By the Nutriveda editorial team · Updated 5 November 2026
Rhubarb (Rheum rhabarbarum) is a perennial plant whose long, sour leaf stalks are cooked like a fruit, in compotes, crumbles and jams; only the stalks are eaten, because the leaves are poisonous. 100 g of raw rhubarb has 21 kcal, 1.1 g of sugar, 29 µg of vitamin K and 86 mg of calcium, though much of that calcium is bound by oxalic acid. Rhubarb is one of the foods high in oxalate, which matters for people with kidney stones. And because it is so sour, it is almost always eaten with sugar, which changes its numbers more than anything else.
Rhubarb nutrition per 100 g and per portion
| Nutrient | Raw stalks, 100 g | Portion: 1 cup diced, raw (122 g) |
|---|---|---|
| Energy | 21 kcal | 26 kcal |
| Protein | 0.9 g | 1.1 g |
| Fat | 0.2 g | 0.2 g |
| Carbohydrate | 4.5 g | 5.5 g |
| of which sugars | 1.1 g | 1.3 g |
| Fibre | 1.8 g | 2.2 g |
| Vitamin K | 29.3 µg | 36 µg |
| Calcium | 86 mg | 105 mg |
| Potassium | 288 mg | 351 mg |
| Vitamin C | 8 mg | 9.8 mg |
| Manganese | 0.20 mg | 0.24 mg |
| Magnesium | 12 mg | 15 mg |
Source: USDA FoodData Central, SR Legacy: “Rhubarb, raw” (FDC 167758), checked 5 November 2026. The record gives 1 stalk = 51 g and 1 cup diced = 122 g; the portion column is calculated. Values rounded. These numbers are for rhubarb without sugar.
What sugar does to it. Raw rhubarb is too sour for most people to eat plain, so recipes add sugar. If you stew 500 g of rhubarb with 100 g of sugar, every 100 g of rhubarb in the pot carries about 20 g of added sugar, around 18 times the 1.1 g it has on its own. The WHO advises keeping free sugars below 10% of daily energy, about 50 g a day on 2,000 kcal, so one generous bowl of sweet compote can use up a large part of that. Honey and syrups count as free sugars too. This is not a reason to skip rhubarb, only to know where the sugar in a rhubarb dessert comes from.
Glycemic index
Rhubarb is not listed in the international GI tables (Atkinson 2008), so there is no measured value. Raw stalks have 4.5 g of carbohydrate per 100 g, but the effect of a rhubarb dish on blood sugar depends mostly on the sugar added to it. More on the topic in What is the glycemic index.
Health benefits: what the evidence says
Rhubarb is a flavour more than a nutrient source. What the stalks do offer, by the USDA record:
- Very few calories. 21 kcal per 100 g, mostly water, which leaves room for a sweetener without making a dessert heavy, if you keep the sugar moderate.
- Vitamin K. 29 µg per 100 g, about 39% of the EU reference intake (75 µg). Vitamin K is needed for normal blood clotting.
- Some fibre and potassium. 1.8 g of fibre and 288 mg of potassium per 100 g.
- Calcium, on paper. 86 mg per 100 g looks good, but NIH names rhubarb among the foods high in oxalic acid and explains that oxalic acid lowers calcium absorption. Do not count rhubarb as a calcium source.
How to eat rhubarb
- Remove every leaf: cut the leaf blade off completely and throw it away, and trim the dry base of the stalk. Never cook the leaves like chard or spinach.
- Stewed: cut the stalks into 2-3 cm pieces and simmer with a splash of water for 5-10 minutes until they fall apart. Add sugar at the end, a little at a time, and taste.
- Use sweet fruit instead of part of the sugar: rhubarb with strawberries is the classic pair, and apples work well too. Their sugars come inside whole fruit, which the WHO does not count as free sugars, so you need less added sugar.
- Baked: as a crumble or a fruit layer under oats, for example as a rhubarb version of an apple and oat crumble.
- With yogurt: cold stewed rhubarb over Greek yogurt makes a quick breakfast or dessert. A bit of ginger or orange zest suits it.
- Storing: keep the stalks in the fridge wrapped or in a bag. Rhubarb freezes well, chopped and raw.
Who should be careful
- The leaves are poisonous. According to MedlinePlus (US National Library of Medicine), rhubarb leaf blades contain oxalic acid and possibly anthraquinone glycosides. Eating them can cause burning in the mouth and throat, nausea, vomiting, diarrhoea, stomach pain, kidney stone-type pain and, in severe cases, breathing trouble and seizures. The stalk can be eaten. If someone, especially a child, has eaten leaves, contact a poison centre or emergency services.
- Kidney stones. NIDDK lists rhubarb, with spinach, nuts, peanuts and wheat bran, among the foods people who have had calcium oxalate stones may want to avoid, to lower oxalate in the urine. NIDDK also says that calcium itself does not cause these stones and in the right amounts can block stone-forming substances in the gut, so do not cut out dairy on your own. If you have had stones, follow the plan your doctor gives you.
- Warfarin. A cup of rhubarb has about 36 µg of vitamin K. NIH advises people on warfarin to keep their vitamin K intake consistent, so rhubarb is fine in steady amounts rather than in sudden large quantities.
- Diabetes. Plain rhubarb has little sugar; sweetened compote, jam and pie can have a lot. Check the recipe or the label.
Traditional view (Ayurveda)
In Usha and Vasant Lad’s food guidelines, rhubarb appears among the fruits: favourable for Vata and on the list to avoid for Pitta and Kapha. This is a traditional view, not a clinical finding.
Related entries and articles
- Strawberries – rhubarb’s classic partner, sweeter so you need less sugar
- Sorrel – a sour leafy relative from the same plant family
- Spinach – another high-oxalate food
- Buckwheat – surprisingly, from the same plant family as rhubarb
- Greek yogurt – for stewed rhubarb
- Healthy desserts without sugar
FAQ
Are rhubarb leaves poisonous?
Yes. MedlinePlus lists oxalic acid, and possibly anthraquinone glycosides, in the leaf blades, with symptoms from mouth burning and vomiting to kidney pain and seizures. Cut the leaves off and throw them away; only the stalks are eaten.
Is rhubarb bad if I have kidney stones?
Rhubarb is high in oxalate, and NIDDK includes it among the foods people with calcium oxalate stones may want to avoid. If you have had stones, ask your doctor or dietitian whether and how much rhubarb fits your plan.
Can you eat rhubarb raw?
The stalks can be eaten raw, though they are very sour and still contain oxalate. Some people dip thin slices in a little sugar, but rhubarb is usually cooked; the USDA record for raw stalks has 21 kcal and 1.1 g of sugar per 100 g before anything is added.
Sources
- USDA FoodData Central, SR Legacy: Rhubarb, raw (FDC 167758). fdc.nal.usda.gov
- MedlinePlus Medical Encyclopedia: Rhubarb leaves poisoning. medlineplus.gov
- NIDDK: Eating, Diet, and Nutrition for Kidney Stones. niddk.nih.gov
- NIH Office of Dietary Supplements: Calcium, Fact Sheet for Health Professionals. ods.od.nih.gov
- NIH Office of Dietary Supplements: Vitamin K, Fact Sheet for Health Professionals. ods.od.nih.gov
- World Health Organization: Healthy diet, fact sheet. who.int
- Regulation (EU) No 1169/2011, Annex XIII – nutrient reference values. legislation.gov.uk
- Atkinson FS, Foster-Powell K, Brand-Miller JC. International Tables of Glycemic Index and Glycemic Load Values: 2008. Diabetes Care 2008;31(12):2281-2283. PMC
- Lad U, Lad V. Food Guidelines for Basic Constitutional Types, from Ayurvedic Cooking for Self-Healing, 2nd ed. The Ayurvedic Institute. ayurveda.com
This page is for information only and is not medical or dietary advice.