Rhubarb nutrition facts
Rhubarb is a perennial vegetable grown for its attractive succulent rose red color edible leafy stalks. This cool season herbaceous plant is native to Siberia and popular in many regions of Europe and North America as “pie plant.” In its natural habitat, the plant spreads at the ground surface as large spread. Botanically it belongs to the family of polygonaceae, of the genus Rheum, and known as Rheum rhabarbarum.
Rhubarb is easy to grow and lives for many years (10-15 years) once established. The plant is usually propagated by dividing the old rhizomes (roots). Well grown plant feature broad heart shaped, dark green leaves with 12 to 18 inches long leaf petioles. It is these stalks, which are used, and their top greens discarded, as they are unfit for human consumption. Usually its stalks can be harvested from second year onwards after planting when the foliage spread and stalks reached sufficient girth of about one to two inches thick.
Several cultivars exist. Some of popular varieties grown in the USA are Canada red, cherry red, Burgess `Colossal’, MacDonald, ruby, valentine…etc. Generally, red variety preferred as they have more subtle stalks.
Health benefits of Rhubarb
- Rhubarb is one of the least calories vegetable. 100 g fresh petioles provide just 21 calories. Nonetheless, it contains some vital phyto-nutrients such as dietary fiber, poly-phenolic anti-oxidants, minerals, and vitamins. Further, its petioles contain no saturated fats or cholesterol.
- The stalks are rich in several B-complex vitamins such as folates, riboflavin, niacin, vitamin B-6 (pyridoxine), thiamin, and pantothenic acid.
- Red color stalks contain more vitamin-A than green varieties. Further, the stalks also contain small amounts of poly-phenolic flavonoid compounds like ß-carotene, zeaxanthin, and lutein. These compounds convert to vitamin A inside the body and deliver same protective effects of vitamin A on the body. Vitamin A is a powerful natural anti-oxidant and is required by body for maintaining the integrity of skin and mucus membranes. It is also an essential vitamin for vision. Research studies suggest that natural foods rich in vitamin A helps body protect against lung and oral cavity cancers.
- Like in other greens like kale, spinach; rhubarb stalks also provide good amounts of vitamin-K; 100 g of fresh stalks provide 29.3 µg or about 24% of daily recommended intake. Vitamin K has potential role in bone health by promoting osteotrophic (bone formation and strengthening) activity. Adequate vitamin-K levels in the diet helps limiting neuronal damage in the brain; thus, has established role in the treatment of Alzheimer's disease.
- Its stalks also contain healthy levels of minerals like iron, copper, calcium, potassium, and phosphorus. However, most of them do not absorbed into the body as they subject to chelating by oxalic acid into insoluble complexes and excreted out from the body.
| Principle | Nutrient Value | Percentage of RDA |
|---|---|---|
| Energy | 21 Kcal | 1% |
| Carbohydrates | 4.54 g | 3% |
| Protein | 0.90 g | 2% |
| Total Fat | 0.20 g | 1% |
| Cholesterol | 0 mg | 0% |
| Dietary Fiber | 1.8 g | 5% |
| Vitamins | ||
| Folates | 7 mcg | 2% |
| Niacin | 0.300 mg | 2% |
| Pantothenic acid | 0.085 mg | 1.5% |
| Pyridoxine | 0.024 mg | 2% |
| Riboflavin | 0.030 mg | 2% |
| Thiamin | 0.020 mg | 2% |
| Vitamin A | 102 IU | 3.5% |
| Vitamin C | 8 mg | 13% |
| Vitamin E | 0.27 mg | 2% |
| Vitamin K | 29.3 µg | 24% |
| Electrolytes | ||
| Sodium | 4 mg | 0.5% |
| Potassium | 288 mg | 6% |
| Minerals | ||
| Calcium | 86 mg | 8.5% |
| Copper | 0.021 mg | 2% |
| Iron | 0.22 mg | 3% |
| Magnesium | 12 mg | 3% |
| Manganese | 0.196 mg | 8.5% |
| Phosphorus | 14 mg | 2% |
| Selenium | 1.1 µg | 2% |
| Zinc | 0.10 mg | 1% |
| Phyto-nutrients | ||
| Carotene-α | 0 µg | -- |
| Carotene-ß | 61 µg | -- |
| Crypto-xanthin-ß | 0 µg | -- |
| Lutein-zeaxanthin | 170 µg | -- |
Selection and storage
Fresh rhubarb stalks are readily available in the markets from April until August. If you are growing them in the backyard, harvest them by grabbing the base of the leaf petiole (stalk), simultaneously pull and twist as you do it in shearing celery stalks. Immediately separate the petiole from the leaf part (leaf blade). Green tops of rhubarb contain oxalic acid as well as poisonous glycosides. In addition, greens drain away nutrients from the stalk.
While buying from the markets buy fresh, firm, crispy bright red color stalks. They usually put for sale in bunch along with other common greens. Avoid those with dull, slump or bruise or blemishes on the surface. Once at home, harvested or purchased stalks should be placed in a plastic bag and stored inside the refrigerator set at 32°F and 95 percent relative humidity. This way the stalks stay fresh for about 2-3 weeks.
In the shops, one may also find ready to use, processed rhubarb preparations like canned, freeze-dried form...etc.
Preparation and serving methods
To prepare, trim the ends using paring knife. Wash them in cold running water, gently scrubbing the surface using fingers. Cut stalks into 1/2-inch to 1-inch pieces using paring knife. Usually their extreme tartness is somewhat tamed by addition of sugar, honey, syrups...etc.Fresh rhubarb stalks have rich sweet-tart flavor. In general, petioles of young crinkled leaf tops have less or no strings and have sweet flavor.
Here are some serving tips:
- Its crispy, juicy stalks can be used in the preparations of sauces, preserve, jellies, jams, syrups, sorbet, juice…etc.
- Rhubarb is best remembered for its delicious pies.
- It can also be used in the preparations of tarts, puddings, crumbs, pancakes, muffins, strudel...etc.
Safety profile
Top green part of rhubarb leaf (blade) contains unusually high amounts of oxalic acid, a naturally occurring substance found in some vegetables. 100 g of leaves contain about 0.59 - 0.72 mg of oxalates. Lowest published lethal dose (LDLo) of oxalate in humans is 600 mg/kg. Oxalate can cause severe symptoms even at much lower concentrations than this on the human body. Symptoms may include burning in the eyes, mouth, and throat; skin edema, difficulty breathing. In severe cases, it can result in kidney failure, convulsions, coma, and death.