Consuming green juices has become popular as a strategy to detoxify the body and promote a healthy lifestyle. However, recent scientific studies indicate that excessive intake of oxalate-rich juices could trigger kidney damage and other complications in the urinary tract.

In this article, we will talk about oxalate kidney injury, also known as oxalate nephropathy. We will explain its causes, the risk factors related to excessive consumption of certain foods and supplements, and share recommendations to maintain a healthy balance in the diet.

What is oxalate and why is it relevant?
Oxalate is an anion naturally present in a variety of foods, especially green leafy vegetables (such as spinach and kale), fruits, nuts, and other plant products. Regular consumption of oxalate in moderate levels is usually safe for healthy people, as the body eliminates it primarily through urine.

However, in certain circumstances, excessive intake of oxalate can lead to the accumulation of calcium oxalate crystals in the kidneys, increasing the risk of developing nephrolithiasis (kidney stones) or oxalate kidney injury (oxalate nephropathy).

The significance of oxalate lies in its ability to deposit in the nephron and damage the tubular epithelium, which can cause inflammation and even progress to chronic kidney disease. People with a history of kidney disease or excessive consumption of green juices are especially prone to hyperoxaluria, a condition characterized by elevated urinary excretion of oxalate.

What is oxalate kidney injury? Oxalate kidney injury, also known as oxalate nephropathy, is a form of acute or chronic kidney damage resulting from the formation and deposition of calcium oxalate crystals in the renal parenchyma. This process can lead to inflammation, fibrosis, and progressive decline in kidney function.

Although hyperoxaluria can occur due to genetic causes (primary hyperoxaluria), most cases of oxalate nephropathy arise from excessive dietary oxalate intake, accompanied by other risk factors.

Mechanism of kidney damage
The process begins when the kidney's capacity to excrete oxalate is exceeded. Calcium oxalate crystals form in the tubular lumen, adhering to renal epithelial cells and causing direct toxicity and inflammation. Over time, the inflammatory response leads to fibrosis, tubular atrophy, and progressive kidney failure.

Associated risk factors
Excessive intake of oxalate-rich vegetables: Daily consumption of green juices made with large amounts of spinach, kale or chard can raise oxalate levels above what the body can handle.

High vitamin C consumption: High doses of vitamin C are partially converted to oxalate in the body, which increases the total oxalate load and promotes crystal formation.

Dehydration: Lack of adequate fluid intake reduces urine volume, which concentrates oxalates and increases the risk of crystallization.

Gastrointestinal disorders: Pathologies such as inflammatory bowel disease, bariatric surgery or malabsorption can increase the absorption of oxalate in the intestine, exacerbate hyperoxaluria and increase the risk of kidney injury.

Chronic kidney disease: Patients with underlying kidney dysfunction have a lower capacity to excrete oxalate, leaving them more exposed to crystal formation and tubular damage.

Advanced age and diabetes: Studies indicate a higher incidence of oxalate nephropathy in elderly people and in patients with diabetes, possibly due to alterations in excretory function or changes in the renal microvasculature.

Green juices and excess oxalate
Green juices generally combine fruits and green leafy vegetables rich in beneficial compounds such as vitamins, minerals and antioxidants. However, excessive inclusion of certain vegetables (spinach, chard, beets, kale) can produce an excessively high intake of oxalate. In addition, a typical smoothie, without a calcium balance or proper hydration, can become a vehicle for the appearance of secondary hyperoxaluria.

Myths and realities
Myth: “The greener, the better.”
Reality: Although green vegetables offer essential nutrients, a disproportionate consumption of ingredients high in oxalate could increase the risk of kidney damage.
Myth: “They are perfect for replacing all