It is a fact – cooking food destroys nutrients. No matter you like it or not.
Most people heard this statement at least once in their lifetime. Cooking or preparing food with the use of heat results in more nutrient loss than freezing or drying. In case of drying, the amount of nutrient loss depends on the method used, duration and temperature.
Raw spinach versus cooked spinach. According to research, it is better to eat tomatoes and carrots slightly cooked while spinach raw. After all, raw spinach looks much better than cooked one!
There are exceptions to this rule though as the level of some nutrients increases when food is heated. Some examples are beta-carotene, lycopene and ferulic acid. Note, that I am talking about the heat that is produced in the process of steaming not high-temperature cooking such as frying, roasting, grilling or even boiling. In case of boiling, nutrients are washed into the water.
According to New York research led by Veronica Dewanto in 2002, upon heating the level of beta-carotene, lycopene and ferulic acid goes up because heat breaks down tough cellulose-rich cell walls within which these nutrients reside. Cellulose is found in cell walls of roots, leaves, stalks and stems. In the world of cooking, these parts are called “vegetables”. Compare them to seed-bearing parts of a plant or “fruits” containing minimum amount of cellulose. That is why when you eat a raw carrot (containing beta-carotene) or beets (rich in ferulic acid), the number of chews you make far outweighs the number of chews you make when you eat an orange.
Ferulic acid is a powerful antioxidant found in stems, leaves and seeds of most plants. Its extraordinary ability to fight free radicals makes it one of the key ingredients in anti-aging cosmetics, sunscreens and drugs. In addition, this acid is also used in food industry as a natural preservative. It has a range of other properties, among which, is ability to counteract inflammation, allergies, formation of cancerous cells, virus and microbial activity. Ferulic acid is found in high level in bamboo shoots, rye, sweet corn, red beets and brown rice. In fact, bamboo shoots contain more ferulic acid per 100 gram of a product than rye, sweet corn, red beets and brown rice combined. On average, a 100 grams of bamboo shoots contain 244 mg of ferulic acid.
Now, back to nutrients that ARE damaged upon heat processing. They include the majority of vitamins, minerals and phytonutrients. Look at the chart below.
Maximum losses of selected vitamins and minerals when subjected to freezing, drying and cooking. Source: Modified from Nutritiondata.self.com
For example, let’s take the essential vitamin B1 or thiamin, the third from the top on this chart. In your body, it is responsible for production of energy, synthesis of DNA molecules and conduction of nerve impulses. It is found in small amounts in nearly all foods. In fact, many common vegan foods such as cereal grains, legumes and nuts contain enormous amounts of this vitamin. Yet, it is one of the most common nutrient deficiencies in the western world. The reason is that vitamin B1 is one of those nutrients that is too delicate for heat processing. To be precise, up to 55% of the vitamin is destroyed via cooking.
It is clear from the chart that when processing raw foods, in general, the greatest loss of nutrients happens when food is subjected to heat. The chart has just a few examples of vitamins and minerals known to science. Moreover, not a single phytonutrient is listed here. Besides vitamins and minerals, phytonutrients are compounds that keep humans nourished and free of diseases. Not fats, carbohydrates or proteins. As of today, more than 25,000 phytonutrients are known to science and new ones are discovered every day. It is true that some phytonutrients may be locked within tough cell walls and not easily accessible to human digestion. However, if human bodies are not designed to expel them, maybe there is a reason behind it. Nonetheless, if you are concerned about getting as much nutrients as possible from your food, the problem can be partly solved with a high-quality blender without the use of heat.
As a summary, think about why execute the gifts of nature which are still metabolically alive after harvest turning them from aromatic masterpieces providing you with plethora of nutrients to wrinkled objects stripped most of their goodness…
Main references:
Dewanto, V., Xianzhong, W., Kafui, K.A., Rui, H.L. (2002). Thermal Processing Enhances the Nutritional Value of Tomatoes by Increasing Total Antioxidant Activity. Journal of Agriculture and Food Chemistry, 50, 3010−3014.
Kumar, N., Pruthi, N. (2014). Potential Applications of Ferulic Acid from Natural Sources. Biotechnolgy Reports, 86-93.
Hey Margarita, I’ve been looking into eating more raw foods which is how I came across your site. You’ve certainly opened my eyes on a more scientific level of what’s actually happening. Do you have any suggestions or recommendations about books that I could read further about making the switch to going raw? Thanks 🙂
Thank you for commenting Amanda.
Certainly this is a wise move and it would positively impact your entire lifestyle of you are really into it.
I would suggest first reading Dr. Douglas Graham’s book called The 80/10/10 Diet. You can read about this surprisingly committed raw fooder here.
Hi Margarita,
Very good article, I really enjoyed reading it!
To be honest, I didn’t know about the vitamin b1, I knew about the b12, I learn something new every day:)
The table is very interesting, I will print this page and use it as a guide.
Thank you very much for this helpful information!
Thank you Daniella!
B12 along with B1 are two of those eight known B vitamins. The role of B12 is critical as it is essential for smooth functioning of the brain and nervous system in general. In fact, this is the only vitamin that is hard to get eating only vegan foods and therefore most vegans and raw fooders take it as a supplement just to cover their backs. I personally drink organic (chicken) raw eggs yolks since there is loads of B12 in yolks.
I am glad you liked the article.