Is rhubarb safe to eat in October? (Health benefits)
In this brief guide, we will answer the question “Is rhubarb safe to eat in October?”. We also will discuss the uses of rhubarb and its health benefits.
Is rhubarb safe to eat in October?
Yes, rhubarb is safe to enjoy throughout the year, including October. Rhubarb is a versatile vegetable, cultivated in various regions and thanks to greenhouse cultivation, it remains readily available for a significant portion of the year.
Known for its prized petioles or stalks, rhubarb can be harvested as early as mid to late spring in temperate climates, with field-grown varieties available until September. Freshly harvested rhubarb stalks are firm and shiny, making them perfect for consumption. In addition, the roots of rhubarb plants are typically harvested from those that have reached the age of four or older.
This meticulous process takes place in autumn, usually during October when the roots are carefully cleaned and any external fibers are removed. Afterward, they undergo a thorough drying process. Once completely dried, the rhubarb root is finely ground into powder and securely stored in a sealed container. (1)
What are the safety concerns with Rhubarb?
It’s a well-established fact that the leaves of the rhubarb plant are toxic because of their oxalic acid content. There’s a common misconception that the entire plant becomes poisonous as the summer progresses, making it unsafe to consume in September or October. However, this notion is incorrect.
The primary source of toxicity in rhubarb is its leaves, whereas the stems, or petioles, which are the edible part of the plant, are considerably less toxic. It’s worth noting that children are more commonly affected by poisoning from rhubarb than adults. (2)
What are the dangers of oxalic acid?
Oxalic acid is nephrotoxic and exhibits corrosive properties, with a lethal dose typically ranging from approximately 10 to 25 grams, depending on the individual’s age. In the bloodstream, oxalate binds with calcium to form insoluble calcium oxalate, potentially leading to severe hypocalcemia and involuntary muscle contractions.
Rhubarb leaves, on average, contain about 0.5% oxalic acid, along with significantly higher levels of non-toxic malic acid. The long-term consumption of rhubarb can pose issues for individuals with kidney disorders, gout, and rheumatoid arthritis because oxalic acid binds to essential nutrients.
Oxalic acid can also combine with metal ions such as Ca2+, Fe2+, and Mg2+ to create deposits of corresponding oxalates, which may irritate the gastrointestinal tract and kidneys. For rats, the lethal dose (LD50) for oxalic acid is 375 mg per kilogram of body weight.
To put this into perspective for a 65 kg person, approximately 25 grams of pure oxalic acid would be needed to cause death. Rhubarb poisoning manifests with symptoms including abdominal pain, diarrhea, persistent and severe vomiting, followed by internal bleeding, convulsions, and ultimately coma. (1, 2)
How is rhubarb harvested and stored?
After harvesting the aboveground portions of the plant, the leaf blades are separated from the stalks, which then undergo a processing phase. During the cutting process, if the stalk tissues sustain any damage, there is a risk of reduced moisture content in the petioles.
To prevent this, it is advisable to employ cold storage techniques and monitor humidity levels within the storage chamber. For optimal cooking and freezing, it is recommended to use freshly harvested stalks.
To maintain rhubarb’s freshness, it should be stored in a cold and moist environment, ideally within the temperature range of 32°-40°F (0°-4°C) and at a relative humidity of around 95 percent.
Maintaining both cold and moist conditions can be challenging, as refrigerators provide the necessary cold but tend to dry out the air. An alternative method proven effective for rhubarb preservation involves wrapping the petioles in aluminum foil. (3)
What are the health benefits of rhubarb?
For more than two millennia, rhubarb root has served as a gentle yet potent and efficient laxative, aiding in complete intestinal emptying and thorough bowel cleansing. This remarkable effect is attributed to the presence of anthraquinone glycosides, which act as natural stimulants, making rhubarb valuable in the management of chronic constipation.
Rhubarb’s therapeutic properties are attributed to a wealth of bioactive compounds, including anthraquinones, hydroxyanthraquinone, aloe-emodin, emodin, rhein, stilbene, rhaponticin, dietary fiber, and more.
These bioactive elements have demonstrated a wide range of health benefits, such as antioxidant, anticancer, antimicrobial, antidiarrheal, antidiabetic, anti-inflammatory, diuretic, and hepatoprotective activities, among others.
Furthermore, traditional Indian medicine has recognized rhubarb’s value not only as a purgative but also as an antimicrobial agent and an effective remedy for treating skin wounds and cold sores. In this region, rhubarb extracts have been traditionally employed to address issues like boils and abdominal disorders. (1, 4)
How is rhubarb used?
Edible, non-toxic varieties of rhubarb, as well as specific cultivars within the species, have been used for both culinary and medicinal purposes. The nutrient-rich petioles, or leaf stalks, are often used as a vegetable after cooking, and they serve various culinary roles.
In Traditional Chinese Medicine (TCM), rhubarb is recommended for addressing conditions such as fever, constipation, abdominal pain, appendicitis, kidney failure, liver cancer, and hypertension.
The dried rhubarb root has been traditionally utilized as a potent cathartic agent, and its laxative effects are documented, with some believing it may aid in weight loss for individuals struggling with obesity. (4)
How rhubarb is cooked?
Rhubarb is employed in a variety of culinary creations, including juices, pickles, salads, sauces, jams, and sweet pies. While the petioles are recognized for their nutraceutical value, dried rhubarb rhizome, or root, also holds significant medicinal properties.
The color of rhubarb stalks, which can range from pink or pinkish-red to green, is largely dependent on the cultivar and is thought to influence its taste. A preferred method for preparing rhubarb involves cooking it with sugar. Red and pink stalks are generally considered sweeter than their green counterparts. (4)
In this brief guide, we answered the question “Is rhubarb safe to eat in October?”. We also discussed the uses of rhubarb and its health benefits. In my studies, I was able to find out that there is no problem in consuming rhubarb in October and that the plant does not become toxic past its harvest season. Its leaves on the other hand are poisonous and should not be consumed.
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CLEMENTI, Elisabetta M.; MISITI, Francesco. Potential health benefits of rhubarb. In: Bioactive foods in promoting health. Academic Press, 2010. p. 407-423.
Crews, C., & Clarke, D. Natural Toxicants: Naturally Occurring Toxins of Plant Origin. Encyclopedia of Food Safety, 261–268. 2014.
ZARDZEWIAŁY, Miłosz et al. Ozone treatment as a process of quality improvement method of rhubarb (Rheum rhaponticum L.) petioles during storage. Applied Sciences, v. 10, n. 22, p. 8282, 2020.
BHAT, Rajeev. Bioactive Compounds of Rhubarb (Rheum Species). Bioactive Compounds in Underutilized Vegetables and Legumes, p. 239-254, 2021.