Are kale stems as healthy as the leaves?
Kale has become an incredibly popular leafy green in recent years. Its dark green leaves are packed with vitamins, minerals, and powerful plant compounds that provide many health benefits. But what about the stems? Are kale stems just as nutritious and healthy as the leaves?
Beginning Content
Kale stems are often removed and discarded before eating the leaves. However, some people argue the stems are perfectly edible and provide additional nutrition. This article examines whether kale stems offer the same health benefits as the leaves.
Kale Leaf Nutrition
First, let’s look at why kale leaves are so popular among health-conscious consumers. Here is an overview of the impressive nutrition in just 1 cup (67 grams) of raw, chopped kale leaves:
| Nutrient | Amount | % Daily Value |
|---|---|---|
| Vitamin A | 206% DV | 10,302 IU |
| Vitamin C | 134% DV | 80.4 mg |
| Vitamin K | 684% DV | 547 mcg |
| Vitamin B6 | 9% DV | 0.2 mg |
| Manganese | 26% DV | 0.5 mg |
| Calcium | 9% DV | 93.6 mg |
| Copper | 10% DV | 0.2 mg |
| Potassium | 9% DV | 296 mg |
| Magnesium | 6% DV | 23.4 mg |
As you can see, kale leaves provide abundant vitamins, minerals, and antioxidants. They are especially high in vitamins A, C, and K.
Vitamin A
Kale is an excellent source of vitamin A, which supports eye and skin health, gene expression, and immune function (1).
One cup (67 grams) of kale contains over 200% of the Recommended Dietary Allowance (RDA) for vitamin A.
Vitamin C
Kale provides 134% of the RDA for vitamin C per cup (67 grams). Vitamin C is an antioxidant that helps boost immunity and synthesize collagen, a structural protein important for skin health (2).
Vitamin K
Kale is probably best known as an amazing source of vitamin K. One cup (67 grams) contains a whopping 684% of the RDA.
Vitamin K plays a vital role in blood clotting and bone metabolism (3).
Other Nutrients
In addition to vitamins A, C, and K, kale provides lots of manganese, copper, potassium, magnesium, and B vitamins. These support bone health, blood pressure regulation, immune function, and cellular metabolism (4, 5, 6).
Kale Stem Nutrition
Now that we’ve reviewed the impressive nutrient profile of kale leaves, let’s see how the stems compare.
Unfortunately, there is limited research on the exact nutrition content of kale stems. However, we can make some estimates based on the nutrition they provide:
| Nutrient | Amount in Stems |
|---|---|
| Fiber | Abundant |
| Vitamin C | High |
| Vitamin K | Lower than leaves |
| Beta-carotene | Minimal |
Fiber
Kale stems are an excellent source of fiber. Fiber moves through your digestive tract undigested, promoting fullness, gut health, and regular bowel movements (7).
The stems contain more fiber than the leaves per gram. Chewing well and consuming the fibrous stems may benefit digestive health.
Vitamin C
Kale stems are also a good source of vitamin C. However, they likely contain less than the leaves due to their lighter green color.
Still, eating the stems in addition to the leaves can help boost your vitamin C intake.
Vitamin K
Kale stems contain vitamin K but in lower amounts than the dark green leaves. One study found the vitamin K content of the stems to be about 70% lower than the leaves (8).
Nevertheless, they still provide this important vitamin that many people don’t get enough of.
Beta-carotene
Kale leaves get their dark green color from chlorophyll and antioxidants like beta-carotene. Beta-carotene is a carotenoid that your body converts into active vitamin A.
Since kale stems are lighter in color, they contain very little beta-carotene and thus minimal vitamin A.
Potential Concerns With Kale Stems
Eating kale stems in addition to the leaves can provide extra fiber, vitamin C, vitamin K, and other nutrients. However, there are a few potential downsides to consider.
Tough Texture
The main issue with kale stems is that they can be fibrous and tough. The flat leaves are tender and easy to chew, but the stems take more effort.
Their tough, rubbery texture can be unpleasant and make kale less enjoyable to eat. Proper cooking is necessary to soften the stems and make them more palatable.
Goitrogens
Kale stems contain goitrogens like the leaves do. Goitrogens are compounds that may suppress thyroid function by interfering with iodine uptake.
Those with thyroid issues should limit intake of raw kale to about 1–2 servings per week. Cooking kale helps reduce the goitrogen content (9).
Pesticide Residue
Since kale stems grow above ground, they are more prone to pesticide residue than the leaves. Consider washing stemmed kale especially well or buying organic.
Oxalates
Kale stems contain oxalic acid, an anti-nutrient that can bind to minerals like calcium and iron, reducing their absorption. Oxalates also aggravate kidney problems in those with kidney disease.
While oxalates are found in most plant foods, those with kidney issues may want to limit kale stem consumption and cook stems thoroughly to reduce oxalate content.
Tips for Eating Kale Stems
Here are some tips to help you enjoy kale stems:
- Chop stems into small pieces to reduce toughness.
- Massage raw kale salads with dressing to soften the stems.
- Cook stems thoroughly by steaming, boiling, braising, or roasting.
- Blend cooked stems into smoothies, soups, or sauces.
- Dehydrate stems into crunchy kale chips.
Conclusion
Kale stems provide extra fiber, vitamin C, vitamin K, and other nutrients. However, they are lower in some nutrients like vitamin A compared to the leaves.
Stems contain anti-nutrients that may moderately impact thyroid function and mineral absorption in some individuals. Those with kidney issues should be especially mindful of oxalates.
When prepared properly, kale stems can be an excellent addition to a healthy diet. Their added nutrition and fiber outweigh potential anti-nutrient effects for most people.
In conclusion, consuming kale stems in addition to the nutrient-dense leaves can help increase the overall nutritional value of this healthy, leafy green vegetable.
