Conclusive evidence supporting or rejecting the usefulness of any given nutraceutical is hard to come by. For example, although vitamin E, an antioxidant, has been shown to reduce endothelial dysfunction in CKD patients, it also has been implicated in increasing all-cause mortality.
“The studies and evidence are always evolving,” says Rebecca Wright, editor of Nutraceuticals World, an industry magazine. “Some of these ingredients have been around for 5,000 years. Not everything can be considered in terms of double-blind, placebo-controlled trials—especially in the case of these products.”
The research knife can cut two ways, making someone less of a believer rather than a stronger one. At one time, Dr. Kopple advocated use of the amino acid-derived l-carnitine, which had received a lot of scientific support as a useful nutraceutical in CKD.
He has published several papers on the nutrient, reporting on his own short-term trials that have often yielded benefits. Long-term clinical trials of carnitine treatment in renal failure patients, however, have produced ambiguous results at best. “There has never been a reproducible clear benefit with carnitine as there is with, say, furosemide.”
Those rare individuals with genetic defects involving the carnitine-synthesis apparatus become severely deficient in carnitine—a lethal situation. Carnitine can be a lifesaving substance for them. “So for these rare cases, carnitine could be considered a quintessential nutraceutical,” Dr. Kopple said.
As a clinical consultant and nephrology dietitian for both pre-dialysis and hemodialysis patients, Goeddeke-Merickel has seen patients respond favorably to carnitine and cites clinical studies in which dialysis patients have reported improved quality of life during l-carnitine administration.
Negativity not helpful
CKD patients, in particular, are prone to use nutritional supplements and any other OTC product that promises to help them rebuild muscle and feel more energetic. Therefore, it is imperative for physicians to screen patients for such usage and try to do so with an open mind.
A dismissive attitude from the doctor will not discourage patients from using these products; it may only prompt them to be more secretive about doing so. During hospital admissions for CKD patients, surgeons sometimes see increased bleeding times. Only later do they find out that this may be linked with a nutraceutical or botanical the patient has taken but has not acknowledged to the doctor beforehand, Goeddeke-Merickel says.
Dangerous mixtures possible
The patient may be consuming supplements that contain a dangerous mixture of products. A Chinese herb mixture, for example, can include licorice powder, black pearl, or artemisia (wormwood), all of which can be nephrotoxic. Single-ingredient herbal extracts may be a safer choice, but any ingredient must be reviewed by a doctor, pharmacist, or dietitian, Goeddeke-Merickel says.
To decrease sodium levels, CKD patients may think they should ingest agents with diuretic properties, such as juniper, celery seed, or horsetail. These can be toxic to the kidneys and otherwise harmful.
Furthermore, CKD patients often have other maladies that they may try to relieve with nutraceuticals, such as glucosamine and chondroitin for osteoarthritis. “Just be-cause a nutraceutical isn’t specific to CKD doesn’t mean that CKD patients aren’t using it,” Goeddeke-Merickel cautions.
For example, she often is asked about the safety of fish-oil supplements. Although their cardiovascular benefits have been legitimized by research, these products can potentiate dangerous bleeding problems in CKD patients.