According to the U.S. National Kidney Foundationhere are five foods health experts advise avoiding to keep your kidneys healthy:

1. Soda

Soda is one of the major contributors to kidney damage. Packed with sugar—whether natural or artificial—soda offers empty calories that can lead to weight gain. A typical 12 oz. (355 ml) cola contains about 152 calories, and larger servings are even worse.

Studies have linked soda consumption to kidney disease, osteoporosis, metabolic syndrome, and dental issues. Even diet sodas, which are lower in calories, contain artificial sweeteners and additives with no nutritional value.

Replacing soda with water, or infusing it with fresh fruit for flavor, is a healthier option for your kidneys.

2. Processed deli meats

Cold cuts like bologna, ham, and salami are heavily processed and high in sodium, which is used to enhance flavor, texture, and shelf life, according to Healthline. Excess sodium raises blood pressure and damages the kidneys, so it is best to limit their consumption, especially if you have kidney disease or diabetes.

Instead, opt for fresh, lean alternatives like roasted turkey or chicken, and always choose low-sodium, nitrate-free options to better protect your kidney health.

3. Butter

Butter, made from animal fat, is high in cholesterol and saturated fats, which can increase the risk of kidney disease. Margarine is often marketed as a healthier alternative, but it may contain trans fats, which are also harmful.

For healthier options, use oils like canola or olive oil for cooking and spreading. These oils are lower in saturated fat and contain beneficial monounsaturated fats that support overall kidney function.

4. Mayonnaise

Mayonnaise is a calorie-dense food high in saturated fats. One tablespoon of mayonnaise contains about 103 calories. While low-fat or fat-free versions are available, they often contain added sodium, sugar, and preservatives, which are not beneficial for kidney health.

A healthier alternative is plain non-fat Greek yogurt, which is rich in protein and can serve as a creamy, nutritious base for salads without the extra calories and fat.

5. Frozen meals

Frozen or pre-made meals, such as frozen pizza and microwaveable dinners, offer convenience but often contain excessive amounts of sugar, sodium, and unhealthy fats. These processed foods can contribute to the development of type 2 diabetes, which in turn increases the risk of kidney disease.

If you rely on frozen meals, it is important to read the labels carefully. Look for meals that are labeled “low sodium” or “no added sodium,” and avoid those with added sugar, fillers, or preservatives. For a healthier approach, balance these meals with fresh fruits and vegetables.