I don't think one needs a high level of scientific knowledge to look at and understand the basic information on food labels. You only have to look at values per 100g and compare that with other similar products.
So, using the example jess gave of Cheerios:
- calories per 100g = 378
- carbohydrates per 100g = 74g
- of which sugars per 100g = 21g
I happen to have some Jordans Country Crisp Chunky Nuts cereal in my cupboard, which I eat sometimes with an own brand fruit and fibre cereal. Jordans box has:
- calories per 100g = 477
- carbs = 58.7
- sugars = 18.8
So it's higher in calories but lower in carbs and sugar. Surely it doesn't take much food knowledge to know that it's probably the nuts that are providing the extra calories and accounting for the lower sugar content? The nuts also provide more fat, more protein, and more fibre. Better food value, in short.
You don't have to read the whole blurb to get a good idea from a food packet.
Another basic idea is the order in which ingredients are listed because the proportions are listed in descending order. So, for example from Jordans packet: wholegrain cereals, sugar, nuts and then a few peripherals. Compare with the Cheerios: wholegrain cereals, sugar, peripherals.
Food value-wise, not a lot of difference between them, then, except for the nuts.