Does microwaving food destroy its nutritional content? © Getty Images

Does microwaving food destroy its nutritional content?

Cooking in general does reduce the nutritional value of food, but by how much and is your microwave that much worse?

Asked by: Lucas Barnden, Tonbridge

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Cooking, in general, destroys some vitamins. But not nearly as many as people think. Vitamin C, thiamine (B1), pantothenic acid (B5) and folate (B9) will all be denatured to varying degrees, but folate requires temperatures well beyond 100°C to destroy it, and pantothenic acid deficiency is virtually unheard of.

All the other main nutrients in food – carbs, fats, proteins, fibre and minerals – are either unaffected or made more digestible by heat. Cooking bursts open plant cells, which increases the amounts available to you. Your body will absorb a lot more of the antioxidants beta-carotene and phenolic acid from carrots, and the lycopene in tomatoes, when they’re cooked. There’s nothing about microwaves that damages food more than other cooking methods. In fact, microwaving can actually preserve nutrients.

Boiling vegetables tends to leach out the soluble vitamins into the cooking water, and ovens expose food to much longer cooking times and higher temperatures. Because microwaves penetrate food, they heat it much more efficiently and quickly, so there is less time for vitamins to break down and you don’t get a crust on the outside that has been heated much more than the middle. Microwaved food has about the same nutrient levels as steamed food.


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