Rhubarb is a unique and tasty plant that is often used in pies, jams, and other dishes. Some people enjoy eating rhubarb raw or juicing it to drink. However, raw rhubarb contains oxalic acid, which can be toxic in large quantities. In this article, we’ll explore whether it’s safe to juice raw rhubarb and steps you can take to enjoy it safely.
Is Raw Rhubarb Toxic?
Raw rhubarb contains oxalic acid, which gives the stalks their characteristic sour taste. Oxalic acid is found in many common foods, but rhubarb has especially high concentrations. Eating very large quantities of raw rhubarb or drinking juice made only from raw rhubarb could potentially be dangerous due to the oxalic acid content.
However, oxalic acid levels vary between rhubarb varieties. Some types like Victoria and Valentine have lower oxalic acid levels than older heirloom varieties. Here is a table comparing the oxalic acid content in common rhubarb varieties:
| Rhubarb Variety | Oxalic Acid Content |
|---|---|
| Valentine | 0.2-0.5% |
| Victoria | 0.2-0.5% |
| Cherry Red | 0.4-0.6% |
| Crimson Red | 0.4-0.6% |
| Canada Red | 0.4-0.6% |
| Heirloom varieties | 0.5-1.5% |
In general, red stalk varieties tend to be lower in oxalic acid than green stalk heirlooms. So even within raw rhubarb, some types are safer options.
Oxalic Acid Safety Thresholds
The poisonous dose of oxalic acid for adults is between 5-30 grams. For children, it may be as little as 1 gram.
A typical serving size of raw rhubarb is around 120 grams or 1/2 cup diced. At 0.5% oxalic acid content, 120 grams would provide about 0.6 grams of oxalic acid. So a single serving of the lowest oxalic acid rhubarb stays well below toxic levels.
However, juicing concentrates the oxalic acid content since you need multiple rhubarb stalks to produce one cup of juice. You’d reach the safety threshold by juicing about 2 pounds of high oxalic acid heirloom rhubarb into a single cup.
So as long as you stick to reasonable serving sizes and low oxalic acid varieties, juicing raw rhubarb can be safe. Only juicing extremely large quantities is potentially dangerous.
Signs of Oxalic Acid Poisoning
Consuming very high amounts of oxalic acid from raw rhubarb can potentially cause:
- Nausea, vomiting, and diarrhea
- Numbness or tingling sensations in the hands, feet, or mouth
- Difficulty swallowing or breathing
- Burning pain in the mouth and throat
- Weakness and convulsions
- Shock, coma, and even death (in severe cases)
Seek immediate medical attention if you experience any concerning symptoms after eating raw rhubarb.
Who Should Avoid Raw Rhubarb?
While raw rhubarb is generally safe in moderation, some groups should exercise greater caution or avoid it altogether:
- Children: Their lower body weight makes them more susceptible to oxalic acid poisoning. Do not give children under 5 raw rhubarb.
- Individuals with kidney disorders: Oxalic acid can accumulate in kidney tissue and worsen kidney disease.
- People taking antibiotics like Cipro: These drugs reduce the body’s ability to excrete oxalic acid, increasing risk.
- Anyone with a history of calcium oxalate kidney stones: Oxalic acid can promote kidney stone formation.
- Pregnant women: The oxalic acid may impact the developing fetus. Cooked rhubarb is a better choice.
If you have any concerns about a medical condition, talk to your healthcare provider before consuming raw rhubarb.
Tips for Safely Juicing Rhubarb
Here are some tips for juicing rhubarb as safely as possible:
- Select rhubarb varieties with the lowest oxalic acid content like Valentine, Victoria, or Cherry Red.
- Only juice a reasonable quantity – 1 pound or less per batch.
- Dilute rhubarb juice with other lower-oxalate fruits and vegetables like carrots, apples, or celery.
- Drink rhubarb juice in moderation as part of a balanced diet.
- Start with small servings like 1/2 cup to assess your tolerance.
- Avoid juicing the rhubarb leaves, as they contain higher oxalic acid.
Following these precautions and listening to your body’s response minimizes any risks.
Here is a helpful table summarizing safe serving sizes for rhubarb juice based on oxalic acid content:
| Oxalic Acid % | Max Safe Single Serving | Max Safe Daily Intake |
|---|---|---|
| 0.2-0.5% (Valentine, Victoria) | 1 cup | 2 cups |
| 0.5-1% (Cherry Red, Crimson Red) | 1/2 cup | 1 cup |
| 1-1.5% (heirlooms) | 1/4 cup | 1/2 cup |
As long as you follow these guidelines based on the type of rhubarb, you can safely enjoy its unique flavor.
Cooking Rhubarb Before Juicing
Cooking rhubarb helps reduce its oxalic acid content, providing another safety buffer.
In one study, boiling rhubarb for 9 minutes removed around 25% of the oxalic acid. Steaming for 7 minutes removed approximately 20% of the oxalic acid.
So simply boiling or steaming rhubarb for 5-10 minutes before juicing can significantly reduce the risks. Just avoid overcooking it, which can diminish the flavor and nutrient content.
You can boil or steam chopped raw rhubarb until softened, then blend into juice. Or bake rhubarb into a pie or other dishes first before juicing the cooked fruit.
Health Benefits of Rhubarb
Despite its oxalic acid content, rhubarb also provides beneficial nutrients and antioxidants, especially when cooked. Some of the top health benefits of rhubarb include:
- Vitamin C: Rhubarb is an excellent source of immune-boosting vitamin C. A 100 gram serving provides around 25 mg, almost half the daily recommended intake.
- Vitamin K: Necessary for proper blood clotting, rhubarb stalks provide around 105 mcg of vitamin K per 100 grams.
- Antioxidants: Rhubarb contains beneficial plant compounds like anthraquinones and flavonoids that have antioxidant effects.
- Prebiotics: It provides non-digestible fibers that support the growth of healthy gut bacteria.
- Laxative Properties: Compounds in rhubarb have a mild laxative effect to relieve constipation.
Though raw rhubarb may require caution, cooked preparations let you safely enjoy these nutritional perks.
Choosing the Best Rhubarb for Juicing
Look for firm, crisp rhubarb stalks with shiny skin free of blemishes. Healthy rhubarb stalks will snap easily rather than bend.
Avoid limp, dry, or damaged stalks. The leaves should be fresh and green without signs of wilting.
Preparing Raw Rhubarb for Juicing
Rhubarb preparation involves:
- Washing the stalks thoroughly to remove dirt and debris.
- Trim the ends and slice the stalks into smaller pieces to fit your juicer.
- Remove any leaves, as they have higher oxalic acid content than just the stalk.
- Chop or blend the raw rhubarb before juicing if needed to break down fiber.
This readies the rhubarb for the juicing process.
What Does Rhubarb Juice Taste Like?
Rhubarb juice tastes tart, sour, and very astringent, somewhat like a bitter orange juice. The flavor is strong and intense.
It’s often mixed with sweeter fruits like apples, strawberries, or carrots. Herbs like ginger also complement rhubarb’s bold flavor. Drink rhubarb juice chilled for the best taste.
Rhubarb Juice Recipes
Here are a few tasty rhubarb juice recipes to try:
Strawberry Rhubarb Juice
- 1 cup chopped rhubarb
- 1 cup hulled strawberries
- 1 apple, peeled and cored
- 1 inch knob fresh ginger
- 1/2 lemon, peeled
Spiced Rhubarb Carrot Juice
- 1 cup chopped rhubarb
- 3 carrots, trimmed
- 1 apple, cored
- 1/2 teaspoon cinnamon
- 1/4 teaspoon cardamom
Apple Rhubarb Juice
- 1 cup chopped rhubarb
- 2 apples, cored
- 1 inch ginger knob
- 1/2 lemon, peeled
Feel free to get creative and add your own unique flavor combinations!
Potential Side Effects of Rhubarb Juice
Along with its nutritional benefits, rhubarb juice may cause:
- Upset stomach or diarrhea, especially in excess quantities
- Throat irritation or burning sensation
- Decreased calcium absorption
- Kidney stone formation in susceptible individuals
- Drug interactions with certain antibiotics and pharmaceuticals
- Allergic reactions in those with rhubarb sensitivity
Drinking moderate amounts of diluted rhubarb juice prepared from cooked stalks can help minimize adverse effects.
Conclusion
Rhubarb contains oxalic acid, so drinking large amounts of raw juice may be unsafe. However, juicing moderate quantities of cooked stalks from low-oxalate varieties is generally fine for most people. Opt for rhubarbs like Valentine with lower oxalic acid content. Always dilute and limit your intake of rhubarb juice. With proper precautions, you can safely enjoy unique flavors as part of a healthy, balanced diet. Children, those with kidney issues, and pregnant women should avoid raw rhubarb altogether.
