What are the health benefits of watercress?

Watercress is a dark, leafy green grown in natural spring water. For the past few decades, watercress has been used as little more than a plate garnish but is now seeing resurgence in popularity as one of the next big super foods.

An ancient green said to have been a staple in Roman soldiers diets, watercress is actually a part of the cruciferous (also known as brassica) family of vegetables along with kale, broccoli, arugula and Brussels sprouts.

Hippocrates, the father of medicine, used watercress to treat his patients. Watercress was widely available until the 19th century and watercress sandwiches were a staple of the working class diet in England.

As more varieties of salad leaves were cultivated over the next 100 years, watercress became known as a poor man's food and was eventually shoved off our plates. Its newfound popularity is partly due to its high ANDI score (Aggregate Nutrient Density Index). The ANDI score measures vitamin, mineral and phytonutrient content in relation to caloric content.

To earn high rank, a food must provide a high amount of nutrients for a small amount of calories. Watercress received the highest rank possible. If you are looking for food to eat to improve your health and shrink your waistline, look no further than watercress.

This article provides a nutritional breakdown of watercress and an in-depth look at its possible health benefits, how to incorporate more watercress into your diet and any potential health risks of consuming watercress.

Contents of this article:

• Nutritional breakdown of watercress
• Possible health benefits of consuming watercress
• How to incorporate more watercress into your diet
• Potential health risks of consuming watercress

Nutritional breakdown of watercress

Watercress, along with beetroot and other leafy greens, contain a very high level of dietary nitrate.

An ancient green said to have been a staple in Roman soldiers diets, watercress is actually a part of the cruciferous (also known as brassica) family of vegetables.

High intakes of dietary nitrate have been shown to lower blood pressure, reduce the amount of oxygen needed during exercise and enhance athletic performance.² Moderate intakes do not appear to have the same effects.¹

According to the USDA National Nutrient Database, two cups of fresh watercress (about 68 grams) contains only 7 calories.

Two cups of watercress also have 1.6 grams of protein, 0.1 grams of fat, and 0.9 grams of carbohydrate (including 0.3 grams of fiber and 0.1 grams of sugar).

Consuming 2 cups of watercress will meet 212% of vitamin K, 48% of your vitamin C, 44% of vitamin A, 8% of calcium and manganese, 6% of potassium and 4% of vitamin E, thiamin, riboflavin, vitamin B-6, magnesium and phosphorus needs for the day.

Possible health benefits of consuming watercress

Consuming fruits and vegetables of all kinds has long been associated with a reduced risk of many adverse health conditions. Many studies have suggested that increasing consumption of plant foods like watercress decreases the risk of obesity, diabetes, heart disease and overall mortality while promoting a healthy complexion, increased energy, and overall lower weight.

Cancer prevention and treatment

Studies have consistently shown that a compound in cruciferous vegetables known as 3,3'-diindolylmethane (DIM) has protective effects against cancer, but a recent study shows there is also hope for using it as a shield to protect healthy tissues during cancer treatment.

In a study conducted at Georgetown University, rats were given a lethal dose of radiation. Some were left untreated, and others were treated with a daily injection of DIM daily for 2 weeks. All the untreated rats died, but over 50% of those receiving the DIM remained alive at the 30-day mark. 

The same researchers did the experiment on mice and found similar results. They were able to determine that the DIM-treated mice had higher counts or red and white blood cells and blood platelets, which radiation therapy often diminishes.

Eating high amounts of cruciferous vegetables has also been associated with a lower risk of lung and colon cancer. Studies have suggested that the sulfur-containing compounds (namely sulforaphane) that give cruciferous vegetables their bitter bite are also what give them their cancer-fighting power.

Sulforaphane is now being studied for its ability to delay or impede cancer with early promising results associated with melanoma, esophageal, prostate, breast and pancreatic cancers. 

Researchers have found that the sulforaphane compound can inhibit the enzyme histone deacetylase (HDAC), known to be involved in the progression of cancer cells. The ability to stop HDAC enzymes could make sulforaphane-containing foods a potentially powerful part of cancer treatment in the future.³

Watercress also contains high amounts of chlorophyll, which has shown to be effective at blocking the carcinogenic effects of heterocyclic amines generated when grilling foods at a high temperature.⁴

Lowering blood pressure

People who consume diets that are low in the minerals calcium, magnesium and potassium are more likely to have high blood pressure. These minerals are thought to bring blood pressure down by releasing sodium out of 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 when they are consumed in food. 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 like watercress have been shown to have multiple vascular benefits, including reducing blood pressure, inhibiting platelet aggregation, and preserving or improving endothelial dysfunction.

In general, a diet rich in all fruits and vegetables has been shown to help maintain healthy blood pressure.

Maintaining healthy bones

Low intakes of vitamin K have been associated with a higher risk for bone fracture. Adequate vitamin K consumption improves bone health by acting as a modifier of bone matrix proteins, improving calcium absorption and reducing urinary excretion of calcium.⁵ Eating just one cup of watercress would meet your daily need for vitamin K.

Treating diabetes

Watercress contains the antioxidant alpha-lipoic acid, which has been shown to lower glucose levels, increase insulin sensitivity and prevent oxidative stress-induced changes in patients with diabetes. Studies on alpha-lipoic acid have also shown decreases in peripheral neuropathy or autonomic neuropathy in diabetics.

Of note, most studies have used intravenous alpha-lipoic acid, there is uncertainty whether oral supplementation would elicit the same benefits.⁶

How to incorporate more watercress into your diet

Watercress is most commonly consumed fresh in salads but can also be incorporated into pastas, casseroles and sauces just like any other green. Watercress will sauté faster than tougher greens like kale and collard greens because of its tenderness and lends a mild, slightly peppery taste to any dish.

Try making watercress soup or mix watercress into soup near the end of cooking.

Choose watercress with deep green crisp leaves and no signs of wilting. Store in the refrigerator and use within a few days of purchase.

• Throw a small handful of watercress and blend 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 with ground black pepper and freshly grated Parmesan cheese. Eat as a side dish or top your baked potato
• Add arugula to your wrap, sandwich or flatbread
• Mix watercress into soup near the end of cooking.

Potential health risks of consuming watercress

If you are taking blood-thinners such as Coumadin (warfarin) it is important that you do not suddenly begin to eat more or fewer foods containing vitamin K, which plays a large role in blood clotting.

If improperly stored, nitrate-containing vegetable juice may accumulate bacteria that convert nitrate to nitrite and contaminate the juice. High levels of nitrite can be potentially harmful if consumed.

Consult with your physician before starting a high-nitrate diet if you have cardiovascular disease or associated risk factors. A high-nitrate diet may interact with certain medications such as organic nitrate (nitroglycerine) or nitrite drugs used for angina, sildenafil citrate, tadalafil, and vardenafil.³

According to the Linus Pauling Institute at Oregon State University, very high intakes of cruciferous vegetables have been found to cause a decrease in thyroid hormone function in animals. There has been one reported case of an elderly woman developing severe hypothyroidism after eating an estimated 1 to 1.5 kg/day of raw bok choy for several months.

It is the total diet or overall eating pattern that is most important in disease prevention and achieving good health. It is better to eat a diet with a variety than to concentrate on individual foods as the key to good health.

References:

1.        Moderate dose of watercress and red radish does not reduce oxygen consumption during graded exhaustive exercise, Meamarbashi A, Alipour M. Avicenna J Phytomed, 2014 Jul;4(4):267-72, accessed 4 November 2014.
2.        Reap the benefits of beetroot juice - evidence suggests it improves heart health and athletic performance, Ellen Coleman, MA, MPH, RD, CSSD, Today’s Dietitian, Vol. 14 No. 2 P. 48, February 2012 issue, accessed 8 September 2014.
3.        Powerful prostate cancer fighters - from arugula to wasabi, cruciferous veggies pack a powerful punch, Densie Webb, PhD, RD, Today’s Dietitian
, Vol. 13 No. 10 P. 20, October 2011 issue, accessed 8 September 2014.
4.        Anticancer compounds found in food, Machowsky, Jason, MS, RD, CDN, CSCS, Nutrition 411, last reviewed February 2012, accessed 8 September 2014.
5.        Bone health: looking beyond calcium, Nutrition 411, last reviewed March 2009, accessed 8 September 2014.
6.        Alpha-Lipoic Acid, Nutrition 411, last reviewed August 2012, accessed 3 June 2014.