Your diet is probably dangerously acidic but there’s a simple solution

Standing in the bathroom with a strip of litmus paper, my heart races as I prepare to dip it into my urine. My hope is that it won’t turn red, signaling acidity—this isn’t a casual test, but a personal check on whether my dietary choices are putting my health at risk. Acidic urine is a rough indicator of excessive dietary acid load; signs that I might be setting myself up for various health problems. Thankfully, the remedy is straightforward: adjust my diet. If the litmus paper does indicate acid, I plan to up my leafy greens and recheck. 

While it may seem like pseudoscience, an increasing number of nutrition experts suggest that overlooking dietary acid load may result in missed opportunities for healthier eating. According to Hana Kahleova at the Physicians Committee for Responsible Medicine in Washington, excessive dietary acid load correlates with elevated risks for chronic diseases like kidney disease, liver issues, cancer, and even mental health struggles such as anxiety and depression. 

Surprisingly, the majority of us are likely not heeding this warning, especially those following a typical Western diet. The positive news is that, unlike the damage caused by high sodium or caloric intake, changing dietary habits can quickly reverse high dietary acid loads—if you know which foods contribute to acidity. Evidence is emerging that links dietary acid load to chronic disease promotion, providing new insights into our eating practices. 

This connection between diet and the body’s acid-alkaline balance was noted as far back as the 1960s when healthcare professionals discovered the typically acidic nature of human urine, contrasting with the slightly alkaline tendencies in vegetarians. Researchers investigated this further through a now-outdated method known as the acid ash test, which involved incinerating foods and examining the resulting ash. This approach purported to demonstrate how the end products of food digestion impacted the body’s acid-alkaline balance.

In 1968, researchers at Harvard asserted that high dietary acid loads could contribute to osteoporosis and sarcopenia by forcing the body to break down bone and muscle to neutralize the excess acidity. Although this theory lost favor due to insufficient evidence linking acidic diets to osteoporosis risk, the concept of dietary acid load has resurrected in contemporary discussions. 

Understanding the acidity of foods involves basic chemistry principles. Most may recall using litmus paper to gauge pH levels, where a reading of 0 to 14 showcases acidity to alkalinity, with 7 considered neutral. The body maintains blood and cell fluid pH levels closely, ideally around 7.35 to 7.45, which is slightly alkaline. 

“Our bodies must keep pH levels stable,” Kahleova states. Deviating from this balance, particularly dropping below 7.35, can lead to metabolic acidosis—a rare condition that may cause symptoms such as rapid heartbeat and confusion. Typically, acidosis occurs due to underlying health issues rather than diet, though extremely high protein diets or other factors like dehydration can also contribute.  

What contributes to excessive acidity?

The body generates acids primarily through respiration, creating carbon dioxide (which converts to carbonic acid in water) and through food digestion; the latter produces a range of acids. While the lungs effectively expel carbon dioxide, dietary sources of acid contribute to what is known as dietary acid load (DAL). 

To sustain a slightly alkaline state, our body must excrete as much acid as it ingests. When faced with excess acidity, the kidneys filter, excretNing the surplus into urine while reclaiming alkaline bicarbonate for the bloodstream. Most people’s kidneys manage this method efficiently, but nearing the lower pH limit can lead to low-grade metabolic acidosis—less severe than acute acidosis but still a concern.

The categorization of foods as acidic or alkaline relies on their metabolic byproducts rather than their raw form. Interestingly, many foods perceived as acidic, like citrus fruits, are metabolized to form alkaline byproducts, due to the citric acid they release becoming bicarbonate. Fruits and vegetables boast proteins that also yield alkaline metabolites, contrasting sharply with animal proteins, which tend to increase acidity due to sulfur-containing amino acids and others. 

Additional dangers of a Western diet

The alarm may ring loud now, as typical Western diets consist of high levels of animal products, refined grains, salt, and ultra-processed foods, but scarce amounts of fruits and vegetables—an ideal setup for developing low-grade metabolic acidosis. Researchers assert that chronic exposure to high dietary acid loads is prevalent among those following a Western diet, as noted by Ilias Attaye from Erasmus University Medical Center. 

Yet tackling this issue involves more than just shifting away from a Western diet. Various components like certain fruits contain compounds that lead to oxalic acid formation, which may hinder their potential alkalinity. Fruits such as beets, blackberries, and cherries can contribute to acidity, which presents an unexpected setback in finding truly alkaline options. 

Determining dietary acid load is a complex task. Simple urine pH tests do not provide precise clinical measurements. A validation method for assessing dietary acid load is Potential Renal Acid Load (PRAL), established in the 1990s to replace the acid-ash test. This method evaluates potential acid or alkaline production when a specific food is metabolized, resulting in a numerical score ranging from -15 to +35. Lower scores indicate alkaline properties, while higher scores denote acidity. 

Calculating PRAL involves five nutrients: protein, phosphorus, calcium, magnesium, and potassium. While protein and phosphorus increase the PRAL score, calcium, magnesium, and potassium decrease it. Consequently, animal-based foods tend to score higher on the acidic scale, while plant foods usually result in negative scores. For example, meats range from roughly 8-10 on the PRAL scale, cheese can be as high as 34, whereas many vegetables and fruits fall below zero, particularly leafy greens which are at -14. Alcoholic beverages register as almost neutral.

Although PRAL can be adapted based on individual factors like body size, it does not accommodate salt levels, which can underestimate dietary acid load. Commonly, the chloride ions from salt are found mainly in processed foods, many of which already incorporate PRAL scores considering salt content. Importantly, PRAL serves as a useful benchmark for gauging whether a diet leans towards acidity or alkalinity, thus highlighting healthier eating options.

For those intrigued by dietary acidity, calculated PRAL values are accessible through resources that enumerate common food scores. After noting your daily consumption, you can compile your PRAL for the day, typically denoted in mEq/d. A score below 60 suggests a balanced range, while anything notably higher points to potential trouble.

After tracking my intake for a few days—an effort hindered by focusing solely on raw foods—I consistently found my PRAL hovering around 70 mEq/d, reflective of a typical Western dietary lifestyle. Despite my vegetarian status—though one heavily fond of cheese—my score still flagged concerns. Healthy kidneys can manage between 40 and 60 mEq of acid daily comfortably, though excess burden can arise, leading to low-grade metabolic acidosis coupled with its health implications. 

The kidneys often bear the blunt of dietary acidity, experiencing chronic fatigue from the additional pressure, which may gradually lead to mild chronic kidney impairment. This can create a feedback loop where deteriorating kidney health exacerbates acid elimination issues, paving the way for low-grade metabolic acidosis to worsen, leading to more severe acidosis. Dietary recommendations for kidney health often advocate for lower PRAL, emphasizing preemptive action to ensure kidney sustainability. 

How acidity affects health

There is mounting evidence linking high dietary acid loads to renal health degradation. Increasing research points toward low-grade metabolic acidosis being a potential factor in numerous chronic diseases, including diabetes, obesity, liver dysfunction, cardiovascular conditions, hypertension, cancer, and mood disorders. Although correlation does not imply causation at this stage, bigger studies are on the horizon, aiming to further establish these connections and refine dietary guidelines.

The relationship between high DAL and obesity is more substantiated. Kahleova recently conducted a trial where overweight individuals followed either a Mediterranean diet or a low-fat vegan diet for 16 weeks, switching at the halfway mark. Although the Mediterranean approach yielded minimal weight changes, participants on the vegan plan lost an average of 6 kilograms, as calorie reduction accounted for a portion of this weight loss. Kahleova suspects that a significant part is due to differences in DAL, noting that although both diets showed alkaline benefits, the vegan diet registered a markedly more alkaline PRAL (around -19.3 mEq/d) compared to -1.6 mEq/d for the Mediterranean diet. This alkalinity enhances metabolic efficiencies, allowing the body to burn calories more effectively. 

Explaining how excess acidity translates to chronic health conditions requires further investigation, though Attaye theorizes it might be linked to low-grade inflammation caused by the stress response initiated by burdened kidneys. Over time, prolonged inflammation becomes a risk factor for various health issues. 

The increasing understanding of dietary acid load (DAL) highlights a robust connection with premature mortality risk. A recent comprehensive review found that for each additional 10 mEq/d in acid load, the chance of dying from any cause escalates by 3%. 

The insights amassed around dietary acid load may soon influence health recommendations similarly to the established Mediterranean diet. Unlike the debunked alkaline diet fallacy—which falsely claims that all acidity is detrimental—an evidence-based low-acid diet focuses on nutritional balance. This approach aligns with existing healthy eating advice by advocating reduced consumption of animal products, salt, and processed items while enhancing fruit and vegetable intake. 

Understanding the relationship between diet and disease is evolving, particularly with the expanding focus on dietary acid load. This nuanced perspective indicates that making smart nutritional choices can significantly impact health outcomes. After testing my acid levels, I found my initial result was indeed acidic, but after consuming spinach, my litmus paper test produced the desired alkaline results. 

According to Kahleova, “This reinforces our agency over dietary choices. It’s a straightforward adjustment that everyone can implement.”