Spinach Is Healthy — But It's Not Without Its Side Effects
Updated on October 28, 2025
ON THIS PAGE
ON THIS PAGE
Spinach is one of the healthiest foods to eat. It's loaded with vitamins and minerals but low in calories. It fills you up quickly and can be prepared in a multitude of ways.
However, as with everything else, moderation is key. Eating too much spinach may cause issues like digestive distress and the formation of kidney stones due to its high oxalate content.
Here's what to know about the possible side effects of eating spinach.
Spinach and Kidney Stones
Along with kale, beets, and most nuts, spinach is a kidney stone–forming food. This veggie boasts high levels of oxalates. Too many oxalates in your kidneys increase your risk of kidney stones, especially if you are dehydrated.
Eating high-oxalate foods like spinach and nuts promotes stone formation in people susceptible to them. A high intake of oxalates may lead to calcium oxalate stones, the most common type of kidney stone. This type forms when oxalate concentration is above normal.
If oxalates are a concern for you, you can reduce the oxalate content of spinach by 40 percent by boiling it and then dropping it into ice water. Cooking spinach breaks down oxalates and helps you absorb more calcium, which also lowers your risk of developing stones.
Eating calcium-rich foods like dairy products with spinach can also reduce your risk of forming kidney stones.
Effects of Spinach on Digestion
One serving of raw spinach, about two-thirds of a cup, provides almost 2 grams of fiber. A serving of cooked spinach contains even more fiber.
Fiber promotes digestive health, prevents constipation, and slows sugar absorption into your bloodstream. Too much fiber, on the other hand, can have the opposite effect. Bloating, gas, diarrhea, constipation, stomach cramps, and other gastrointestinal symptoms may occur when you add too much fiber to your diet too quickly.
Some studies suggest that fiber may interfere with mineral absorption. However, the research is mixed. Since fiber is considered safe, no upper intake has been set for it.
The fiber in spinach can help you maintain a healthy weight, suppressing your appetite and keeping your digestive system running smoothly. Some individuals may experience gastrointestinal symptoms. Increasing your fiber intake suddenly, for example, is more likely to cause digestive distress than gradually adding more fiber to your diet.
Spinach and Salicylates
Salicylates are natural compounds found in many plants, including spinach. When you have a sensitivity to salicylates, or if you have an aspirin intolerance, you may need to avoid eating certain fruits and veggies. Spinach, broccoli, chile peppers, cucumbers, and squash have a higher amount of salicylates.
For those with a sensitivity to salicylates, the most common reactions include fatigue, a stuffy or runny nose, sneezing, headaches, skin rash and itching, and stomach upset.
Research suggests that limiting the amount of spinach you eat can lessen these side effects, though more studies are needed.
The Takeaway
- Eating spinach can increase your risk of forming kidney stones if you're susceptible to them. Cooking spinach or eating it with calcium-rich foods like dairy products can help lower this risk.
- When consumed in moderation, spinach is a healthy addition to most diets. Adding too much spinach to your diet too quickly can upset your digestive system. If you experience bloating, indigestion, or other gastrointestinal discomfort, downsize your portions and then slowly increase your serving size.
- People with a salicylate sensitivity or aspirin intolerance may experience fatigue, allergylike symptoms such as a stuffy nose and sneezing, headaches, and stomach upset after eating spinach.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
- Mayo Clinic Minute: What can you eat to avoid kidney stones? Mayo Clinic. March 30, 2023.
- How to prevent kidney stones. Harvard Health Publishing. June 13, 2023.
- Calcium Kidney Stones. National Kidney Foundation. September 2, 2025.
- Branch J. 8 Vegetables That Are Healthier Cooked. Consumer Reports. September 27, 2019.
- 7 Reasons You Should Eat More Spinach. Cleveland Clinic. February 16, 2024.
- Dietary fiber: Essential for a healthy diet. Mayo Clinic. December 11, 2024.
- Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Institute of Medicine. 2006.
- Understanding Salicylate Sensitivity. Academy of Nutrition and Dietetics.
- Salicylate Sensitivity: Symptoms and Management. Cleveland Clinic. June 25, 2025.
Meet Our Experts
Kayli Anderson, RDN
Medical Reviewer
Member of American College of Lifestyle Medicine
Kayli Anderson has over a decade of experience in nutrition, culinary education, and lifestyle medicine. She believes that eating well should be simple, pleasurable, and sustainabl...
Andra Picincu, CN, CPT
Author
Andra Picincu is a certified nutritionist, personal trainer, and content writer with more than 15 years of experience. She holds bachelor’s degrees in psychology and in marketing a...