Boost your immune system with this trick

A little bit of sunshine and a big bowl of fresh red grapes -- that's not just a recipe for a terrific early autumn snack.

It's also a recipe for good health and proper immune system function.

The vitamin D you get from sunlight is one of the most powerful nutrients around, while the resveratrol found in red grapes is an antioxidant known to fight the effects of aging.

Each on its own can give your immune system a lift. But this is a case where 1 + 1 equals more than two -- because new research shows how the two compounds go together like peanut butter and jelly when it comes to immune system support.

Together, they can actually enhance a critical immune system gene called cathelicidin antimicrobial peptide, or CAMP for short -- and it's a gene you need to fight disease, especially infection caused by bacteria.

Of the hundreds of compounds tested on the CAMP gene, the two that stood out for having this effect were vitamin D and a class of nutrients known as stilbenoids that includes the resveratrol I just mentioned as well as the pterostilbene found in blueberries.

You can of course get both by enjoying fresh fruit. But if you need more immune support -- or if berries and grapes aren't in season where you live -- you can get many of the same nutrients from an antioxidant supplement blend or resveratrol capsules.

And while sunshine is the best natural source of vitamin D, the very real threats of sunburn and skin cancer means you should limit your time outdoors (and use an all-natural sunscreen when you are exposed).

Supplements are a safe and inexpensive way to get the D you need for good health and immune system function without the risks of excess sunlight. Most people need between 2,000 IUs and 5,000 IUs per day.