Associate Professor, Doctor Nguyen Bach, Head of the Nephrology - Dialysis Department at Thong Nhat Hospital, explains that kidneys are responsible for eliminating toxins, including salt (sodium). When the body consumes too much sodium, the kidneys must intensify their activity to filter and excrete the excess salt. An organ that is consistently overworked over an extended period will gradually decline in function, making a high-salt diet a significant risk factor for kidney failure. Additionally, a diet high in salt also raises blood pressure, further damaging the kidneys.

According to Doctor Bach, not only the glomeruli but the entire kidney filtration system is strained when the body's sodium levels are elevated. More blood flows to the kidneys for filtration, and the renal tubules also work harder to excrete salt. If this continues for many years, the glomeruli will become overactive, enlarge, then scar, ultimately leading to impaired function.

Kidney damage occurs subtly

Associate Professor Bach emphasizes that a high-salt diet does not immediately damage kidneys after a few meals. The danger lies in maintaining this habit for many years. He likens the process to someone constantly pushing their body to overwork; initially, the body might cope, but in the long run, it will become exhausted.

To illustrate, the doctor compares it to a football match with 11 players. If one player receives a red card early in the game, the remaining 10 players can continue, but they must exert themselves for over 80 minutes and will quickly tire. Conversely, if a player is sent off only a few minutes before the end, the team can still manage. Similarly, short-term kidney overload typically does not cause significant consequences, but if the kidneys must process excess salt daily, the risk of functional decline is unavoidable.

Many people do not realize they are consuming too much salt because taste buds adapt over time. Newborns, accustomed to the very mild taste of breast milk, gradually develop a preference for stronger flavors as they grow and consume increasingly seasoned food.

"Eating salty food becomes a habit, and without salt, it doesn't taste good," he says, noting that a high-salt diet is similar to smoking or coffee consumption in how easily it forms a habit and how difficult it is to quit.

Many people cannot do without a salty dipping sauce at meals. Illustration: Bui Thuy

Reducing salt lowers cardiovascular risk

Beyond its impact on the kidneys, excess salt directly affects the cardiovascular system by increasing blood pressure. According to Doctor Bach, studies show that merely reducing salt intake can lower blood pressure by about 10-20 mmHg without medication. This is a significant reduction, contributing to a decreased risk of cardiovascular complications and protecting kidney function.

The burden of kidney disease in Vietnam is also increasing. Surveys indicate that about 12,8% of Vietnamese adults suffer from man tinh kidney disease, equivalent to nearly 8,7 million people, but most are unaware of their condition because it progresses silently. Many cases are only detected at late stages, requiring dialysis or kidney transplantation.

Associate Professor Bach states that man tinh kidney disease is becoming more common due to various factors like population aging, diabetes, hypertension, obesity, and unhealthy lifestyles. A high-salt diet is just one factor, but it is very prevalent as it appears daily in meals. Not only salt in seasonings, but also many processed foods, preserved foods, or high-protein foods increase the burden on the kidneys.

End-stage kidney failure patients undergoing dialysis at Thong Nhat Hospital. Photo: Phung Tien

No early warning signs

Kidney damage from a high-salt diet progresses silently, offering almost no early warning signs. Many people only discover the disease after significant kidney function decline. One of the more common signs is increased blood pressure, but many are complacent, attributing it to stress, late nights, or fatigue, and thus do not seek medical checks.

To prevent the disease, Associate Professor Bach recommends annual health check-ups, including a urine test, which is a simple yet valuable screening method. Individuals with diabetes, hypertension, obesity, a high-salt diet, or a family history of kidney disease need closer monitoring.

Remember to drink plenty of water, starting the day with a 300 ml glass immediately upon waking to help cleanse the body. Maintain a healthy diet, limiting salty foods. Increase physical activity. Avoid stimulants, do not smoke, and limit alcohol consumption.

According to the doctor, no tricks or foods can substitute for reducing salt. To change taste preferences, salt intake must be gradually reduced to allow taste buds to adapt, similar to quitting smoking or coffee. "Salty food only provides temporary palatability. When recognizing this as an unhealthy habit, everyone should proactively moderate their intake to protect their kidneys and cardiovascular health," he says.

Le Phuong