If you overcook fish or meat, does it lose nutrients in the same way vegetables do, or will it just affect the taste?
Liam Hughes, by email

Cooking meat and fish makes them taste nicer and also makes them easier to digest, but cooking often does result in the loss of certain nutrients, especially if you cook at high temperatures for a long time. Protein is altered by heat, and when cooking conditions are seriously hot it can become less available for use in the body.

As well as protein, the B vitamins found in meat and fish are all water-soluble and most are sensitive to heat. Around 20 per cent of thiamin (vitamin B1), which helps us obtain energy from food, is lost during cooking. Riboflavin (vitamin B2), which also provides energy, can be lost in meat juices and vitamin B6 and folate can be lost to some extent in cooking. So it’s healthiest to cook your meat and fish as quickly as possible or, for a roast, on as low a heat possible.