Getting smart on brain supplements requires a healthy dose of skepticism. Many supplements haven't been scientifically proven to improve brain health or have any real impact on cognitive performance.

There are, however, some supplements that doctors actually recommend for keeping your brain healthy. Just ask Dr. Tara Swart, a neuroscientist, medical doctor, and leadership coach who focuses on combining nutrition and neuroscience to help others achieve peak brain performance. The author of the recent book The Source: The Secrets of the Universe, the Science of the Brain, Swart also serves as the chief science officer at supplement company Heights.

Below, Swart cuts through the hype on six popular brain supplements and explains what's really worth taking.

1. Blueberry extract

Antioxidants help keep brain cells healthy, and blueberries are a great source. They also contain a group of flavonoids called anthocyanins that can help increase the brain's neuronal signaling abilities and glucose distribution. This helps with learning, concentration, and memory. Some studies suggest consuming up to 400mg of blueberries per day. "Most people aren't doing that, so a blueberry extract or powder in a supplement is good way to get that," Swart says.

2. Coconut oil

Research shows that coconut oil can boost cognitive performance, but its high levels of saturated fat mean it's not for everyone. Separately, because only people with genetics from countries where coconut trees naturally grow can metabolize some of the other oils found in coconut oil, it can be better to take a medium chain triglyceride (MCT) supplement, as MCT is the key ingredient in coconut oil when it comes to brain health. "It's MCT that you want," Swart says. "MCT oil is more effective in terms of the brain-boosting benefits and it doesn't have the problems of metabolizing."

3. Ginkgo biloba

Though Ginkgo biloba has been trusted to help improve memory in Chinese culture for centuries--and even led to clinical studies as a possible treatment for Alzheimer's--those claims were debunked. "There's a lot of folklore that it is very good for your memory, but that's actually been proved by modern science not to be correct," Swart says.

4. Magnesium

A crucial mineral for metabolic function, magnesium doesn't have a direct effect on the brain, but it is one of the few brain supplements Swart recommends everybody take. Why? For starters, up to 75 percent of people in the modern world don't get enough of it. What's more, when humans are stressed, our bodies use so much magnesium that we end up running on empty and doing damage to our brain. "You can't eat enough nuts, seeds, and leafy greens to replace magnesium when you're under severe stress, so you actually have to supplement it," Swart says. "Magnesium balances out stress levels that would have had a toxic effect on your brain."

5. Matcha

Studies suggest there's no better natural source of antioxidants than matcha green tea. Made from a green tea leaf powder that contains a type of antioxidant called epigallocatechin gallate (EGCG)--which is not found in other foods--matcha tea has 10 times the antioxidants of a cup of regular brewed green tea. Another ingredient found in matcha, L-theanine, can improve cognitive function, stimulate relaxation, and reduce anxiety. "If you're just dunking a bag of green tea into your mug for two minutes, that's not going to have the same effect as the ingredients that are in matcha," Swart says. 

6. Omega oils

Omega-3 fish oil contains docosahexaenoic acid (DHA), which is critical for the structure of the brain and found primarily in the frontal lobes. This area is important for memory, processing information, and emotions. Omega-3 fish oil also contains eicosapentaenoic acid (EPA), which augments the effects of DHA through its effects on overall health. One study found that taking an omega-3 supplement was linked to a 30 percent reduction in developing symptoms of depression, while a lack of DHA has been linked to memory problems and diseases including Alzheimer's and dementia. "DHA is particularly good for your brain and your eyes," Swart says.