Some foods to help combat stress are:

Oily fish like tuna or salmon have vitamins B6 & B12
Oranges, blueberries and other food high in Vitamin C
Almonds are high in vitamin B2 & E, magnesium & zinc
Milk is high in vitamins B2 & 12, calcium & protein
Beef is high in B vitamins, zinc & iron

High protein foods are good to help provided balanced energy levels
Antioxidants help flush the body of free radicals which are released when you are stressed

Green tea is the highest in anti-oxidants, and normal black tea is also a good source
Chicken & fish are great sources of protein, as well as milk
Starting your day with wholegrain cereal with milk is a great way to start a (mostly) stress free day
Eating smaller meals and a small snack in between will help keep stress at bay
Snacking on almonds, cheese and vegetable sticks and fruit like oranges will help keep you full between meals and avoid sugar filled snacks, as well as making it easier to eat smaller meals at breakfast, lunch & dinner

If you have trouble sleeping, having a small snack about half an hour before bed might help you sleep, as well as help with eating a smaller breakfast the next morning if you are used to a bigger breakfast than cereal.

Don't forget to aim for 5 serves of vegetables during the day to help get lots of good vitamins & minerals to help combat stress. Asparagus is great, and the darker green the vege, th higher in iron, and potatoes are a great source of protein. Try have each vegetable a different color, as the color of food indicates the sort of vitamins and minerals in it... Variety is the key!

Go easy on the sugar & caffeine - it promotes stress by raising sugar levels, which then fall once the caffeine or sugar runs out. And if you do drink it, stop in the early afternoon so it's out of your system by bedtime.

Ok, hope that helps with reducing stress and the impact it has on your body...