Written by Lindsay Christensen, MS, CNS, LDN
8 Toxins That Harm the Kidneys and How to Reduce Your Exposure
Our kidneys may be the most underappreciated organs in our bodies, yet their role in maintaining our health is vital. Unfortunately, we face an array of toxins in our modern world that threaten our kidney function. The increasing amount of toxins in our environment and the notable impact of these toxins on our kidneys may partly explain why rates of chronic kidney disease (CKD) are exploding; since 1990, the prevalence of CKD has increased 30% (1) The dramatically increased global burden of CKD is likely due to our growing exposure to environmental toxins and burgeoning rates of chronic conditions, such as type 2 diabetes and hypertension, both of which damage the kidneys. However, well before CKD becomes an issue, subtler declines in kidney function can occur. Read on to learn about eight toxins that harm the kidneys and how you can reduce your exposure to these toxins to protect your kidney function.
The Kidneys: Your Underappreciated but Vital Organs!
Our kidneys regulate several critical bodily functions, including:
- Filtering our blood (an astounding 150 quarts of it daily, to be exact!) helps us rid our bodies of various endogenously-derived and exogenously acquired toxins. Toxins filtered by the kidneys include ammonia, urea, creatinine, toxins from Phase II hepatic detoxification, and heavy metals. (2)
- Helping our bodies maintain a healthy balance of electrolytes, including sodium, potassium, and calcium.
- Synthesizing vitamin D: In the renal proximal tubules of the kidneys, 25-OH vitamin D, the inactive form of the vitamin, is converted into 1,25-OH vitamin D, the active form of vitamin D. (3)
The toxin-filtering effects of the kidneys are significant. Our kidneys engage several processes to filter toxins from our blood and prepare them for elimination in the urine. First, the glomeruli, tiny clusters of looped blood vessels in the kidneys, filter out many small- and medium-sized substances. The proximal tubules of the kidneys harbor active transporters, including multidrug resistance-associated proteins (MRPs) that usher toxins from the blood into the urine. Passive diffusion of some toxins, namely fat-soluble toxins, also occurs in the renal tubules. The kidneys use adenosine triphosphate (ATP), the body’s cellular energy currency, to fuel the active transporters in the kidneys. If the mitochondria of kidney cells cannot produce sufficient ATP, toxin elimination will be compromised. (4)
Despite their critical roles in helping our bodies eliminate toxins and maintain balanced levels of vitamin D and electrolytes, our kidneys are delicate and susceptible to damage induced by toxins. A variety of toxins have been found to adversely impact the kidneys. Let’s discuss some of the most significant toxins that affect the kidneys and how we can reduce our exposure to these damaging compounds.
8 Toxins That Harm the Kidneys and How to Reduce Your Exposure
Many substances that we encounter in our environment are toxic to the kidneys. Furthermore, some foods we eat and even byproducts of bacterial dysbiosis generated within our gastrointestinal tracts can compromise kidney function. In fact, declines in kidney function with age may be due to kidney damage accumulated throughout one’s lifetime in response to the toxin burden one has accrued.
Let’s discuss some of the exogenous and endogenous toxins that can harm the kidneys and how you can avoid these detrimental substances.
Lipopolysaccharide (LPS), also known as “endotoxin,” is a molecule consisting of a lipid (a fat) and a polysaccharide (a carbohydrate molecule) found in the outer membrane of Gram-negative bacteria. When we find LPS in the body, it is commonly derived from Gram-negative bacteria in the gut, such as Escherichia coli (E. coli), Pseudomonas, and Enterobacteriaceae. While it is normal to have a certain level of endotoxin present in the gut, this molecule really starts to cause problems once released into the blood circulation. Once LPS enters the blood circulation, it triggers a chronic inflammatory response by the immune system. Research indicates that this inflammatory response can damage the kidneys. (5)
Levels of LPS are significantly increased in individuals with concurrent type 2 diabetes and chronic kidney disease (CKD) and positively correlated with markers of inflammation, including TNF-alpha, IL-6, and C-reactive protein. In fact, emerging research suggests that the gut-kidney axis, a bidirectional signaling pathway between the gut microbiota and the kidneys, exerts a profound influence over kidney health.(6)
Citrinin is a mycotoxin produced by certain species of harmful molds, including Aspergillus and Penicillium. that is frequently found in the food chain. It is commonly found in grains, including rice and corn, fermented meat products such as salami, and some dried herbs and spices. Citrinin is rapidly absorbed in the gastrointestinal tract and distributed to the kidneys, where it causes cell death in the kidney tubules, altering kidney function. (7)
To minimize exposure to citrinin through food, buy grains and nuts as fresh as possible and seek out options that are grown locally (this leads to the grains and nuts spending less time in storage and transport, where there is the opportunity for mold growth to occur). To avoid citrinin exposure from indoor mold growth, keep your living space at a low humidity level, don’t ignore moldy smells in your home, and regularly check your plumbing system for leaks.
High Blood Sugar (Hyperglycemia)
High blood sugar (hyperglycemia) is a harmful scenario for the kidneys. In fact, hyperglycemia is one of the mechanisms by which type 2 diabetes contributes to the progression of kidney damage in CKD. According to recent research, high blood sugar levels contribute to kidney damage by causing oxidative stress and disrupting mitochondrial energy production in the kidneys. (8, 9)
Chronic hyperglycemia is caused predominantly by poor dietary choices, including eating a diet high in processed carbohydrates (bread, pasta, cereal, cookies, etc.) and added sugars.
Fructose, a sugar (monosaccharide), doesn’t acutely raise blood glucose and causes hyperglycemia. However, this doesn’t mean that fructose is a safe sweetener! In fact, a growing body of research indicates that concentrated fructose from added sugars and processed foods is harmful to the kidneys. (10)
In the standard American diet, fructose is primarily consumed in added sugars, including sucrose (table sugar, which is 50% fructose and 50% glucose) and high-fructose corn syrup (which is 55% fructose and 45% glucose). While we typically think of sugar as harmful to our waistlines, a growing body of research indicates that our kidneys are also harmed by fructose. (11) Fructose consumption depletes cellular energy, ATP, in the kidneys and raises levels of a substance called uric acid. Uric acid builds up and blocks the kidneys from removing waste while also promoting scarring of the kidneys and reducing their function. Fructose intake also increases blood pressure, which can increase pressure in the blood vessels of the kidneys, contributing to kidney damage. Interestingly, fructose consumed through the whole, unprocessed foods, such as fruits, doesn’t have the same effect as fructose from added sugars. The reason fruits don’t harm the kidneys is that the fructose they contain isn’t concentrated; furthermore, fruits also contain antioxidant compounds with kidney-protective effects.
Excessive Sodium from Processed Foods
Excessive intakes of sodium, such as through processed and refined foods, may induce kidney damage by raising blood pressure, which strains the kidneys. (12) In fact, the consumption of ultra-processed foods rich in sodium is strongly associated with declines in kidney function in adults. (13) Omitting processed foods from our diets and instead of eating whole, minimally-processed foods supports better blood pressure regulation and may protect kidney function.
Persistent Organic Pollutants (POPs)
Persistent organic pollutants (POPs) are toxic synthetic chemicals resistant to environmental degradation that persist in our environment. POPs include polychlorinated biphenyls (PCBs), dioxins, and furans; these substances are released into the environment through manufacturing, combustion, and other industrial processes. Recently, even bisphenol A (BPA), a plasticizer commonly found in consumer products such as plastic water bottles and children’s toys, has been added to the POP family of chemicals.
Research indicates that chronic exposure to dioxin (14), PCBs (15), and BPA (16) is associated with a deterioration of kidney function. Dioxin exposure can occur through drinking water contamination and the consumption of meat, dairy, and eggs from farm animals that have been exposed to dioxin. Possible sources of PCB exposure include using old fluorescent lighting or electrical devices made more than 30 years ago, which can leak PCBs when they heat up, and eating food (such as fish and meat) contaminated with PCBs that have leached into the environment. Try the following strategies for reducing your exposure to BPA:
- Get rid of plastic water bottles and food storage containers (such as Tupperware) in your home and replace these items with stainless steel or glass water bottles and glass food storage containers.
- Limit your intake of canned foods, which often contain BPA in the can liner. Focus on eating fresh foods instead.
- Decline paper receipts when you’re at the store, as receipt paper is coated in BPA and can easily be absorbed through the skin when we handle receipts with our hands. If you can’t avoid handling a receipt, wash your hands after handling it.
- If you must use plastic food containers at home, avoid placing them in the dishwasher and microwave, as the heat from these appliances can break down the plastic and cause a release of BPA.
Sobering research suggests that humans consistently consume a frightening amount of plastic – nearly 5 grams per week (an amount of plastic the size of a credit card) weekly. (17) Many of these plastics that we eat, drink, and inhale are microplastics, fragments of plastic less than 5 mm in length.
Microplastics are an emerging toxin of concern for multiple reasons: They are microscopic and nearly impossible to filter out of our drinking water using available filtration technologies, they readily pollute our oceans and waterways, and they are shed from countless consumer products, ranging from plastic grocery bags to microfiber fleece jackets.
While we don’t yet have comprehensive solutions for avoiding microplastics due to their ubiquity in our environment, here are a few ideas that may help mitigate your exposure:
- Avoid bottled water. Invest in a water filtration system at home so you can drink filtered tap water.
- Never heat food in a plastic container.
- Don’t store food in plastic containers.
- Vacuum your home regularly to clean up microplastics deposited in household dust.
- Purchase and wear clothes made with natural materials, such as cotton and wool, rather than clothes made with synthetic fibers such as polyester.
Last but not least, an array of heavy metals can harm the kidneys. Cadmium, a heavy metal released into the environment through smelting and the burning of fossil fuels, is highly toxic to the kidneys and can accumulate in these organs, causing lasting damage. (20) Lead, mercury, and uranium are also nephrotoxic. (21, 22, 23)
The best ways to avoid cadmium exposure are not smoking and avoiding dietary sources of this metal; wheat and rice are significant contributors of cadmium in our diets. (24) Lead exposure is primarily a concern if you live in a home built before 1978 (when lead-based paints were banned), have water pipes that contain lead, or engage in hobbies that involve working with lead, such as doing stained glass work. (25)
Mercury exposure comes primarily from eating mercury-contaminated seafood, having mercury amalgams in your teeth, or exposure to mercury through industrial sources such as living near a coal-burning power plant. (26) Uranium exposure occurs primarily through consuming contaminated food or drinking water. Living near federal government facilities that previously made or tested nuclear weapons or facilities that mine or process uranium increases the risk of exposure to uranium. (27)
Our environment is rife with toxins that can harm our kidneys, necessitating that we take special care of these delicate, vital organs. Now more than ever before, we need to be cognizant of environmental toxin sources and take steps to reduce our exposure. To protect your kidney health over the long term, take care of your gut health, avoid processed foods (especially those with added sugars that contain fructose or spike blood glucose), avoid mycotoxin-contaminated food, and minimize your exposure to environmental toxins as much as possible.