It's surprising how many people assume a rat lives on much the same diet as a rabbit or guinea pig, ie, completely vegetarian and rather bland. This is not true.

Rats, like us, are omnivores. They enjoy and require both meat and veg.
The best idea if you wish to provide your rats with top quality nutrition is to make your own mix. A lot of people use The Shunamite Diet. This is fairly easy to make yourself, and most of the ingredients should be possible to find near you. This is by far the best diet I've come across and I would recommend it to all rat owners.

The bulk of my rats diet is fresh food, and I noticed a dramatic improvement in their condition as soon as I began to offer more fresh and less commercial rat food. In the wild, rats would not live on factory made pellets, they would eat a huge variety of foods like eggs, berries, nuts, carrion and human-left overs. Im a firm believer that whats natural is whats best, so my rats get as close to a natural diet as I can provide. Rats relish table scraps and theres not much they wont eat. They love potato, pasta, porridge, and chicken. It is not considered fair to keep a rat on a vegetarian diet since in order to be in top condition they require amino acids which can only be found in meat. It is especially important that babies and nursing mothers are not forced to live on a vegetarian diet. Adult rats can survive on a vegetarian diet, but they get no real benefits from it and I personally feel it is unfair to force a rat to eat a diet which is unnatural to it.

Rats should not be given peppers, onions, or anything too spicey or hot, though they are partial to mildly spicey food. Oranges cause kidney problems in male rats so they are a definate no, as is orange juice, though they are supposedly fine for females. Personally, I would rather not take the chance. Also, don't give them fizzy drinks as they cannot burp and so it will give them a stomach ache.

Rats are much like us in their food preferences and like variety, they get very bored of eating the same bland mix every day, just as we would. Therefore I like to give my rats an interesting dinner every night. Basically, if I wouldn't be prepared to eat it myself, I don't expect my rats to. However, like us, rats tend to prefer the things which aren't as good for them. Rats adore chocolate, biscuits and chips but these should only be fed in moderation. A treat now and then is fine but just as you yourself wouldn't eat chocolate every day, your rat shouldn't either. However, Chocolate is not toxic to rats as it is to dogs; this is a myth. A little bit of chcolate can actually be benefical to sick rats with breathing problems as it can open up the airways.

Baby rats have slightly different dietry requirements to older rats. They need more protien which you can give with soya milk (porridge made from soya milk is always good) a small bite dog kibble with a protien content of about 20%, cat food (high-life foil tray cat food is good) and sunflower seeds. However, adult rats should not have too much protien as it can cause skin problems.

There is a very good book available called 'The Scuttling Gourmet' by Alison Campbell which goes into rat nutrition in great detail. It is a must have for all rat owners.

Rats love eating so be creative!