You might be surprised to learn that arsenic is micromineral naturally found in our food and in the soil. However, in higher amounts, arsenic is a toxic heavy metal. Even though arsenic poisoning is lethal, it’s important to realize that lower-level chronic exposure to arsenic can negatively impact kidney health. In this blog, we will discuss arsenic and kidney health
By Majd Isreb, MD, FACP, FASN, IFMCP
Arsenic and Kidney Health
Exposure to Arsenic has been associated with increased risk for cancer, and it is also linked to kidney disease. In this blog, we discuss the sources of arsenic exposure, how our body handles arsenic, its effects on the kidneys, and the genetic and epigenetics of arsenic.
Sources of exposure
Drinking water appears to be the greatest source of arsenic exposure worldwide. In addition, exposure from ingested foods comes from food crops grown in arsenic-contaminated soil or irrigated with arsenic-contaminated water. Even if the water you drink is filtered and does not have arsenic, it is possible that the food that you eat is contaminated with arsenic, particularly rice. Arsenic is also found in high concentrations in cigarettes.
Found naturally in the environment, arsenic is mobile and cannot be destroyed. When arsenic compounds interact with oxygen or other molecules or bacteria it changes into different forms that can dissolve in water. Cosmetics and personal care products are another often overlooked major source of exposure.
How our body detoxifies arsenic
After ingestion or exposure, arsenic is metabolized and detoxified by a process called methylation. An enzyme called arsenic methyltransferase (AS3MT) adds a methyl groups to arsenic compounds to help neutralize it and eliminate it. This enzyme has been detected in human liver, kidney, bladder, heart, lung, testes and adrenal glands. Glutathione, known as the master antioxidant also plays a key role in arsenic detoxification.
The various arsenic forms bind to glutathione. The compound arsenic-glutathione can easily exit the cells and circulate in the blood. The glutathione-bound arsenic compound can be excreted by the kidneys or in the bile. The kidneys are the major site of elimination of arsenic and they are, therefore, highly exposed to it. Arsenic can also accumulate in the kidneys. Many transporters have been implicated in arsenic excretion in the tubules portion of the filtering units of the kidneys (the nephron). Inhibition or genetic changes in these transporters can lead to enhanced arsenic toxicity.
Interestingly, the water channel, aquaporin 3, has been found to increase the uptake of arsenic in the kidneys. These channels play a crucial role in water handling by the kidneys. They help our body preserve water. Increasing water intake decrease the incorporation of these channels to the cells of the tubules in the kidneys. Therefore, increasing filtered water intake can help decreasing the kidney exposure to arsenic.
Finally, a transporter called multidrug resistance transport protein 2 (MRP2) transport arsenic-glutathione complexes and excrete them out of kidney cells into the urine. Studies show that the increase in the production of glutathione and MRP-2 increase the body’s ability to detoxify arsenic. Selenium is important for this process and selenium deficiency can enhance arsenic toxicity.
Arsenic effects on the kidneys
Acute exposure of the kidneys to toxic levels of arsenic leads to inflammation in the tubules of the kidneys. This can lead to protein loss in the urine. It can also lead to elevated calcium levels in the blood. Arsenic exposure activates cell growth can lead to cancer. Arsenic can also lead to oxidative stress and cellular injury. Arjunolic acid (an anti-oxidant which is present in fruit specially guava) was found to decrease the toxicity of the arsenic on the kidneys. Zinc is also protective. Chronic exposure can lead to high blood pressure, protein loss in the urine, and chronic kidney disease.
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Genetics and Genomics Impact on Arsenic Toxicity
You can now see that various processes are involved in the handling of arsenic by the body from detoxification to transport to elimination. Genetic variants of any of these steps can either be protective or can increase arsenic toxicity. For example, a single nucleotide polymorphism (SNP), or genetic mutation, that increases glutathione production can be protective since glutathione helps to eliminate arsenic safely. However, a SNP in the gene that codes for MRP2 may potentially decrease arsenic excretion leading to increased toxicity.
Arsenic accumulation and toxicity can lead to oxidative DNA damage. It also inhibits DNA repair. This explains the increased risk for cancer after exposure to arsenic. Chronic exposure to even small concentrations of arsenic can have synergistic effect on other factors that can cause cancer such as UV light and smoking.
Arsenic exposure can cause indirect DNA damage through processes of DNA methylation and histone acetylation. These altered epigenetic expressions have been linked to kidney inflammation and damage. More recently, it was noted that long term exposure to low level of arsenic (below what is considered safe by the EPA guidelines) were associated with epigenetic changes that caused kidney scarring.
[bctt tweet=” it was noted that long term exposure to low level of arsenic (below what is considered safe by the EPA guidelines) were associated with epigenetic changes that caused kidney scarring.” username=”inkidney”]
The Bottom Line
Most arsenic exposure is due to drinking and showering with unfiltered water. Arsenic exposure leads to extensive cellular damage which increases the risk for cancer and kidney disease. Nutritional deficiencies can enhance its toxicity, but you can take steps to reduce your risks.
- Choose a home filtration device that effectively removes heavy metals, including arsenic. Not all consumer filters will remove arsenic, consider upgrading to Clearly filtered, Multipure and Aquasauna water filter systems.
- Always choose organic produce whenever possible, However, when it comes to rice and teas – organic isn’t enough. Look for products that screen for arsenic levels.
- Antioxidants are protective against arsenic damage, so a diet high in antioxidants like citrus fruit, green tea, blueberries, and dark chocolate will be naturally protective. Enhance detoxification by eating dark leafy greens, cruciferous veggies (like broccoli, kale, and cabbage), and sulforaphane-rich foods like garlic and onion contain high concentrations of nutrients that increase our detoxification capacity.
- Load up on fiber and mineral-rich root veggies, which help trap and eliminate toxins through your digestive system.
- There are several lifestyle modifications that can support improved detoxification, including Epsom-salt baths, sauna, lymphatic massage, sweat-inducing workouts, and dry brushing.
- If like many Americans you’re not having consistent daily bowel movements, you’re not adequately detoxifying and should consider working with a healthcare provider to address your digestion and motility.
Foot Note:
There are different forms of arsenic compounds. There are organic and inorganic forms with different oxidation states. The inorganic forms are easier to absorb by the gut and, therefore, are more hazardous. The most commonly ingested inorganic compounds are the trivalent and the pentavalent forms (depending on the level of oxidation). The trivalent forms appear to be the most toxic.
