How to cook without destroying nutrients

There are advantages to cooking your food. For example, cooking makes fiber easier to digest and promotes the absorption of certain nutrients.

But there are also downsides to cooking: it diminishes the food’s nutritional quality because it destroys some of the vitamins and minerals. As a matter of fact, many vitamins – including vitamins C, B1 and B9 – are sensitive to heat, and cooking can easily eliminate up to half their initial volume.

But not all cooking methods are created equal: some techniques are better at preserving nutritional quality. The longer the cooking time and the higher the temperature, the more nutritional content is lost. We spoke with nutritionist Anthony Berthou, who gave us an overview of a variety of cooking methods.

This technique uses a low-temperature steamer (meaning the temperature remains below 212°F). It is the most appealing solution to optimize nutritional quality and preserve as many vitamins and minerals as possible.

It also maintains the flavor and texture of foods. This appliance is frequently used to cook vegetables, but it works with many other foods, such as legumes, fruits, poultry and fish.

Stir-frying is very common in Asian cuisine: the technique consists in sautéing foods in a wok or skillet.

This is a very quick cooking method: food is seared on high heat for just a few seconds, which limits the deterioration of the food’s inherent nutritional quality.

This cooking method is also appealing because it does not require much oil.

The French term “en papillote” refers to cooking ingredients in parchment (or aluminum foil). With this method, food is sealed in a pouch made from aluminum foil or parchment paper, then cooked in an oven or microwave. The food is protected inside the pouch, which helps to preserve nutrients.

However, cooking en papillote is usually done at a high temperature (250°F or higher), which diminishes the food’s nutritional quality.

If you opt for this method, it is better to use parchment paper to prevent any transfer of metal particles from the aluminum foil to your food. In addition, aluminum foil cannot be used in microwave ovens; only parchment paper is suitable for using a microwave to cook en papillote.

Furthermore, you should never add any acid (e.g., lemon, white wine or vinegar) when cooking with aluminum because the acidity promotes the absorption of aluminum.

To poach foods in water, the food is held at a high temperature for a lengthy period, which lowers its nutritional quality. Thus, it is preferable to poach at a low temperature and to avoid bringing foods to a boil.

In addition, some of the minerals (and vitamins, to a lesser extent) migrate into to the cooking liquid. Thus, we recommend that you consume this poaching liquid where possible. You should also choose organic vegetables to avoid consuming any pesticides that may have migrated into the cooking water.

Baking takes a long time and often requires very high temperatures. Thus it has a major impact on nutritional quality.

Furthermore, it promotes the Maillard reaction, which is the chemical reaction that occurs in high-temperature cooking and creates Maillard products. The reaction lends foods a brown color and enhances their flavors. For example, Maillard products are responsible for the characteristic taste of the crispy skin on an oven-roasted chicken. However, Maillard products encourage oxidative stress, which accelerates cellular aging and increases the risk of cancer (see our post on antioxidants).

Pan frying also requires high temperatures and a relatively long cooking time. As such, this cooking method should be limited.

It is also important to choose an oil suited to cooking: olive oil for low temperatures and coconut oil for high temperatures. You should never bring an oil to its smoke point, as this makes it toxic.

Similarly, you should absolutely avoid browning butter. If you cook with butter, choose ghee (i.e., clarified butter) because it tolerates higher temperatures better than butter.

When you grill meat, the fats in the meat drip into the charcoal and catch flame: the resulting smoke contains a carcinogenic substance (benzopyrene) and several other toxic compounds that permeate the meat.

According to a study, a grilled 3.5-ounce steak may contain as much benzopyrene as 120 cigarettes (Kaisennan, 1996). This is why it is recommended that the meat be cooked at least 4 inches from the coals.

If you cannot resist grilled meats in the summer, the best approach is to use a plancha or a vertical grill, which allows the smoke to escape into the sky without entering the meat. You should also marinate your foods before cooking as it reduces the amount of toxic compounds they absorb.

There is wide disagreement among experts about the dangers of microwave cooking. Some believe that, if the microwave oven is not damaged, it cannot emit dangerous amounts of radiation.

However, others are concerned because microwaves cause unnatural changes in food structures by agitating their water molecules, and we do not yet know the full extent of the potential effects and consequences of such action.

Because the matter has not been settled, it is advisable to use the microwave in moderation.

This high-temperature cooking method favors the production of troublesome compounds through the Maillard reaction.

In addition, browning food in a fryer also produces acrylamide, a molecule that promotes the development of cancer and becomes neurotoxic in high volumes. This molecule is formed mainly when sugars are present. For example, the sugar in potatoes will encourage the production of acrylamide when cooked in a fryer.

Finally, deep frying foods increases their fat content. Frying oils are usually high in omega-6 and saturated fatty acids, two kinds of fat that are already over-consumed (see our post on fats).