You're running out the door to meet a client for a lunch, but your mind is back at the office, where duties and documents are piling up. Fear not. Science has the scoop on what to order for maximum productivity when you get back to work.

Here are seven foods commonly found on the menu, and why your brain will thank you for ordering them.

1. Spinach

Whether it's steamed, sautéed, or in a salad, spinach will help you remember facts and figures for that late-afternoon strategy session when your mind begins to go mushy.

Research shows the lutein, folate and B vitamins in spinach can improve mental alertness and memory. And the antioxidants in spinach act as bodyguards for your brain, protecting them from free-radical damage that can cause memory loss and cognitive decline.

"So you'd do yourself a favor in both the short and long term," says Sarah Jacobs, health coach and co-founder of The Wellness Project NYC, "to order the spinach and beet salad at lunch."

Which brings us to the next brain-boosting menu item:

2. Beets

The natural nitrates in this root vegetable actually boost blood flow to your brain, according to researchers at Wake Forest University. This not only enhances mental performance, it also increases energy, to help you avoid that mid-afternoon slump.

"Beets are great brain food," says Shauna Goodwin of Boston Health Coaches. She points out that the flavonoids responsible for increasing your energy levels can also lift your mood.

3. Olive oil

Olive oil is a key component of the Mediterranean diet, known to boost longevity and immunity. This healthy fat is scientifically proven to help learning and memory. So it's a good choice for dipping your bread or drizzling on your salad if you want to be sure to retain information from that upcoming meeting.

Olive oil has high levels of vitamin K, which studies show can help your brain process information faster. It's also packed with polyphenols, which can actually reverse learning and memory deficits.

Studies show it can even protect the brain against Alzheimer's.

As a bonus, this memory-boosting oil also has high levels of cancer-fighting antioxidants.

4. Salmon

Want to be laser-focused this afternoon? Salmon has DHA and omega-3 fatty acids, which not only increase brain function and concentration, but also help "grow new brain cells and protect the ones we already have," says Jennie Fagen, a New York City health coach with a degree in brain and cognitive science.

Research shows eating salmon can improve memory and learning.

It's even a natural antidepressant, according to Jean Carper, author of Your Miracle Brain, who writes about fish oil "boosting brain levels of the feel-good neurotransmitter serotonin."

Carper also lists mackerel, herring, sardines and anchovies among other fish with "smart fats."

5. Tomatoes

With nearly 10,000 varieties of tomatoes worldwide, you're sure to find a favorite form of this famous fruit, which studies show can super-charge your mind by helping you learn and remember information.

Whether you choose them in salad, sauce or soup, tomatoes have high levels of lycopene, an antioxidant that helps fight free radicals. Those are the pesky chemicals that damage brain cells. So eating tomatoes can help prevent that damage, which in turn helps you think more logically and solve problems more constructively.

Have you noticed that tomatoes have a slight sweetness? According to Fagen, the health coach with the brain and cognitive science degree, eating tomatoes early in your meal is a great way to fulfill sugar cravings without spiking your blood sugar.

"When our blood sugar is stable," Fagen says, "we are able to think more clearly and make more constructive decisions."

6. Eggs

Your next business brunch can boost your brain function and make you more alert, if you go for the omelet, the scramble, or the benedict.

A Harvard Medical School publication calls eggs the "brain food that fends off cognitive decline." Packed with supportive antioxidants, eggs can also give you more energy and better concentration.

The yolks are especially beneficial for brain function, because of a nutrient called choline, which a recent study links to better performance on cognitive tests.

7. Dark chocolate

If you've saved room for dessert, science says dark chocolate can lift your mood and fuel your focus. That's because of powerful antioxidants called flavonoids, which improve memory, learning and decision making.

Dark chocolate also contains magnesium to help you de-stress, and a small amount of caffeine, to make you more alert.

So if you're looking to increase your focus, decrease your stress level, and satisfy your sweet tooth, go ahead and splurge on a dark chocolate dessert. Science supports it.