PORTLAND -- If you’re sick of getting sick, you may just need to change your diet. Some experts say by bulking up on nine immunity-boosting foods, you can help ward off colds and flus.

Amrit Khalsa likes to top off her shopping cart with a rainbow of fruits and vegatables.

“I suppose you could call me a health nut,” Khalsa said.

But this health nut says she used to get sick quite a lot. It was at age 19, living in New York City, when she had a wakeup call.

“It was Christmas Eve and I basically passed out on the escalator,” she said.

Now, Khalsa eats for optimum health. She feasts on foods that boost her immune system and keep her well.

“I notice the change it my health when I’m not eating like this,” Khalsa said.

Experts say you can do the same.

Kaiser Permanente Registered Dietician Janet Muckridge explained that by eating lots of fruits and vegetables, you can avoid getting sick. But she said there are nine foods that will help keep your immune system especially strong.

First, she said the live active cultures found in yogurt can help keep your gut free of disease-causing germs.

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“The probiotic benefits that come from yogurt has an effect on the digestive system which is where we get our immune enhancement from,” Muckridge said.

Fish and shellfish, namely oysters, lobster, salmon, tuna, crabs and clams, have high levels of selenium and omega-three fatty acids, which also help keep colds and flus at bay.

Add a few mushrooms to your meal, throw in some oats and barley, and you've increased your intake of antioxidants.

“The antioxitants help prevent cells from getting damaged,” Muckridge said.

Garlic and tea have been long thought to fight infection. Their benefits are becoming more and more apparent. Muckridge said black tea is best, but warns against too much caffeine.

And here's one that may surprise you -- beef! It's high levels of zinc helps development of white blood cells, which attack viruses and bacteria. Muckridge said if you don't eat meat, there are alternatives.

“A lot of cereals are fortified with zinc,” she said. “Also yogurt and milk are a good source.”

Sweet potatoes are next. They’re a great source of vitamin A, which helps in disease prevention.

Then there's the old tried and true chicken noodle soup. Mom was right. It can snuff out those sniffles.

“They believe that the salt content may help reduce mucous,” Muckridge said. “So that’s why you feel like you have some relief with symptoms.”

Khalsa said the key is shopping the perimeter of the grocery store. That’s where she finds fresh, whole foods that keep her out of the doctor's office and in great health.

“They’re clean for my body its clean fuel,” Khalsa said. “I’m not clogging it down with a lot of processed foods. So I operate more smoothly.”