The Hidden Risks of Herbal Supplements and Vitamins for People With CKD

For people living with a disease, supplements can offer something many are looking for–hope.

"People with chronic diseases are usually looking for something to make it all better,” DeWaal said. “Healthcare professionals should embrace this because they're motivated patients and they want to do something positive for their health."

Instead of immediately discouraging supplement use, de Waal focuses on understanding why a patient is taking a product in the first place.

“Building trust”, she said, “is often the first step toward helping patients make informed decisions.”

One of the biggest misconceptions about supplements is that they have the same testing and oversight as prescription medications.

But that's simply not the case.

"Supplements and herbal remedies don't undergo the same type of stringent research that prescription medications undergo,” Dr. Meaney said. “There aren't clinical trials in thousands of patients to evaluate the effectiveness and the safety of those."

He also pointed out that quality can vary dramatically from one product to another.

"The Food and Drug Administration doesn't regulate these products. So, you're essentially relying on the manufacturer to follow quality and purity standards that they are not necessarily required to do."

That lack of oversight can create problems.

"There has been a lot of research in this area that shows these types of products can be contaminated with heavy metals,” said Dr. Meaney. “Other studies have found that up to 50% of supplements had some type of microorganism growing in them."

For people whose kidneys are already under stress, these contaminants are especially concerning.

Many people also don't realize that supplements can interact with prescription medications.

"Herbal products and supplements can interact poorly with each other and with prescription medications," Dr. Meaney said. "Our dialysis patients in particular take anywhere from eight to twelve prescription medications per day. Kidney transplant patients are pretty close to that in the immediate post-transplant period."

And the consequences of bad drug interactions can be devastating. 

"One of the first reports on this was about an interaction between St. John's Wort and an immunosuppressant called cyclosporine in a transplant patient,” he said. “It decreased the amount of cyclosporine in them, leading to the kidney transplant being rejected."

That's why patients should always discuss supplements with their healthcare team before starting them.

Learn more about herbal supplements and kidney disease. 

What's listed on the front of the bottle isn't always the whole story.

"You have to look at the inactive ingredients as well as the active ingredients in a supplement," de Waal said. "And we're not even sure if they're fully disclosing. For example, it may say preservatives, but that could be a phosphorus additive."

Many people focus on a supplement's advertised benefits but overlook fillers, preservatives, and other ingredients. For people with kidney disease, those hidden ingredients may affect important mineral levels, including phosphorus, potassium, and calcium.

Learn more about nutrients and kidney disease. 

While healthcare providers rarely recommend herbal supplements, vitamins are a different story. 

"We may prescribe vitamin supplements to treat a deficiency. For example, there are people with kidney disease whose vitamin D levels are low,” de Waal said. “They may need a prescribed supplement.”

However, she cautioned against taking vitamins without guidance from a healthcare professional.

"Doctors need to monitor you," de Waal said. "People with kidney disease hold on to things longer, so there is a potential for vitamin levels to get too high.”

Learn more about vitamins and kidney disease. 

When it comes to supporting kidney health, de Waal says nutrition should come before supplements.

"Supplements don't make a bad diet better,” she said. “I'm a food-first person. I feel that it’s important to do your best to get most of the nutrients you need from what you eat."

She also pointed to growing research around plant-forward eating patterns, including Mediterranean-style diets, which may help support kidney health and improve the gut microbiome.

"We're learning more and more about the microbiome and how important it is for people’s overall health,” she said. “We do know that plant-forward eating supports the kidneys and a healthy microbiome.”

Learn more about plant-based diets. 

Both experts ended with the same message: tell your healthcare team about everything you take.

Having honest conversations and seeking guidance from healthcare professionals will help you make safer, more informed decisions about supplements and your kidney health.

Ready to begin your kidney nutrition journey? Get started with NKF’s Nutrition Hub.