To avoid developing a vitamin deficiency, you should get the recommended amount of vitamins. But there is little evidence that taking more gives you a mental boost.

That is, there is no evidence that taking “megadoses” of vitamins either slows intellectual decline or prevents dementia.

Certain vitamin deficiencies, if they are severe enough, can impair brain functioning. The best-known example is vitamin B12 deficiency. It can mimic dementia. Taking supplements or eating foods with added B vitamins prevents that problem.

It is true that vitamins are involved in brain health.

For example, vitamin D helps keep blood vessels healthy. Good blood flow ensures that brain cells get needed nutrients and oxygen.

Vitamin E is an antioxidant. It can counter the effect of so-called “free radicals.” Free radicals are molecules that can cause cell damage. Vitamin E may provide some protection against such damage in the brain.

Fortunately, it is not hard to get the vitamins you need.

Vitamin B6 is in fish and starchy vegetables. Vitamin B12 is in fish, meat, eggs and dairy products. Vitamin C is in many fruits and vegetables. Many foods and drinks in the U.S. contain extra vitamin D. Vitamin E is in nuts, seeds, and vegetable oils. Folate you’ll find in many foods, including leafy green vegetables, beans and grains.

So get what you need. But there is no evidence that supplements slow cognitive decline. They probably don’t prevent dementia. And they don’t make you smarter!

In fact, no vitamin supplement can substitute for a healthy diet. Healthy food provides vitamins, minerals and a host of other naturally occurring nutrients. Your brain needs all of them.

Are you concerned that your diet is not adequate? A daily multivitamin can ensure you get the recommended daily amounts. But for now, there is not enough evidence to recommend taking extra supplements to revitalize your brain.