Cooking Vegetables for Optimum Nutrition

For a lot of paleo lovers, it is very difficult to decide if they should consume their veggies in the raw form or after cooking or heating. But the decision doesn’t gets any easier here. For example, it is very tricky to identify the precise cooking method, cooking temperature and duration of heat exposure. This is mainly because, nutritionists believe that that excessive cooking (or over-cooking) has a negative effect on the nutritional value of your veggies. Based on several clinical and experimental studies, it has been observed that improper cooking techniques can reduces the nutrients and water content, while also reducing the anti-nutrients present in the vegetables that interferes with the absorption of vitamins and minerals.

Likewise, you can’t consume all the veggies in the raw form because, according to a new study, cooking increases the antioxidants concentration and digestibility index in some vegetables (1, 2).

So what’s the verdict?

It can be safely assumed that different vegetables have different nutritional composition and tolerance to heat. Therefore, it is highly recommended to adopt different cooking techniques for the retention of optimal nutritional value.

Some of the popular and recommended paleo cooking methods for different vegetables include:

Boiling

Broccoli

According to a study reported in the Journal of Food and Agricultural Chemistry (1), investigators suggested that cooking in water helps a great deal in preserving the natural nutritive value of vegetables. This is especially true for antioxidants like carotenoids. Boiling also helps in improving the concentration of some nutrients in the vegetables. Traditionally, boiling is a better choice in terms of vitamins and nutrient preservation as compared to frying. The color of vegetables can also be retained with appropriate boiling techniques adding to the aesthetic and flavor quality of your meals.

The negative effects of boiling include; loss of some vitamins and minerals. You can reduce the nutrient loss by utilizing the water/ soup of veggies instead of draining or discarding it.

Examples: Potatoes, peas, carrots

Frying and Sautéing

Grill vegetables carrots and beets frying. Closeup

Long frying might cause damage to the vitamins due to excessive heat exposure. Nutritionists recommend frying for small period of time to preserve the vitamins present in the vegetables. Frying or sautéing is an excellent cooking modality if you are looking to cook vegetables with fat or some form of animal protein.

The negative side-effect is; exposure to oxidative stress may convert some vegetables into junk fats (this is especially common in situations when you re-use the same oil on different vegetables).

Example; sting beans, sweet potatoes

Baking/Roasting

tart with broccoli and cheese with blue cheese on a wooden board

Baking/roasting helps in maintaining some minerals and vitamins already present in vegetables due to no requirement of water addition.

But on the other side, some vegetables might get damaged in roasting/baking process. Formation of AGEs is another negative side or roasting that causes stress and speeds-up the aging process. According to a new study reported in peer reviewed Journal of the Science of Food and Agriculture (2), investigators explained that excessive and penetrating heat can destroy the nutritional quality by two mechanisms:
1. Degradation of nutrients due to heat.
2. Higher excitability of phytonutrients due to changes in the texture of vegetables.

Example: sweet potatoes, broccoli, squash

Slow-cooking

Soup

The temperature in slow-cooking is usually kept below the boiling point that causes minimum loss of nutrients. Slow-cooking can also be referred to as the long-cooking method and is usually preferred with you are cooking a meal with animal proteins. To improve the maximum nutritional value, add the vegetables at the end of cooking process when you are about to remove the pan from the flame.

Example: Squash, sweet potato

Steaming

Mixed vegetables on a plate

It is a gentle cooking process with minimum loss of water content of the veggies. The process generally helps in increasing the antioxidant and nutrient value of food. In fact according to a new research reported in the Food Chemistry journal (3) steaming even helps in preserving the most fragile vitamins such as vitamin C from degradation in addition to polyphenols. According to the data reported by Miglio and colleagues (1), steaming also helps in preserving the texture of vegetables as opposed to boiling.

The negative side of the process includes the complete absence of fats. According to paleo dieters, low-fat foods is not a benefit at all. So, keep a side dish tossed or sautéed in little fat or oil or do the same with your steamed vegetables.

Example: Broccoli, spinach

Microwaving

Gemse - Tiefkhlkost

The process includes less water than other methods with short time for cooking which is helpful to maximize the nutrient content of food. Research show that microwaving the vegetables preserves more amount of vitamin C in comparison to boiling technique; that’s why it is considered as the best method for the preservation of antioxidant levels.

The biggest harm of microwaving the vegetables is; exposure to poisonous radiation that may cause cancer. Additionally, some of the vegetables including cauliflower may lose antioxidants and phenols during microwaving process. Another negative side-effect of microwaving the veggies is, dryness and sogginess that may destroy the texture, appearance and flavor quality of the vegetables.

Example: corns, carrots, spinach

Fermenting

It is not considered as a true physical cooking method per se but if you are a paleo lover, you may want to try fermentation for the maintenance of excellent health. Fermented vegetables are rich in fermenting bacteria, yes bacteria! Consumption of fermented vegetables and pickles help in repopulating the gut flora and maintenance of digestive system.

The negative side of fermentation includes, a slight rise in histamine levels that can aggravate the risk of allergies (especially if you are genetically susceptible).

Example: carrots, cucumber, peppers

Spiralizing

Healthy zucchini noodle dish with chicken on white plate on wood table

As discussed in the article, every cooking methods includes some advantages and disadvantages, you must opt for a method after learning about the nutritional value and composition of your meals. If this seems like a lot of work, feel free to incorporate spiralizing as a vegetable preparation technique.

Spiralizing increases the surface area of your vegetables; thereby facilitating the cooking process without exposing your nutrients to extremely high temperature for prolonged periods of time. You can also retain maximum amount of texture, color and consistency of your veggies with spiralizing.

References:
1. Miglio, C., Chiavaro, E., Visconti, A., Fogliano, V., & Pellegrini, N. (2007). Effects of different cooking methods on nutritional and physicochemical characteristics of selected vegetables. Journal of Agricultural and Food Chemistry, 56(1), 139-147.
2. Palermo, M., Pellegrini, N., & Fogliano, V. (2014). The effect of cooking on the phytochemical content of vegetables. Journal of the Science of Food and Agriculture, 94(6), 1057-1070.
3. Mazzeo, T., N’Dri, D., Chiavaro, E., Visconti, A., Fogliano, V., & Pellegrini, N. (2011). Effect of two cooking procedures on phytochemical compounds, total antioxidant capacity and colour of selected frozen vegetables. Food Chemistry, 128(3), 627-633.
4. Ling, Y., Wang, H., Yong, W., Zhang, F., Sun, L., Yang, M. L., … & Chu, X. G. (2011). The effects of washing and cooking on chlorpyrifos and its toxic metabolites in vegetables. Food Control, 22(1), 54-58.

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