The wrong foods -- or the wrong amounts of the right foods -- can have a bad effect on mental performance and mood.

And with some foods, there's a trade-off. Caffeine, sugar and guarana, for example, can boost physical energy and even help your brain think more quickly and clearly. But if you go beyond your body's tolerance level, they can also make you irritable and nervous, with a post-boost crash as a bonus.

Balance is the Goal ...

... But the tricky bit is, every body is different. No two are affected exactly the same way by the same foods ... which is why it's important to chat with a health professional before making abrupt or severe changes in our diets.

We all need protein, carbohydrates and veggies in our diet. Usually a simple balance, perhaps supplemented by a multi-vitamin, will suffice. But when we're feeling out of whack (or just plain wacky), it might be time to focus on specific foods. Fresh is always best, and the less processing, the better.

Mild Depression: Moderate amounts of caffeine can provide temporary relief. A cup or two a day is usually fine. Slower, but more conducive to longer-term change over time, are foods packed with B-vitamins and folic acid. Beautiful B foods include whole grains, legumes (beans, peas and nuts), leafy greens, broccoli, artichokes and eggs. Spinach, orange juice and liver are great sources of folic acid. Selenium-rich foods, like seafood and shellfish, fresh red meats, Brazil nuts and sunflower seeds can also provide a lift.

Stress Relief: Carbohydrates boost serotonin levels, which can benefit mood and reduce distractability. Whole-grain foods and fruits are best. Turkey and lettuce contain tryptophan, which can provide a mild mellow-out.

Memory & Concentration: There's a lot of truth in the old "fish is brain food" tale. People who eat fish at least once a week may not only feel better quickly, but they may forestall, or at least minimize, memory loss as they age. Similar benefits can be found with:

• cruciferous vegetables (cabbage-like veggies such as broccoli, cauliflower, Brussels sprouts and, well, cabbage)
• leafy vegetables like spinach, kale and collard greens
• red fruits and veggies such as berries (straw-, black-, blue- or rasp-), cherries, red apples (with peel), currants and red onions
• eggs

Alertness: Protein provides an energy boost (can't be, like, alert and stuff if you're dragging). Meats/fish, dairy products and eggs are the best-known sources of protein, but legumes and whole grains are also protein-rich. Tea is also helpful for maintaining alertness with few, if any, jitters.

Please ignore my personal food pyramid. I'm in the middle of remodeling it, anyway. Just a light remodel, though -- radical rebuilds make me awful cranky.

Here's to fresher food and happier heads for all of us!