You might have one: a small box you put in the back of your refrigerator with contents that help to neutralize odors or settle a sour stomach when it’s mixed in water. Do you think about that old-fashioned household staple, baking soda, possibly helping to improve patients recovering from kidney transplants and decrease their risk of cardiovascular disease? Maybe not so much.

And yet that humble substance found in every grocery store – sodium bicarbonate – may be able to do just that by helping to reestablish balance when an individual’s blood acid levels get too high because of difficulty recovering from a kidney transplant or chronic kidney disease.

The imbalance can lead to metabolic acidosis and a host of serious problems, said Dr. Jessica Kendrick, a kidney specialist who practices at the UCHealth Kidney Disease and Hypertension Clinic – Anschutz Medical Campus.

“Metabolic acidosis causes bone disease, protein loss, muscle weakness, progression of kidney disease and increased risk of heart attack, stroke, and other cardiovascular problems,” said Kendrick, who is also a professor at the University of Colorado School Medicine.

A kidney transplant boost from sodium bicarbonate?

Kendrick leads a randomized, blinded study at UCHealth University of Colorado Hospital that tests whether a daily regimen of sodium bicarbonate in pill form can reduce these risks in kidney transplant patients and help to improve function in their new organs.

“Theoretically [sodium bicarbonate treatment] is a simple way to address a cascade of problems,” Kendrick said.

The idea and practice of using sodium bicarbonate to manage acid levels in kidney transplant patients isn’t new, Kendrick said. Studies after the fact have suggested that patients with low bicarbonate levels had an increased risk of kidney transplant failure and cardiovascular problems, she said. But because bicarbonate treatment to decrease acid levels and thus prevent those problems hasn’t been formally studied, it’s not considered a universal standard of care, she added.

New paths of investigation in sodium bicarbonate treatment after kidney transplant

Kendrick noted that an overseas trial studied whether sodium bicarbonate treatment could reduce the risk of metabolic acidosis and decrease graft failure, prevent bone loss and improve mortality in kidney transplant patients. Her study, however, is the first to also scrutinize cardiovascular problems caused by metabolic acidosis, like stiffening of arteries and narrowing of blood vessels. In addition, Kendrick’s team is the only one taking kidney biopsies and studying the tissue for clues to possible biological changes that might be attributed to the sodium bicarbonate treatment.

“We are looking for changes within the tissue that can’t be seen in blood tests alone,” Kendrick said. “No one else is doing that.”

One target of the tissue study is measuring levels of complement activation – a component of the immune system that drives the body’s defense against invading microbes – in recruits who receive the sodium bicarbonate treatment and those who receive a placebo. Complement activation is normally a vital protective process, but an overreaction can cause serious inflammation, which in turn can thicken connective tissue and increase cardiovascular disease risk, Kendrick said.

“Data from animal models has shown that if you give bicarbonate and normalize acid levels, complement activation in the kidneys is turned off,” she said. “We will take tissue to see if that happens in our study patients.”

The five-year study aims to enroll 120 patients (more than 40 have enrolled thus far) and is recruiting patients who have had a transplanted kidney for one year. Half will take sodium bicarbonate pills twice a day for a year, while the others will take placebo pills. The team will follow the recruits for a year, with return visits at three, six and 12 months, and an optional kidney biopsy taken at the beginning and end of the study.

More than one path to lower acid levels in the blood

Kendrick noted patients have another natural way to decrease the acid levels in their blood: eat a predominantly plant-based diet.

“People in the United States generally have more acid in their blood because we eat diets with more animal protein,” she said. “Earlier studies of kidney disease have shown that increasing the amount of fruits and vegetables in the diet has the same effect as taking bicarbonate.”

That’s easier said than done, largely because many patients with kidney disease come from areas of low socioeconomic status, where food deserts and the expense of fresh food make maintaining a healthy diet difficult, Kendrick said. The challenge of designing diets and feeding recruits for her own study made using sodium bicarbonate an easier choice, she added.

“Bicarbonate is readily available and inexpensive,” Kendrick said. “You could take bicarbonate out of the box.”

A chronic kidney disease ordeal

Mike Davis, 73, of Commerce City, was the first patient enrolled in Kendrick’s study and has finished it. He’s helping her to study what could be a relatively simple treatment for improved kidney health, but his struggle with kidney disease has been anything but simple. It began with the father he barely knew.

Davis was only 8 years old when his dad passed away in 1958 from polycystic kidney disease (PKD). The inherited condition causes fluid-filled sacs to develop in the kidneys. With time, the cysts take over space in the kidneys and decrease their ability to filter and remove waste from the blood.

“I didn’t think much of it,” Davis said of learning later in his life that he too had PKD. He went on to study mechanical engineering and manage concrete work on a host of projects in Colorado. He considered himself healthy during a long career that he said featured a grand total of one week of unemployment.

It thus came as a rude surprise in 2006 when Davis’s primary care physician told him after a physical and an ultrasound of his kidneys that he had PKD. Subsequent bloodwork showed that his kidneys had lost a great deal of function. Over the next decade-plus, he saw a kidney specialist regularly, but his disease slowly progressed despite his taking shifting combinations of medicines and participating in two drug trials in an attempt to stave off dialysis.

However, by 2019, Davis said, his estimated glomerular filtration rate (eGFR) – the key measure of the kidney’s ability to filter toxins – was around 15%, or on the brink of failure. That year, after a battery of tests, he got on the list to receive a kidney transplant. That was the good news. The bad news was he would have to join the long national list of people waiting for a donor organ. That meant an estimated six-year wait for a guy who was almost 70 years old.

A health decline and then a deliverance

Davis nearly lost even that slim chance of a donor organ when he endured an aneurysm repair and consecutive brain bleeds on each side of his head while he was on the waiting list. After the procedure to stop the second brain bleed, the team at the UCHealth Transplant Center took him off the waiting list, although he retained his place in line while he recovered.

The adversity didn’t discourage Davis’s family and friends from supporting him. Most notably, his daughter-in-law served as his champion in seeking a live donor – either a family member or an altruistic Samaritan – as a match for a transplant. However, the chances of that effort succeeding grew increasingly remote as time passed. Then the “stars aligned,” as Davis now puts it.

One night, he got an invitation to have some pizza with Andrea Coleman, his wife’s niece. Coleman announced that after months of exhaustive testing at UCHealth, she had been approved as a donor for “Uncle Mike.” On Dec. 2, 2020, UCHealth transplant surgeon and University of Colorado School of Medicine associate professor, Dr. Thomas Bak, successfully performed the surgery.

“It was a miracle I found a live donor,” Davis said three years after Coleman’s selfless act. For her part, Coleman lives a healthy, athletic life with one kidney. She also became and remains a committed advocate for others to consider becoming a living donor. As a Kidney Donor Athlete, she summited Mount Kilimanjaro in 2022.

“She wants people to know you can still lead a normal life with one kidney,” Davis said.

Joining the bicarbonate study to help others with kidney disease

As for Kendrick’s study, Davis said signing up to help others is in his nature. He’s been a hospice volunteer for more than 15 years and participated in the HALT and REPRISE studies of PKD drug treatments despite not expecting that he’d get much help personally from either one.

His first question when Kendrick’s team called him was: “How much blood are you going to take? I’ve seen a lot of needles.” When he asked what drug he was going to take and learned it was sodium bicarbonate pills, he said, “Is that it?” He remembered he’d gotten bicarbonate treatment before his transplant.

Davis readily agreed to participate and followed his daily regimen of taking two pills per day, not knowing whether he was receiving bicarbonate or a placebo.

But that wasn’t really the point of participating, he said.

“I certainly hope the study turns out to be something positive,” Davis said. “I grew up without a father because of [kidney disease]. That’s been a regret that I never got to know my dad. Joining the study seemed like a thing I should do.”

For more information on the study, contact Rachael Reddin [email protected] or 303-724-7789.