Here's another reason to embrace a diet rich in fruit and vegetables: the nutrients in them can help keep away the negative effects of air pollution.

A study conducted on 209 patients in London between the years of 2008 and 2010, who were admitted into an area hospital due to COPD (Chronic obstructive pulmonary disease) or asthma, found that they were more likely to be hospitalized for issues related to the air pollution if their bodies were low in Vitamin C.

All had an increased risk of breathing problems if air pollution was high. European standards for air pollution are the same as the ones that The U.S. Environmental Protection Agency has set, at 50 micrograms per cubic meter of coarse particulate matter. Pollutants made up out of coarse particle matter have a diameter that is usually a fifth of the diameter of a human hair.

Researchers believe that Vitamin C alleviates the effects of air pollutants because of its antioxidant properties. Antioxidants protect the body from dangerous molecules called free radicals that damage cells. Research has indicated that free radicals may play a role in the development of heart disease, cancer, and respiratory diseases.

Cristina Casonova and her colleagues at the Imperial College London studied the levels of Vitamin C and other vitamins and genes, and the role they played in the development of asthma and COPD. Most of the patients were 54 to 74, although some participants were as young as 18. Many patients were former smokers.

They found that, for every 10 mcg/m3, the risk of hospitalization for breathing-related issues increased 35 percent for people with COPD or asthma. For those who had low levels of Vitamin C, that number was increased by 1.2 times. That correlation held true even when researchers excluded the elderly and former smokers in their analysis, though they did find that former smokers tended to have lower levels of Vitamin C than non-smokers.

Car exhaust and power plants are sources of particulate matter.

Citrus fruits, broccoli, and spinach, for example, are good sources of Vitamin C.

Researchers are unclear yet as to whether the link between Vitamin C and respiratory diseases exists for people without these diseases.

The study is published in journal Epidemiology.