We frequently get asked about the safety of certain herbal medicines as people have heard from their doctor or read on various websites that herbs shouldn’t be taken if you have CKD.
One specific herb we often get asked about is Urtica dioica or Nettle leaf. It usually goes something like this: ‘Why are you recommending Nettle leaf when it’s dangerous for people with kidney disease?’ And I guess there are two answers to that question. The first being that we wouldn’t recommend ANYTHING that was dangerous for people with CKD. The second answer is there is NO EVIDENCE that Nettle leaf is dangerous for people with CKD and in fact, the opposite is actually true- Nettle leaf can be beneficial for people with CKD.
Now, don’t get me wrong, I am completely supportive of people questioning the information they are reading or being told. After all, we are all responsible for our own health and wellbeing and part of that includes asking questions and making decisions about what we are putting into our body- from food, to medications, to supplements.
One of the amazing things about the internet is that there is so much information right at our fingertips. And one of the negative things about the internet is that there is so much information right at our fingertips.
So how do you sort through what’s true and what’s not?
That’s probably a question for another day or else I might find myself going off on a bit of a tangent here but one thing to ask is where is the evidence for what I am reading (or being told). And here’s the thing, I searched for evidence showing that Nettle is ‘risky’ for people with kidney disease (as certain websites state) and I couldn’t find it anywhere.
Read on if you’d like to know what I did find.
Firstly though, let’s start at the beginning.
What is Nettle?
Nettle, or Stinging Nettle, is a shrub that comes from northern Europe and Asia. Its scientific name is Urtica dioica. The plant has a long history of use as a source for traditional medicine, food, tea, and even textile raw material. The leaves and roots are most commonly used for medicinal reasons but it’s important to know that they have different actions so can’t be used interchangeably. This article is going to be discussing Nettle leaf which is the form of stinging nettle shown to have benefits in kidney disease.
Nettle leaf was traditionally regarded as a blood purifier, a styptic (stops bleeding), a stimulating tonic, and a diuretic. It was used to treat diarrhea, arthritis, discharges, chronic diseases of the colon, chronic skin eruptions, and urethral and bladder irritation.
Actions of Nettle leaf include:
- Stops bleeding
- Blood sugar lowering
- Alterative- has a purifying and detoxifying effect and aids in the clearance of metabolic waste
Nettle leaf in Kidney Disease
So why do we recommend people with CKD use Nettle leaf?
Let’s take a closer look at some of the actions of Nettle leaf that make it a beneficial herb for people with kidney disease.
Nettle leaf has diuretic properties which means that it may help the kidneys get rid of excess fluid from the body. This has benefits when it comes to helping to relieve edema (swelling), can help to lower blood pressure, may help to prevent urinary tract infections by preventing bacteria from adhering to the wall of the bladder or urinary tract, may reduce the risk of kidney stones developing and can be beneficial for inflammatory conditions of the urinary tract.
By increasing diuresis, the removal of metabolic products and toxins from the body may also be increased, alleviating the excess load on the kidneys.
Blood Pressure Lowering
Multiple animal studies have shown that Nettle leaf can lower both systolic and diastolic blood pressure. This blood pressure-lowering effect is likely related to Nettle leaf’s diuretic properties however animal and test-tube studies also show that Nettle leaf may lower blood pressure by stimulating nitric oxide production which acts as a vasodilator. Vasodilators relax the muscles of the blood vessels, helping them widen and therefore lower blood pressure.
Also, Nettle has compounds that may act as calcium channel blockers, which relax your heart by reducing the force of contractions, resulting in lowering blood pressure.
If you asked a herbalist to list off some key antioxidant herbs, Nettle leaf probably wouldn’t top their list, but it turns out that maybe it should!
As more research into the actions of Nettle leaf has been conducted, we now know that Nettle leaf has a powerful antioxidant activity. It increases levels of antioxidants within the body such as glutathione and it also increases the activity of our bodies own endogenous antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT).
Oxidative stress has a critical role in the pathophysiology of kidney disease, and many complications of kidney disease are mediated by oxidative stress, oxidative stress-related mediators, and inflammation.
One study that really highlights Nettle leaf’s protective effect on the kidneys was an animal study assessing the effect of Nettle on kidney toxicity induced by the nephrotoxic antibiotic gentamicin. This study found that nettle extract protected the animals from alterations in the level of blood urea nitrogen (BUN) and serum creatinine and when sections of their kidneys were examined, the group treated with Nettle showed almost normal kidney tissue compared to the group given gentamicin alone. This protective effect of Nettle was attributed largely to its antioxidant activity.
Nettle leaf has historically been used to treat pain and sore muscles and is frequently recommended in the treatment of arthritis because of its anti-inflammatory actions.
As you may have heard me discuss before, inflammation is common in people with CKD and is involved in both the development of CKD and its progression. The degree of inflammation is related to the level of kidney dysfunction and is also linked to the presence of other symptoms (like proteinuria, osteoporosis, protein energy wasting) and conditions that are related to kidney disease like cardiovascular disease.
Over time, inflammation leads to damage and scarring in the kidneys so addressing inflammation needs to be a key consideration when it comes to protecting and healing the kidneys as well as reducing the risk of other conditions related to kidney disease.
Numerous studies have shown that Nettle leaf can cause a significant reduction in inflammation, shown both by a reduction in levels of various inflammatory cytokines within the body and a reduction in inflammatory related pain in conditions like arthritis.
Research shows us that IL-1, IL-6, IL-1ß, and TNF-a are some of the key cytokines that contribute to kidney damage. Nettle leaf has been shown to lower the levels of these specific inflammatory cytokines (among others) within the body.
Protects against kidney stones
As I mentioned earlier, Nettle leaf may also reduce the risk of kidney stones because of its diuretic properties but also because animal studies have shown that treatment with Nettle leaf was found to decrease elevated levels of urinary calcium, oxalate and creatinine and significantly decrease the deposits of calcium and oxalates in the kidneys.
In one specific study, Nettle leaf actually dissolved calcium oxalate kidney stones in rats, supporting previous reports that it may be beneficial for the treatment of kidney and urinary tract disorders.
Protective effect on renal injury
An animal study was performed that tested the protective effect of Nettle on renal ischemia-reperfusion injury following kidney transplantation. Renal ischaemia-reperfusion injury is caused by a sudden temporary impairment of blood flow to the kidneys and is associated with a strong inflammatory and oxidative stress response causing severe injury to the kidneys.
The study concluded that Nettle attenuates renal injury and has a protective effect against renal damage. Researchers believe the protective effect is due to Nettle inhibiting renal damage, apoptosis, and cell proliferation.
Supplementing with Nettle leaf
If looking to supplement with Nettle, first make sure you are purchasing Nettle leaf not Nettle root as each form of the herb has distinct therapeutic actions. Secondly, we recommend Nettle leaf be taken as a tea which makes it an easy addition to your current supplement regime.
When making your Nettle leaf tea, add one teaspoon to boiling water and drink one to two cups a day.
As always, we recommend discussing any new herbs with your healthcare practitioner before starting on them.
For those who are taking blood pressure-lowering medications please be aware that drinking Nettle leaf tea may have an additive effect so care may need to be taken and I would recommend monitoring your blood pressure when starting on Nettle leaf.
Also, because Nettle leaf has a diuretic effect it may need to be avoided in people already taking pharmaceutical diuretics.
Hopefully, I’ve given you a better understanding of why we recommend Nettle leaf as part of our Kidney Disease Solution Program and have allayed any concerns you may have had from being told that Nettle should be avoided by people with CKD.
If you’ve found this article useful, please let me know by clicking the ‘SHARE’ button below and head over to our Facebook page if you’ve got any questions or comments.