The Vitl Nutrition Team / 6 Apr 2018
High heat is great for speeding up the cooking process but sadly that doesn't always preserve the nutritional value of food very well. Here’s the lowdown on different cooking methods and when they should be used and when to avoid them.
Broiling involves exposing the food to high heat right below the heat source in order to brown foods on the outside leaving them tender on the inside. Whilst this can add to the flavour and texture of foods, it can generate increased amounts of unhealthy compounds called acrylamide, which is thought to be a carcinogen. Other potentially harmful chemicals include polycyclic aromatic hydrocarbons (PAH) which have been associated with cancer.
Grilling can also produce acrylamide too as the heat source but less is known about the harmful effects of this type of cooking. However, the occasional grill isn’t likely to be detrimental to your health.
Roasting starchy vegetables (such as potatoes) and toasting bread until it’s well done can pose a health risk as the sugars in these foods convert to acrylamides which are carcinogenic. It’s best to lightly toast your bread and cook your potatoes until golden yellow.
Both these quick and versatile ways to cook are ok as long as you’re doing it the right way! Keep cooking times short (as longer cooking times are thought to impact the nutritional value), and use an oil that doesn’t burn or go rancid easily. This means the oil should have a high smoke point - good examples include avocado oil and rapeseed oil.
Poaching involves simmering your foods (so heating the liquid up to under its boiling point) in a bath of either water or a both. This form of cooking can be used not only for eggs (brunch anyone?) but chicken and fish too. You might want to use a meat thermometer to check your proteins are cooked through (it can be harder to tell when poaching), and watch your salt and calorie intake if you’re poaching in stocks or milk respectively. Like boiling, you’ll lose some nutrients (i.e. B vitamins) as they leach out into the poaching liquid so if you can, it’s good to consume some of the poaching liquid too.
Boiling is a less preferred method of cooking as some nutrients, particularly water-soluble ones like B vitamins and vitamin C can leach out into the water which is then discarded. Steaming offers a much better way of retaining the nutrients in your food. When it comes to microwaving, it’s up for debate about whether it’s detrimental to the nutritional content of foods. It offers quick cooking times which means that fewer nutrients are lost, and doesn’t involve water which can lead to the loss of nutrients1.
Some advocate eating as many raw foods as possible to avoid all possible destruction of nutrients. However, the antioxidant capacity is actually higher some foods when they are cooked! This is often because tough cellular walls are broken down in the process of cooking giving you access to those nutrients. The antioxidant lycopene in tomatoes is best absorbed when they’re cooked and the beta-carotene in carrots (converted to vitamin A in your body) is better accessed when they’re lightly cooked.
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