Rhubarb: Key Nutrients, Benefits, and Full Nutrition Profile

Rhubarb refers to the edible stalks of the rhubarb plant, which is known scientifically as Rheum rhabarbarum.

In this evidence-based guide, we examine rhubarb’s key nutrients, its potential benefits and drawbacks, and what recent scientific research shows.

While rhubarb is botanically a vegetable, it is widely used as a fruit in a culinary sense, and it is a notable source of fiber, calcium, and vitamin K. However, not all of these nutrients in rhubarb are easy to absorb, which we will explain in detail.

Key Nutrients in Rhubarb

Data source note: We typically use USDA data for our nutritional values, but the USDA only has cooked rhubarb data for ‘sweetened’ rhubarb. Looking at the nutritional data, this likely involves large amounts of added sugar and isn’t an accurate portrayal of the nutrient profile of pure rhubarb. For enhanced accuracy, we therefore chose to source our rhubarb nutritional data from the NCC Food and Nutrient Database’s entry for cooked, unsweetened rhubarb.

A 240g cup of cooked, unsweetened rhubarb contains 34 calories and provides notable amounts of the following nutrients:

• Carbohydrates: 6.0g
• Fiber: 3.12g
• Vitamin K: 53% of the daily value (% DV)
• Calcium: 36% DV
• Manganese: 19% DV
• Vitamin C: 13% DV
• Potassium: 13% DV
• Magnesium: 10% DV

Fiber

With 3.12 grams of fiber, a 240g cup of cooked rhubarb provides 11% of the daily value for fiber.

Rhubarb contains both soluble and insoluble fiber, with soluble fiber helping to slow digestion and feed the microbiota (beneficial bacterial microbes in the gut). In contrast, insoluble fiber may help to improve regularity as it adds bulk to stools, potentially reducing the risk of constipation.

Vitamin K

Based on absolute concentration, the most notable nutrient in rhubarb is vitamin K, which is present in the form of phylloquinone (vitamin K1).

A cup serving provides 63.84 mcg, which is 53% of the daily value.

Vitamin K plays an important role in bone health. According to the results of a 2022 systematic review, vitamin K was associated with a decreased fracture risk.

Calcium

Calcium is also an essential mineral that has key functions for bone health. A cup serving of cooked rhubarb provides 466 mg of calcium, which is equal to 36% of the daily value.

However, because rhubarb contains a significant amount of oxalic acid (oxalate), only a small amount of this calcium is bioavailable. This is because oxalate binds calcium, meaning that our body cannot use most of the calcium present in rhubarb.

In short, this means that while rhubarb is technically high in calcium, it is a poor dietary source of the mineral. Other than calcium and vitamin K, a cup of rhubarb is not high (>20% DV) in other essential nutrients.

Potential Health Benefits and Scientific Research

There is limited high-quality research on rhubarb in the form of clinical trials involving human participants. While there is a lot of research on rhubarb roots and extracts of them, there is little on the actual rhubarb stalks that people eat.

However, some studies have found rhubarb may have potential benefits in specific contexts.

In the following section, you can see an overview of these research findings, what they mean, and their limitations:

Rhubarb and High Cholesterol

A systematic review published in 2010 found that rhubarb stalk may help support decreases in LDL cholesterol (LDL-C), which is sometimes referred to as bad cholesterol.

However, there was only a limited number of studies and participants this was tested in, and more extensive research is necessary to confirm this.

Without further confirmatory research in this area, we should be cautious about the results. However, it is possible that rhubarb consumption may lower LDL-C through its soluble fiber content.

In this regard, a 2023 systematic review of randomized controlled trials found a dose-response association between soluble fiber intake and reductions in LDL-C. These results showed that each daily 5-gram increase in soluble fiber had a significant impact on lowering LDL-C.

That said, NCC data suggests a 240-gram cup of cooked rhubarb contains only around 1.10 grams of soluble fiber.

Based on this, rhubarb can contribute to total daily soluble fiber intake, but it doesn’t provide a significant amount on its own.

Potential Drawbacks

There are two major potential drawbacks to consider regarding rhubarb, and these include the high sugar content of typical rhubarb recipes and its high oxalate levels.

Rhubarb is Typically High in Added Sugars

Rhubarb has an extremely sour, tart flavor, primarily due to the high concentrations of malic acid it contains. For this reason, most people add sugar for sweetness as they cook and mash rhubarb, meaning it can be a significant source of added sugar.

To show just how much sugar can be added to rhubarb, the NCC database shows the following sugar content for both sweetened and unsweetened rhubarb:

• Sweetened rhubarb: 34.56g sugar per 240g cup
• Unsweetened rhubarb: 2.88g sugar per 240g cup

When discussing fruit and vegetable intake, the latest Dietary Guidelines for Americans recommend choosing options “with no or very limited added sugars.“

High Oxalate Levels

Research indicates rhubarb stalks can contain 1080 mg oxalate per 100 grams of fresh weight, making it a significant dietary source of oxalate.

In contrast, low-oxalate diets are typically described as containing less than 50–100 mg oxalate per day.

While it is okay for most people to eat a typical serving of foods high in oxalate, this compound, also known as oxalic acid, can potentially have some negative effects:

• Binding calcium: Oxalate binds to calcium, creating calcium oxalate crystals. This significantly reduces the bioavailability of calcium in rhubarb or calcium consumed alongside rhubarb.
• Calcium oxalate kidney stones: Calcium oxalate crystals may raise the risk of kidney stones in people prone to developing them. For this reason, some people prone to kidney stones are advised to follow a low-oxalate diet.

Full Nutrition Profile

Now that we know a bit more about rhubarb’s key nutrients and potential benefits and drawbacks, let’s examine its full nutritional values.

Based on nutritional data from the NCC Food and Nutrient database, the following tables show the complete nutritional profile of unsweetened, cooked rhubarb both per 240g cup and per 100g.

Nutrient	Per 100g (% DV)	Per 240g cup (% DV)
Calories	14 kcal	34 kcal
Carbohydrates	2.50g (<1%)	6.00g (<1%)
Fiber	1.30g (5%)	3.12g (11%)
Sugars	1.20g	2.88g
Fat	0.60g (1%)	1.44g (2%)
Saturated fat	—	—
Monounsaturated fat	—	—
Polyunsaturated fat	—	—
Omega-3	—	—
Omega-6	—	—
Protein	1.00g (2%)	2.40g (5%)
Cholesterol	0 mg (0%)	0 mg (0%)

Vitamins

Vitamin	Per 100g (% DV)	Per 240g cup (% DV)
Vitamin A (RAE)	5.33 mcg (<1%)	12.80 mcg (1%)
Vitamin C	5.0 mg (6%)	12 mg (13%)
Vitamin D	0 mcg (0%)	0 mcg (0%)
Vitamin E	0.18 mg (1%)	0.43 mg (3%)
Vitamin K	26.6 mcg (22%)	63.84 mcg (53%)
Thiamin (B1)	0.03 mg (3%)	0.07 mg (6%)
Riboflavin (B2)	0.02 mg (2%)	0.05 mg (4%)
Niacin (B3)	0.20 mg (1%)	0.48 mg (3%)
Pantothenic acid (B5)	0.08 mg (2%)	0.19 mg (4%)
Vitamin B6	0.02 mg (1%)	0.05 mg (3%)
Folate (B9)	8.00 mcg (2%)	19.20 mcg (5%)
Vitamin B12	0 mcg (0%)	0 mcg (0%)
Choline	7.90 mg (1%)	18.96 mg (3%)

As the table shows, a cup of cooked rhubarb is high in vitamin K and also provides a notable amount of vitamin C.

Minerals

Mineral	Per 100g	Per 240g cup
Calcium	194 mg (15%)	466 mg (36%)
Iron	0.29 mg (2%)	0.70 mg (4%)
Magnesium	18 mg (4%)	43.20 mg (10%)
Phosphorus	26 mg (2%)	62.40 mg (5%)
Potassium	261 mg (6%)	626.39 mg (13%)
Sodium	1 mg (<1%)	2.40 mg (<1%)
Zinc	0.11 mg (1%)	0.26 mg (2%)
Copper	0.04 mg (4%)	0.10 mg (11%)
Manganese	0.18 mg (8%)	0.43 mg (19%)
Selenium	0.40 mcg (<1%)	0.96 mcg (2%)

With over 20% of the daily value for calcium, a cup of cooked rhubarb is technically high in calcium. However, as mentioned previously, rhubarb is not a good dietary source of calcium due to its oxalate content.

A cup of rhubarb also offers notable amounts of copper, magnesium, manganese, and potassium.

Rhubarb in a Nutshell

Overall, rhubarb provides a good range of nutrients, including high levels of vitamin K and moderate amounts of copper, fiber, magnesium, manganese, and potassium.

For those who enjoy the flavor of rhubarb, it can play a role in a healthy diet. However, its calcium content shouldn’t be a reason for its consumption, since the amount of bioavailable calcium it provides is low.

Additionally, using large amounts of added sugar in rhubarb-based recipes may push it from being a healthy dietary addition to one to limit.

References