Your body already regulates its own pH with remarkable precision, keeping blood between 7.35 and 7.45 at all times. You can’t dramatically shift that number through diet or lifestyle alone, because your lungs, kidneys, and blood buffers constantly correct any drift. But what you eat and how you live does influence the acid load your body has to process, and reducing that burden appears to have real benefits for stress hormones, kidney health, and metabolic function.
How Your Body Controls Its Own pH
Three systems work together to keep your blood in its narrow pH range. Your blood contains chemical buffers, primarily bicarbonate and hemoglobin, that neutralize small surges of acid immediately. Your lungs adjust how much carbon dioxide you exhale, since CO2 dissolved in blood forms an acid. And your kidneys filter out excess acids while recycling bicarbonate back into the bloodstream. This system is so efficient that even drinking highly alkaline water barely registers. Harvard Health Publishing notes that even if alkaline water slightly raised blood pH, your kidneys would rebalance it almost immediately.
So when people talk about “lowering acidity,” they’re not really talking about changing blood pH. They’re talking about reducing the total acid load the body has to neutralize, which eases the workload on your kidneys and may lower stress hormone output.
Why Acid Load Matters Even If Blood pH Stays Stable
A high-protein diet low in fruits and vegetables forces the kidneys to work harder to excrete acid. That process triggers a hormonal chain reaction: your pituitary gland increases output of a signaling hormone, which raises cortisol and aldosterone production so the kidneys can ramp up acid excretion. In a crossover study comparing different diets, participants eating a lower-protein, plant-leaning diet excreted about 30% less cortisol in their urine than those on a standard protein-heavy diet. Chronically elevated cortisol is linked to visceral fat storage, insulin resistance, and inflammation, so reducing the acid load your body processes may have metabolic benefits well beyond pH.
Foods That Increase and Decrease Acid Load
Researchers use a metric called Potential Renal Acid Load (PRAL) to score how much acid or base a food generates after digestion. Negative scores mean the food has an alkalizing effect. Positive scores mean it adds to your acid burden. Here’s how major food groups rank per 100-gram serving:
- Most alkalizing: Fruits and fruit juices (-3.1), vegetables (-2.8), mineral-rich beverages like certain mineral waters (-1.7)
- Neutral: Fats and oils (0), milk and non-cheese dairy (1.0)
- Moderately acid-forming: Bread (6.7), pasta (6.7), flour (7.0), fish (7.9), meat and meat products (8.0)
- Most acid-forming: Lower-protein cheeses (9.5), high-protein cheeses like parmesan (up to 34.2)
Raisins scored the lowest PRAL of any individual food tested, at -21 per 100 grams. At the other extreme, parmesan cheese topped the list at 34.2. You don’t need to eliminate acid-forming foods entirely. The goal is shifting the overall balance so that fruits, vegetables, and other alkalizing foods make up a larger share of your plate.
Why Citrus Fruits Are Alkalizing Despite Tasting Acidic
Lemons and oranges taste sour because of citric acid, but after your body metabolizes them, their potassium and organic acid content has an alkalizing effect. The potassium increases kidney excretion of potassium ions in exchange for sodium, while bicarbonate is released in the process. Clinical studies found that orange and grapefruit juice both raised urine pH (making it more alkaline) and increased urinary citrate, a compound that helps prevent kidney stones. Lemon juice raised citrate levels but didn’t significantly change urine pH on its own.
Practical Dietary Shifts
You don’t need to follow a strict “alkaline diet” to meaningfully reduce your body’s acid burden. A few changes make a large difference:
- Add vegetables to every meal. Even one extra serving of leafy greens or root vegetables shifts your daily PRAL score in the alkaline direction.
- Eat more fruit. Berries, bananas, raisins, citrus, and melons all have strongly negative PRAL scores.
- Reduce cheese intake. Hard, high-protein cheeses are the single most acid-forming food category. Swapping some cheese for plant-based toppings or lower-protein dairy options helps considerably.
- Balance protein sources. Meat, fish, and eggs are all acid-forming. You don’t have to go vegetarian, but pairing protein with generous portions of vegetables offsets the acid load.
- Choose potassium-rich foods. Potassium salts from plant foods are the main driver of the alkalizing effect. Potatoes, bananas, spinach, and avocados are all good sources.
Hydration and Alkaline Water
Staying well hydrated supports kidney function, which is your body’s primary tool for excreting acid. Plain water does this effectively. Alkaline water (typically pH 8 to 9) doesn’t offer meaningful additional benefit for systemic pH. Because stomach acid is extremely acidic, any alkaline water you drink gets neutralized almost immediately in your stomach. The temporary pH increase is so brief that it has no lasting effect on your blood chemistry. Alkaline water may offer short-term relief from acid reflux symptoms, but that’s a local effect in the esophagus and stomach, not a change in whole-body acidity.
Exercise and Acid Clearance
Intense exercise generates lactic acid in your muscles, but this is temporary and self-correcting. Your liver and kidneys filter lactic acid out of your blood and convert it back into glucose for future energy use. This clearance happens so quickly that lactic acid levels typically return to normal as soon as you stop the intense activity, well before you’d experience any complications.
Regular moderate exercise supports the systems that manage acid balance. It improves circulation (helping deliver acid to the liver and kidneys for processing), supports healthy kidney function over time, and helps manage cortisol levels. The brief acid spike during a hard workout is not something to worry about or try to prevent.
Baking Soda and Supplements
Sodium bicarbonate (baking soda) is a direct alkalizing agent that doctors sometimes prescribe for diagnosed metabolic acidosis. Some people use small amounts to neutralize stomach acid, with typical doses ranging from about one to two and a half teaspoons dissolved in cold water. But it comes with real limitations: it contains a large amount of sodium, which can worsen high blood pressure, kidney disease, or heart conditions. It can also interfere with other medications if taken within one to two hours of them, and long-term use increases the risk of side effects.
Potassium citrate supplements are sometimes used to raise urine pH, particularly for people prone to kidney stones. But for most people, getting potassium from food (fruits and vegetables) is safer and more effective than supplementing.
When Acidity Is a Medical Problem
True metabolic acidosis, where blood pH drops below 7.35, is a medical condition with noticeable symptoms: rapid and unusually deep breathing (as the body tries to blow off CO2 to compensate), confusion, and lethargy. It’s typically caused by kidney disease, uncontrolled diabetes, severe dehydration, or toxic exposures. Diagnosis requires blood gas testing and metabolic panels. This is fundamentally different from the general “acid load” that dietary changes address. If you’re experiencing those symptoms, that’s not a situation where eating more vegetables will help.
For everyone else, the practical takeaway is straightforward: eat more plants, stay hydrated, and don’t waste money on alkaline water. Your body handles the chemistry. You just control how hard it has to work.