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

Vegetable	Cooking treatment	Vitamin C mg/kg	% Vitamin C vs. Raw	Vitamin K mg/kg	% Vitamin K vs. raw
Broccoli	Raw	668.04	100%	1.54	100.00%
	Boiled	370.04	52.85%	1.59	98.89%
	Blanched	615.42	88.86%	1.69	108.81%
	Steamed	761.48	111.21%	1.90	123.08%
	Microwaved	836.15	112.76%	1.71	101.76%
Carrot	Raw	39.92	100.00%	0.04	100.00%
	Boiled	56.62	55.33%	0.04	85.02%
	Blanched	32.15	72.71%	0.03	71.86%
	Steamed	33.49	70.51%	0.04	69.87%
	Microwaved	63.00	92.02%	0.06	85.35%
Chard	Raw	163.04	100.00%	1.59	100.00%
	Boiled	0.00	0.00%	2.95	116.23%
	Blanched	124.58	59.69%	2.38	116.73%
	Steamed	0.00	0.00%	2.24	105.60%
	Microwaved	173.43	67.64%	2.82	112.62%
Mallow	Raw	ND	ND	3.41	100.00%
	Boiled	ND	ND	3.00	81.75%
	Blanched	ND	ND	2.17	56.71%
	Steamed	ND	ND	2.66	69.33%
	Microwaved	ND	ND	2.03	44.28%
Potato	Raw	58.30	100.00%	0.02	100.00%
	Boiled	30.57	49.79%	0.03	141.16%
	Blanched	44.73	73.20%	0.02	94.71%
	Steamed	51.08	83.65%	0.03	75.98%
	Microwaved	62.98	76.86%	0.03	95.32%
Spinach	Raw	337.48	100.00%	2.34	100.00%
	Boiled	220.14	40.12%	3.69	94.93%
	Blanched	283.96	57.85%	3.35	97.27%
	Steamed	262.78	44.75%	3.61	87.70%
	Microwaved	499.26	91.10%	4.67	121.21%
Sweet Potato	Raw	131.35	100.00%	ND	ND
	Boiled	95.20	73.86%	ND	ND
	Blanched	88.92	67.70%	ND	ND
	Steamed	81.32	59.44%	ND	ND
	Microwaved	183.73	100.21%	ND	ND
Zucchini	Raw	151.30	100.00%	0.19	100.00%
	Boiled	131.82	63.71%	0.23	87.09%
	Blanched	163.86	87.01%	0.23	93.78%
	Steamed	199.53	89.24%	0.25	90.22%
	Microwaved	205.80	92.73%	0.29	101.95%

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

Vegetable	Cooking treatment	Total-tocopherol CWa (mg/kg)	Total-tocopherol TRb (%)
Broccoli	Raw	17.85b	100.00b
	Boiled	29.57a	161.16a
	Blanched	30.07a	164.28a
	Steamed	29.37a	162.34a
	Microwaved	28.55a	144.86a
Carrot	Raw	3.74	100.00
	Boiled	3.04	69.46
	Blanched	3.49	84.26
	Steamed	3.98	89.79
	Microwaved	5.55	86.62
Chard	Raw	10.74d	100.00c
	Boiled	23.50a	136.71a
	Blanched	15.73c	114.50b
	Steamed	15.00c	104.31bc
	Microwaved	17.40b	102.80c
Mallow	Raw	9.11b	100.00b
	Boiled	14.43a	147.78a
	Blanched	14.05a	141.33a
	Steamed	14.94a	146.25a
	Microwaved	15.23a	128.12ab
Potato	Raw	0.56a	100.00a
	Boiled	0.43cd	71.38c
	Blanched	0.50ab	84.11b
	Steamed	0.39d	66.15cd
	Microwaved	0.47bc	59.96d
Spinach	Raw	20.03	100
	Boiled	52.00	138.37
	Blanched	44.82	154.64
	Steamed	57.56	165.42
	Microwaved	56.68	174.45
Sweet potato	Raw	5.68bc	100.00a
	Boiled	5.44c	97.18ab
	Blanched	5.56c	98.24ab
	Steamed	6.28b	107.59a
	Microwaved	6.10b	96.17ab
Zucchini	Raw	2.99	100.00
	Boiled	4.74	116.24
	Blanched	3.56	96.25
	Steamed	4.60	105.01
	Microwaved	4.93	112.17

β-Carotene Content in Vegetables by Cooking Method

Sample	Cooking treatment	β-Carotene CWa (mg/kg)	β-Carotene TRb (%)
Broccoli	Raw	2.56ab	100.00ab
	Boiled	2.33bc	89.40ab
	Blanched	2.01c	78.23b
	Steamed	2.71ab	105.93a
	Microwaved	3.02a	109.71a
Carrot	Raw	29.38	100.00
	Boiled	16.23	47.36
	Blanched	19.02	58.29
	Steamed	14.06	40.02
	Microwaved	20.66	40.80
Chard	Raw	15.22d	100.00b
	Boiled	30.06a	124.22a
	Blanched	21.28c	109.36ab
	Steamed	25.40b	125.37a
	Microwaved	26.78b	112.06a
Mallow	Raw	34.99b	100.00ab
	Boiled	41.39ab	109.92ab
	Blanched	46.42a	119.16a
	Steamed	33.89b	85.61b
	Microwaved	46.56a	101.94ab
Spinach	Raw	27.56	100.00
	Boiled	27.56	100.00
	Blanched	46.54	102.43
	Steamed	41.18	84.67
	Microwaved	51.58	114.67
Potato	Raw	ND	ND
	Boiled	ND	ND
	Blanched	ND	ND
	Steamed	ND	ND
	Microwaved	ND	ND
Sweet potato	Raw	ND	ND
	Boiled	ND	ND
	Blanched	ND	ND
	Steamed	ND	ND
	Microwaved	ND	ND
Zucchini	Raw	0.72	100.00
	Boiled	.41	42.13
	Blanched	.66	74.33
	Steamed	.87	82.47
	Microwaved	.82	77.21

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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