Your body already keeps your blood pH locked between 7.35 and 7.45, and no drink will move that number. Your lungs and kidneys constantly adjust acid-base balance by expelling carbon dioxide and excreting or reabsorbing bicarbonate. What certain drinks can do is shift your urine pH toward the alkaline side, which has some real (if modest) health benefits, particularly for kidney stone prevention. Understanding the difference between changing blood pH and changing urine pH is the key to separating useful advice from hype.
Why Your Blood pH Doesn’t Change
The idea behind “alkalizing the body” is that eating or drinking acidic things makes your whole system more acidic, leading to disease. This isn’t how it works. Your blood pH averages 7.40, and your pulmonary and renal systems are the two main regulators keeping it there. Your lungs blow off carbon dioxide (an acid) with every breath, and your kidneys fine-tune the balance by filtering out fixed acids and recycling bicarbonate. These systems are so effective that only serious medical conditions like kidney failure or uncontrolled diabetes can push blood pH outside its normal range.
What food and drink do change is the acid load your kidneys have to process, and that shows up in your urine. Researchers measure this with a score called Potential Renal Acid Load, or PRAL. A negative PRAL score means a food or drink produces a net alkaline effect on your urine. A positive score means it adds to the acid your kidneys need to clear. So when people talk about “alkalizing drinks,” what they’re really describing are beverages with a negative PRAL score that reduce the work your kidneys do to maintain balance.
Drinks With the Strongest Alkaline Effect
Coffee, tea, and fruit-based drinks consistently score as net alkaline. Coffee has a PRAL of about -2.4 per 6-ounce cup, which surprises many people who assume it’s acidic because of its taste. Tea comes in at -0.5 per cup. The real standouts, though, are fruit juices and fruit-infused water, because fruits as a category average -3.1 per 100 grams, with some scoring much higher. A single pear scores -4.8, an apple -4.0, an orange -3.5, and a quarter cup of raisins hits -8.4.
Freshly squeezed citrus juice and lemon water are among the most popular alkalizing drinks, and the logic behind them is sound. Citric acid from lemons and oranges is metabolized in your body, and a portion of the citrate that gets absorbed escapes breakdown and ends up directly in your urine. In studies on normal subjects, urinary citrate excretion peaked about two hours after an oral dose of citric acid and stayed elevated for several hours. Higher urinary citrate is specifically useful because citrate binds to calcium in urine, reducing the formation of calcium-based kidney stones.
Milk, by contrast, has a slightly positive PRAL of 1.6, making it mildly acid-forming. Bananas and cherries also score on the acidic side despite being fruits, so not every plant food fits the pattern.
What About Alkaline Water?
Alkaline water, typically sold at pH 8 to 9.5, is one of the most marketed “alkalizing” products. For general health, there’s little evidence it does anything your tap water doesn’t. Your stomach acid (pH around 1.5 to 3.5) neutralizes it almost immediately.
One specific exception involves acid reflux. A lab study found that water at pH 8.8 permanently inactivated pepsin, the stomach enzyme that damages throat and esophageal tissue in people with reflux disease. The alkaline water also had a stronger acid-buffering capacity than conventional water. This is a test-tube finding, not a clinical trial, but it suggests a narrow scenario where high-pH water could be a helpful add-on for people dealing with reflux symptoms. For everyone else, plain water remains the best-supported choice for hydration and kidney stone prevention. No beverage other than water has been clearly shown in randomized controlled trials to prevent kidney stones.
Apple Cider Vinegar Doesn’t Deliver
Apple cider vinegar is one of the most commonly recommended “alkalizing” drinks online. The theory is that its alkali load of about 21 milliequivalents per liter could increase citrate excretion by alkalinizing the system. A randomized crossover trial put this to the test, having healthy volunteers drink apple cider vinegar for one week. The result: no significant changes in 24-hour urinary parameters, including urine pH and volume. The same trial tested coconut water, diet orange soda, and lemon water alongside it, and none of the treatment arms produced significant effects on urine pH either. Apple cider vinegar has other potential benefits, but shifting your body’s acid-base chemistry isn’t one of them.
Baking Soda: Effective but Risky
Dissolving baking soda (sodium bicarbonate) in water is the most direct way to deliver alkaline compounds to your body, and it genuinely does raise urine pH. Some athletes have used it before competition hoping to buffer lactic acid. But MedlinePlus classifies baking soda overdose as a real medical concern. Symptoms include nausea, vomiting, diarrhea, muscle spasms, muscle weakness, irritability, and convulsions. If those gastrointestinal symptoms aren’t controlled, serious dehydration and electrolyte imbalances can follow, potentially triggering heart rhythm disturbances. The margin between a dose that shifts urine pH and a dose that causes problems is not wide, making this a poor DIY strategy.
Does Any of This Protect Your Bones?
One of the biggest claims behind alkaline diets is that they prevent bone loss. The theory, called the acid-ash hypothesis, proposes that an acidic diet forces your body to pull calcium from bones to buffer the acid, weakening your skeleton over time. A large meta-analysis covering 17 studies and more than 80,000 people found no significant relationship between dietary acid load and fracture risk. Bone mineral density showed a weak association with one measure of dietary acid load, but not with others, and the connection to actual fractures wasn’t there. An earlier systematic review reached the same conclusion: no evidence that an alkaline diet is a protective determinant of bone health.
This doesn’t mean fruit-heavy diets are bad for bones. Fruits and vegetables supply potassium, magnesium, vitamin C, and other nutrients that genuinely support bone health. But the mechanism is nutritional, not about pH.
A Practical Approach
If you want to lower your dietary acid load, the most effective and evidence-backed strategy is simple: drink more water and eat more fruits and vegetables. Black coffee, unsweetened tea, and citrus-infused water all carry negative PRAL scores and fit easily into a daily routine. Squeeze half a lemon into a glass of water a few times a day if you like the taste. Blend whole fruits into smoothies for a bigger alkaline effect, since the fruit itself carries a stronger PRAL score than juice alone.
Skip the expensive alkaline water unless you’re specifically managing reflux symptoms. Don’t drink baking soda solutions without medical guidance. And treat apple cider vinegar as a salad dressing, not an alkalizing supplement, because the clinical data doesn’t support the claim. The real benefits of so-called alkalizing drinks come from hydration, citrate, and the nutrients in whole fruits, not from shifting your blood pH, which your body handles on its own.