How cooking affects the nutrient content of food

Comment la cuisson affecte la teneur en nutriments des aliments

Eating nutritious foods can improve your health and energy levels.

Surprisingly, the the way in which you cook your food has a major effect on the amount of nutrients it contains.

This article explores how various cooking methods affect the nutrient content of foods.

Nutrient content is often changed during cooking

Cooking food improves digestion and increases the absorption of many nutrients .

For example, the protein of eggs cooked is 180% more digestible than raw eggs .

However, some cooking methods reduce several key nutrients.

The following nutrients are often reduced during cooking:

  • Water-soluble vitamins: vitamin C and B vitamins - thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), folic acid (B9) and cobalamin (B12)
  • Fat soluble vitamins: vitamins A, D, E and K
  • Minerals: mainly potassium, magnesium, sodium and calcium

Boil, simmer and poach

Boiling, simmering, and poaching are similar water-based cooking methods.

These techniques differ in water temperature:

  • Poaching: less than 82°C
  • Simmering: Between 85 – 93 °C
  • Boiling: 100°C

Vegetables are generally an excellent source of vitamin C, but much of it is lost when cooked in water.

In fact, boiling reduces vitamin C content more than any other cooking method. Broccoli , spinach, and lettuce can lose up to 50% or more of their vitamin C when boiled .

Because vitamin C is water soluble and sensitive to heat, it can escape from vegetables when immersed in hot water.

B vitamins are also heat sensitive. Up to 60% of thiamin, niacin and other B vitamins can be lost when meat is simmered and its juices run out.

However, when the liquid containing these juices is consumed, 100% of the minerals and 70-90% of the B vitamins are retained .

On the other hand, boiled fish has been shown to preserve the content omega-3 fatty acids much more than frying or the microwave .

Grill and grills

The grill and the grills are similar methods of dry heat cooking.

When grilling, the heat source comes from below, but when grilling, it comes from above.

Grilling is one of the most popular cooking methods because of the great flavor it imparts to food.

However, up to 40% of B vitamins and minerals can be lost when broiling or broiling when the nutrient-rich juices leak out of the meat .

There are also concerns about polycyclic aromatic hydrocarbons (PAHs), which are potentially carcinogenic substances that form when meat is grilled and fat drips onto a hot surface.

However, researchers have found that PAHs can be reduced by 41-89% if drips are removed and smoke is minimized .


The microwave is a cooking method easy, convenient and safe .

Short cooking times and reduced exposure to heat preserve the nutrients in microwave foods .

In fact, studies have shown that microwaving is the best method to retain garlic 's antioxidant activity. and mushrooms .

Meanwhile, about 20-30% of the vitamin C in green vegetables is lost in the microwave, which is lower than most cooking methods .

Roasting and cooking

Roasting and baking refers to cooking food in a dry heat oven.

Although these terms are somewhat interchangeable, roasting is generally used for meat while baking is used for bread, muffins, cakes, and similar foods.

Most vitamin losses are minimal with this cooking method, including vitamin C.

However, due to long cooking times at high temperatures, the B vitamins in roasted meat can decrease by up to 40% .

stir-fried foods

Food is cooked in a saucepan over medium to high heat in a small amount of oil or butter.

These techniques are very similar, but with stir-frying the food is often stirred, the temperature is higher, and the cooking time is shorter.

In general, it is a healthy way to prepare food.

Cooking for a short time without water prevents the loss of B vitamins, and adding fat improves the absorption of plant compounds and antioxidants .

A study revealed that the absorption of beta carotene was 6.5 times greater in sautéed carrots than in raw carrots .

In another study, lycopene blood levels increased 80% more when people consumed tomatoes sautéed in olive oil than without .

On the other hand, stir-frying has been shown to significantly reduce the amount of vitamin C in broccoli and red cabbage .


Frying involves cooking food in a large amount of fat - usually oil - at high temperature. The food is often coated in batter or breadcrumbs.

It is a popular way of preparing food because the skin or coating maintains a seal, which ensures that the interior stays moist and cooks evenly.

The fat used for frying also makes the food very good.

However, not all foods are suitable for frying.

Oily fish are best sources omega-3 fatty acids, which have many health benefits. However, these greases are very delicate and prone to damage at high temperatures.

For example, frying tuna has been shown to degrade its omega-3 content by up to 70-85%, while cooking causes only minimal losses .

In contrast, frying preserves vitamins C and B, and it can also increase the amount of fiber in potatoes by converting their starch to resistant starch .

When oil is heated at a high temperature for a long period of time, toxic substances called aldehydes are formed. Aldehydes have been linked to an increased risk of cancer and other diseases .

The type of oil, temperature and cooking time affect the amount of aldehydes produced. Heating the oil also increases the formation of aldehyde.

If you want to fry food, do not overcook it and use one of the oils them healthier for frying.

Steam cooking

Steaming is one of the best cooking methods for preserving nutrients, including water-soluble vitamins, which are sensitive to heat and water .

Researchers found that steaming broccoli, spinach, and lettuce only reduced their vitamin C content by 9–15% .

The downside is that steamed vegetables can taste bland. However, this is easily remedied by adding a little seasoning and oil or butter after cooking.

Tips for Maximizing Nutrient Retention While Cooking

Here are 10 tips to reduce nutrient loss during cooking :

  1. Use as little water as possible when poaching or boiling.
  2. Consume the liquid left in the pan after cooking the vegetables.
  3. Add the meat juices flowing into the pan.
  4. Only peel vegetables after they have been cooked. Even better, do not peel at all to maximize their fiber and nutrient density.
  5. Cook vegetables in smaller amounts of water to reduce the loss of vitamins C and B.
  6. Try to eat cooked vegetables within days (a day or two), as their vitamin C content may continue to decrease when cooked foods are exposed to air.
  7. If possible, cut food after cooking. When foods are cooked whole, they are less exposed to heat and water.
  8. If possible, cook vegetables for only a few minutes.
  9. When cooking meat, poultry and fish , use the shortest cooking time necessary for safe consumption.
  10. Do not use baking soda when cooking vegetables. Although it helps maintain color, vitamin C will be lost in the alkaline environment produced by baking soda.

The essential

It is important to select the right cooking method to maximize the nutritional quality of your meal.

However, there is no perfect cooking method that retains all the nutrients.

In general, shorter cooking at lower temperatures with minimal water will produce the best results.

Don't let the nutrients in your food leak out.

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