MVIIIHealth The MVIII app
← Back

Research · Diets

Alkaline diet

A higher diet acid load raised urine calcium, but calcium balance and a bone breakdown marker did not change in healthy adults, and reviews found no evidence that an alkaline diet protects bone. A cancer review found no trials. In small kidney disease trials from one group, added fruits and vegetables slowed kidney decline against usual care without raising potassium.

Add to Bio HackChecked 2026-11-13
Status
A dietary pattern, not a regulated product.
Also called
alkaline ash diet, acid-alkaline diet, acid-ash diet, alkaline eating, pH diet, low acid load diet, dietary acid reduction
Followed for
bone health, osteoporosis prevention, cancer prevention, kidney health

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help1

Reported risks0

No risks sourced yet.

What people follow it for, and what was found

Shown to help1

Limited

Kidney disease progression

Small trials from one research group found fruits and vegetables slowed kidney function decline against usual care in kidney disease, about as much as sodium bicarbonate.

Compared with oral sodium bicarbonate [4]; oral sodium bicarbonate or usual care [5], [6]; people with a lower diet acid load [7]

The numbers and sources
Effect
In stage 4 kidney disease, eGFR after 1 year did not differ between fruits and vegetables and oral sodium bicarbonate. Metabolic acidosis improved in both, more with bicarbonate, and urine markers of kidney injury fell in both [4]. Over 5 years in people with hypertension and heavy albuminuria, eGFR fell 1.08 mL/min/1.73 m² a year with fruits and vegetables, 1.17 with bicarbonate and 1.94 with usual care, and systolic blood pressure was lower with fruits and vegetables [5]. In a post hoc analysis of stage 3 disease, 0 of 36 people on fruits and vegetables, 2 on bicarbonate and 6 on usual care had a heart attack or stroke over 5 years [6]. In observational studies, a higher diet acid load was linked to chronic kidney disease (RR 1.31, 95% CI 1.06 to 1.62) [7].
Population
71 adults with stage 4 kidney disease from hypertension on ACE inhibitors [4]; 153 adults with hypertension and macroalbuminuria [5]; 108 adults with stage 3 kidney disease and metabolic acidosis [6]; 9 observational studies [7].
Sources
[4], [5], [6], [7]
Caveats
All the trials come from one research group. The cardiovascular count is post hoc [6], and [7] is observational. The diet added fruits and vegetables, so more than acid load changed.

Not shown to help2

Moderate

Bone health

Not shown to protect bone: in healthy adults, a higher diet acid load raised urine calcium without changing calcium balance or a bone breakdown marker.

Compared with diets with a different acid load, made by changing the amount or type of protein [1]; lower or higher diet acid loads, from foods or alkaline salts, in trials and cohorts [2]

The numbers and sources
Effect
In 5 randomized studies that met calcium-study quality standards, higher net acid excretion raised urinary calcium (p < 0.0001), but was not related to calcium balance (p = 0.38, power 94%) or to the bone breakdown marker N-telopeptide (p = 0.95) [1]. A review of 55 studies, including 22 randomized interventions and 11 cohorts, found that calcium balance studies did not show whole-body calcium loss with higher acid excretion, and that no intervention study measured fractures or bone strength [2].
Population
Healthy adults whose acid-base intake was changed through foods, protein or alkaline salts [1][2].
Sources
[1], [2]
Caveats
The two reviews share most authors [1][2]. No trial measured fractures [2].
Limited

Cancer

Limited evidence: a systematic review found no trials, and its one cohort study found no link between diet acid load and bladder cancer.

Compared with people with a lower diet acid load, in one cohort [3]

The numbers and sources
Effect
Of 8,278 citations, one study qualified. No randomized trials and no studies of cancer treatment were found. The one cohort found no link between diet acid load and bladder cancer (OR 1.15, 95% CI 0.86 to 1.55), including in long-term smokers (OR 1.72, 95% CI 0.96 to 3.10) [3].
Population
One cohort study with a low risk of bias [3].
Sources
[3]
Caveats
One cohort, one cancer type [3].

How trials defined it

The kidney trials gave fruits and vegetables in amounts calculated to halve dietary acid, against oral sodium bicarbonate at 1.0 mEq per kg a day [4] or 0.3 mEq per kg a day [6], for 1 to 5 years [4][5][6]. The bone studies changed acid load by altering the amount or type of protein [1], and the wider bone review included alkaline diets and alkaline salts [2].

Risks

Checked, no increase found1

Limited

Potassium in advanced kidney disease

One trial in stage 4 kidney disease found plasma potassium did not rise over a year of added fruits and vegetables.

The numbers and sources
Effect
Plasma potassium did not increase in either the fruit and vegetable group or the bicarbonate group over 1 year [4].
Population
71 adults with stage 4 kidney disease from hypertension, on ACE inhibitors [4].
Sources
[4]
Caveats
One trial. The abstract gives no potassium values [4].

Claims tested and not found

  1. That an alkaline diet prevents bone loss. Higher acid load did not change calcium balance or a bone breakdown marker, and a causal review found no evidence that an alkaline diet protects bone [1][2].
  2. That diet acid load causes cancer. The one qualifying cohort found no link with bladder cancer [3].

Sources

  1. Fenton TR, Lyon AW, Eliasziw M, et al. Meta-analysis of the effect of the acid-ash hypothesis of osteoporosis on calcium balance. Journal of Bone and Mineral Research. 2009. https://doi.org/10.1359/jbmr.090515
  2. Fenton TR, Tough SC, Lyon AW, et al. Causal assessment of dietary acid load and bone disease: a systematic review & meta-analysis applying Hill's epidemiologic criteria for causality. Nutrition Journal. 2011. https://doi.org/10.1186/1475-2891-10-41
  3. Fenton TR, Huang T. Systematic review of the association between dietary acid load, alkaline water and cancer. BMJ Open. 2016. https://doi.org/10.1136/bmjopen-2015-010438
  4. Goraya N, Simoni J, Jo CH, et al. A comparison of treating metabolic acidosis in CKD stage 4 hypertensive kidney disease with fruits and vegetables or sodium bicarbonate. Clinical Journal of the American Society of Nephrology. 2013. https://doi.org/10.2215/cjn.02430312
  5. Goraya N, Madias NE, Simoni J, et al. Kidney and Cardiovascular Protection Using Dietary Acid Reduction in Primary Hypertension: A Five-Year, Interventional, Randomized, Control Trial. The American Journal of Medicine. 2024. https://doi.org/10.1016/j.amjmed.2024.06.006
  6. Goraya N, Munoz-Maldonado Y, Simoni J, et al. Treatment of Chronic Kidney Disease-Related Metabolic Acidosis With Fruits and Vegetables Compared to NaHCO3 Yields More and Better Overall Health Outcomes and at Comparable Five-Year Cost. Journal of Renal Nutrition. 2021. https://doi.org/10.1053/j.jrn.2020.08.001
  7. Mofrad MD, Daneshzad E, Azadbakht L. Dietary acid load, kidney function and risk of chronic kidney disease: A systematic review and meta-analysis of observational studies. International Journal for Vitamin and Nutrition Research. 2021. https://doi.org/10.1024/0300-9831/a000584

Everything in the library