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Too much protein: effects on your acid-base balance
Anyone who consciously eats a high-protein diet as part of a fitness program or a low-carb diet has clear goals in mind. However, what many people fail to consider is that too much protein can become a challenge for the body's acid-base balance. To better understand the reasons for this, we will take a deep dive into the metabolic level in this article.
• Introduction
• Why does too much protein challenge the acid-base balance?
• How your body reacts to excess acidity
• Sulfur-containing amino acids: Why too much protein puts your kidneys into overdrive
• Phosphates in food: The underestimated second acidifying agent
• Ammonia: The third factor in protein-induced acid load
• Glycine: The amino acid often overlooked in high-protein diets
• What too much protein can mean for your calcium balance
• Sources & Bibliography
Themen dieses Blogartikels:
Introduction
Whether for building muscle mass, for more power during exercise, or for increasing well-being – a high-protein diet makes sense in many life situations. However, it is important to understand how animal protein in particular affects the body and that proteins do not only offer advantages. This is because a protein-rich diet can affect the acid-base balance and slow you down in achieving your goals.
That is why it is worth taking a look behind the scenes. More precisely, at the metabolism. Below, you will find out how your body metabolizes certain components of proteins and what effects too much protein can have on your body's own acid buffer system.
Why does too much protein strain the acid-base balance?
Is your focus on protein-rich foods? Then protein sources like lean meat, fish, eggs, or cheese are likely staples of your diet plan. High-protein foods provide lasting satiety and contain proteins that serve as building blocks for your cells, are involved in processes like digestion and energy production, and transport nutrients.
Those who specifically choose animal protein often do so for good reason: animal protein is more easily converted into the body's own protein. One method for evaluating the protein quality of foods is the Digestible Indispensable Amino Acid Score (DIAAS). The DIAAS indicates how well a protein meets the requirement for indispensable amino acids. Measured by this, animal proteins perform better on average than most plant-based ones.¹
What many do not consider, however, is that metabolizing proteins, especially from animal food sources, produces acid.
This is how your body reacts to too much acid
To keep the blood's pH value stable, the body must neutralize this acid. It can use various buffer systems for this, primarily bicarbonate. The kidneys play a dual role here: they produce new bicarbonate to replenish the buffer while simultaneously excreting the degradation products that accumulate during acid neutralization.
Although the kidneys are capable of replenishing bicarbonate, consistently consuming too much protein can lead to an increase in your body's metabolic workload. In addition to acid, there are other substances that strain the buffer system. Sulfur-containing amino acids, phosphate, and ammonia, in particular, can force the kidneys to work overtime. Let's look at the details now.
Sulfur-containing amino acids: Why too much protein puts the kidneys into overdrive
Protein is made up of amino acids. There are 20 different amino acids found in proteins, and two of them contain sulfur: methionine and cysteine. If your body has absorbed more methionine and cysteine through protein-rich food than it currently needs for certain processes, it must break them down in the liver due to a lack of storage capacity.
This is precisely where it becomes critical. Because during this process, the sulfur contained in methionine and cysteine oxidizes into sulfate. In and of itself, this is not a bad thing. Sulfate is involved in the regulation of proteins, among other things.²
This is how acid comes into play
However, the body must excrete excess sulfate through the kidneys. This is because acid is produced at the same time as sulfate, which the body must neutralize. The reason: When sulfur is oxidized to sulfate, sulfuric acid is produced, which exists in the body as sulfate and free hydrogen ions. With a permanently high protein intake, this can subsequently mean a persistent acid load for you.³
Phosphates in food: The underestimated second acidifier
Phosphate is the form in which the chemical element phosphorus almost exclusively occurs in the body and in food. The two terms are therefore often used synonymously. In addition to protein, phosphorus is found in meat, fish, and cheese.
However, there is a second source of phosphorus: many processed products such as sausages and soft drinks like cola contain phosphate additives. You can usually recognize them quite easily by looking at the list of ingredients, where they appear in the form of E-numbers. The problem with these additives: the intestine can only absorb about 40 to 60 percent of natural phosphate. In contrast, it absorbs phosphate additives in food almost completely.⁴
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What does the varying phosphate uptake mean for everyday life?
The differences in phosphorus absorption make a significant difference in practice:
- Half a liter of cola contains around 100 milligrams of added phosphorus, which corresponds to an amount of about 300 milligrams of phosphate. It ends up almost completely in the blood
- In contrast, only about 40 to 60 milligrams of 100 milligrams of phosphorus from natural sources, such as a piece of meat, is absorbed
For the same amount of phosphorus, the body therefore absorbs significantly more from additives. For comparison: For adults, the estimated value for an adequate intake is 550 milligrams of phosphorus per day.⁵
Why is too much phosphate a challenge for the body?
While phosphate is an important mineral and a component of bones and teeth, among other things, the kidneys must excrete more phosphate if intake is consistently high. If blood phosphate levels remain elevated, this can be linked to vascular calcification and affect the function of the inner vessel walls. Observational studies also show that phosphate levels in the blood, even at the upper end of the normal range, are associated with a higher risk of cardiovascular disease, even in people with healthy kidneys.⁶
Phosphate can also influence the acid-base balance. However, this depends on the source: while the phosphoric acid in cola can increase the acid load, other phosphate additives such as sodium phosphates are not acidic.⁷
Ammonia: The third factor for acid load from protein
Sulfur and phosphate are not the only reasons why too much protein keeps your acid-base balance occupied. When excess amino acids from proteins are broken down, nitrogen is produced in the form of ammonia in addition to sulfate. Since ammonia is toxic and should not accumulate in the blood, the body reacts by initiating a urea cycle.⁸
Urea cycle explained simply: How the body disposes of ammonia
To get rid of ammonia, the liver must step in. It converts ammonia into the less harmful urea. Just like sulfate, the body can excrete urea via the kidneys through urine.
A protein-rich diet can boost urea formation because the breakdown of amino acids produces nitrogen and triggers the urea cycle.⁹ However, an elevated urea level in the blood does not have to be solely attributable to a high protein intake, but can have various causes that are worth investigating.
Arginine, ornithine, and citrulline: The building blocks of this process
For your liver to reliably convert and eliminate ammonia, it needs a functioning transport system. This task is performed by the three amino acids ornithine, citrulline and arginine ¹⁰:
- Ornithine absorbs the nitrogen from the ammonia, thereby becoming citrulline
- In the next step, citrulline is converted into arginine
- Finally, the liver cleaves the finished urea from arginine. What remains is ornithine, which restarts the cycle from the beginning
None of these three substances is consumed during the cycle. Instead, the body converts the building blocks into one another and ultimately returns them to the starting point.
Ornithine plays a special role in this process: this substance is a non-proteinogenic amino acid. This means it is not a component of proteins and is not incorporated into muscles, enzymes or other proteins.
Glycine: The amino acid often overlooked in high-protein diets
The acid-base balance is not just about acid-forming substances, but also about building blocks required for protein metabolism. One example is glycine. It is the smallest amino acid and is ingested through a protein-rich diet.
However, the demand for glycine can increase with a very high-protein diet, especially if it is based on muscle meat. While the body can produce glycine itself, it cannot do so indefinitely.
- Glycine is one of the main building blocks of collagen, which, for example, ensures bone strength
- At the same time, the amino acid is required for the synthesis of the body's own antioxidant, glutathione
- In the liver, glycine binds certain metabolic waste products and foreign substances so that the kidneys can excrete them more effectively¹¹
What too much protein can mean for your calcium balance
A high-protein diet tends to increase the dietary acid load. A healthy body can generally cope with this well: the kidneys excrete the acid, and blood pH remains stable. The acid load can nevertheless be relevant for bone metabolism, for instance because more calcium may be excreted in the urine as a result.
In our overview article on the acid-base balance, you will learn everything about the precise connections and why minerals are important for buffering.
Conclusion
A look at metabolism shows: Metabolizing protein produces acid, which can place additional demands on your buffer system and your kidneys. However, this does not mean that you have to forgo protein. With healthy kidney function, current evidence indicates that a high protein intake is unproblematic.
Nevertheless, it is worth taking a closer look and understanding the effects of protein from different sources. How much and what kind of protein makes sense for you depends on your needs and your goals for fitness and well-being. Our guides on acid-base balance in the MITOcare blog show what happens in your body as a result and what that means for you. There you will also find valuable everyday tips for balanced nutrition, relaxation, and better performance.
More blog articles on this topic
Acid-base balance explained simply: What really influences nutrition, kidneys, and pH levels
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This article is based on carefully researched sources:
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