Snapping at your coworkers? Break for a lunch high in omega-3s. These polyunsaturated fatty acids are one of your best defenses against period-induced crankiness. There's an established link between people with depression and a low level of omega-3s, and a 2003 study in the journal Diabetes & Metabolism suggested that these fatty acids keep stress hormones like cortisol and adrenaline in check.
Best bet: Ask for your fish grilled and served with a side of iron-and-magnesium-rich spinach (a magnesium deficit can trigger migraines and make you feel zonked). Or order sushi made with wild salmon, mackerel or arctic char, all of which have high levels of omega-3s and low levels of potentially toxic mercury.