Controversy sells. “New” catches your attention. “The latest” is what you need to hear. But in the day when people tell you you need to unlearn everything you ever knew about nutrition, it’s nice to know that some things don’t change. Kidney stone prevention is one of those things.
A lot of nutrition science has not changed over the years. We actually know very well what the best food is for homo sapiens. Over the past 30-plus years, from studies back in the 1990s to the latest guidelines in 2025, the recommendations for preventing kidney stones have hardly changed at all:
- High fluid intake
- Adequate dietary calcium
- Potassium-rich fruits and vegetables
- Moderation in animal protein
- Not adding too much salt
Those are the main pillars of the advice. It’s not because they haven’t examined it over and over. They have. And there’s newer data that backs up what was known in the 1990s and even before that.
Even though kidney stone prevalence is higher than it used to be (now affecting nearly 10% of adults in the USA, up from 5-6% in the 1990s), the causes and prevention remain essentially unchanged. So let’s take a closer look at this. You can be confident that a lot of what we tell you has been known for a long time.
The Foundations: Insights from the 1990s
The 1990s began a renaissance in nutrition research, with large, prospective cohort studies establishing clear dietary links. We have referred to the Health Professionals Follow-up Study and the Nurses Health Study many times because we have derived a lot of information from these Harvard studies.
Health Professional Follow-Up Study Findings
In 1993, researchers published their findings from following over 45,000 men from the Health Professionals Follow-up Study. They found that low dietary calcium dramatically raised stone risk, with the highest intake quintile showing a 34% lower relative risk (adjusted RR 0.66, 95% CI 0.49-0.90) compared to the lowest. Conversely, high animal protein intake increased risk by 33% (RR 1.33, 95% CI 1.00-1.77), likely due to elevated urinary calcium and acid load. Protective factors included high potassium (from fruits and vegetables; RR 0.49, 95% CI 0.35-0.68) and ample fluid intake (RR 0.71, 95% CI 0.52-0.97). These findings showed that you needed to get enough calcium and potassium to be protective, and warned people that eating a protein-heavy diet was a risk factor for kidney stones.
Nurses’ Health Study Findings
A 1997 analysis of 91,000 women in the Nurses’ Health Study revealed similar patterns: high dietary calcium reduced risk by 35% (RR 0.65, 95% CI 0.50-0.83), while supplemental calcium oddly raised it by 20% (RR 1.20, 95% CI 1.02-1.41)—a nuance later tied to timing and absorption. High sucrose (RR 1.52, 95% CI 1.18-1.96) and sodium (RR 1.30, 95% CI 1.05-1.62) were culprits, but high fluid (RR 0.61, 95% CI 0.48-0.78) and potassium (RR 0.65, 95% CI 0.51-0.84) offered strong protection.
They didn’t comment on high protein diets in this study, possibly because women are not as tempted to follow a high protein diet as men are. This evidence backed up what we showed above as being the pillars of preventing kidney stones: adequate dietary calcium, drinking enough fluids, potassium-rich fruits and vegetables, being aware of sodium, and not too much animal protein.
The Modern Landscape: 2020s Guidelines and Research
Fast-forward to 2025, and the American Urological Association (AUA), European Association of Urology (EAU), and National Kidney Foundation (NKF) echo these 1990s insights almost verbatim. The AUA’s 2019 guideline (reviewed 2025) urges 1,000-1,200 mg daily dietary calcium for calcium stone formers, sodium restriction (<2,300 mg/day), and limiting non-dairy animal protein to curb urinary calcium and uric acid. The NKF’s 2025 plan includes 2-3 quarts (2-3 L) of fluid daily, low-fat dairy for calcium, and potassium-packed produce to boost citrate—a stone inhibitor. These guidelines also call for limiting high oxalate foods if someone is shown to have high urinary oxalate, which isn’t part of the findings from the 90s.
Recent data reinforces this. A 2025 NHANES analysis linked daily citrus, melons, berries, tomatoes, and dairy to 11-22% lower odds of stones (OR 0.78-0.89). The CARI Guidelines (updated October 2025) emphasize an overall whole-foods diet pattern, 2.5 L or more of fluid intake daily, less than <2,300 mg sodium daily, a high calcium intake (1,000 mg daily for people <70 years of age) to decrease the absorption of oxalate by binding to it in the GI tract (calcium oxalate is poorly absorbed), a diet rich in fruits and vegetables, with limited intake of non-dairy animal protein. Overall, the guidelines are consistent between the various groups.
What Hasn’t Changed: A Side-by-Side Comparison
The overlap is striking. Below is a table that distills key factors from the 1990s studies into today’s guidelines, showing how the evidence has held firm.
Dietary Factor
1990s Evidence (RR/OR)
2025 Guidelines/Research Recommendations
Continuity Note
Fluid Intake
High: ↓ risk (Men: 0.71; Women: 0.61)
2-3 L/day; ↓ risk 40-50% if >2.5 L urine
Unchanged cornerstone; prevents concentration.
Dietary Calcium
High: ↓ risk (Men: 0.66; Women: 0.65)
1,000-1,200 mg/day from food; ↓ risk 30-50%
Core protection via oxalate binding; avoid low-calcium traps.
Potassium (Fruits/Veg)
High: ↓ risk (Men: 0.49; Women: 0.65)
Increase for citrate; ↓ risk 10-20% per 1g
Boosts urine pH; now tied to DASH patterns.
Animal Protein
High: ↑ risk (Men: 1.33)
Limit to 0.8-1 g/kg; ↑ risk 10-15% per 25g
Drives acid load; plant alternatives now emphasized.
Sodium
High: ↑ risk (Women: 1.30)
<2,300 mg/day; ↓ urinary calcium 20-50%
Consistent calciuria trigger; processed foods culprit.
Sugars/Fructose
High sucrose: ↑ risk (Women: 1.52)
Limit added sugars; ↑ risk 20-30%
Evolving to include SSBs; ties to obesity surge.
Sources: 1993/1997 studies; AUA/EAU/NKF 2025. RR = relative risk; OR = odds ratio.
The Clarity of Consistent Nutrition Science
The consistency and the stability of this evidence debunk the myth that nutrition science is hopelessly confusing. To prevent kidney stones, decades of cohort studies, such as the Nurses’ Health Study and HPFS, and other studies have shown what works in real life. Yet there are still profiteers who push a high-protein diet and keto diets for weight loss. They say you don’t need to eat vegetables, whole grains are poisonous, legumes contain lectins that are toxic, and animal protein has never been linked to an increase in cancer.
The Fallacy Of Ignoring Prospective Cohort Studies In Favor Of Randomized Controlled Trials
Often, they ignore these population cohort studies, discounting them, saying they don’t meet their criteria. After all, prospective cohort studies give “correlations”, not “causations”. They’re not randomized controlled trials, so some YouTube influencers cross them off their list because they don’t meet a high enough standard of evidence.
But that’s just nonsense because RCTs are not feasible with populations over long periods of time. And since dietary factors work slowly over a person’s life, you need to follow people for a long time to figure out the relationships between food and disease. A six-month randomized controlled trial will never give you this data.
But this science shows that diet and lifestyle can reduce the risk of kidney stones by more than 50%. And we discovered this by conducting prospective cohort studies.
Conclusion: Prevention as Timeless Wisdom
More people may have kidney stones now than 30 years ago, but we still know how to reduce their risk. The message is still unchanged:
- High fluid intake
- Adequate dietary calcium
- Potassium-rich fruits and vegetables
- Moderation in animal protein
- Not adding too much salt
There isn’t one diet for preventing kidney stones and another diet for diabetes, and a third diet for osteoporosis, and a fourth one for arthritis. The same style of eating pattern that is healthy for people addresses all of these things, and much more. Don’t be confused by those who spread confusion for profit’s sake.
Hallelujah Diet has been leading the way in showing people how to eat healthily and how to restore health in their God-given body/temple. We want everyone to be able to complete the mission God has put them on earth to accomplish. And so we urge you to pay attention and make amends so kidney stones are not in your future.
