Do sweets affect kidney function?

The impact of sweets and sugary foods on kidney health is a common concern. Kidneys play a vital role in filtering waste and toxins from the blood. Consuming too much sugar can put extra strain on the kidneys, potentially leading to problems over time. This article will examine the evidence on how sweets and added sugars affect kidney function and disease risk. Quick answers to key questions include:

– Do sweets directly damage the kidneys? There is no evidence that moderate sugar intake directly damages kidney tissue. However, excess intake can contribute to kidney disease risk factors.

– Does sugar cause kidney stones? High fructose corn syrup has been linked to increased kidney stone risk. Limiting sweets may help prevent recurrent stones.

– Can sweets worsen kidney disease? Added sugars appear to worsen markers of kidney function in those with chronic kidney disease. Reducing sugar intake is advisable for these patients.

– Do artificial sweeteners harm the kidneys? There is no strong evidence that non-nutritive sweeteners like aspartame negatively impact the kidneys.

How do sweets impact kidney function?

The main way that high intakes of sugar impact the kidneys is by contributing to metabolic abnormalities like obesity, diabetes, and high blood pressure. All of these conditions place extra strain on the kidneys and increase the risk of developing chronic kidney disease.

Specifically, added sugars contribute empty calories without nutrients. This can lead to weight gain and obesity, a major risk factor for kidney disease. Obesity also increases inflammation, placing stress on kidney structures.

Diets high in sugar, especially fructose from sources like soda, have been strongly linked to insulin resistance. This reduces the body’s ability to properly regulate blood sugar levels, contributing to type 2 diabetes. Diabetes is the leading cause of kidney failure in the U.S. Uncontrolled blood sugar damages the small blood vessels in the kidneys over time.

Excess sugar may also indirectly contribute to high blood pressure (hypertension). This can damage the delicate kidney filters and small blood vessels. Hypertension accounts for around 25% of chronic kidney disease cases.

So while sweets don’t necessarily directly damage the kidneys, the metabolic effects can burden the kidneys over years and decades. Reducing added sugar intake is widely recommended to protect long-term kidney function.

Do artificial sweeteners affect the kidneys?

Artificial sweeteners like aspartame, sucralose, and saccharin provide sweetness without calories or spikes in blood sugar. There has been some speculation around whether these non-nutritive sweeteners negatively impact kidney health. However, reviews of the evidence have found no clear sign of harm to the kidneys from consuming artificial sweeteners within recommended limits.

A 2010 review looked at studies on various artificial sweeteners, including saccharin, sucralose, aspartame, acesulfame K and stevia preparations. They concluded that these alternatives are safe even for people with chronic kidney problems, including those on dialysis. Another 2022 review also found no convincing evidence that non-nutritive sweeteners cause kidney toxicity or stones.

Overall, there is no strong research linking regulated, non-nutritive sweeteners to direct kidney damage or disease. Switching from sugar to artificial sweeteners may even benefit the kidneys by reducing calories and blood sugar spikes. However, moderation is still advised, as very high intakes of some sweeteners could have unknown effects.

Do specific sugars harm the kidneys?

When it comes to added sugars, all are high in empty calories with risks attached to overconsumption. However, some research has looked into whether certain sugars are worse for the kidneys than others.


Fructose is one type of simple sugar found naturally in fruits, vegetables and honey. It is also commonly added to processed foods and beverages as high fructose corn syrup. Multiple studies have linked high fructose consumption to increased risk factors for kidney disease.

In particular, fructose intake has been associated with:

– Insulin resistance and type 2 diabetes. Diets high in fructose have been shown to impair insulin sensitivity and contribute to fatty liver disease, raising diabetes risk. As diabetes is the leading cause of kidney failure, limiting fructose from processed foods may benefit kidney health.

– Hyperuricemia. Fructose metabolism creates uric acid, which can raise blood levels. Chronic hyperuricemia is linked to gout and kidney stone formation.

– Kidney stones. Fructose can increase uric acid and oxalate in the urine, raising the risk of painful calcium oxalate and uric acid kidney stones.

– Chronic kidney disease (CKD). Several studies have found associations between high fructose diets and worsening markers of kidney function, particularly in those with existing CKD. This may be related to uric acid effects or insulin resistance.

Based on this research, the evidence suggests that added fructose from high fructose corn syrup and processed foods may be among the worst sugars for kidney health. However, naturally occurring fructose in whole foods appears less concerning in moderate amounts.


Sucrose, or table sugar, consists of glucose and fructose bonded together. It provides four calories per gram. Like most added sugars, excess sucrose in the diet is linked to obesity, diabetes, and high blood pressure. Therefore, overconsumption also indirectly raises kidney disease risk through these pathways.

However, sucrose does not appear to have the same direct effects on the kidneys as fructose. For instance, sucrose only raises uric acid levels in people with conditions like gout or metabolic syndrome. Additionally, sucrose does not seem to increase kidney stone risk.

Overall, while sucrose is high in empty calories, it may not have the same level of direct kidney effects as fructose sources like high fructose corn syrup. Still, limiting added sucrose can help reduce the overall risk burden on the kidneys.


Glucose, or dextrose, is a simple sugar and carbohydrate that all cells utilize for energy. It has four calories per gram. Consuming large amounts of glucose can spike blood sugar levels. Chronic hyperglycemia contributes to kidney damage indirectly through promoting diabetes.

However, there is limited evidence that glucose alone directly damages the kidneys or causes kidney stones. For instance, one study found fructose raised kidney stone risk markers in teens, while glucose did not. For kidney health, glucose is likely safer than added fructose when consumed in moderation.


Lactose is the naturally occurring sugar found in dairy products. It is made up of glucose and galactose. There is no evidence linking lactose sugar to kidney problems. Unless an individual has lactose intolerance or avoids dairy, there are no specific kidney-related reasons to limit lactose.

Do sweets contribute to kidney stones?

Consuming high amounts of certain sugars may increase the risk of developing painful kidney stones. The most well-studied link is between fructose and uric acid stones.


Multiple studies have found associations between high fructose intake and kidney stone risk. Proposed mechanisms include:

– Increased uric acid production. Fructose metabolism generates uric acid, raising urine levels. High uric acid excretion saturates urine, leading to uric acid stone formation.

– Low urine pH. Fructose acidifies urine pH, which encourages uric acid and calcium oxalate stone development.

– Higher oxalate. Fructose may boost absorption of oxalate from foods, increasing urine concentrations. High oxalate urine promotes calcium oxalate stones.

– Dehydration. High fructose soda and processed foods have diuretic effects. Chronic low fluid intake thickens the urine, increasing risk of various stones.

Based on this evidence, limiting fructose from added sugars may help prevent recurrent kidney stones in susceptible individuals.


In contrast to fructose, studies on sucrose (table sugar) show mixed results regarding kidney stone risk. Some researchers hypothesize that the glucose component of sucrose may help offset the risks from fructose. More research is needed on the potential stone-forming impacts of sucrose specifically.

Artificial sweeteners

There is limited evidence that non-nutritive sweeteners increase kidney stone risk. Early concerns with saccharin have not been proven. A 2006 study found saccharin could bind with calcium, potentially promoting stone formation. However, human data has not confirmed artificial sweeteners as stone-forming agents. Regardless, those prone to stones should minimize consumption of all sweeteners.

Can cutting sweets improve kidney function?

For those already showing signs of compromised kidney function, limiting added dietary sugars may help slow progression of kidney disease. Small interventions studies have shown promising results:

– A 2014 study had participants with stage 3 chronic kidney disease cut added sugars for 6 weeks. This led to significant improvements in eGFR, a measure of kidney function, vs no change in the control group.

– In a one year study of stage 3-4 CKD patients, a low sugar diet reduced serum uric acid levels and slowed eGFR decline compared to standard dietary advice.

– Among diabetics with albuminuria (early kidney damage), following a low sugar diet for 4 weeks decreased albuminuria by 29% vs 2% for controls.

Reducing added fructose may have particular benefits. One study found just 6 weeks of a low fructose diet in CKD patients lowered serum uric acid, blood pressure, and eGFR compared to controls.

Overall, this research indicates limiting added sugars can support kidney function in those with existing kidney disease. However, long-term studies are still needed. Work with a renal dietician to develop an individualized low sugar nutrition plan.

Takeaway on sweets and the kidneys

There is no evidence sweets in moderation directly damage the kidneys or cause kidney disease. However, excess added sugar intake can indirectly tax the kidneys over time by contributing to obesity, diabetes, hypertension and inflammation. These metabolic conditions are the leading causes of chronic kidney disease.

Fructose, specifically from high fructose corn syrup and sodas, appears most concerning for kidney health. Links are seen with kidney stones, gout, insulin resistance and worsening kidney function markers. For those prone to stones or with existing CKD, limiting fructose may provide benefits.

Overall, enjoying sweets occasionally will not harm healthy kidneys. But a diet high in added sugars, especially fructose, promotes kidney disease risk factors. Reducing sugary food intake, staying well hydrated, controlling weight, and properly managing diabetes are key steps to maintain lifelong kidney function.

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