Rhubarb has been used as a traditional medicine for over 2,000 years. Historically, rhubarb consumption is used to treat constipation, inflammation, viral infections, diabetes, and tumors. The main pharmacological ingredient is emodin, and the main source of consumption of it is from eating rhubarb. The roots and rhizomes of rhubarb contain about 2.31 mg/g of emodin. Emodin has been studied extensively in recent years, because of the health effects on gut health, anti-bacterial and anti-viral, anti-inflammatory, anti-fibrosis, anti-cancer, and anti-allergy.
- Gut health: Studies have shown improvement in ulcerative colitis in mice with rhubarb ingestion. Additionally, rhubarb consumption in mice has also been shown to prevent liver inflammation caused by alcohol intake, due to the gut microbiota and amino acids. Other studies demonstrated that administering rhubarb to critically ill patients increased intestinal microdiversity. Microbiome diversity is important in critically ill patients, because an alteration in the gut microbiome promotes disease. Critically ill patients are also at risk for inadequate nutrition consumption.
- Anti-bacterial and antiviral: Rhubarb has efficient antibacterial activities against a variety of bacteria, including Staphylococcus aureus, bifidobacteria, Lactobacillus, Helicobacter pylori (H. pylori), Escherichia coli (E. coli), methicillin-resistant Staphylococcus aureus (MRSA), and multidrug-resistant Helicobacter pylori. In fact, rhubarb has stronger inhibition of E. coli, Listeria monocytogenes (listeriosis), Klebsiella pneumonia (pneumonia), and Bacillus subtilis (pneumonia, endocarditis) than standard antibiotics.
- Anti-inflammatory: One study found that rats with acute pancreatitis could be treated with rhubarb orally (150 mg/kg). Studies on emodin found in rhubarb, have also been found to treat other inflammatory diseases, reverse cell damage, and reverse overall tissue damage. Examples of acute inflammatory diseases that can be treated with rhubarb include acute pancreatitis, acute cholecystitis, and appendicitis. Studies have also shown that chronic inflammatory diseases can also be treated with rhubarb. Examples of these include rheumatoid arthritis, osteoarthritis, and Alzheimer’s disease. (I’m sure there are more chronic inflammatory diseases that rhubarb can treat, I just haven’t found the studies that have proven it yet.)
- Anti-fibrosis: Fibrosis is scarring or abnormal thickening of tissue. Fibrosis is a common outcome of chronic organ diseases like chronic liver injury, chronic kidney disease, and pulmonary interstitial disease. One study found that emodin (20 mg/kg) from rhubarb, treated rats with pulmonary fibrosis. Another study found that emodin can treat renal fibrosis.
- Anti-cancer: Rhubarb has been shown to prevent a variety of tumors in the digestive, respiratory and reproductive systems. These include stomach cancer, pancreatic cancer, nasopharyngeal carcinoma, lung adenocarcinoma, and ovarian carcinoma. This is due to rhubarb’s ability to promote the degradation of β-catenin protein, and negatively regulate the Wnt signaling pathway. Additionally, rhubarb can inhibit the metastasis (spread) of lung cancer, gastric cancer, and ovarian cancer.
- Anti-allergy: Studies have suggested that rhubarb can have antihistamine agents, which are used to treat allergies. Rhubarb has been shown to reduce β-hexosaminidase activity. Further development of emodin derived from rhubarb could be used as a therapeutic agent for immediate and chronic allergic diseases.
Common Pesticides Applied to the Rhubarb Plant
Carbendazim: Carbendazim is a fungicide that is widely used in agriculture. It is commonly applied to fruits, vegetables, and lettuce. Studies have shown that carbendazim can cause cancer, infertility, hereditary mutations in germ cells, and developmental issues in offspring. You can read more about these studies here.
Acetamiprid: Acetamiprid is a fairly new insecticide, and is gaining popularity in the agricultural industry. It is most commonly applied to fruits and some lettuce. Due to recent studies on health and environment effects, Acetamiprid has been banned in France. Studies have shown that exposure to acetamiprid causes neurotoxicity, endocrine disruption, and oxidative stress. The main observed affects of endocrine disruption lead to a decrease in blood testosterone levels, changes in the microanatomy of the testes, and changes in the pathway of testosterone production. Oxidative stress has been linked to several chronic diseases like cardiovascular disease, Alzheimer’s disease, dementia, COPD, osteoarthritis, and diabetes. You can read more about these studies here.
Azoxystrobin: Azoxystrobin is a broad-spectrum fungicide commonly applied to cereals, turfgrasses, grapevines, potatoes, fruits, nuts, and vegetable crops. Studies have found that Azoxystrobin has toxic effects in animals at embryonic stages. These toxic effects have been linked to cause significantly higher incidence of malformations, autism, neurodegeneration, and death in offspring with prenatal exposure. Studies have also shown that adult exposure to Azoxystrobin causes oxidative stress. Oxidative stress has been linked to several chronic diseases like cardiovascular disease, Alzheimer’s disease, dementia, COPD, osteoarthritis, and diabetes. You can read more about these studies here.
You can enjoy fresh a fresh rhubarb harvest from May to July in most states. In zones 9 and higher, rhubarb will be ready for harvest from March to May.
Rhubarb is often sold in crowns or starter plants from a nursery. Rhubarb can be planted in early spring (as soon as the soil is workable or reaches 50° F), or early fall (September 21 – October 1) giving enough time for the roots to establish before the first frost. Be sure to plant the rhubarb crown in full sun to partial shade. If you are in zone 6 or higher, plant your rhubarb in a place with afternoon shade. Give each rhubarb plant 4 square feet to grow, as rhubarb can shade and cover surrounding plants. If you wish to divide rhubarb, divide it in the early spring. Avoid planting the rhubarb next to sunflowers, thistles, cucumbers, tomatoes, pumpkins, and melons. Otherwise, rhubarb is a great companion plant.
Growing rhubarb from seed is another option. In zones 9 and higher, rhubarb can be grown as an annual plant. In zones 9 and higher, start rhubarb seeds in a shady spot in late August to early October. Transplant when seedlings reach about 4 inches tall. Be sure to provide afternoon shade to the rhubarb plant, and don’t let it dry out in the heat. In zones 8 and lower, start seeds 8 – 10 weeks before the last frost date. Transplant 2 weeks before the last frost date, when seedlings are about 4″ tall. If you are in zones 6 – 8, provide afternoon shade to the rhubarb. If you are in zones 5 or lower, plant the rhubarb in full sun.
Rhubarb is ready for harvest, as soon as the stalks emerge. To harvest, simply pull the stalk from the trunk of the rhubarb. Be sure to leave at least 1/3 of the stalks behind for plant health. If it is the first year of transplant, hold off until next year to harvest. This will allow the plant to focus its energy on growing roots instead of replenishing stalks.
Rhubarb tastes best when harvested in late spring or early summer. You can still use rhubarb harvested in late summer, however, the taste will be subpar as it goes to seed. (This is also when strawberry plants are ready for harvest.) Slow down on harvesting rhubarb stalks and leave more stalks intact in late summer, so that the plant can recover and prepare for winter. Stop harvesting when the first frost of the fall occurs.
Most rhubarb plants will produce 2 to 6 pounds (6 to 24 cups) for harvest per year. In most states, rhubarb is a cold hearty perennial plant that will produce a crop every year. New red and green stalks will emerge for weeks, especially after harvesting. Freezing is the quickest way to preserve rhubarb from the garden, especially while trying to accumulate enough rhubarb needed to cook a large recipe.
- Room temperature: Rhubarb keeps for a few days at room temperature.
- Refrigerator: Rhubarb keeps for about 3 weeks in the refrigerator.
- Freezer: Rhubarb keeps for about 12 months in the freezer. Tip: Remove the leaves and dice the rhubarb before freezing so that it is ready to use in your favorite recipe. Then there is no need to thaw for cutting. To prevent the rhubarb from clumping together into a big frozen block, initially spread the rhubarb and freeze on a baking tray for an hour. Then transfer to a freezer container, and return to the freezer.
- Canning: Canned rhubarb lasts 18 months, and is acidic enough to be water bath canned.
Taste the Rhubarb Recipes