Flavonoids are natural plant substances found in fruit, vegetables, tea, cocoa and many herbs. They are among the most powerful natural antioxidants and anti-inflammatory agents. This review shows that flavonoids can slow the progression of chronic kidney disease (CKD) and support kidney function.
In chronic kidney disease, oxidative stress, inflammation and damage to the blood vessels play an important role . play a central role. Flavonoids counteract these processes on several levels: They intercept free radicals, inhibit inflammatory messenger substances, improve blood flow to the kidneys and protect the kidney cells from toxins and metabolic breakdown products.
Particularly promising are certain flavonoid groups such as quercetin, epigallocatechin gallate (EGCG) from green tea, naringenin from citrus fruits and anthocyanins from berries. In animal and human studies, these substances have improved kidney function, reduced protein losses in the urine and reduced inflammation in the kidneys.
Conclusion: A diet rich in flavonoids – i.e. lots of fruit, vegetables, berries and tea – or targeted supplements can help to protect the kidneys and slow down the development of chronic kidney disease.
Background
Chronic kidney disease (CKD) is a growing global health problem. It leads to a gradual deterioration of kidney function and is closely linked to inflammation, oxidative stress and metabolic disorders. Current pharmacological therapies can only halt the progression of the disease to a limited extent. For this reason, research is increasingly focusing on plant bioactive substances such as flavonoids.
Flavonoids – structure and properties
Flavonoids are a large group of secondary plant substances with over 8000 known representatives. The most important include
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Flavonols (e.g. quercetin, kaempferol),
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Flavanones (e.g. naringenin, hesperidin),
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Flavones (e.g. apigenin, luteolin),
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Flavanols (e.g. catechins from green tea),
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Anthocyanins (e.g. from berries) and
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Isoflavones (e.g. genistein from soy).
These compounds have strong antioxidant and anti-inflammatory properties and can regulate signaling pathways that are crucial for cell protection, metabolism and regeneration.
Mechanisms of kidney protection
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Reduction of oxidative stress
Flavonoids increase the activity of the body’s own protective enzymes (SOD, catalase, glutathione peroxidase) and reduce reactive oxygen species that damage kidney cells.
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Inflammation inhibition
They inhibit pro-inflammatory signaling pathways such as NF-κB and MAPK and reduce cytokines (TNF-α, IL-1β, IL-6), which are involved in chronic inflammation in the kidney.
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Inhibition of fibrosis
Chronic kidney damage often leads to scarring (fibrosis). Flavonoids block profibrotic factors such as TGF-β1 and thus prevent progressive scarring of the kidney tissue.
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Improvement of endothelial function and blood circulation
By activating NO synthase, flavonoids promote vasodilation and improve microcirculation in the kidneys, which stabilizes oxygen and nutrient supply.
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Modulation of metabolic pathways
They influence signaling pathways such as AMPK, Nrf2, and PPAR-γ, which play a central role in energy balance, insulin sensitivity and inflammation regulation.
Preclinical and clinical evidence
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In animal models, quercetin showed a significant improvement in kidney function and a reduction in urea, creatinine and inflammation levels.
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EGCG from green tea reduced oxidative damage and improved glomerulus filtration.
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Naringenin protected against nephrotoxic substances and inhibited fibrosis.
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In studies, anthocyanins reduced inflammatory markers and improved antioxidant capacity in patients with metabolic syndrome.
Clinical studies in humans are still limited, but show positive trends in blood sugar, lipid and inflammation parameters, which indirectly stabilize kidney function.
Safety and compatibility
Flavonoids are well tolerated in normal quantities. Side effects are rare and usually occur at extremely high doses. Natural consumption via a plant-rich diet is safe and beneficial to health.
Conclusion
Flavonoids represent a promising, natural supplement for for the treatment of chronic kidney disease. Their effects are based on the combination of antioxidant, anti-inflammatory, vasoprotective and metabolism-regulating potential.