A Spicy Dilemma: When Is Turmeric Bad For Your Kidneys?

Turmeric is an Indian spice that has been a part of Ayurveda medicine¹ for centuries. The active ingredient called curcumin doesn't just give turmeric its yellow color; it comes with various potential health benefits.

Curcumin has antioxidant and anti-inflammatory mechanisms that help with various health issues, including heart conditions, liver disease, and certain inflammation-related chronic diseases.² However, high doses of this ingredient could be harmful to your kidneys and lead to the formation of kidney stones.

How is turmeric bad for kidneys? Let's take a closer look.

How does turmeric work?

Turmeric's active ingredient, curcumin, comes with substantial biological properties. Research³ shows that curcumin can help manage oxidative and inflammatory conditions. It may also help with:

• Rheumatoid arthritis

• Anxiety

• Hyperlipidemia (high cholesterol)

• Metabolic syndrome

• Exercise-induced inflammation

• Muscle soreness

• Diabetes prevention

• Diabetic cardiomyopathy⁴

• Inflammatory bowel disease

• Cancer

• Alzheimer's disease

Curcumin is a polyphenol that belongs to the ginger family. Polyphenols are the most effective antioxidants that you receive from your diet. They protect the body's tissues against oxidative stress.

Oxidative stress⁵ occurs when there is an imbalance between the production and accumulation of oxygen-reactive species (also called free radicals) in your cells and tissues. Generally, oxidative stress is harmful to the human body. It can play an important role in developing such conditions as diabetes, cancer, coronary heart disease, and inflammation.

Curcumin protects your body from free radicals that prevail when oxidative stress occurs. This, in turn, protects your cells from damage.

It's worth noting that while curcumin is the active ingredient of turmeric, its content in this spice is rather low. Curcuminoids (active compounds in turmeric) comprise around 2%–9%⁶ of turmeric. Pure curcumin makes up about 75% of all curcuminoids in turmeric.  

Bioavailability

Due to poor absorption, curcumin has poor bioavailability (how much of the substance can enter your bloodstream). Meanwhile, if a person has rapid metabolism, the therapeutic effect of curcumin is even lower.

However, when combined with other elements, the bioavailability of this ingredient can increase dramatically. For example, when you eat turmeric together with black pepper, the bioavailability of curcumin may increase by an impressive 2000%.⁷

Is turmeric bad for kidneys?

In most cases, taking small doses of turmeric to spice up your food is safe. However, you must consult your doctor if you plan to take curcumin supplements. Besides mild side effects such as headaches, diarrhea, and nausea, curcumin could cause kidney stone formation.

What are the negative effects of taking turmeric?

One of the most important things to remember about this beneficial spice is that it increases urinary oxalate levels.

Curcumin is high in soluble oxalates. These oxalates attach themselves to calcium and create insoluble calcium oxalate, which is responsible for most kidney stones. Around 75%⁸ of all kidney stones are calcium oxalate.

Remember that you don't need to consume large doses of turmeric to face the risk of kidney stones. Supplemental doses can significantly affect urinary oxalate levels and boost the risk of developing kidney stones in susceptible people.

Even when consumed in small doses, turmeric can also cause mild side effects — despite being classified as "generally recognized as safe" by the US Food and Drug Administration. These include:

• Upset stomach

• Acid reflux

• Diarrhea

• Dizziness

• Headaches

Potential health benefits of turmeric

Turmeric, or, to be more precise, curcumin, has a variety of health benefits. Studies⁹ demonstrated its numerous beneficial effects, including:

• Antioxidative. It protects against free radical damage (this can benefit cancer prevention, lower the chances of developing age-related eye diseases, and may prevent heart disease).

• Anti-inflammatory. It reduces inflammation by decreasing histamine levels and possibly by raising the production of natural cortisone.

• Hepatoprotective. Curcuminprotects the liver from numerous toxins, mostly as a result of antioxidant properties.

• Better circulation. Turmeric prevents platelets from binding together (this improves circulation but can prevent clotting).

• Antimutagenic. It can prevent new cancers caused by chemotherapy or radiation therapy.

• Antimicrobial. It can stop the growth of various bacteria, parasites, and fungi.

• Cardiovascular. Curcumin can protect the cardiovascular system by lowering cholesterol and triglyceride levels.

• Gastric. It plays a significant role in treating gastric ulcers. Some gastrointestinal ulcers are caused by a bacterium called helicobacter pylori. Curcumin protects the stomach lining from inflammation caused by this bacterium and prevents the ulcer from occurring.

In addition to health benefits, turmeric can play a significant role in slowing down the aging process. The powerful antioxidant and inflammatory properties of curcumin can postpone the onset of age-related diseases and improve the health status of older people.

Benefits of turmeric to people with kidney problems

While curcumin can cause kidney stone formation, it also has various benefits for people with kidney problems.

Eases chronic kidney disease

A recent study¹⁰ demonstrates that taking curcumin supplements increases the levels of beneficial gut microbes that limit toxic activity. This can be beneficial for controlling chronic kidney disease.  

Curcumin stimulates the production of proteolytic enzymes (enzymes that break down proteins) that help metabolize uremic toxins (indoxyl sulfate and p-cresyl sulfate), both of which contribute to the progression of chronic kidney disease.

When the damage to the kidneys becomes worse, the amount of the above toxins usually increases. However, study participants who took curcumin didn't experience an increase in uremic toxins.

While more studies need to be done to confirm this, there is a good chance that curcumin may slow down the overall progression of chronic kidney disease.

Complementary therapy for hemodialysis patients

People who live with chronic kidney disease require hemodialysis often. This treatment removes waste and water from your blood when your kidneys can't do it properly. Unfortunately, hemodialysis can remove beneficial antioxidants from the patient's body and contribute to oxidative stress.

Given turmeric's anti-inflammatory and anti-oxidative effects, it's possible to use it as a complementary treatment for hemodialysis patients.  

May prevent the progression of polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a hereditary kidney condition that occurs in around 0.1%–0.4% of people worldwide. During the course of the disease, a patient develops multiple growing cysts in both kidneys. When cysts become big, they disrupt kidney function.

Studies¹¹ have shown that curcumin slowed the growth of such cysts in mice. This demonstrates its potential to become a part of the ADPKD treatment.

Overall, curcumin's anti-oxidative and inflammatory properties can benefit many kidney conditions. However, more studies must be done to prove its safety and efficacy for patients with kidney problems.

If you have a kidney condition and want to take turmeric, speak to your doctor about it. The possibility of developing kidney stones can offset the benefits of this spice.

How much turmeric can I consume a day?

According to the World Health Organization,⁵ taking 1.4mg of turmeric per pound (0–3mg per kg) of your body weight per day is safe. However, you should still discuss the dosage with your doctor.

The amount of turmeric you can consume safely depends on your medical history and your predisposition to kidney stones. Even supplemental doses may be harmful to your health. That's why it's imperative to consult a doctor before taking turmeric-based supplements.

If you plan to take curcumin to treat a certain condition, your doctor needs to weigh the pros and cons of such therapy. The amount and duration differ depending on the disease, its progression, and your medical history.

When to consult a doctor

If you are experiencing any of the above side effects after taking turmeric, you should stop using it. Talk to your doctor about possible replacements if you are taking curcumin supplements to complement any therapies.

Turmeric has anticoagulant properties, which means it's a natural blood thinner. People who take Warfarin or other blood-thinning medication should be careful. The combination of turmeric and anticoagulants could result in heavy bleeding.  

You should consult your doctor before taking turmeric supplements if you have:¹²

• Diabetes

• Iron deficiency (turmeric limits iron absorption)

• Gallbladder problems

• Blood-clotting disorder

• Cancer

• Endometriosis or uterine fibroids

More studies need to be done to reveal the efficacy of small doses of turmeric for pregnant women. 

The lowdown 

While it is generally a safe spice, consuming too much turmeric could lead to certain side effects, including the formation of kidney stones. If you are predisposed to kidney stones, you should avoid taking curcumin-based supplements before speaking to your doctor.

Besides a possible negative effect on your kidneys, turmeric can be highly beneficial for people with chronic kidney disease and other health conditions. To ensure you reap all the benefits of this remarkable spice without suffering the side effects, consult your doctor.