Watercress is a dark, leafy green that grows in natural spring water. Historically, people have used watercress as little more than a garnish. Now, however, it is seeing a resurgence in popularity as one of the latest superfoods.

Watercress is an ancient green that may have been a staple in the diet of Roman soldiers. It is also a member of the cruciferous family, alongside kale, broccoli, arugula, and Brussels sprouts.

Its newfound popularity is partly due now to a growing awareness of its dense nutritional content.

In this article, we explain the benefits of watercress, give a breakdown of its nutrients, and clarify its potential health risks for certain individuals.

We also provide ideas to help people incorporate more watercress into their diet.

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Watercress may have protective effects against cancer.

Consuming all types of fruits and vegetables, including watercress, has links to better overall health.

According to a 2019 review of studies, eating a range of fruits and vegetables can reduce inflammation and the risk of chronic diseases.

As a consequence of this, these food groups also seem to decrease the risk of premature mortality and disability.

Cancer prevention and treatment

A 2019 review showed that a compound in cruciferous vegetables that scientists call 3,3′-diindolylmethane (DIM) has protective effects against cancer.

Recent research in test tubes and animals has concluded that eating a lot of cruciferous vegetables has an association with a lower risk of triple-negative breast cancer and bladder cancer.

Studies have suggested that a compound called sulforaphane is also what gives these vegetables their beneficial effects against cancer. This is a compound that contains sulfur and gives cruciferous vegetables their bitter taste.

Authors of a 2015 test tube study found that sulforaphane can inhibit the activity of the enzyme histone deacetylase (HDAC) in some cancer cells. HDAC can contribute to cancer progression.

The ability to interfere with HDAC enzymes could mean that foods containing sulforaphane potentially support cancer management. Further investigation is necessary, however.

Lowering blood pressure

People who do not consume enough calcium, magnesium, and potassium in their diets are more likely to have high blood pressure.

These minerals are thought to bring blood pressure down by releasing sodium from the body and helping arteries dilate.

It is important to note that taking these minerals in supplement form will not provide the same health benefits as consuming them as part of a healthful diet.

Watercress contains all three of these healthy minerals and can help improve intake.

According to a 2013 study published in the British Journal of Clinical Pharmacology, foods containing dietary nitrates such as watercress have multiple benefits for the blood vessels.

These benefits include reducing blood pressure, inhibiting the buildup of platelets, and preserving or improving endothelial dysfunction.

In general, research has shown that a diet containing all types of fruits and vegetables may help a person maintain healthy blood pressure.

Maintaining healthy bones

A low intake of vitamin K can increase an individual's risk of bone fracture.

Adequate vitamin K consumption improves bone health by modifying the proteins that form bone, improving how the body absorbs calcium, and reducing the amount of calcium that a person loses in their urine.

Eating just one cup of watercress a day would help a person meet their daily requirement of vitamin K.

Watercress is also a good source of calcium, which further supports bone development and strength.

Treating diabetes

Watercress contains the antioxidant alpha-lipoic acid. This compound can:

  • lower glucose levels
  • increase insulin sensitivity
  • prevent oxidative stress-induced changes in people with diabetes

Studies on alpha-lipoic acid have also shown that it can decrease nerve damage in people with diabetes. The Food and Drug Administration (FDA) has approved supplementary alpha-lipoic acid to treat diabetic neuropathy. However, its effects in the diet are still unclear.

A 2019 study on 60 women with gestational diabetes found that daily supplementation of alpha-lipoic acid reduces several markers of the condition.

A 2019 study on 135 participants with type 2 diabetes found that a 600 milligram (mg) dose of alpha-lipoic acid significantly reduced many signs of the condition.

However, most studies on alpha-lipoic acid used intravenous doses. There is uncertainty whether consuming alpha-lipoic acid in the diet provides the same benefits.

Read more on the 10 best foods for managing diabetes.

Providing dietary nitrates

Watercress, along with beetroot and other leafy greens, contains a very high level of dietary nitrate, which increases nitric oxide and can have positive effects on health.

A 2019 study on rats showed that a high intake of dietary nitrate could lower blood pressure.

A study of the effects of a high dose of dietary nitrates on humans demonstrated that it may reduce the amount of oxygen a person needs during exercise and enhance athletic performance.

However, another study found that a moderate intake of dietary nitrates does not appear to have the same effects on exercise. Other studies found that watercress does not improve exercise performance.

Further research in this area is necessary to confirm the benefits of dietary nitrates.

According to the United States Department of Agriculture's FoodData Central database, 1 cup of fresh watercress weighing about 34 grams (g) contains less than 4 calories.

A single cup of watercress also provides:

  • 0.782 g of protein
  • 0.034 g of fat
  • 0.439 g of carbohydrate
  • 0.17 g of fiber

Consuming 1 cup of watercress can also help a person get the following nutrients:

  • vitamin K
  • vitamin C
  • vitamin A
  • calcium
  • manganese
  • potassium
  • vitamin E
  • thiamin
  • riboflavin
  • vitamin B-6
  • magnesium
  • phosphorus

People most consume watercress in salads. However, a person can also incorporate watercress into pasta dishes, casseroles, and sauces.

Watercress will sauté faster than tougher greens such as kale and collard greens because of its tenderness. It lends a mild, slightly peppery taste to any dish.

Choose watercress with deep green, crisp leaves, and no signs of wilting. People should store it in the refrigerator and use it within a few days of purchase.

Ways to include watercress in the diet include the following:

  • Throw a small handful into your favorite fruit juice or smoothie.
  • Add watercress to your next omelet or egg scramble.
  • Make a pesto using watercress.
  • Chop watercress and add it to pasta sauce.
  • Sauté watercress in a small amount of extra virgin olive oil and season it with ground black pepper and freshly grated Parmesan cheese. Eat it as a side dish or as a topping for a baked potato.
  • Add watercress to any wrap, sandwich, or flatbread.
  • Mix watercress into soup near the end of cooking.

Here, learn more about kale, a similar green vegetable.

For individuals managing a blood clotting disorder with blood-thinning medications such as warfarin, it is important not to change their intake of vitamin K suddenly.

This is because vitamin K has an essential role in blood clotting and can interfere with some medications, including warfarin.

If a person does not refrigerate vegetable juice that contains nitrates, this may lead to a buildup of bacteria. These bacteria convert nitrate to nitrite and contaminate the juice.

High levels of nitrite can be potentially harmful. A 2016 article in The Journal of the American Heart Association compiled evidence from researchers at a workshop run by National Heart, Lung, and Blood Institute. They drew associations between high levels of nitrite and an increased risk of stomach cancer.

For these reasons, people should be careful to refrigerate juices, including any that contain watercress.

Despite these risks, watercress is a highly nutritious and versatile leafy green. People can include it as part of a balanced diet.

Individuals should consume a varied diet with many different fruits and vegetables as the key to healthful living.

Q:

How do I correctly store watercress to reduce the possible risks of dietary nitrites?

A:

Oxidation of nitrates will occur less quickly when a person stores watercress in the refrigerator.

Wrapping the stems in a wet paper towel or placing the stems in a cup of water will make watercress last longer.

Natalie Olsen, RD, LD, ACSM EP-C Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.