Dark chocolate may give your brain a boost, studies suggest Here's a reason not to feel so guilty about your afternoon chocolate fix.

Here's a reason not to feel so guilty about indulging in your afternoon chocolate fix.

Dark chocolate may be giving your brain, immune system and eyes a real boost. This week, researchers brought out three new studies singing the praises of this delectable treat.

Scientists in one study allowed lucky volunteers to eat one dark chocolate bar, about 1.5 ounces, and then studied their brain waves with a machine called an E.E.G. Researchers found an increase in gamma waves 30 minutes after eating the chocolate.

"Gamma frequency is associated with neurosynchronization, in other words neuroplasticity.... It is the highest level of cognitive processing,” Dr. Lee Berk, the principal investigator of this study, explained. Neuroplasticity describes the brain’s ability to efficiently connect thoughts and ideas.

Scientists believe that gamma waves are a sign that your nerve cells are firing on all cylinders. They are able to talk to each other in a manner that leads to optimum learning and memory formation.

Immunity booster

In another study, Berk looked at how dark chocolate affects the immune system. Again, participants ate a dark chocolate bar, and scientists studied their blood work for the following week. They found an increase in anti-inflammatory markers as well as an increase in T cells, infection-fighting cells. These findings are overall “great for immunity,” according to Berk.

It's important to know that both of these studies were very small, with only 10 blessed participants. Not to mention, these results were presented at a scientific meeting, not published in a journal, which means they were not highly scrutinized, or “peer-reviewed,” before they were revealed.

A dark chocolate vision boost

But another study was published in JAMA Ophthalmology, a journal produced by the American Medical Association. In two different tests, they gave 30 participants two chocolate bars, both dark and milk chocolate, and conducted vision tests about two hours later. After eating dark chocolate, the participants had small improvements in their vision.

The most significant: improvement in contrast sensitivity, meaning your ability to tell the difference between objects in a low light or high-glare setting. In real life, contrast sensitivity comes into play when driving at night, for example.

It is unclear why dark chocolate affects vision; however, the authors think it has to do with the blood vessels in the eye. Cacao, the main ingredient in dark chocolate, has been shown to positively affect blood pressure and blood vessel function. This new research suggests that dark chocolate allows for more blood flow to back of the eye, therefore improving vision.

But make sure it's really dark -- 70 percent cacao

Before you gorge yourself on brownies and hot fudge sundaes in the name of science, all of these studies are very specific to dark chocolate.

Researchers used dark chocolate with 70 percent cacao, a recipe reserved for the darkest of dark chocolate. This usually means the chocolate tastes more bitter than sweet because only 30 percent of the candy bar is sugar and milk.

"It’s really not a candy," Berk said of the chocolate used in his study. "It’s the sugar that’s a candy, not the cacao.”

If your favorite chocolate bar only has 11 percent cacao, that means that 89 percent is likely sugar and fat. So read the label before you claim to eat chocolate in the name of your health.

Berk believes that dark chocolate has serious potential from a health perspective. In his future research, he wants to see if cacao's effects on the brain could help treat diseases like dementia and autism.

"Chocolate may be a medicinal product if appropriately studied," he added.

Laura Shopp, M.D. is a third-year pediatrics resident affiliated with Indiana University who works in the ABC News Medical Unit.