Food is processed for many reasons; primarily to make it safe to eat, give it a longer shelf life, and make nutrients more available.
Although it is true that food processing can involve the addition of some things that aren’t so good for our health (like salt), other forms of processing can actually be beneficial.
Vitamin C is one of the most volatile vitamins, meaning it is easily damaged (the molecule changes shape) or lost from foods during processing and cooking.
It is most commonly found in fresh fruit and vegetables, so when you are cooking try to steam your veg, as vitamin C can be lost into the cooking water when you boil vegetables.
Freezing fresh fruit and veg denatures the enzyme which breaks down vitamin C, so these will still contain a good amount of vitamin C.
Salt (also called sodium chloride) is added as a preservative and flavour enhancer. We do need a certain amount of sodium in our diet, but it is easy to have too much in our diet – mainly coming from salt. A diet high in salt has been associated with high blood pressure and a higher risk of heart attack and kidney disease. SACN (Scientific Advisory Committee on Nutrition) recommends that adults consume no more than 6g of salt per day. As a reference, a 30g packet of Lightly Salted Kettle Chips contains 0.3g of salt. Sometimes sodium is recorded on the back of packets. An easy way to convert this to grams of salt is to times grams of sodium by 2.5.
Mineral content of wheat
Milling wheat to produce flour removes the outer layer of the grain where a large amount of the iron, zinc and selenium content of the grain is found. However, phytate is also removed with this outer layer. Phytate is a storage molecule found in plants, but it can inhibit the absorption of some minerals – mainly iron, zinc and selenium. So, the overall amount of minerals that our bodies can absorb increases when wheat is milled.
Most commercial bread and breakfast cereals are also fortified with may minerals, so will contribute a good amount to your diet.
Calcium is another mineral that can be made more available by processing food. The bones of tinned fish can be eaten as they are soft. This is a very rich source of calcium.
Calcium is also added to many fortified dairy products and dairy free alternatives such as soya milk.