What you can take for your kidneys depends on whether you’re trying to keep healthy kidneys in good shape, slow down early kidney disease, or prevent kidney stones. The good news is that several options, from simple hydration habits to specific supplements and prescription medications, have solid evidence behind them. Here’s what actually works, what to be cautious about, and what to avoid entirely.
Water: The Simplest Thing You Can Take
Staying well hydrated is the most basic and effective thing you can do for your kidneys. Water helps your kidneys flush waste products and prevents the mineral buildup that leads to kidney stones. There’s no magic number that works for everyone. Your needs depend on your age, body size, climate, exercise level, and whether you’re pregnant or ill. The old “eight glasses a day” rule is a rough guideline, not a prescription.
One important exception: if you have advanced kidney disease or are on dialysis, you may need to restrict fluids. When kidneys can no longer produce enough urine, extra water accumulates in the body and can cause serious problems. In that case, your care team will give you a specific daily limit.
Omega-3 Fatty Acids
Fish oil supplements have a meaningful benefit for kidney health. A meta-analysis of studies on omega-3 fatty acid supplementation found that higher-dose fish oil was associated with lower levels of protein in the urine, which is one of the key markers of kidney damage. Omega-3s also appear to reduce the risk of progressing to end-stage kidney disease, likely because they help control blood pressure, a major driver of kidney decline. You can get omega-3s from fatty fish like salmon, mackerel, and sardines, or from fish oil capsules.
Vitamin D
Your kidneys play a central role in activating vitamin D. They contain the enzyme that converts the inactive form (which your skin makes from sunlight) into the form your body actually uses. As kidney function declines, this conversion slows down. Less functioning kidney tissue means less of the activating enzyme, and rising levels of a hormone called FGF-23 further suppress what’s left. The result is that people with even moderate kidney disease are often vitamin D deficient.
Kidney disease guidelines define deficiency as blood levels below 10 to 15 ng/mL and insufficiency as levels between 10 and about 30 ng/mL. If your levels are low and you have early to moderate kidney disease, a standard vitamin D supplement can help. People with more advanced disease may need an activated form that bypasses the kidney’s conversion step, which requires a prescription. Getting your vitamin D levels checked is a reasonable starting point if you’re concerned about kidney health.
Potassium Citrate for Kidney Stones
If your goal is preventing kidney stones, potassium citrate is one of the most effective options. Citrate works in two ways: it directly blocks calcium crystals from forming, and it raises your urine pH (makes it less acidic), which prevents uric acid and cystine stones from developing. It’s available by prescription and is typically taken with meals.
People who form stones often have low citrate levels in their urine, a condition that makes the mineral-rich environment inside the kidney far more likely to produce crystals. Supplementing with potassium citrate corrects this. It’s used for calcium stones, uric acid stones, and cystine stones, with the target urine pH adjusted depending on the stone type. Your doctor can check your urine composition to determine whether low citrate is part of your stone risk.
Eating Less Protein
This isn’t something you “take,” but adjusting your protein intake is one of the most well-studied ways to slow kidney disease progression. When kidneys are damaged, filtering protein waste puts extra strain on the remaining functional tissue. Reducing that workload measurably slows the decline.
For people with moderate kidney disease (and no diabetes), current guidelines from the National Kidney Foundation recommend about 0.55 to 0.60 grams of protein per kilogram of body weight per day. For a 150-pound person, that works out to roughly 37 to 41 grams of protein daily, considerably less than most people eat. If you have diabetes, the target is slightly higher at 0.6 to 0.8 g/kg/day to help maintain blood sugar control.
The evidence is compelling. In one 18-month trial, end-stage kidney disease developed in 27% of patients eating a normal diet compared to just 6% in the group eating restricted protein. The key is maintaining adequate calories while reducing protein, so working with a dietitian is important to avoid malnutrition.
Prescription Medications That Protect Kidneys
A class of medications originally developed for type 2 diabetes has turned out to be remarkably protective for the kidneys, even in people without diabetes. These drugs work by changing how the kidneys filter sugar, but the protective benefits go well beyond blood sugar control. They reduce pressure inside the kidney’s filtering units and lower protein leakage into urine.
The clinical trial results are striking. In major studies, these medications reduced the risk of serious kidney outcomes (including kidney failure, significant loss of function, and death from kidney causes) by 30% to 47% depending on the specific drug and study. One trial in patients with a common type of kidney inflammation called IgA nephropathy showed a 71% reduction in the composite kidney outcome, along with a 26% drop in urine protein levels. These medications are now recommended for people with chronic kidney disease regardless of whether they have diabetes, and they represent one of the biggest advances in kidney care in decades. Your doctor can determine whether you’re a candidate.
What to Avoid
Knowing what not to take matters just as much. Over-the-counter anti-inflammatory painkillers like ibuprofen and naproxen are the most common kidney-damaging medications people take without thinking twice. These drugs work by blocking chemicals called prostaglandins throughout the body, but in the kidneys, those same prostaglandins are essential for maintaining blood flow to the filtering units. Block them, and blood flow drops.
The risk is dose-dependent. Ibuprofen doses above 1,200 mg per day (that’s just three standard over-the-counter pills) have been linked to increased risk of acute kidney injury. Daily use for more than a year raises the risk of chronic kidney disease. Even two weeks of continuous use is associated with a higher risk of kidney damage. For older adults or people with existing kidney problems, the risk is amplified regardless of the specific drug. Acetaminophen (Tylenol) is generally the safer choice for routine pain relief when kidney health is a concern.
Herbal Supplements: Limited Evidence
Astragalus, a root used in traditional Chinese medicine, has shown some promise in small studies of diabetic kidney disease, with improvements in waste product levels and urine protein. However, the evidence is limited to small trials, many conducted alongside conventional treatments, making it difficult to isolate the herb’s independent effect.
Be cautious with herbal supplements in general if you have any degree of kidney disease. The kidneys filter everything you ingest, and many herbal products contain compounds that can accumulate to harmful levels when kidney function is reduced. Some, like aristolochic acid found in certain traditional remedies, are directly toxic to kidney tissue. If you want to try an herbal supplement, discuss it with your doctor first, especially if your kidney function is already impaired.