is an anti-stone substance, and therefore, this combination of the two makes the urine favorable for the formation of calcium oxalate and uric acid kidney stones.
Nutrient Displacement
Whereby an excessive intake of proteins is made in relation to the daily calorific needs, then other nutrients will be displaced since protein intake cannot increase endlessly. Mostly, the nutrient displacement is associated with inadequate intake of micronutrients, antioxidants, and phytochemicals contained in carbohydrates, fruits, fats, and vegetables.
Effects on Gut Flora
An abundance of protein that cannot be digested will end up in the colon, where it will modify the gut flora from being made up of carbohydrate fermenters, which make short-chain fatty acids, into protein fermenters, which form toxins like ammonia, hydrogen sulfide, and p-cresol.
