You swapped soda for smoothies, started eating spinach salads, and cut back on fried food, but somehow, your doctor says your kidney numbers are off. How is that possible?
The truth is, even foods that seem good for you can quietly strain your kidneys if eaten in excess or without the right balance.
Your kidneys are the body’s natural filters — two fist-sized organs that sit just below your ribs, working 24/7 to remove waste and extra fluid from your blood.1 They also help control blood pressure, balance electrolytes, and keep your bones and heart strong.1
But when kidneys are stressed or damaged, waste starts to build up, and what used to be “healthy” can suddenly become harmful.
Understanding what your kidneys need and what they don’t could literally save your life.
What Your Kidneys Actually Do
Your kidneys filter about 200 quarts of fluid from your blood each day! Most of it is cleaned and returned to your body, while about 2 quarts turn into pee, stored in the bladder until you need to go to the bathroom.2
Inside each kidney are a million tiny filters called nephrons, which remove toxins, balance water and salt, and send waste out as urine.1
Your kidneys are multitaskers. On a day-to-day basis they:
- Filter waste from your blood.2
- Balance electrolytes like sodium and potassium.2
- Regulate blood pressure and red blood cell production.2
- Keep your bones strong by managing calcium and phosphorus.2
But they can only handle so much. Over time, high blood pressure, diabetes, poor hydration, or a high-sodium diet can cause tiny blood vessels in the kidneys to scar. Once that happens, they can’t repair themselves, leading to chronic kidney disease (CKD).2
When Things Go Wrong
Common warning signs include:
- Swelling in ankles, legs, or around the eyes.3
- Foamy or dark-colored urine.3
- Fatigue and shortness of breath.3
- High blood pressure or headaches.3
- Metallic taste or loss of appetite.3
The Unequal Burden in Our Communities
Chronic kidney disease doesn’t affect everyone equally. In the U.S., Black adults are nearly three times more likely to develop kidney failure than white adults.4
Hispanic/Latino communities also face disproportionately high rates of diabetes and hypertension — two major kidney risk factors.4 These aren’t just personal health issues; they’re structural. In fact:
- Neighborhoods with fewer grocery stores make it harder to access low-sodium, fresh foods.4
- Limited access to healthcare means fewer early screenings.4
- Environmental stressors like pollution and unsafe drinking water increase risk.4
That’s why awareness matters. When we know better, we can do better and help each other live longer, healthier lives.
Foods That May Be Hurting Your Kidneys
Even the healthiest diets can go wrong if they’re not kidney-friendly. Here’s what to watch out for and what to do instead.
1. Spinach and Leafy Greens
Why it seems healthy: These foods are packed with vitamins, fiber, and iron, spinach is a superfood staple.5
The hidden risk: Spinach and other dark leafy greens like beet greens and Swiss chard are high in oxalates, natural compounds that can combine with calcium to form kidney stones. If your kidneys are already sensitive, too much spinach can make matters worse.5
Better option: Swap spinach for kale, romaine, or cabbage. These foods are lower in oxalates but still full of nutrients. If you love spinach, lightly cook and eat it in moderation, and drink plenty of water to help flush oxalates out.5
2. Avocados
Why it seems healthy: Avocados are rich in heart-healthy fats and potassium, often recommended for heart and blood pressure support.5
The hidden risk: Too much potassium can be dangerous for people with kidney problems. When kidneys can’t remove excess potassium, levels build up in the blood, leading to irregular heartbeat or muscle weakness.5
Better option: Enjoy smaller portions (half an avocado or less) and balance with low-potassium foods like apples, berries, or green beans.5
3. Protein Powders and Shakes
Why it seems healthy: Protein supports muscle repair and weight management.
The hidden risk: High-protein diets, especially from powders or shakes, can overwork the kidneys, forcing them to filter more waste.6 Over time, this can accelerate kidney decline, especially in people with diabetes or preexisting kidney disease.6
Better option: Aim for moderate protein (about 0.8g per kilogram of body weight per day). Choose plant-based proteins like beans, lentils, and tofu, or blend smoothies with Greek yogurt and fruits instead of powders.
4. Almonds and Other Nuts
Why it seems healthy: Nuts are high in healthy fats, fiber, and protein, which are great for the heart and brain.7
The hidden risk: Nuts, seeds, and nut-based milks (like almond milk) are high in phosphorus and oxalates, both of which can strain the kidneys or contribute to stone formation when levels rise.7
Better option: Enjoy nuts as a small snack (a handful, not a bag), and rotate with unsalted sunflower seeds or pumpkin seeds, which are lower in phosphorus. Avoid overusing nut-based milks and opt for oat or rice milk instead.
5. Coconut Water
Why it seems healthy: It’s marketed as nature’s electrolyte drink that is low in sugar, full of potassium, and hydrating.
The hidden risk: That same potassium content can be too high for anyone with reduced kidney function. Plus, some brands add sodium for flavor balance, creating a double strain on the kidneys.8
Better option: Stick with plain water or infused water (add slices of lemon, cucumber, or mint). If you enjoy coconut water, keep it as an occasional treat, not a daily habit.
Protecting Your Kidney Health
Your kidneys are resilient, but they need care. Protecting them doesn’t mean restriction, it means awareness.
Here’s how to keep them strong:
- Hydrate regularly. Water helps kidneys flush toxins and prevent stones.9
- Watch your blood pressure and blood sugar. These are the leading causes of kidney disease.9
- Limit salt. Most adults eat double the daily sodium limit. Choose fresh foods over processed ones.9
- Don’t overdo protein. Balance plant and animal sources.9
- Read supplement labels. Some contain hidden phosphorus or potassium.9
- Get tested annually. Ask your doctor for a creatinine and eGFR test. These tests measure how well your kidneys are working.9
A Call to Action
Chronic kidney disease is often called the silent epidemic because it shows no symptoms until it’s advanced. But silence isn’t safety, it’s a risk.
Start small: swap one food, read one label, have one conversation with your provider.Your kidneys are working for you every second of every day and now it’s your turn to return the favor.
References
- NIH. (2018, June ). Your Kidneys & How They Work. Retrieved from NIH: National Institute of Diabetes and Digestive and Kidney Diseases: https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work
- NKF. (2024, October 15). Kidney Function. Retrieved from National Kidney Foundation: https://www.kidney.org/kidney-topics/kidney-function
- NKF. (2023, September 11). Chronic Kidney Disease (CKD). Retrieved from National Kidney Foundation: https://www.kidney.org/kidney-topics/chronic-kidney-disease-ckd
- AKF. (2025, September 3). Understanding kidney disease risks: Race and ethnicity. Retrieved from American Kidney Fund: https://www.kidneyfund.org/all-about-kidneys/risk-factors/understanding-kidney-disease-risks-race-and-ethnicity
- Ajmera, R. (2023, November 1). 17 Foods to Avoid With Kidney Disease. Retrieved from Healthline: https://www.healthline.com/nutrition/foods-to-avoid-with-kidney-disease
- Ko, G.-J. K., Rhee, C. M., Kalantar-Zadeh, K., & Joshi, S. (2020). The Effects of High-Protein Diets on Kidney Health and Longevity. Journal of the American Society of Nephrology. doi:10.1681/ASN.2020010028
- NKF. (2025). Nuts and Seeds. Retrieved from National Kidney Foundation: https://www.kidney.org/kidney-topics/nuts-and-seeds
- NKF. (2023, July 1). Is Coconut Water Good for My Kidneys? Retrieved from National Kidney Foundation: https://kidneyhi.org/blog/is-coconut-water-good-for-my-kidneys/
- NKF. (2025). 6-Step Guide to Protecting Kidney Health. Retrieved from National Kidney Foundation: https://www.kidney.org/kidney-topics/6-step-guide-to-protecting-kidney-health
