Alkaline Diet: What Food Can and Cannot Change About Your pH

The alkaline diet is built on the idea that some foods make your body acidic and others make it alkaline, and that shifting toward alkaline foods improves health. The first half of that idea does not hold up: your lungs and kidneys keep blood pH in a narrow range of about 7.35 to 7.45 no matter what you eat. Food can change the pH of your urine, which is how the kidneys get rid of extra acid or base. Systematic reviews have found no good evidence that an alkaline diet protects bones or affects cancer. The genuine upside is simpler: the diet pushes people toward more fruit and vegetables, which most Americans do not eat enough of.

Peptide Labs does not sell alkaline diet products or alkaline water. This article is general nutrition information, not medical advice.

What the alkaline diet claims

Alkaline diet books sort foods into acid-forming and alkaline-forming groups. Meat, fish, eggs, cheese and grains usually land on the acid side; most fruits and vegetables on the alkaline side. Many versions also discourage coffee, alcohol and processed food. The promise is that eating mostly alkaline foods balances the body’s pH and, depending on the author, supports bones, energy, weight or disease resistance. Some sellers add alkaline water, pH test strips and so-called alkalizing powders.

The idea has been promoted hard. In 2017, the author of The pH Miracle book series was sentenced in San Diego County to three years and eight months on two counts of practicing medicine without a license, according to NBC San Diego, after giving intravenous infusions at his ranch. That case does not settle the science, but it is a reminder to separate the diet’s food choices from the claims attached to it.

Blood pH vs urine pH: why food cannot change your blood

pH measures how acidic or alkaline a fluid is on a scale from 0 to 14, with 7 as neutral. Blood is normally slightly alkaline, at about 7.35 to 7.45, according to the MSD Manual. Three systems hold it there. Chemical buffers in the blood, mainly bicarbonate, absorb sudden shifts within seconds. The lungs adjust how much carbon dioxide you breathe out by changing the speed and depth of breathing. The kidneys excrete extra acid or base in urine, a slower process that takes hours to days.

Because of this, eating a steak or a salad does not move blood pH in a healthy person. When blood pH does fall outside its normal range, it is a sign of a medical problem such as lung or kidney disease or uncontrolled diabetes, and it is measured with a blood gas test in a clinic, not a strip at home.

Urine is different. The kidneys use urine to dump whatever acid or base the diet adds, so urine pH does change with food. Researchers Thomas Remer and Friedrich Manz showed in the 1990s that a food’s potential renal acid load (PRAL), calculated from its protein, phosphorus, potassium, calcium and magnesium, predicts how acidic the urine becomes (correlation 0.83 between net acid excretion and urine pH in their data). A 2022 German study found that vegans had less acidic urine than omnivores. So when alkaline diet followers test their urine and see the number rise, the test is working. It simply shows the kidneys doing their job, not a change in the blood.

Alkaline foods and acidic foods: what PRAL shows

The table applies the published PRAL formula (Remer and colleagues, 2003) to USDA FoodData Central SR Legacy values per 100 grams of each food. Negative numbers mean the food leaves an alkaline load for the kidneys to excrete; positive numbers mean an acid load. The figures are estimates for comparison, not targets.

Three things stand out. First, a food’s own acidity does not predict its effect: lemon juice is strongly acidic in the glass, yet it is alkaline-forming once metabolized, which is why claims about lemon water alkalizing the body confuse the two ideas. Second, PRAL is not a health score. Raisins rank as one of the most alkaline-forming foods while cola is neutral, and protein-rich foods such as fish, eggs and dairy rank as acid-forming even though they supply nutrients many people need (see our list of protein foods). Third, the alkaline side is dominated by potassium-rich produce, which is the main reason the pattern can look healthy.

What systematic reviews found

The most cited claim is that an acid-forming diet pulls calcium out of bone to buffer the blood. The researcher Tanis Fenton and colleagues at the University of Calgary tested that acid-ash hypothesis in a series of reviews:

• Calcium balance (2009, Journal of Bone and Mineral Research): a meta-analysis limited to the highest-quality randomized calcium studies (5 of 16 met the criteria). More acid excretion raised urine calcium, but it did not change whole-body calcium balance or a marker of bone breakdown. The authors concluded that promoting the alkaline diet to stop calcium loss is not justified.
• Phosphate (2009, Nutrition Journal): 12 studies with 269 people. Extra phosphate, often blamed as acid-forming, lowered urine calcium and did not reduce calcium balance, the opposite of what the hypothesis predicts.
• Bone disease (2011, Nutrition Journal): 55 studies, including 22 randomized trials. The review found that a causal link between dietary acid load and osteoporosis is not supported, and no evidence that an alkaline diet protects bone health.
• Cancer (2016, BMJ Open): from more than 8,000 citations, only one study qualified, a cohort that found no association between diet acid load and bladder cancer. There were no randomized trials and no studies of alkaline diets or alkaline water in cancer care. The authors wrote that there is almost no research either way and that promoting these ideas for cancer is not justified.

Not every review is as negative. A 2012 narrative review by Gerry Schwalfenberg suggested there may be some value in more alkaline eating for chronic disease and called for more studies, but a narrative review does not apply the strict selection rules of a systematic one. For bones, the practical guidance is unchanged: our guides to bone support and calcium cover what the evidence does support.

Alkaline water claims

Alkaline water is sold with a pH above 7, either naturally from minerals or after passing through an ionizer. Claims range from better hydration to cancer protection. The evidence is thin. The study most often quoted is a 2012 laboratory experiment in which water at pH 8.8 inactivated the digestive enzyme pepsin in a test tube; it measured no outcomes in people. The 2016 BMJ Open review found no studies at all on alkaline water and cancer.

Physiology explains why big claims are unlikely. Anything you drink reaches a strongly acidic stomach first, and whatever is absorbed is handled by the same buffers, lungs and kidneys that keep blood pH steady. Alkaline water is still water and is fine for staying hydrated, but there is no good evidence that it changes blood pH or health outcomes compared with ordinary drinking water.

Does the alkaline diet work? The real upside

Does the alkaline diet work for the reasons its books give? No. But its food list overlaps with advice that is well supported: eat more vegetables, fruit, beans and nuts, and less processed food. That matters because most Americans fall short. A CDC report using 2019 survey data found that only 12.3% of US adults met fruit intake recommendations and 10.0% met vegetable recommendations.

Eating more produce raises intake of potassium, fiber and many other nutrients, which our guides to potassium-rich foods and fiber-rich foods describe with USDA numbers. Our guide to potassium citrate explains the one place an alkaline load is used deliberately, under medical supervision. The trade-off is that strict versions cut protein foods, dairy and grains that are not harmful, which can make a diet harder to sustain and short on protein or calcium. The sibling guide to the South Beach diet looks at another named diet with a mixed evidence record.

Who should be careful

• Kidney disease: NIH notes that people whose kidneys cannot excrete potassium normally, including some with chronic kidney disease or on certain blood pressure medicines, can be harmed by high potassium intake. Fruit and vegetable changes should go through their care team.
• Strict elimination: dropping whole food groups can leave gaps in protein, calcium and vitamin B12; a registered dietitian can help.
• Alkalizing products: powders, drops and pills sold to raise body pH have no evidence behind that claim. Ask a clinician before using any of them, especially with kidney or heart conditions.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; ask a healthcare provider before a major diet change or a new supplement, especially if you take medicines, are pregnant or have a chronic health condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

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