Fall favorites -- apples, cranberries, sweet potatoes -- are beneficial all year long, expert says.

(HealthDay)—Many cancer-fighting fruits and vegetables are at their nutritional peak in the fall, and it's a good time to incorporate them into your diet, a nutritional expert advises.

For example, research suggests that eating an apple a day really may keep the doctor away, by helping to prevent throat, mouth, lung and possibly , noted Stacy Kennedy, a senior nutritionist at the Dana-Farber Cancer Institute in Boston.

Apples contain a nutrient called quercetin, which protects the cell's DNA from damage that could lead to cancer.

"The key is to eat them raw and with the skin on. That's where many of the nutrients are found," Kennedy said in an institute news release.

Cranberries, another healthy fall favorite, are in season and at their nutritional peak now. Kennedy suggested stocking up on bags of cranberries and freezing them for use throughout the year, because there is evidence that the benzoic acid found in these berries may inhibit lung and , and some forms of leukemia.

Among the brightly colored fresh vegetables that are available at this time of year are beets, carrots and parsnips. Kennedy suggests serving generous portions of these.

"The brighter and richer the pigment, the higher the level of cancer-fighting nutrients," Kennedy said.

Dark, leafy vegetables such as kale, broccoli, cabbage and are also important, she pointed out. People who eat plenty of these vegetables have lower rates of lung, prostate and .

"Kale is a top choice because it's rich in phytonutrients called indoles, which stimulate liver detoxification and help fight cancer," Kennedy said.

Orange vegetables such as carrots, , squash and pumpkins are all packed with nutrients called carotenoids, which have been linked to the prevention of colon, prostate, breast and lung cancer, Kennedy said.

Color is key to finding cancer-fighting foods in any season, Kennedy added. "Eating a plant-based diet is the best way to help lower your risk of cancer all year long," she said.

More information: The U.S. National Cancer Institute has more about cancer prevention.