What is the Healthiest Way to Cook Vegetables?

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While roasted vegetables is my family’s most favorite way to enjoy them, it turns out that it’s not the healthiest way to cook vegetables.😔

So what is the healthiest way to cook vegetables? It’s an important question to ask and to know.

But it turns out that it’s not at all a simple answer for various reasons that we shall endeavor to touch on succinctly.

However, there is a general conclusion that tends to apply to most vegetables, so we’re starting there.

The Healthiest Way to Cook Vegetables

Steaming tends to be the best way to cook vegetables for the maximum nutrient retention and bioavailability of nutrients.

The following chart is from a study on the effect of different cooking methods on a handful of different kinds of vegetables as an overview.

Healthy Vegetable Cooking Methods

Unfortunately, this first cooking method study does not include information on roasted vegetables, so we’ll have to research and include that separately.

Unfortunately, roasted vegetables are not the healthiest method, so while we’re not roasting them all the time, we’re still enjoying wonderful roasted vegetable recipes for some meals.

NOTE: Mallow is included in this list because this is an Asian study where mallow is a common vegetable. While lesser known in North America, the leaves, seeds and roots of the mallow plant are all edible and medicinally beneficial vegetable.

Vitamin C and Vitamin K Content in Vegetables by Cooking Method

VegetableCooking treatmentVitamin C mg/kg% Vitamin C vs. RawVitamin K mg/kg% Vitamin K vs. raw
BroccoliRaw668.04100%1.54100.00%
Boiled370.0452.85%1.5998.89%
Blanched615.4288.86%1.69108.81%
Steamed761.48111.21%1.90123.08%
Microwaved836.15112.76%1.71101.76%
CarrotRaw39.92100.00%0.04100.00%
Boiled56.6255.33%0.0485.02%
Blanched32.1572.71%0.0371.86%
Steamed33.4970.51%0.0469.87%
Microwaved63.0092.02%0.0685.35%
ChardRaw163.04100.00%1.59100.00%
Boiled0.000.00%2.95116.23%
Blanched124.5859.69%2.38116.73%
Steamed0.000.00%2.24105.60%
Microwaved173.4367.64%2.82112.62%
MallowRawNDND3.41100.00%
BoiledNDND3.0081.75%
BlanchedNDND2.1756.71%
SteamedNDND2.6669.33%
MicrowavedNDND2.0344.28%
PotatoRaw58.30100.00%0.02100.00%
Boiled30.5749.79%0.03141.16%
Blanched44.7373.20%0.0294.71%
Steamed51.0883.65%0.0375.98%
Microwaved62.9876.86%0.0395.32%
SpinachRaw337.48100.00%2.34100.00%
Boiled220.1440.12%3.6994.93%
Blanched283.9657.85%3.3597.27%
Steamed262.7844.75%3.6187.70%
Microwaved499.2691.10%4.67121.21%
Sweet PotatoRaw131.35100.00%NDND
Boiled95.2073.86%NDND
Blanched88.9267.70%NDND
Steamed81.3259.44%NDND
Microwaved183.73100.21%NDND
ZucchiniRaw151.30100.00%0.19100.00%
Boiled131.8263.71%0.2387.09%
Blanched163.8687.01%0.2393.78%
Steamed199.5389.24%0.2590.22%
Microwaved205.8092.73%0.29101.95%

ND = Not Detected. Note that for Vitamin C and Vitamin K relates to “content in water-soluble fraction after treatment”, and the percentage (%) retention is the respective cooking method compared to the raw sample as the baseline.

Total Vitamin E Tocopherols by Cooking Method

VegetableCooking treatmentTotal-tocopherol CWa (mg/kg)Total-tocopherol TRb (%)
BroccoliRaw17.85b100.00b
Boiled29.57a161.16a
Blanched30.07a164.28a
Steamed29.37a162.34a
Microwaved28.55a144.86a
CarrotRaw3.74100.00
Boiled3.0469.46
Blanched3.4984.26
Steamed3.9889.79
Microwaved5.5586.62
ChardRaw10.74d100.00c
Boiled23.50a136.71a
Blanched15.73c114.50b
Steamed15.00c104.31bc
Microwaved17.40b102.80c
MallowRaw9.11b100.00b
Boiled14.43a147.78a
Blanched14.05a141.33a
Steamed14.94a146.25a
Microwaved15.23a128.12ab
PotatoRaw0.56a100.00a
Boiled0.43cd71.38c
Blanched0.50ab84.11b
Steamed0.39d66.15cd
Microwaved0.47bc59.96d
SpinachRaw20.03100
Boiled52.00138.37
Blanched44.82154.64
Steamed57.56165.42
Microwaved56.68174.45
Sweet potatoRaw5.68bc100.00a
Boiled5.44c97.18ab
Blanched5.56c98.24ab
Steamed6.28b107.59a
Microwaved6.10b96.17ab
ZucchiniRaw2.99100.00
Boiled4.74116.24
Blanched3.5696.25
Steamed4.60105.01
Microwaved4.93112.17

β-Carotene Content in Vegetables by Cooking Method


Sample
Cooking treatmentβ-Carotene CWa (mg/kg)β-Carotene TRb (%)
BroccoliRaw2.56ab100.00ab
Boiled2.33bc89.40ab
Blanched2.01c78.23b
Steamed2.71ab105.93a
Microwaved3.02a109.71a
CarrotRaw29.38100.00
Boiled16.2347.36
Blanched19.0258.29
Steamed14.0640.02
Microwaved20.6640.80
ChardRaw15.22d100.00b
Boiled30.06a124.22a
Blanched21.28c109.36ab
Steamed25.40b125.37a
Microwaved26.78b112.06a
MallowRaw34.99b100.00ab
Boiled41.39ab109.92ab
Blanched46.42a119.16a
Steamed33.89b85.61b
Microwaved46.56a101.94ab
SpinachRaw27.56100.00
Boiled27.56100.00
Blanched46.54102.43
Steamed41.1884.67
Microwaved51.58114.67
PotatoRawNDND
BoiledNDND
BlanchedNDND
SteamedNDND
MicrowavedNDND
Sweet potatoRawNDND
BoiledNDND
BlanchedNDND
SteamedNDND
MicrowavedNDND
ZucchiniRaw0.72100.00
Boiled.4142.13
Blanched.6674.33
Steamed.8782.47
Microwaved.8277.21

REFERENCE: Study by Lee S, Choi Y, Jeong HS, Lee J, Sung J. Effect of different cooking methods on the content of vitamins and true retention in selected vegetables. Food Sci Biotechnol. 2017 Dec 12;27(2):333-342. doi: 10.1007/s10068-017-0281-1. PMID: 30263756; PMCID: PMC6049644.((https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6049644/))

Summary of Best Cooking Methods for the Vegetables in This Study

Here’s a summary of the cooking methods that retain the highest nutrients for each vegetable based on the data provided in the scientific research.

1. Broccoli – Healthiest Cooking Method

Microwaving appears to be the best method for retaining nutrients in broccoli. It has the highest retention of Vitamin E (total tocopherols) at around 144.86%, and β-carotene at around 109.71%. This method may help to minimize nutrient loss by reducing cooking time.

2. Carrots – Healthiest Cooking Method

The cooking method that best retains Vitamin C and Vitamin K for carrots is microwaving. Similarly, microwaving also retains the most Vitamin E, but in terms of β-Carotene, raw consumption is superior.

3. Chard – Healthiest Cooking Method

For chard, boiling and microwaving seem to be the best options. Boiling retains the most Vitamin E (total tocopherols) at 136.71%, while microwaving has the highest β-carotene retention at 112.06%.

4. Mallow – Healthiest Cooking Method

Blanching is the best method for retaining nutrients in mallow. The researched showed that to be the highest retention for both Vitamin E (total tocopherols) and β-carotene at 141.33% and 119.16% respectively.

5. Potato – Healthiest Cooking Method

Boiled potatoes, followed by microwaved potatoes proved to retain the highest levels of Vitamin K while steaming retained the most vitamin C.

6. Sweet Potato – Healthiest Cooking Method

Steaming is the best cooking method for sweet potatoes in terms of Vitamin E (total tocopherols) retention at 107.59%. Data for β-carotene was not determined.

7. Spinach – Healthiest Cooking Method

For spinach, boiling and microwaving are the best methods for retaining nutrients. Boiling shows the highest retention for Vitamin E (total tocopherols) at 158.37%, while microwaving has the highest β-carotene retention at 114.67%.

8. Zucchini – Healthiest Cooking Method

Microwaving appears to be the best method for retaining nutrients in zucchini. It shows the highest retention for both Vitamin E (total tocopherols) and β-carotene at 110.98% and 77.21% respectively.

It’s important to note that the nutrient content can vary based on specific cooking methods and other factors, and these findings might not apply to every situation.

As you can see, the highest nutritive content of vegetables isn’t so simple because it varies by vegetable, nutrient and cooking method.

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