Rhubarb Nutrition Facts: Health Benefits, Side Effects & Uses

Rhubarb is a distinctive vegetable known for its bright red stalks and tart flavor. While it’s commonly mistaken for a fruit due to its culinary uses in pies and desserts, rhubarb offers a unique nutritional profile that deserves closer examination. Understanding rhubarb nutrition can help you make informed decisions about incorporating this tangy vegetable into your diet.

This comprehensive guide explores everything you need to know about rhubarb nutrition, from its vitamin and mineral content to potential health benefits and important safety considerations.

What is Rhubarb?

Rhubarb (Rheum rhabarbarum) is a perennial vegetable characterized by its thick, celery-like stalks that range from deep red to pink or pale green. Despite being classified as a fruit by the U.S. Department of Agriculture for regulatory purposes, rhubarb is botanically a vegetable.

Native to Asia, rhubarb has been used for thousands of years in traditional medicine. Today, it’s cultivated primarily in temperate regions of North America, Europe, and Asia, requiring cold winters to thrive. The plant produces large, triangular leaves on sturdy stalks that emerge in spring and early summer.

Only the stalks are edible—the leaves contain toxic levels of compounds and should never be consumed. The stalks have an intensely sour taste due to their high acid content, which is why they’re typically cooked with sweeteners.

Rhubarb Nutrition Facts

Rhubarb is relatively low in calories while providing several important nutrients. The nutritional content can vary depending on whether it’s raw or cooked and whether sugar has been added during preparation.

Raw Rhubarb Nutrition

One cup (122 grams) of raw, diced rhubarb contains approximately:

• Calories: 26
• Carbohydrates: 5.5 grams
• Fiber: 2.2 grams
• Protein: 1.1 grams
• Fat: 0.2 grams
• Vitamin K: 35.7 mcg (45% of Daily Value)
• Vitamin C: 9.8 mg (16% of DV)
• Calcium: 105 mg (11% of DV)
• Potassium: 351 mg (10% of DV)
• Manganese: 0.2 mg (10% of DV)
• Magnesium: 14.6 mg (4% of DV)

Cooked Rhubarb Nutrition

When cooked without added sugar, rhubarb retains most of its nutrients. However, many traditional rhubarb recipes include significant amounts of sugar, which substantially increases the calorie and carbohydrate content.

A 100-gram serving of stewed rhubarb with added sugar contains approximately 116 calories and 31 grams of carbohydrates, compared to just 21 calories and 4.5 grams of carbohydrates in the same amount of unsweetened cooked rhubarb.

Key Vitamins and Minerals in Rhubarb

Vitamin K

Rhubarb is an excellent source of vitamin K1 (phylloquinone), providing nearly half of the daily requirement in just one cup of raw stalks. Vitamin K plays a crucial role in blood clotting and bone health. Adequate vitamin K intake is associated with improved bone density and reduced risk of fractures.

Vitamin C

With about 16% of the daily value per cup, rhubarb provides a decent amount of vitamin C, an essential antioxidant that supports immune function, collagen production, and iron absorption.

Calcium

While rhubarb contains notable amounts of calcium, this mineral is largely bound to oxalic acid, forming calcium oxalate. In this form, calcium has very limited bioavailability, meaning your body cannot efficiently absorb and use it. Therefore, rhubarb should not be considered a reliable calcium source.

Potassium

Rhubarb provides approximately 10% of the daily potassium requirement per cup. This essential mineral helps regulate blood pressure, supports proper muscle and nerve function, and maintains healthy fluid balance.

Fiber Content in Rhubarb

Rhubarb is a good source of dietary fiber, providing about 2.2 grams per cup of raw stalks. This represents roughly 8% of the recommended daily fiber intake for adults.

The fiber in rhubarb includes both soluble and insoluble types. Soluble fiber can help lower cholesterol levels and stabilize blood sugar, while insoluble fiber promotes digestive health and regular bowel movements.

Adequate fiber intake is associated with numerous health benefits, including reduced risk of heart disease, type 2 diabetes, and certain types of cancer.

Antioxidant Compounds in Rhubarb

Beyond basic vitamins and minerals, rhubarb contains a variety of bioactive compounds with antioxidant properties. These substances help protect your cells from damage caused by free radicals and oxidative stress.

Anthocyanins

The red and pink pigments in rhubarb stalks come from anthocyanins, powerful antioxidants also found in berries, red grapes, and red cabbage. Research suggests anthocyanins may help reduce inflammation and protect against cardiovascular disease.

Rhubarb varieties with deeper red coloring generally contain higher levels of anthocyanins than green or pale varieties.

Proanthocyanidins

These condensed tannins are found in significant amounts in rhubarb. Proanthocyanidins have been studied for their potential cardiovascular benefits and their role in supporting urinary tract health.

Polyphenols

Research indicates that rhubarb may contain higher total polyphenol content than many other vegetables, potentially rivaling even nutrient-dense greens like kale. Polyphenols are plant compounds with antioxidant and anti-inflammatory properties.

Other Bioactive Compounds

Rhubarb contains several other notable compounds including:

• Quercetin: A flavonoid with anti-inflammatory and antihistamine properties
• Emodin: An anthraquinone studied for its potential antimicrobial effects
• Resveratrol: A compound also found in red wine, associated with various health benefits

Health Benefits of Rhubarb

While research specifically on culinary rhubarb is limited, studies have examined both the whole vegetable and its isolated compounds, suggesting several potential health benefits.

May Support Cardiovascular Health

Several components of rhubarb may contribute to heart health. The fiber content can help lower LDL (bad) cholesterol levels, while compounds like resveratrol and emodin have been studied for their effects on lipid metabolism.

Research has found that certain compounds in rhubarb may help regulate cholesterol levels and support healthy blood lipid profiles. However, these effects are not unique to rhubarb—many fiber-rich vegetables offer similar cardiovascular benefits.

Provides Antioxidant Protection

The diverse array of antioxidant compounds in rhubarb, including anthocyanins, proanthocyanidins, and various polyphenols, may help protect cells from oxidative damage. This protection could potentially reduce the risk of chronic diseases associated with oxidative stress, including certain cancers and neurodegenerative conditions.

The antioxidant content is highest in rhubarb varieties with deeper red coloring and in the outer layers of the stalks.

May Support Digestive Health

The fiber in rhubarb supports digestive health by promoting regular bowel movements and feeding beneficial gut bacteria. Additionally, rhubarb root has a long history of use in traditional medicine for digestive complaints, though the stalks used in cooking contain different concentrations of active compounds.

Supports Bone Health

The high vitamin K content in rhubarb contributes to bone health. Vitamin K is essential for the production of proteins involved in bone mineralization and has been associated with reduced fracture risk in older adults.

May Help with Weight Management

At only 26 calories per cup when consumed raw or cooked without added sugar, rhubarb is a low-calorie food that can add volume and flavor to meals without significantly increasing caloric intake. Its fiber content also promotes feelings of fullness.

Oxalic Acid and Calcium Oxalate in Rhubarb

One of the most important considerations regarding rhubarb nutrition is its high content of oxalic acid and calcium oxalate. Understanding these compounds is crucial for safe consumption.

What Are Oxalates?

Oxalic acid is an organic compound naturally present in many plants. When it binds with calcium, it forms calcium oxalate crystals. Rhubarb is among the highest dietary sources of these compounds, particularly in the leaves.

Oxalate Content Variation

The oxalate content in rhubarb varies depending on several factors:

• Plant part: Leaves contain extremely high levels (toxic amounts), while stalks contain moderate to high levels
• Variety: Different rhubarb varieties have varying oxalate concentrations
• Growing season: Traditionally, oxalate levels are thought to increase from spring through summer
• Growing conditions: Forced rhubarb (grown in darkness) typically has lower oxalate content
• Preparation method: Cooking can reduce oxalate content by approximately 30-87%, depending on the method

Effects on Nutrient Absorption

Calcium oxalate in rhubarb binds calcium in a form that cannot be absorbed by the human body. This is why rhubarb should not be relied upon as a calcium source, despite its seemingly high calcium content on paper.

Oxalates may also interfere with the absorption of other minerals to a lesser extent, including iron and magnesium, though this effect is generally minimal when rhubarb is consumed as part of a varied diet.

Safety Concerns and Side Effects

While rhubarb stalks are safe for most people when consumed in moderation, there are important safety considerations to keep in mind.

Rhubarb Leaves Are Toxic

The leaves of rhubarb contain dangerously high levels of oxalic acid and other toxic compounds. Consuming rhubarb leaves can cause serious symptoms including:

• Nausea and vomiting
• Abdominal pain
• Burning in the mouth and throat
• Difficulty breathing
• Kidney problems
• In severe cases, seizures and coma

Always remove and discard all leaf material before using rhubarb stalks. Even small amounts of leaf tissue can cause symptoms.

Kidney Stone Risk

The high oxalate content in rhubarb stalks poses a risk for individuals prone to kidney stones, particularly calcium oxalate stones, which account for about 80% of kidney stones.

When consumed in large amounts, dietary oxalates can increase urinary oxalate excretion, potentially leading to the formation of calcium oxalate crystals in the kidneys and urinary tract. Over time, these crystals can develop into kidney stones.

If you have a history of kidney stones or are at increased risk, consult with a healthcare provider before consuming rhubarb regularly.

Hyperoxaluria

Excessive oxalate consumption can lead to hyperoxaluria, a condition characterized by high levels of oxalate in the urine. This can result in:

• Kidney stone formation
• Calcium oxalate crystal deposits in various tissues
• Potential kidney damage with chronic exposure

Most people can handle moderate amounts of dietary oxalates without problems, but individuals with certain genetic conditions or those lacking specific beneficial gut bacteria may be more susceptible.

Who Should Avoid or Limit Rhubarb?

Consider avoiding or strictly limiting rhubarb if you:

• Have a history of kidney stones, especially calcium oxalate stones
• Have been diagnosed with hyperoxaluria
• Have inflammatory bowel disease or other conditions affecting gut health
• Have kidney disease or impaired kidney function
• Are taking medications that interact with vitamin K (such as certain blood thinners—consult your healthcare provider)
• Have a vitamin B6 deficiency (which may increase oxalate problems)

Recent Research on Long-term Consumption

Emerging research has raised questions about the effects of long-term consumption of certain rhubarb compounds. Some studies suggest that prolonged intake of high doses of anthocyanins from rhubarb might have adverse effects on kidney function, though more research is needed to fully understand these potential risks in the context of normal dietary consumption.

Gut Bacteria and Oxalate Metabolism

Interesting research has revealed that certain beneficial gut bacteria, particularly Oxalobacter formigenes, can break down and neutralize dietary oxalates in the digestive tract before they’re absorbed. Individuals lacking these bacteria may be more vulnerable to oxalate-related problems.

Factors that can reduce beneficial oxalate-degrading bacteria include antibiotic use, certain dietary patterns, and digestive disorders.

How to Reduce Oxalate Content in Rhubarb

If you want to enjoy rhubarb while minimizing oxalate exposure, consider these strategies:

Cook Before Eating

Cooking rhubarb significantly reduces its oxalate content. Studies show that various cooking methods can decrease oxalate levels by 30-87%. Boiling tends to be most effective, as oxalates leach into the cooking water.

Discard Cooking Water

When boiling rhubarb, discard the cooking liquid rather than consuming it, as it will contain concentrated oxalates that have leached from the stalks.

Choose the Right Variety

If available, select rhubarb varieties known to be lower in oxalates. Forced rhubarb, which is grown in darkness and harvested earlier in the season, typically contains less oxalic acid and has a milder flavor.

Consume with Calcium-Rich Foods

Eating rhubarb alongside calcium-rich foods may help bind oxalates in the digestive tract before absorption, potentially reducing their availability. However, this same binding effect means the calcium won’t be absorbed either.

Practice Portion Control

Moderation is key. Occasional consumption of reasonable portions is unlikely to cause problems for most people, but regularly eating large amounts increases risk.

Culinary Uses for Rhubarb

Rhubarb’s distinctive tart flavor makes it a versatile ingredient in both sweet and savory dishes. While traditionally paired with large amounts of sugar, creative cooking can highlight rhubarb’s unique taste in healthier preparations.

Traditional Sweet Preparations

• Pies and tarts: Classic rhubarb pie or strawberry-rhubarb combinations
• Crumbles and crisps: Topped with oat-based streusel
• Compotes and sauces: Served over yogurt, oatmeal, or ice cream
• Jams and preserves: Alone or combined with berries
• Baked goods: Muffins, cakes, and bars

Lower-Sugar Options

To enjoy rhubarb with less added sugar:

• Pair with naturally sweet fruits like strawberries, apples, or oranges
• Use small amounts of honey, maple syrup, or alternative sweeteners
• Add warm spices like cinnamon, ginger, or vanilla to enhance perceived sweetness
• Gradually reduce sugar in recipes to adapt your palate to rhubarb’s natural tartness

Savory Applications

Rhubarb can add a tangy dimension to savory dishes:

• Chutneys and relishes: Pair with pork, duck, or fatty fish
• Salad components: Roasted or raw in small amounts
• Braised with meats: Adds acidity to rich dishes
• Pickled: For a unique condiment

Beverages

Rhubarb’s tartness works well in drinks:

• Rhubarb juice or cordial
• Infused water or iced tea
• Smoothies (in small amounts for tanginess)
• Cocktails and mocktails

How to Select and Store Rhubarb

Selecting Fresh Rhubarb

When purchasing rhubarb, look for:

• Firm, crisp stalks without soft spots or blemishes
• Bright, vibrant color (red, pink, or green depending on variety)
• Stalks that are not too thin (pencil-thin stalks may be tougher) or extremely thick
• Fresh-looking, recently cut ends

Note that color doesn’t indicate ripeness or sweetness—some varieties remain green even when fully mature.

Storage Tips

• Refrigerator: Wrap unwashed stalks in a damp cloth or perforated plastic bag and store in the crisper drawer for up to 2 weeks
• Freezer: Cut into pieces and freeze on a baking sheet, then transfer to freezer bags for up to 6 months. No blanching necessary
• Preparation: Wash just before using, not before storage

Preparing Rhubarb for Cooking

Follow these steps for safe preparation:

1. Remove all leaves: Cut off and discard all leaf material—even small amounts are toxic
2. Trim the ends: Cut off both the top (where leaves were attached) and bottom of each stalk
3. Wash thoroughly: Rinse stalks under cool running water
4. Remove strings if needed: Older stalks may have tough strings that can be peeled away like celery
5. Cut as directed: Slice into pieces according to your recipe (typically 1/2 to 1-inch pieces)

Rhubarb in Traditional Medicine

While this article focuses on culinary rhubarb stalks, it’s worth noting that rhubarb root has been used in traditional Chinese medicine for thousands of years, long before the stalks became popular in Western cuisine.

The dried root of certain rhubarb species (typically Rheum palmatum or Rheum officinale, rather than culinary varieties) contains different concentrations of compounds and has been used traditionally for digestive complaints.

However, the root used medicinally is different from the stalks used in cooking, both in species and in the concentration of active compounds. If you’re interested in medicinal applications, consult with a qualified healthcare provider rather than attempting to self-treat with culinary rhubarb.

Growing Your Own Rhubarb

Rhubarb is a relatively easy perennial to grow in home gardens, particularly in climates with cold winters:

• Climate requirements: Needs cold winter dormancy period (below 40°F) to thrive
• Location: Prefers full sun to partial shade
• Soil: Well-draining, rich, slightly acidic to neutral soil
• Harvesting: Wait until the third year after planting before harvesting; harvest only in spring and early summer
• Method: Pull stalks from the base rather than cutting; never remove more than half the stalks at once
• Flower stalks: Remove flower stalks as they appear to direct energy into stalk production

Frequently Asked Questions About Rhubarb Nutrition

Is rhubarb a fruit or vegetable?

Botanically, rhubarb is a vegetable (specifically, the edible leaf stalks of the plant). However, in the United States, it’s legally classified as a fruit for regulatory purposes since it’s primarily used in sweet dishes like fruits typically are.

Can I eat rhubarb raw?

Yes, rhubarb stalks can be eaten raw, though they’re extremely tart. Some people enjoy small amounts of raw rhubarb dipped in sugar or salt. However, cooking reduces the oxalate content, making it safer for regular consumption.

How much rhubarb is safe to eat?

For most healthy individuals, occasional consumption of a cup or two of cooked rhubarb is generally considered safe. However, those with kidney issues or a history of kidney stones should consult a healthcare provider about appropriate limits.

Does rhubarb color affect nutrition?

Red rhubarb typically contains more anthocyanin antioxidants than green varieties, but the basic nutritional profile is similar. Color doesn’t indicate ripeness or quality—some varieties are naturally green even when fully mature.

Can rhubarb help with weight loss?

Rhubarb is very low in calories and high in fiber when prepared without added sugar, which may support weight management by adding volume and promoting fullness. However, traditional rhubarb desserts with lots of added sugar won’t have this benefit.

Is frozen rhubarb as nutritious as fresh?

Frozen rhubarb retains most of its nutritional value, making it a convenient option when fresh rhubarb isn’t in season. Some vitamin C may be lost during freezing, but most nutrients remain intact.

Conclusion

Rhubarb is a nutritionally interesting vegetable that offers several health benefits, particularly as a source of vitamin K, fiber, and various antioxidant compounds. Its unique tart flavor can add variety to both sweet and savory dishes.

However, rhubarb’s high oxalate content means it should be consumed in moderation, particularly by individuals prone to kidney stones or those with kidney problems. Always remove and discard the toxic leaves, and consider cooking rhubarb to reduce oxalate levels.

When prepared thoughtfully—especially without excessive added sugar—rhubarb can be part of a healthy, varied diet. As with any food, moderation and variety are key principles for optimal nutrition and health.

If you have specific health concerns or conditions that might be affected by dietary oxalates or vitamin K, consult with a healthcare provider or registered dietitian before adding significant amounts of rhubarb to your diet.

Sources:

• USDA FoodData Central – Rhubarb, raw
• National Institutes of Health – Oxalate metabolism and the gut microbiome
• PubMed Central – Rhubarb compounds and lipid metabolism
• USDA Agricultural Marketing Service – Rhubarb Standards
• National Kidney Foundation – Oxalate and Kidney Stones
• NIH Office of Dietary Supplements – Vitamin K Fact Sheet