Is It Possible to Eat Too Much Parsley?

In the culinary world, parsley hovers somewhere between herb and decorative garnish. While appreciated for its ability to add color and texture to foods, parsley is underutilized as a vegetable. It's rich in vitamins A, C, and K.

As with most foods, eating extremely large amounts of parsley might pose some risks. People who have kidney stones or who take the blood thinner warfarin are typically advised to watch how much parsley they consume, whether as an herb or in supplement form. Vitamin toxicity is theoretically possible from eating too much of this herb, but it's unlikely.

Oxalates

For some people, natural plant chemicals called oxalates might cause problems. People with kidney stones or who are prone to kidney stones may want to avoid oxalate-rich foods (such as parsley) based on their doctor's advice, according to Duke Health.

While several types of kidney stones exist, the most common are calcium oxalate stones, Mayo Clinic says. If you have kidney stones and tests show that they belong to the calcium oxalate class, your doctor will likely advise you to consume less oxalate. Save parsley for garnishing foods by the tablespoon, rather than adding heaping amounts to soups or salads.

Vitamin C

If you ate nothing but parsley for vitamin C, you'd have to eat more than 25 cups a day to overdose on the vitamin, according to the U.S. Department of Agriculture (USDA). But eating large amounts of parsley every day, combined with taking in other C-rich foods and vitamin C supplements, could lead to toxicity. Toxicity is often connected to taking large amounts of vitamin C supplements, Mayo Clinic says. A 1-cup serving of fresh, chopped parsley contains 79.8 milligrams (mg) of the vitamin.

As the Merck Manual notes, 2,000 mg of vitamin C daily is the upper limit you should take. Over that amount, people often report nausea and diarrhea, or develop an antioxidant-prooxidant imbalance. If you have certain blood disorders, vitamin C toxicity can cause your blood to collect too much iron, which can lead to tissue damage.

Vitamin K

Parsley contains a high amount of vitamin K, according to the USDA. Chopped parsley contains 984 micrograms (mcg) of the nutrient per cup, over eight times more than the daily value, says the National Institutes of Health's Office of Dietary Supplements (ODS). Yet even large amounts of parsley won't cause a vitamin K overdose, according to the Merck Manual.

Toxicity from menadione, a synthetic chemical that the body turns into vitamin K, is possible. It's unlikely a person would consume menadione, however, as it's no longer used in dietary supplements or fortified foods intended for people to eat.

People taking the blood thinner warfarin should avoid eating excessive amounts of parsley, according to Iowa Health Care. Excessive vitamin K intake from food or supplemental sources can interfere with the medication's effectiveness.

Vitamin A

A 1-cup serving of fresh, chopped parsley contains 253 mcg of vitamin A RAE (retinol activity equivalents), according to the USDA. This is the measurement used to account for different vitamins converted by the body into retinol, the ODS says.

In general, overdosing on vitamin A supplements represents a greater risk than getting too much of it from foods like parsley. According to the Merck Manual, when vitamin A is taken in supplement form, adults who consume more than 1,500 mcg RAE daily are at risk of chronic toxicity, which can cause osteoporosis. Taking drugs that contain large doses of vitamin A, such as isotretinoin (Accutane), during pregnancy may cause congenital disabilities in the fetus.

Ask your doctor if it is safe to eat large amounts of parsley while taking vitamin supplements.