The dietary acid load (DAL) is a measure of the acid produced from the foods we eat, influencing our body's acid-base balance. This balance is crucial for health, with a diet high in animal proteins and processed foods typically leading to a high DAL and potentially causing low-grade metabolic acidosis. This condition is associated with various health issues, including obesity, cardiovascular diseases, and impaired kidney function. Understanding the impact of DAL on health is increasingly recognized as important for managing and preventing these conditions.
Our body maintains a tight regulation of acid-base equilibrium, aiming to keep blood pH within a narrow range. The kidneys play a vital role in this process by excreting non-volatile acids and reabsorbing bicarbonate to buffer the acids. The DAL, determined mainly by our dietary choices, affects the net endogenous acid production (NEAP) and, consequently, our acid-base balance. Foods rich in animal proteins tend to increase DAL, while fruits and vegetables, high in citrate, have an alkalinizing effect.
The amino acid composition of proteins influences whether a food has an acid or base effect on the body. Animal proteins, which are high in sulfur-containing amino acids like cysteine and methionine, tend to be acid-generating. On the other hand, plant-based proteins contain amino acids that have a net base effect, such as glutamine and glycine. This difference in amino acid composition plays a significant role in determining the dietary acid load.
Urine pH can serve as a simple and cost-effective indicator of DAL and the effectiveness of dietary interventions. However, it's important to note that urine pH may not accurately reflect DAL in individuals with compromised kidney function or renal tubular acidosis. Research suggests that obesity and conditions like diabetes, hypertension, and chronic kidney disease (CKD) are associated with an increased DAL.
To reduce DAL and its associated health risks, dietary patterns rich in plant-based proteins, fruits, vegetables, and nuts are recommended. The DASH and Mediterranean diets are examples of such patterns that can help lower DAL and improve overall health. By focusing on these dietary choices, individuals can better manage their acid-base balance and reduce the risk of developing chronic diseases.
DAL of commonly used food groups and patterns
based on PRAL
| DAL | PRAL/100 g | |
|---|---|---|
| Food group | ||
| Hard cheese | A | 20 |
| Soft cheese | A | 15 |
| Meat (all types) | A | 8 |
| Fish (all types) | A | 8 |
| Pasta | A | 8 |
| Bread | A | 6 |
| Rice | A | 4.5 |
| Biscuits | A | 3 |
| Peas, beans, lentils | A | 2 |
| Milk | A | 1 |
| Soft drinks | A | 10 |
| Egg yolk | A | 25 |
| Egg white | A | 1 |
| Nuts, mean | A | 5 |
| Cookies and milk chocolate, mean | A | 2.5 |
| Cereals and flours, mean | A | 7 |
| Pastries, mean | A | 7 |
| Red wine | B | −2.4 |
| Potatoes | B | −4 |
| Fruits | B | −5 |
| Vegetables, mean | B | −5 |
| Green leafy vegetables | B | −10 |
| Tea | B | −0.5 |
| Coffee | B | −2.5 |
| Dark chocolate 70–80% | B | −7 |
| Fats and oils | N | 0 |
| Dietary pattern | ||
| Ketogenic diet | A | |
| Western diet | A | |
| Mediterranean diet | B | |
| DASH-diet | B | |
Abbreviations: DAL, dietary acid load; PRAL, potential renal acid load A= acid, B= base, N = neutral
The human body maintains a delicate acid-base balance, crucial for overall health. This balance is influenced by dietary intake, as foods are metabolized into acids or bases. The measure of acid load from diet is known as the dietary acid load (DAL), which considers the potential renal acid load (PRAL) from food components like protein and minerals, and the alkalinizing effect of organic acids from fruits and vegetables. Modern Western diets, characterized by high amounts of animal protein and processed foods, typically result in a high DAL, leading to a state of low-grade metabolic acidosis.
A high dietary acid load is associated with various health conditions, including obesity, cardiovascular diseases, impaired kidney function, and bone diseases. It is also linked to increased morbidity and mortality. On the other hand, a diet with a lower DAL, rich in fruits and vegetables, can help maintain acid-base equilibrium and reduce the risk of chronic diseases. Dietary advice is increasingly focusing on DAL rather than just macronutrients to provide a more comprehensive approach to health management.
The acid or base-generating properties of foods, especially proteins, depend largely on their amino acid composition. Animal proteins, rich in sulfur-containing amino acids like cysteine and methionine, tend to be acid-generating. In contrast, plant-based proteins contain amino acids with a net base effect, such as glutamine, glutamate, and glycine. This difference in amino acid composition between animal and plant proteins plays a significant role in the dietary acid load.
A high dietary acid load can adversely affect kidney function, leading to conditions such as chronic kidney disease (CKD) and kidney stones. It is associated with decreased urine pH and lower citrate levels, which can increase the risk of stone formation. In patients with CKD, reducing DAL through increased intake of fruits and vegetables is recommended to slow the decline of residual kidney function. Additionally, a high DAL can result in bone loss and muscle mass loss, further complicating kidney disease.
There is a mechanistic link between high dietary acid load and increased levels of cortisol, a stress hormone. Elevated cortisol levels can increase the risk of depressive disorders. Therefore, managing DAL through diet can have implications not only for physical health but also for mental well-being. In summary, a diet low in DAL, rich in plant-based proteins, fruits, and vegetables, and exemplified by patterns like the DASH and Mediterranean diets, is advisable for maintaining health and preventing chronic diseases.
Summary of the consequences of a high dietary acid load (DAL)
Source: Wieërs, Michiel L A J et al. “Dietary acid load in health and disease.” Pflugers Archiv : European journal of physiology, 10.1007/s00424-024-02910-7. 29 Jan. 2024, doi:10.1007/s00424-024-02910-7 https://link.springer.com/article/10.1007/s00424-024-02910-7 This article is licensed under a Creative Commons Attribution 4.0 International License
Wieërs, Michiel L A J et al. “Dietary acid load in health and disease.” Pflugers Archiv : European journal of physiology, 10.1007/s00424-024-02910-7. 29 Jan. 2024, doi:10.1007/s00424-024-02910-7 https://link.springer.com/article/10.1007/s00424-024-02910-7 This article is licensed under a Creative Commons Attribution 4.0 International License
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