Citrus fruits ran improve blood circulation. In one study, scientists recruited women who suffered from cold weather sensitivity due to poor blood flow - women with chronically cold hands, feet, and toes - and placed them in a highly air-conditioned room. The women in the experimental group drank a solution containing real citrus phytonutrients, while another group (control) drank a placebo (an artificially flavored orange drink). The placebo drinkers grew colder and colder. Due to decreased blood flow, the temperature of the fingertips dropped almost 9 degrees Fahrenheit during the course of the study. Meanwhile, the fingertips of the women who drank real citrus fruits cooled less than half as fast, because their blood flow remained more stable. (The researchers also had both groups of women dip their hands in ice cold water and saw that the citrus drinkers recovered 50 percent faster than the control group.) So eating some oranges before snowboarding can help keep your fingers and toes from getting so cold. But while the warm digits are nice, the reduced risk of stroke associated with higher citrus intake is even better. Study.