6 Reasons to Avoid Eating Too Much Spinach

Versatile and delicious, leafy green spinach is an excellent source of fiber, protein, and various vitamins and minerals. It is a low-calorie addition to your diet, served raw or steamed. Although not a common problem for the average healthy person, too much spinach may cause some rare negative effects under certain circumstances.

According to USDA National Nutrient Database, a cup of cooked spinach contains 49 calories and provides 5 grams of fiber, important for your digestion. Spinach supplies a whopping 181 percent of the daily value for vitamin K; 56 percent DV for vitamin A; 15 percent DV for folate; and 14 percent DV for vitamin C, according to the National Institutes of Health Daily Values. Spinach also contains the minerals calcium, iron, magnesium, phosphorous and potassium. Eating raw spinach is good for you and a tasty addition to any meal.

Calcium is essential for building bones and teeth. It important to get much of your calcium intake from food, and you want to ensure its properly absorbed by your body. Absorption of calcium may be hindered by a compound called oxalic acid, which occurs naturally in many greens including spinach. Per 110 g, spinach contains 0.97 g of oxalic acid, according to the USDA Nutrient Data Laboratory. Oxalic acid can bind with calcium in your intestines to form oxalates, which are insoluble salts. These salts may interfere with absorption, making calcium unavailable to your body. An in-vitro study published in the International Food Research Journal investigated the effect oxalic acid has on calcium. The study demonstrated and verified that oxalic acid decreases the availability of calcium in all salts tested. According to Vegan-health.org, discarding the water after steaming or boiling spinach can reduce the amount of oxalate you consume.

Because spinach has one of the highest contents of oxalic acid among green vegetables, too much spinach may also play a part in the formation of calcium-oxalate, which forms the most common type of kidney stones. In rare cases, eating extreme amounts of oxalate-rich foods, like spinach, can lead to hyperoxaluria, which is excessive urinary excretion of oxalate. When oxalate crystals combine with calcium in the kidneys, they form kidney stones, says Cedar-Sinai Medical Center. Research done in 2016 by USDA Crop Improvement and Protection Research studied the possibility of breeding spinach for low-oxalate content to reduce the adverse effect of the oxalate compound.

Nitrates occur naturally in many plants such as spinach and don't usually cause a concern in human digestion. However, nitrates can be worrisome under certain conditions, especially for infants. A 2017 scientific study published in the African Journal of Traditional, Complementary and Alternative Medicines, investigated the intake and safety of nitrates in green leafy foods, including spinach. According to the European Food Safety authority standards, the recommended daily intake for a person weighing 135 pounds is 222 mg per day, which is an acceptable amounts of nitrates. However, people who consume very large quantities of vegetables for a long period of time, including vegetarians, could have adverse health effects from nitrates. It was also emphasized that you take caution so children don't eat too much spinach combined with commercial baby food that contains nitrates, because it could lead to methemoglobinemia, a condition caused by elevated levels of a form of hemoglobin says HealthLine.

Healthline warns that many home-prepared solid foods can also have too many nitrates for babies. In addition to spinach, these foods include beets, carrots, green beans and squash. The danger of nitrates is one of the reasons parents are advised not to give babies solid food before they are 4 months old.

Plant foods, such as spinach, contain natural purines that your body converts to uric acid. In some individuals who are susceptible to purine-related problems or people who have hyperuricemia – excess uric acid in the blood – purines in excessive amounts of spinach can cause health problems, according to FamilyDoctor.org. If you can't flush the uric acid out through your kidneys, uric acid levels may raise. The result is crystal deposits of uric acid in joints that cause painful gout symptoms. Pharmacy Times warns that foods high in purine, such as spinach, should not be consumed in extremely large amounts.

Spinach has a very high content of vitamin K, which may interact with certain medications. Do not take the anticoagulant warfarin in combination with spinach, because the vitamin K helps clot blood, which might decrease the effectiveness of warfarin in controlling clotting, reports RXList.com. Medications for diabetes help lower blood sugar, but the vitamin K-1 in spinach might cause your blood sugar to go too low if the two are taken in combination.

Allergic reactions to spinach are rare, but some people are sensitive to the salicylates in spinach. People with a low tolerance may have an allergic reaction, even with a small amount of salicylate, warns WebMed.com. Symptoms of an allergy to salicylates include trouble breathing, itching and skin irritations, swelling in hands and feet, and upset stomach from spinach, including diarrhea, gas and bloating.

You could also experience diarrhea from spinach if you eat it with another high fiber source. Eating too much fiber when your body is not accustomed to it can cause gastrointestinal distress. To avoid this, try to introduce fiber slowly into your regular diet.