Which Organs Are Filters?

The filtration of waste products, toxins, and metabolites is an important process within the body. The kidneys and liver are the primary organs which serve this purpose. These organs filter blood with varying purposes: the kidneys, to produce urine and control blood pressure, and the liver, to aid in digestion and detoxification. When these filters are not operating as they should, health suffers greatly. The dysfunction of these filtering organs can sometimes have a common thread.

The Liver

Early stages of liver dysfunction are often asymptomatic. When symptoms do manifest, fatigue is one of the most common. Other symptoms can include right upper-quadrant abdominal pain, bloating, nausea, loss of appetite, and jaundice (yellowing of the skin).[1] Various insults including viruses, alcohol, toxins, and genetic factors, amongst others, can impair liver function.[2] One of the most common liver pathologies, affecting approximately 25% of Canadians, is nonalcoholic fatty liver disease (NAFLD).[3]

Nonalcoholic fatty liver disease is often accompanied by metabolic dysfunction, including insulin resistance, dyslipidemia, and hypertension. Despite its increased prevalence amongst obese individuals, NAFLD can still develop in lean individuals.[4] NAFLD has various stages of progression. More severe stages including cirrhosis (scarring) can become irreversible and be accompanied by an increased risk of hepatocellular carcinoma. Abdominal ultrasound and blood testing—including liver enzymes, albumin, ferritin, and complete blood count—can be used to assess liver health.[5]

The Kidneys

Early stages of chronic kidney disease (CKD) are often asymptomatic, and detection occurs during assessment of comorbid diseases. Issues with kidney function, if not asymptomatic, often present as impaired fluid balance.[6] This can include oedema, hypertension, electrolyte abnormalities, increased or decreased urine output, and fatigue. Amongst kidney pathologies, CKD is one of the most common. CKD has various etiologies. Similarly to NAFLD, CKD is most commonly caused by diabetes, hypertension, and obesity, but may also be associated with old age, autoimmune disease, toxin exposure, infection, and stone obstruction. Complications of uncontrolled CKD include cardiovascular disease, anaemia, and bone diseases. Kidney function can be assessed through urinalysis and bloodwork, including eGFR, albumin, and electrolytes.[7]

Lifestyle Medicine

As cardiovascular disease (CVD) and diabetes are two of the most common causes of NAFLD and CKD, preventative measures for these diseases include those which promote cardiovascular health and reduce the risk of insulin resistance. Regular physical activity is a cornerstone of maintaining cardiovascular and metabolic health. Exercise reduces the risk of type 2 diabetes and cardiovascular disease.[8]^, [9] Exercise also helps improve markers associated with NAFLD, including cholesterol, liver enzymes, and intrahepatic lipid content.[10]

Smoking cessation and limiting alcohol consumption can also be useful strategies for reducing the risk of kidney and liver disease.[11]^, [12] In adults aged 20–39 years, it was found that as smoking quantity increases, renal function declines.[13] With smoking cessation, as the duration of smoke-free periods increases, the risk of adverse kidney health outcomes decreases.[14]

Nutrition can also play a role in the risk of cardiometabolic disorders, which can further increase the risk of NAFLD and CKD. The Mediterranean diet, characterized by a high intake of vegetables, fruits, olive oil, nuts, and fish, is well-studied in the context of cardiovascular and metabolic diseases. In addition to reducing overall mortality and cardiovascular events,[15]^, [16] a Mediterranean diet can also reduce the risk of CKD by 10%.[17]

Berberine

Berberine is a compound found in various herbs, including goldenseal and Oregon grape. Berberine is best known for its antimicrobial, hepatoprotective, and blood glucose– and cholesterol-lowering activity.[18] Administered at a dose of 0.5 g two to three times per day for a minimum of three months, berberine used as an adjunctive therapy significantly reduces liver enzymes, total cholesterol, triglycerides, and LDL cholesterol amongst adults with NAFLD.[19]

Nonalcoholic fatty liver disease has also been found to be associated with dysbiosis, an unhealthy imbalance in intestinal bacteria.[20] In an animal model, berberine administration was shown to modify gut microbiota and improve intestinal membrane integrity, thereby exerting protective effects on NAFLD.[21]

Evidence is also suggesting a potential therapeutic role of berberine in supporting kidney health via the “gut-kidney axis.” Microbiome changes can lead to the production of uremic toxins, which are associated with chronic kidney disease and renal failure.[22] In an animal model with CKD, berberine supplementation was found to reduce the production of renal toxins within the intestine and increase butyric acid production,[23] which has renoprotective effects.[24]

Berberine has also exhibited renoprotective effects in humans. Amongst participants diagnosed with hypertension and type 2 diabetes, administration of berberine alongside conventional hypotensive and hypoglycemic agents led to a significant reduction in renal damage.[25] Participants receiving berberine also exhibited significantly reduced levels of inflammation and oxidative stress.[26]

Summary

The organ “filters” within the body serve an important role in health. Both the liver and kidneys are susceptible to damage by metabolic and cardiovascular dysfunction. Various strategies, including lifestyle measures and supplementation, show evidence for potential prophylactic or therapeutic use.

Dr. Jill Northrup, ND

A Toronto-based naturopathic doctor with a passion for health and natural medicines, she values an evidence-based treatment approach and emphasizes patient education and preventative medicine in her practice.

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