Living in the United States, I have rarely thought about the kidneys as an organ.

While the liver and heart are often discussed, the kidneys are an organ that is hard to pay attention to unless they are causing pain.

However, every time I hear about a relative starting dialysis or someone whose kidney function has declined due to diabetes, I realize the truth in the saying that 'once the kidneys are damaged, it's hard to recover.'

The kidneys act like a filter for our body. They filter over 150 liters of blood daily to remove waste, maintain fluid and electrolyte balance, and are involved in blood pressure regulation and red blood cell production. The problem is that the kidneys often show no symptoms until their function has declined by nearly half. This is why they are nicknamed the 'silent organs.'

The biggest causes of kidney issues are diabetes and hypertension. In the United States, a significant number of chronic kidney disease patients lose kidney function due to these two conditions. Prolonged high blood sugar can damage the small blood vessels in the kidneys, and hypertension continuously puts pressure on the glomeruli, which serve as filters. When combined with obesity, smoking, and lack of exercise, the risks increase even more.

One of the most surprising things about living in the U.S. is the portion sizes and sodium content of food.

Just eating one hamburger can already contain a significant amount of salt from the bun, patty, cheese, and sauce. Adding fries and a soda can easily push a single meal's calorie count over 1,000 kcal. Processed foods like frozen meals, canned goods, deli meats, pizza, and chicken are very high in sodium, and frequent consumption can lead to increased blood pressure.

Sugar is also a concern. In the U.S., refillable sodas are easily accessible, and one drink can contain the equivalent of dozens of sugar cubes. Excessive sugar intake raises the risk of obesity and type 2 diabetes, which ultimately puts stress on the kidneys.

Consuming too much protein is another thing to watch out for. The U.S. has a strong steak and barbecue culture, making it common to eat large portions of meat in one meal. While moderate protein is not an issue for healthy individuals, excessive protein intake can burden the kidneys for those with already reduced kidney function.

Surprisingly common pain relievers can also be a cause. Long-term use of anti-inflammatory pain medications like ibuprofen or naproxen for back or knee pain can reduce kidney blood flow and lead to decreased function. In the U.S., these medications can be easily purchased without a prescription, so caution is necessary.

Kidney disease often has few early symptoms. If you notice significant swelling, excessive foaming in urine, sudden high blood pressure, or increased fatigue, it may indicate that the condition has progressed significantly. Therefore, even without symptoms, it is important to regularly check creatinine and eGFR levels through blood tests and look for protein in urine through urinalysis.

I used to drink water only when I was thirsty, but now I consciously try to stay hydrated. I am reducing dining out, increasing my vegetable intake, and trying to eat as few processed foods as possible. I realize that it is much easier to manage my health now than to become complacent just because my health check results are normal.

The kidneys do not fail overnight. Poor eating and lifestyle habits accumulate over years and decades, gradually reducing function. This is especially true in an environment like the U.S., where high-calorie, high-sodium, and high-sugar foods are common. Instead of feeling secure just because you are young, I believe that managing blood pressure and blood sugar from your 30s, along with maintaining regular exercise and healthy eating habits, is the most reliable way to protect your kidneys for a lifetime.