How Does Cooking Affect the Nutritional Value of Food?

How does cooking affect the nutritional value of food?

When humans first discovered fire, that was when the age of cooking began. Now with seemingly endless ways of cooking foods, from blanching, boiling, microwaving, baking, sauteeing, steaming, grilling, roasting, poaching, simmering—the list goes on and on. It took us hundreds of years to stop and wonder— hmmm does cooking affect the nutritional value of our food? It’s a question that researchers have been poking at for only the last couple of decades. 

We’re here to shed some light on how cooking impacts your food. If you can’t stand the heat (or are curious about what the heat does to your food), then get out of the kitchen and get reading this post!

What Types of Cooking Methods Are There?

Each method of cooking using heat affects foods in different ways. While there are quite a few different cooking methods out there, they can actually be grouped into three different categories: dry heat cooking, moist heat cooking, and combination cooking. Dry heat relies on hot air and no liquid or steam. This type of cooking includes roasting, grilling, broiling, baking, and sauteing. Moist heat cooking involves water, whether it be liquid or steam, to cook foods. The moist heat cooking involves poaching, simmering, boiling, and steaming. The last type of cooking is combination cooking, which incorporates both dry and moist cooking methods— cooking at low heat for a long period of time. Combination cooking includes braising and stewing.

Why Do We Cook Our Food?

We first began cooking our food for safety reasons. Raw foods, particularly fish, meat, and eggs can be filled with bacteria like Campylobacter, Salmonella, and Listeria monocytogenes all of which cause food poisoning. According to the US Food and Safety Inspection Service, “Bacteria grow most rapidly in the range of temperatures between 40 °F and 140 °F, doubling in number in as little as 20 minutes. This range of temperatures is often called the “Danger Zone.” Cooking raw meat, eggs, and fish to certain internal temperatures effectively kills the bacteria. Moreover, according to the FDA “Heating foods to the right temperature for the proper amount of time will kill harmful bacteria that cause foodborne illness. Use a food thermometer to check the internal temperature.” It’s important to note that this is mainly all in regard to raw meat, fish, and eggs. This has very little to do with fruits and vegetables!

Another reason why humans began cooking their food was for digestibility. Cooking food breaks down some of the plant cell walls and fibers, which makes it easier for the body to digest and absorb the nutrients. This one really got us thinking. Does cooking our food really make it easier to digest and absorb nutrients? If so, does that hold true for all food? Skepticism is real here. Let’s dig in more.

What Happens When We Cook Our Food?

Heating food sets off a complex series of chemical and physical changes. Changes do vary according to the type of food that is being cooked, as well as the method used to cook it. While some changes might be conventionally called “advantageous” as the flavor and texture of the food improves, others might be deemed “disadvantageous,” like a reduction in nutrient content and the generation of undesirable compounds. 

An example of “advantageous” cooking would be caramelization. When food is heated, the sucrose in the food starts to melt and then boils. Then, the sucrose decomposes into its component monomer molecules, namely, glucose and fructose. Another example is starch degradation. When the polysaccharide starch is present, such as in potatoes, oats, or pasta, the heat breaks down the glycosidic bonds that link all the individual glucose units together and breaks up the polysaccharides to release the glucose monosaccharides. This leads to a kind of natural sweetness to cooked starches.

Now, on to the metaphorical meat of what happens when we cook our food and how that affects the nutritional composition. Let’s start from the beginning. There are two main types of vitamins: water-soluble and fat-soluble. 

Vitamins B1, B2, B3, B5, B6, B7, B12, and Vitamin C are all examples of water-soluble vitamins.

Vitamins A, D, E, and K are all fat-soluble vitamins. 

As the name points out, water-soluble vitamins are soluble in water and are generally found in foods that have a high content of water. Whereas fat-soluble vitamins are soluble in fat and are usually found in foods that have a high amount of fat like dairy, fish, and oils. 

Why is This Important?

The differences in solubility mean that the method that foods are cooked drastically influences the final vitamin content. Water-soluble vitamins in fruits and vegetables are seriously affected by cooking methods like boiling which involve putting food in water for a long duration of time. 

It’s not just the cooking method that impacts the vitamin content, it’s also the amount of time. Short cooking methods like stir-frying and blanching help to reduce the heat degradation of the content of vitamins when compared to methods that involve more time with heat like baking or roasting. 

How Does Cooking Affect the Mineral Content of Food?

The body cannot function properly without minerals. Just like vitamins, they are essential nutrients for our survival. In fact, there are two types of minerals, known as essential minerals and trace elements. Essential minerals are minerals that the body needs in relatively large amounts (>100mg per day). On the other hand, trace elements are minerals that the body needs in only small amounts (<100mg per day). Interestingly, heating does not directly impact mineral levels. However, minerals are usually leached out when food is cooked in boiling water. As minerals have high heat stability, they are less affected by cooking methods that involve a long period of time.

Cooking Food Creates Undesirable Compounds

While we did mention earlier that cooking foods can lead to the creation of undesirable compounds, we certainly did gloss over it. It’s actually a really, really, really big deal. 

There has been scientific evidence that cooking certain foods can generate carcinogenic compounds. That’s right— cancer-causing compounds. The most well-known of the compounds are nitrosamines. During cooking, nitrosamines are created from nitrites and secondary amines. This happens when things become charred in the smoking, grilling, or frying process. This same compound is found in tobacco. 

Another carcinogenic compound to note is Polycyclic Aromatic Hydrocarbons (PAHs), while most PAHs are not associated with cancer, some are. PAHs occurs when incomplete combustion happens from frying, smoking, or grilling.  

While there are certainly other carcinogenic compounds that result as a part of the cooking process like acrylamide, heterocyclic amines, uran, polycyclic aromatic hydrocarbons, and chloropropanols/esters. 

Chloropropanols/esters are connected to the thermal treatment of processed foods.

To put the science terminology aside for a moment, foods that contain protein or starch like meats, potatoes, or bread may result in the generation of undesirable carcinogenic compounds mainly by these cooking methods: grilling, smoking, frying, roasting, and baking.

To Cook or Not to Cook?

If you are not a vegan and plan on consuming eggs, meat, and fish then cooking is pretty much unavoidable for those types of foods. However, in regard to fruits and vegetables, the method that you cook plays a large role in their nutritional value. Generally speaking, longer cooking times seriously impacts the vitamin value of fruits and vegetables, while even a short amount of time does reduce the nutritional value of your food. 

In fact, boiling reduces the vitamin C content more than any other cooking method. Take for example a few of our favorite vegetables, boiled broccoli and spinach, which lose nearly 50% or more of their vitamin C.

How about vitamin B? When foods with vitamin B are simmered, nearly 60% of B vitamins may be lost. How about when grilled? 40% of B vitamins and minerals may be lost during the grilling process as nutrient-rich juice drips away from the food.

Does Microwaving Impact the Nutritional Value of Food?

While microwaving is a relatively short cooking process, it’s anything but natural. As it uses electricity and microwaves. Microwaves cause water molecules in the food to vibrate, which then produces the heat that cooks food.  When it comes to Vitamin C, in green vegetables 20–30% of vitamin C is lost when food is microwaved. Microwaving your food denatures the integrity of the vitamins. So, don’t do it! 

Foods That Are Healthier to Eat When Consumed Raw:

  • Broccoli: Raw broccoli contains 3x the amount of sulforaphane— a more powerful and potent cancer-fighting plant compound than cooked broccoli!
  • Cabbage: Cooked cabbage destroys the enzyme myrosinase, which is linked to cancer prevention.
  • Onions: Did you know that raw onion is an anti-platelet agent? That means that it plays a role in heart disease prevention. When onions are cooked, this anti-platelet agent is greatly reduced.

Foods That Are Healthier to Eat When Cooked:

  • Mushrooms: Cooking mushrooms helps degrade agaritine, a potential carcinogen found in mushrooms. Cooking also helps release ergothioneine, a powerful mushroom antioxidant.
  • Beans/Legumes: Lectins are dangerous toxins that legumes possess until they are cooked. 
  • Asparagus: Ever tried to eat raw asparagus? Doesn’t work so well. Cooking asparagus breaks down those tough fibrous cell walls, which allows us to access folate and vitamins A, C, and E.
  • Carrots: This one was a shock to us, but cooked carrots contain more beta-carotene than raw carrots.
  • Potatoes: Raw potato anyone? No thank you. Potatoes are just about indigestible.
  • Meat, fish, eggs, and poultry: No surprise here, these types of food may possess bacteria that lead to food-borne illnesses when eaten raw or improperly cooked.

EatToHeal Never-Baked Motto

We here at EatToHeal formulated our Real Food Bars so that they would never have to be baked. We wanted all the incredible bioavailable nutrients, vitamins, and minerals to be accessible to you, 100%, from the first bite to the last bite. No undesirable compounds were created, and you get the maximum benefits of all that each ingredient has to offer.