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How to Cook Green Vegetables Without Losing its Nutrients

Steamed, baked, boiled and more – find the best ways to cook green vegetables here.

A side view of a woman in the kitchen, cooking with a pan with pieces of vegetables next to it.

Any healthcare professional or dietician will usually advise you to consume green vegetables daily to maintain optimal well-being. Whether for health or social reasons, some people have taken this a step further by becoming vegan or vegetarian, or even following a raw vegan diet. 

A raw vegan diet consists of uncooked or heated food at temperatures below 40 to 47 degrees Celsius. It’s derived from the idea that cooking food destroys its nutrients. While there is some truth to this notion, it’s not entirely true as some vegetables are more nutritious when cooked. So, what’s the best way to prepare green vegetables without losing its benefits and nutrients? 

This article delves into how to prepare green vegetables so you can retain their nutrients when it comes to cooking them.

Methods to Prepare Green Vegetables

A close-up of green-coloured vegetables being washed under a sink.
Cooking in boiling water may destroy the nutrients in green vegetables.

It’s common knowledge that drinking water is essential for the human body. Unfortunately, when it comes to preparing vegetables, water can be disadvantageous. Because vitamins such as vitamin C, foliate and niacin in vegetables are water-soluble, they dissolve when cooked or boiled. Leftover water would also usually be drained out, taking vitamins away with it.

Furthermore, cooking requires heat, which is another element that can reduce the nutrients in vegetables. However, heat can also help break down their cell walls and fibres, making them easier to chew and digest. 

In Traditional Chinese Medicine (TCM), cooking with fire is considered yang (Heat). The process dries, hardens and shrinks food. This makes food more difficult to digest, and it’s recommended that people who are yang in nature avoid this method of cooking.

Conversely, cooking with water adds more yin (cold) to food. It moistens, expands and softens food, making it easy to digest and it’s a better cooking method for all types of body constitutions.

Here are some popular cooking methods for green vegetables, and what’s best for which. 

Steaming 

Great for: Broccoli, cauliflower, green beans 

TCM views steaming vegetables as neutral. It doesn’t change the energy of the vegetables cooked much and helps retain its nutrients well.

According to a report published in 2009, researchers investigated the effects of five popular methods of preparation – boiling, microwaving, steaming, stir-frying, and stir-frying followed by boiling – on broccoli. The result showed that steaming caused the lowest loss of the health-promoting compounds.

Boiling 

Great for: Carrots, tomatoes, potatoes 

Boiling green vegetables in water according to TCM warms the vegetables but allows their nutrients to flow into the water, which isn’t ideal. If boiled in too much water, it reduces the yang of the vegetables. This method is best for making soups and stews (stewing) so that the liquid is consumed rather than discarded.

This method of cooking, however, is great for root vegetables. A study in the Journal of Agriculture and Food Chemistry revealed that consuming cooked carrots is much better than raw. Instead of destroying nutrients, cooking can increase the level of beta-carotene. A component in carrots, beta-carotene is converted into vitamin A, which makes carrots the go-to food to maintain eye health

In the same year, the journal published a study on tomatoes. It showed that cooking could boost the lycopene in tomatoes, a red pigment found in tomatoes and reddish-coloured fruits, which is a powerful antioxidant. 

This is also supported by the findings from the Food Science and Biotechnology journal. Certain cooked vegetables have higher contents of fat-soluble vitamins such as beta-carotene.

Frying or stir-frying

A top view of tomatoes being cooked in a pan.
Some vegetables are better stir-fried.

Great for: Potatoes, tomatoes, eggplant, pumpkin, bok choy, spinach, mustard greens, kai lan  

Frying and stir-frying green vegetables gives it yang energy in TCM. Cooking with high heat for a short amount of time retains the crunchiness of the vegetables (yang) but keeps the inside soft and retains the water content (yin) and nutrients. 

A Spain-based study published in Food Chemistry focused on testing four vegetables commonly found in the Mediterranean diet: potatoes, tomatoes, eggplant and pumpkin. The study learned that frying the vegetables in extra virgin oil generates higher phenols. Phenol is an antioxidant that prevents chronic diseases like cancer, diabetes and macular degeneration.

Grilling and griddling 

Great for: Artichokes, asparagus, broccoli, celery, eggplant, green beans, onions, spinach and Swiss chard 

In TCM, grilling allows green vegetables to develop a strong yang and warming effect. However, this method of preparation may cause the development of toxic substances in food and should be less frequently. 

Griddling is a method of cooking where food is heated on a flat iron pan. A 2009 study published in the Journal of Food Science states that griddling might produce the lowest losses of antioxidants in many kinds of vegetables. Additionally, the study also mentioned that boiling and pressure cooking might lead to the biggest decrease in antioxidant activity.

A 2019 research study agreed that griddling, as well as frying, is the preferred way to cook tomatoes and retain high antioxidant activity. 

Baking and roasting 

Great for: Carrots, potatoes, broccoli, cauliflower, asparagus 

According to TCM, baking helps increase yang energy and can balance the cooling effect of cold food (vegetables or raw foods). Roasting green vegetables makes it more warming and when combined with oil or fat can create Damp Heat. 

With all the available cooking methods, it can be concluded that green vegetables will lose their nutrients the most when cooked in a lot of heat or with liquid. The key is choosing the methods that use the least amount of time and water such as steaming and stir-frying. Alternatively, you can make a vegetable stew or soup, so you don’t have to throw out the nutrient-filled water the greens are cooked in.

How you choose to prepare your vegetables should be what produces the best taste and texture for you. Being able to enjoy your vegetables is important, so you can incorporate them in your diet and not feel like it’s a chore. 

This is an adaptation of an article, “烹饪蔬菜最佳的方法?”, which first appeared on the Health123 website. 

References

  1. Medical Xpress. 2013. Steaming broccoli preserves potential power to fight cancer, study finds. [Accessed on 14 August 2022]
  2. National Center for Biotechnology Information. 2009. Effects of different cooking methods on health-promoting compounds of broccoli. [Accessed on 14 August 2022]
  3. Scientific American. 2009. Fact or Fiction: Raw Veggies are Healthier than Cooked Ones. [Accessed on 14 August 2022]
  4. Food Science and Biotechnology. 2017. Effect of different cooking methods on the content of vitamins and true retention in selected vegetables. [Accessed on 14 August 2022]
  5. Universidad de Granada. 2015. Vegetables fried in extra virgin olive oil have more beneficial properties than when boiled. [Accessed on 14 August 2022]
  6. Wiley Online Library. 2009. Influence of Cooking Methods on Antioxidant Activity of Vegetables. [Accessed on 14 August 2022]
  7. Journal of Food Technology Research. 2019. Effect of Domestic Cooking on Physicochemical Parameters, Phytochemicals and Antioxidant Properties of Algerian Tomato (Solanum Lycopersicum L. Var. Marmande). [Accessed on 14 August 2022]
  8. Yuan Qi Acupuncture and Health Centre, Nutrition in Chinese Medicine: Different Cooking Methods? [Accessed 12 September 2022]

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